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Hippophae rhamnoides (H. rhamnoides ) is the primary tree species known for its ecological and economic benefits in arid and semi-arid regions. Understanding the response of H. rhamnoides roots to drought stress is essential for promoting the development of varieties. One-year-old Yulu H. rhamnoides was utilized as the experimental material, and three water gradients were established: control (CK), moderate (T1) and severe (T2), over a period of 120 days. The phenotypic traits and physiological indies were assessed and analyzed, while the roots were subjected by RNA-Seq transcriptome and Tandem Mass Tags (TMT) proteome analysis. Drought stress significantly reduced the plant height, ground diameter, root biomass and superoxide dismutase activity; however, the main root length increased. In comparison with CK, a total of 5789 and 5594 differential genes, as well as 63 and 1012 differential proteins, were identified in T1 and T2, respectively. The combined analysis of transcriptome and proteome showed that the number of differentially expressed genes (DEGs) and differentially expressed proteins (DEPs) associated with T1, T2 and CK was 28 and 126, respectively, with 7 and 36 genes achieving effective KEGG annotation. In T1 and T2, the differential genes were significantly enriched in the plant hormone signal transduction pathway, but there was no significant enrichment in the protein expression profile. In T2, 38 plant hormone signal transduction function genes and 10 peroxisome related genes were identified. With the increase of drought stress, the combined expression of DEGs and DEPs increased. Yulu H. rhamnoides may allocate more resources toward CAT while simultaneously decreasing SOD and POD to mitigate the oxidative stress induced by drought. Furthermore, the molecular mechanisms underlying plant hormone signal transduction and peroxisome-related genes in the roots of H. rhamnoides were discussed in greater detail.

The potential of rhizobacteria with plant growth promoting (PGP) traits in alleviating abiotic stresses, especially drought, is significant. However, their exploitation in the semi-arid regions of Ethiopian soils remains largely unexplored. This research aimed to isolate and evaluate the PGP potential of bacterial isolates collected from groundnut cultivation areas in Ethiopia. Multiple traits were assessed, including phosphate solubilization, indole-3-acetic acid (IAA) production, ammonia production, salt and heavy metal tolerance, drought tolerance, enzyme activities, hydrogen cyanide production, antibiotic resistance, and antagonistic activity against fungal pathogens. The identification of potent isolates was carried out using MALDI-TOF MS. Out of the 82 isolates, 63 were gram-negative and 19 were gram-positive. Among them, 19 isolates exhibited phosphate solubilization, with AAURB 34 demonstrating the highest efficiency, followed by AURB 12. Fifty-six isolates produce IAA in varying amounts and all isolates produce ammonia with AAURB12, AAURB19, and AAURB34 displaying strong production. Most isolates demonstrated tolerance to temperatures up to 40°C and salt concentrations up to 3%. Notably, AAURB12 and AAURB34 exhibited remarkable drought tolerance at an osmotic potential of -2.70 Mpa. When subjected to levels above 40%, the tested isolates moderately produced lytic enzymes and hydrogen cyanide. The isolates displayed resistance to antibiotics, except gentamicin, and all isolates demonstrated resistance to zinc, with 81-91% showing resistance to other heavy metals. AAURB34 and AAURB12 exhibited suppression against fungal pathogens, with percent inhibition of 38% and 46%, respectively. Using MALDI-TOF MS, the promising PGP isolates were identified as Bacillus megaterium, Bacillus pumilus, and Enterobacter asburiae. This study provides valuable insights into the potential of rhizobacteria as PGP agents for mitigating abiotic stresses and contribute to the understanding of sustainable agricultural practices in Ethiopia and similar regions facing comparable challenges.

Cerium dioxide nanoparticles (CeO 2 NPs) have enzyme-like properties and scavenge excess ROS induced by stressors such as drought. However, the underlying molecular mechanisms by which CeO 2 NPs enhance drought resistance are unknown. In this work, both foliar application and soil injection of CeO 2 NPs were used to rice seedlings under a 30 day moderate drought (40% soil relative moisture). Foliar application of 4 mg of CeO 2 NPs per pot reduced excess reactive oxygen species and abscisic acid (ABA) in rice leaves, thereby maintaining chloroplast structural integrity and photosynthetic output, ultimately increasing drought-stressed rice biomass by 31.3%. Genes associated with photosynthesis and ribosome activity provided the foundation by which CeO 2 NPs enhanced rice drought resistance. Importantly, these genes were tightly regulated by ABA due to the large number of abscisic acid responsive elements in their promoter regions. CeO 2 NPs also upregulated the expression of soluble sugar and fatty acid synthesis associated genes in drought-stressed rice, thereby contributing to osmotic balance and membrane lipid stability. These results highlight the potential of CeO 2 NPs to enhance rice photosynthesis and drought-resistant biomolecule accumulation by regulating ABA-dependent responses. This work provides further evidence demonstrating nanomaterials have great potential to sustainably promote stress resistance and climate resilient crops.

Drylands are home to over 38 % of the world's population and are among the areas most sensitive to climate change and human activity. Most xerophytes rely on arbuscular mycorrhizal fungi (AMF) for improved drought tolerance. Although research has focused on crops and economically significant plants, the response of sand-fixation shrubs to AMF under drought conditions remains underexplored. This study aims to investigate how AMF affects the drought adaptation strategies of the sand-fixation shrub Artemisia ordosica. A culture system for A. ordosica and the main symbiotic partner Funneliformis mosseae was established, and phenotypic, metabolomic, and transcriptomic analyses were conducted to assess physiological changes induced by arbuscular mycorrhizal symbiosis (AMS) under varying drought stress conditions. AMS influenced A. ordosica's metabolic pathways and its drought adaptation strategies, promoted the redistribution of sugars and flavonoids, and shaped different metabolic patterns of seedlings and adult A. ordosica. AMS had an important shaping ability in the accumulation of proline at A. ordosica seedlings, but had a significant influence on the accumulation of sugars of A. ordosica at the adult growth stage. AMS enhanced the ability of the host to adapt to extreme drought by modulating metabolites at the adult growth stage of A. ordosica. AMS also facilitated an accumulation of key metabolites under well-watered conditions but also intensified interactions with pathogens, leading to a trade-off between drought adaptation and immune capacity under extreme drought of A. ordosica during the adult growth stage. This study uses metabolome and transcriptome methods to explore AMS effects on A. ordosica's drought adaptation strategies, revealing a significant trade-off between drought adaptation and immune capacity. The findings highlight AMS's role in modifying the drought adaptation strategies of A. ordosica in desert ecosystems, and enhance our understanding of key species for sand fixation and ecological restoration, and maintain ecological security., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Process-based soil-crop models are becoming increasingly important to estimate the effects of agricultural management practices and climate change impacts on soil organic carbon (C). Although work has been done on the effects of crop type and climate on the root:shoot (biomass) ratio, there is a gap in research on the effects of specific environmental or management conditions such as drought, temperature, nutrient limitation, elevated CO 2 or tillage on the root:shoot ratio and thus, atmospheric C sequestration. In this study, we quantified the effects of these factors on the root:shoot biomass ratio by reviewing the current literature, presented common simulation approaches and performed model simulations using different examples. Finally, we identified different research gaps with respect to the root:shoot ratio with the aim of better estimating and predicting atmospheric C sequestration. A predominantly positive response of the root:shoot ratio was observed in case of elevated CO 2 (~12 %), low soil N levels (~44 %), and drought (~14 %). Soil tillage did not affect root:shoot ratio of the major field crops but increased it by ~15 % in case of wheat. There are only few field studies on air temperature increase and the results vary widely (mean - 48 %). The responses of tested models to the mentioned effects root:shoot ratio were slightly positive in case of CO 2 elevation (0 to 2 %) and tillage (0 to 8 %), slightly to clearly positive in the case of drought and N limitation depending on the model (1 to 40 %), and very variable in case of the air temperature scenarios. Our study reveals large model uncertainty (especially on temperature effects), particularly for below ground processes that highlight knowledge gaps in simulating root:shoot ratio. We advocate for the need of more model-oriented specific experiments under abiotic stresses to help model improvement. Such research effort would enable more robust and reliable root:shoot ratio simulations., Competing Interests: Declaration of competing interest We confirm that neither the manuscript nor any parts of its content are currently under consideration or published in another journal. We disclose any financial and personal relationships with other people or organizations that could inappropriately influence (bias) their work., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

In recent years, the increase in extreme climates, such as persistent high temperatures and drought, has adversely affected the growth and development of fast-growing trees. Melatonin (MT) plays an important role in plant responses to biotic and abiotic stresses, yet there is a lack of research on the specific role of limiting enzyme genes for MT biosynthesis in fast-growing woody plants. In this study, we investigated the function of PtoASMT, a key rate-limiting enzyme encoding gene for MT biosynthesis, which can be induced by drought, salt, and the phytohormones ABA, SA and JA. Our results show that: (1) PtoASMT was widely expressed in all tissues of poplar, but was highly expressed in petioles, moderately expressed in roots, stems, shoots and young leaves, exhibiting a typical diurnal expression rhythm in leaves, with the encoded protein localized on chloroplasts; (2) the content of MT was significantly promoted in overexpressing PtoASMT transgenic poplar plants, but there were no obvious differences in their growth and development; (3) overexpressing PtoASMT plants exhibited stronger drought tolerance, accumulating less reactive oxygen species (ROS) under drought stress relative to wild-type plants, whereas knockout PtoASMT plants were more sensitive and accumulated more ROS; (4) overexpressing PtoASMT plants were more resistant to fungi Dothiorella gregaria than WT plants, while knockout plants showed higher sensitivity; meanwhile, the expression of disease resistance-related genes (PRs and JAZ10) was significantly altered. We conclude that PtoASMT enhances the resistance of poplar to drought and Dothiorella gregaria by mediating MT biosynthesis in poplar. These findings contribute to a better understanding the role of ASMT gene in MT accumulation and stress resistance in poplar., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Background: Accumulation of coumarins plays key roles in response to immune and abiotic stress in plants, but the genetic adaptation basis of controlling coumarins in perennial woody plants remain unclear., Results: We detected 792 SNPs within 334 genes that were significantly associated with the phenotypic variations of 15 single-metabolic traits and multiple comprehensive index, such as principal components (PCs) of coumarins metabolites. Expression quantitative trait locus mapping uncovered that 337 eQTLs associated with the expression levels of 132 associated genes. Selective sweep revealed 55 candidate genes have potential selective signature among three geographical populations, highlighting that the coumarins biosynthesis have been encountered forceful local adaptation. Furthermore, we constructed a genetic network of seven candidate genes that coordinately regulate coumarins biosynthesis, revealing the multiple regulatory patterns affecting coumarins accumulation in Populus tomentosa. Validation of candidate gene variations in a drought-tolerated population and DUF538 heterologous transformation experiments verified the function of candidate genes and their roles in adapting to the different geographical conditions in poplar., Conclusions: Our study uncovered the genetic regulation of the coumarins metabolic biosynthesis of Populus, and offered potential clues for drought-tolerance evaluation and regional improvement in woody plants., Competing Interests: Declarations. Ethics approval and consent to participate: We declare that we have provided consent to publish this article and have provided ethical approval for this submission. The manuscript constitutes an original research work and has never been submitted elsewhere, either completely, in part, or in another form for publication. Our research did not involve any human or animal subjects, material, or data. clinical trial number not applicable. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Macroscopic phenotypic changes in plants are frequently employed as a means of evaluating the biological response of plants to external environmental stresses. However, the lack of effective observational tools at the microscopic cellular level hinders the ability to fully comprehend the intricacies of this response. Herein, we developed a plasma membrane fluorescent dye with target-activated green emission complemented with conventional FM dyes, and established a four-dimensional (4D) imaging approach based on this dye for spatio-temporal monitoring of plasma membrane dynamics during cellular responses to external environmental stress. A green fluorescent dye, designated FMG-DBO, was constructed by modifying the bridged unit between the aniline donor and the pyridinium acceptor. Its green emission can be combined with that of conventional FM dyes, enabling high-resolution imaging of plant leaf cells containing chlorophyll. The anchoring ability of the dyes was enhanced by incorporating a rigid diaza[2.2.2]octane unit as an anti-permeability group. The long retention time of the FMG-DBO dye in the plasma membrane enables the tracking of three-dimensional dynamics of the plasma membrane of plant cells. Consequently, an FMG-DBO-based four-dimensional imaging approach was established to monitor dynamic changes of plant cells under external environmental stress at the cellular level. The biological responses of two different drought-tolerant rice root cells to drought stress were examined by this four-dimensional imaging approach. It was observed that the two types of rice root cells exhibited disparate responses to the drought environmen. This approach offers alternative cell-level visualization tools for evaluating the biological responses of plant cells under environmental stress., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The cytoplasm of most plant cells is connected by membrane-lined cell wall channels, the plasmodesmata (PD). Dynamic regulation of sugar, hormone, and protein diffusion through PD is essential for plant development and stress responses. Understanding this regulation requires knowledge of factors and mechanisms that control PD permeability through the modulation of callose levels in the cell wall around PD openings. We investigated PD regulation in leaf epidermal cells in relation to drought stress in Arabidopsis. PD-mediated cell wall permeability was decreased by drought stress and the hormone abscisic acid (ABA), and we tested how this related to several PD-associated genes with drought-responsive expression. Mutants of NON-RACE SPECIFIC DISEASE RESISTANCE/HIN1 HAIRPIN-INDUCED-LIKE 12 (NHL12) showed relatively low PD permeability that was unaffected by drought or ABA treatment. Overexpression of NHL12 in Nicotiana benthamiana epidermal cells increased PD permeability. Moreover, we showed that NHL12 can potentially interact with the callose synthase regulator NHL3 and we explored the effect of NHL12 abundance and/or lower interface permeability on ABA signaling genes. Our results indicate that NHL12 is a drought-responsive negative regulator of PD callose levels and, thereby, interface permeability. Results are discussed in relation to PD function during drought stress and the regulation of intercellular transport., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Society for Experimental Biology.)

Drought is a serious problem that impacts sugarcane production and productivity worldwide. In this current investigation, a codon-optimized choline oxidase ( codA ) gene was transformed into Saccharum hybrid cultivar Co 86032 through Agrobacterium -mediated transformation. The transgenic events with the codA gene driven by the portubi882 (PD2) promoter accumulated elevated levels of glycine betaine (5 - 10µg/g) whereas untransformed control plants accumulated less than 1.5µg/g which in turn maintained the plant health by sustaining transpiration rate (4 - 5 µmol of H 2 O/cm 2 /s) and photosynthetic efficiency (30 - 34 µmol/Co 2 /s) whereas the control plants suffered from 50% reduction under water-deficit stress condition. Morpho-anatomic cross-sections of both transgenic events and control plants exhibited significant differences in the epidermal layer and sclerenchyma cells under stress conditions. The relative water content (71 - 76%) and chlorophyll fluorescence (0.60 - 0.72 Fv/Fm) were higher in transgenic events compared to control plants respectively recorded 59% and 0.50 respectively. In addition, significantly elevated activity of antioxidant enzymes viz., superoxide dismutase (95 - 102 U/g), catalase (65 - 73 umol/min/g), ascorbate peroxidase (1700 - 1900 umol/min/mg) and glutathione reductase (17 - 20 umol/min/mg) were observed in transgenic events along with reduced levels of hydrogen peroxide (14 - 16 µmol/g) and malondialdehyde (14 - 17 nmol/g) content. Transgenic events recorded significantly higher arial biomass content compared to untransformed plant after the drought stress. Overall, the increased expression levels of codA gene in sugarcane events resulted in an enhanced ability to withstand water-deficit conditions., Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-024-04151-y., Competing Interests: Conflict of interestThe authors have declared that no conflict of interests exist., (© King Abdulaziz City for Science and Technology 2024. Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.)

Different practical approaches have been employed to attenuate the destructive impacts of water deficit stress on plants, such as utilization of humic acid, salicylic acid, algae extract, mulching, and microorganisms, as well as silicon application. Nanosilicon significantly moderates the ruinous effects of abiotic and biotic stress in plants through some physiological processes. In this study, the interaction effect of drought stress and nanosilicon on phytochemical and physiological characteristics of hemp (Cannabis sativa L.) was investigated, wherein the four-week-old seedlings were subjected to irrigation treatments at four levels, including 100% (control), 80% (mild stress), 60% (moderate stress), and 40% (severe stress) of field capacity and nanosilicon at three concentrations (0, 0.5, and 1.5 mM) was foliar applied every 10 days in a factorial completely randomized design experiment with three replications for 30 days. Phytochemical and physiological analyses such as photosynthetic pigments, total phenolic and flavonoid content, and antioxidant enzyme activities were conducted. The results indicated that the highest content of Cannabidiol and Tetrahydrocannabinol was achieved using 1.5 mM (1.89%) and 0.5 mM (0.63%) nanosilicon treatments, respectively, under moderate stress. The plants subjected to severe drought stress without nanosilicon application displayed the lowest values of chlorophyll a (0.50 mg/g FW) and b (0.20 mg/g FW). The use of nanosilicon excited the activation of antioxidant enzymes, wherein the plants treated with nanosilicon and drought stress exhibited significantly higher SOD, POD, and APX activities compared to the control. Under all drought stress levels, foliar application of nanosilicon at the highest concentration decreased proline content. The results proposed that the application of 1.5 mM nanosilicon, as a more efficient concentration, improved drought tolerance in hemp plants., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

Hibiscus mutabilis, commonly known as the cotton rose, is a widely cultivated ornamental and has been acclaimed as the representative flower of the 2024 World Horticultural Exposition. The growth and ornamental characteristics of Hibiscus mutabilis can be affected by drought stress. Therefore, we investigated the physiological and metabolic responses of drought-sensitive Hibiscus mutabilis JRX-1 and drought-tolerant Hibiscus mutabilis CDS-4 under drought stress. The results of the physiological analyses revealed that, compared to JRX-1,CDS-4 maintained good growth and greater water use efficiency through stronger antioxidant defences, osmoregulatory capacity and stomatal regulation. A total of 3277 metabolites were identified in positive and negative ion modes, of which 663 metabolites presented changes in expression under drought conditions, including 306 upregulated metabolites and 357 downregulated metabolites. Secondary metabolites, such as flavonoids and diterpenoids, are crucial in the plant response to drought stress. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that the differentially aboundant metabolites were significantly enriched in the pathways valine, leucine and isoleucine degradation; linoleic acid metabolism; one carbon pool by folate; and folate biosynthesis. The results of this study will not only help to elucidate and apply the physiological and metabolic regulatory strategies of Hibiscus mutabilis to improve its adaptation to water deficit conditions, but will also provide valuable guidance to breeders and molecular biologists in the screening and use of drought resistant genes in ornamental plants., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

Drought stress is a common hazard faced by sugarcane growth, and utilizing microorganisms to enhance plant tolerance to abiotic stress has become an important method for sustainable agricultural development. Several studies have demonstrated that Streptomyces chartreuses WZS021 improves sugarcane tolerance to drought stress. However, the molecular mechanisms underlying tolerance at the transcriptional and metabolomic levels remain unclear. We comprehensively evaluated the physiological and molecular mechanisms by which WZS021 enhances drought tolerance in sugarcane, by performing transcriptome sequencing and non-targeted metabolomics; and examining rhizosphere soil properties and plant tissue antioxidant capacity. WZS021 inoculation improved the rhizosphere nutritional environment (AP, ammonia, OM) of sugarcane and enhanced the antioxidant capacity of plant roots, stems, and leaves (POD, SOD, CAT). Comprehensive analyses of the transcriptome and metabolome revealed that WZS021 mainly affects plant drought tolerance through phenylalanine metabolism, plant hormone signal transduction, and flavonoid biosynthesis pathways. The drought tolerance signaling molecules mediated by WZS021 include petunidin, salicylic acid, α-Linoleic acid, auxin, geranylgeraniol and phenylalanine, as well as key genes related to plant hormone signaling transduction (YUCCA, amiE, AUX, CYPs, PAL, etc.). Interestingly, inoculation with WZS021 during regular watering induces a transcriptome-level response to biological stress in sugarcane plants. This study further elucidates a WZS021-dependent rhizosphere-mediated regulatory mechanism for improving sugarcane drought tolerance, providing a theoretical basis for increasing sugarcane production capacity., Competing Interests: Declaration of competing interest All authors declare that there is no conflict of interest., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

Drought stress mitigation by endophytic microorganisms has the potential to enhance crop resilience. This research investigated the effects of M. anisopliae isolate MetA1 (MA) on drought tolerance in wheat plants by evaluating physiological, morphological, biochemical, and yield characteristics of two wheat genotypes, one being drought-susceptible (BR20) and another having drought withstanding capacities (BR28) in a pot experiment under moderate and severe drought conditions. Under drought conditions, root colonization by M. anisopliae ranged from 33.33 to 66.67%. M. anisopliae treated plants increased the plant photosynthetic capacities by increasing photosynthetic pigments, Phi2, gH + , vH + , LEF, ECSt, leaf thickness and decreasing PhiNO, PhiNPQ, NPQt and leaf angle mostly for both genotypes, which contributed significant improvement of plant biomass in drought conditions. Exceptionally, the seed primed with M. anisopliae noticeably improved root length (by up to 17.6%) under drought conditions corroborated with the plant's drought mitigating approach. The stress induced malondialdehyde and hydrogen peroxide levels were dropped significantly by improving enzymatic antioxidants, such as peroxidase, ascorbate peroxidase, superoxide dismutase, catalase, and glutathione S-transferase in both M. anisopliae -primed genotypes. Also, proline content increased in the leaves of M. anisopliae treated plant which indicates better osmotic adjustment. Finally, M. anisopliae seed priming increased yield and yield characteristics of both genotypes in drought as well as non-drought situations with 1000-grain weight improving by up to 41.77% under severe drought. The study proposes a further investigation of M. anisopliae's effect in field settings and its applicability to other crops. Collectively, these findings emphasize the practical potential of M. anisopliae seed priming in boosting wheat production under water-limited circumstances, presenting a realistic technique for minimizing the effect of drought on global food security., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Shah Mohammad Naimul Islam reports equipment, drugs, or supplies was provided by Bangabandhu Sheikh Mujibur Rahman Agricultural University. Shah Mohammad Naimul Islam reports a relationship with Bangabandhu Sheikh Mujibur Rahman Agricultural University that includes: employment. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

Drought is a global issue that has increasingly garnered worldwide attention. Glucosinolates (GSLs) are significant sulfur-containing compounds in cruciferous plants such as pakchoi (Brassica rapa L. ssp. chinensis), and their primary biological functions are exerted through their hydrolysis products. Allyl isothiocyanate (AITC), which is one of the degradation products of GSL, plays a crucial role in plants' response to environmental stresses. To date, the drought-resistant mechanism of AITC has not been fully explored. This study investigated the effects of spraying different concentrations of AITC solutions (1 mM and 10 mM) on the growth parameters, stomatal characteristics, antioxidant indices, and glucosinolate metabolism of pakchoi under drought stress, compared to a control group treated with distilled water. The results showed that under drought stress, AITC treatment significantly improved water retention and restored their growth by promoting stomatal closure and improving photosynthetic capacity in pakchoi; mitigated oxidative stress damage and augmenting the plant's water absorption by increasing the activities of antioxidant enzymes and the concentrations of osmoregulatory substances in pakchoi; the application of AITC restored the glucosinolate metabolism in pakchoi, inhibiting the downregulation of genes associated with GSL synthesis and the upregulation of genes related to degradation that is induced by drought stress, thereby maintaining the balance between GSLs and ITCs. In conclusion, AITC application alleviated the inhibition of pakchoi growth under drought stress by fostering stomatal closure, bolstering antioxidant defenses, and modulating glucosinolate metabolism., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

Drought is a major abiotic stresses that severely hinder plant growth and agricultural productivity. The receptor-like kinase gene, ERECTA, has been proved to play important role in promoting the response to abiotic stress in crops. However, the specific molecular mechanisms underlying the drought resistance mediated by ERECTA in potato (Solanum tuberosum L.) are not well understood. In this study, sequence analysis confirmed that the StERECTA gene contains eight leucine-rich repeat (LRR) domains and an S_TKc domain, and these domains were highly conserved in Solanaceae family. Under drought stress, Arabidopsis thaliana strains overexpressing StERECTA showed increased biomass, proline (PRO) content, and antioxidant enzyme activities compared to the wild-type strains while the mutant ERECTA strain (er105) exhibited opposite phenotype. Additionally, StERECTA overexpression upregulated the expression of drought response marker genes (LEA3, DREB2A and P5CS1), improved levels of ABA and auxin, reduced stomatal density and relative expression level of stomatal development related genes (SPCH, FAMA and MUTE). Furthermore, Co-immunoprecipitation (Co-IP) assays demonstrated that StERECTA physically interacted with the YODA protein. In conclusion, our study provides new insights into the role and regulatory mechanism of StERECTA in response to drought stress. These findings may serve as a basis for genetic improvement of potato to enhance their tolerance to abiotic stress., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier GmbH. All rights reserved.)

Microbial communities in desert riparian forest ecosystems have developed unique adaptive strategies to thrive in harsh habitats shaped by prolonged exposure to abiotic stressors. However, the influence of drought stress on the functional and metabolic characteristics of soil rhizosphere microorganisms remains unknown. Therefore, this study aimed to investigate the effects of drought stress on soil biogeochemistry and metabolism and analyze the relationship between the biogeochemical cycle processes and network of differentially-expressed metabolites. Using metagenomics and metabolomics, this study explored the microbial functional cycle and differential metabolic pathways within desert riparian forests. The predominant biogeochemical cycles in the study area were the Carbon and Nitrogen cycles, comprising 78.90 % of C, N, Phosphorus, Sulfur and Iron cycles. Drought led to increased soil C fixation, reduced C degradation and methane metabolism, weakened denitrification, and decreased N fixation. Furthermore, drought can disrupt iron homeostasis and reduce its absorption. The differential metabolic pathways of drought stress include flavonoid biosynthesis, arachidonic acid metabolism, steroid hormone biosynthesis, and starch and sucrose degradation. Network analysis of functional genes and metabolism revealed a pronounced competitive relationship between the C cycle and metabolic network, whereas the Fe cycle and metabolic network promoted each other, optimizing resource utilization. Partial least squares analysis revealed that drought hindered the expression and metabolic processes and functional genes, whereas the rhizosphere environment facilitated metabolic expression and the functional genes. The rhizosphere effect primarily promoted metabolic processes indirectly through soil enzyme activities. The integrated multi-omics analysis further revealed that the effects of drought and the rhizosphere play a predominant role in shaping soil functional potential and the accumulation of metabolites. These insights deepen our comprehension of desert riparian forest ecosystems and offer strong support for the functionality of nutrient cycling and metabolite dynamics., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

It is well-known that the mycorrhizal type of plants correlates with different modes of nutrient cycling and availability. However, the differences in drought tolerance between arbuscular mycorrhizal (AM) and ectomycorrhizal (EcM) plants remains poorly characterized. We synthesized a global dataset of four hydraulic traits associated with drought tolerance of 1457 woody species (1139 AM and 318 EcM species) at 308 field sites. We compared these traits between AM and EcM species, with evolutionary history (i.e. angiosperms vs gymnosperms), water availability (i.e. aridity index) and biomes considered as additional factors. Overall, we found that evolutionary history and biogeography influenced differences in hydraulic traits between mycorrhizal types. Specifically, we found that (1) AM angiosperms are less drought-tolerant than EcM angiosperms in wet regions or biomes, but AM gymnosperms are more drought-tolerant than EcM gymnosperms in dry regions or biomes, and (2) in both angiosperms and gymnosperms, variation in hydraulic traits as well as their sensitivity to water availability were higher in AM species than in EcM species. Our results suggest that global shifts in water availability (especially drought) may alter the biogeographic distribution and abundance of AM and EcM plants, with consequences for ecosystem element cycling and ultimately, the land carbon sink., (© 2024 The Author(s). New Phytologist © 2024 New Phytologist Foundation.)

The pharmacological properties of the dried root of Scutellaria baicalensis Georgi, a Chinese medicinal herb, include antioxidant, antibacterial, and antiviral effects. In S. baicalensis quality assessment, concentrations of baicalin, wogonoside, baicalein, and wogonin in the root are crucial. Drought stress commonly affects the biomass and build-up of active compounds in medicinal sections of medicinal plants and thus their quality. The molecular mechanisms underlying the response of S. baicalensis to drought stress remain unexplored. To delve into the impacts of drought stress on the growth and metabolic processes of S. baicalensis, as well as to unravel the underlying molecular mechanisms. We found prolonged and intensified drought treatment causes an initial surge in its fresh weight, plant height, and stem diameter followed by a gradual slowdown, while malondialdehyde (MDA) content rises; while the fresh weight, length, superoxide dismutase (SOD), and catalase (CAT) activities peak before declining, and the root's diameter continuously narrows. In this study, flavonoid index ingredient levels in S. baicalensis initially decreased, then rose as the drought duration extended, followed by a notable post-rehydration increase in baicalin, wogonoside, and baicalein content and decrease in levels of wogonin and oroxylin A. Transcriptome sequencing and KEGG analysis revealed a significant enrichment of DEGs involved in phenylpropanoid biosynthesis and plant hormone signal transduction pathways. The expression levels of SbPAL, SbCCL, Sb4CL, SbCHI, SbFNSII, SbF6H, and SbUGT genes in the flavonoid biosynthetic pathway and PYR/PYL, PP2C, ABF, and SnRK2 genes in the abscisic acid signal transduction pathway were significantly changed. Drought responsive SbWRKY34 was selected for the subsequent investigation. SbWRKY34 showed the highest level in stems, and the encoding protein was localized in the nucleus. Overexpression of SbWRKY34 in Arabidopsis thaliana (OE-SbWRKY34 lines) resulted in increased sensitivity to drought stress, with considerably reduced MDA content and elevated SOD and CAT activities. Concurrently, the expression levels of AtCAT3, AtDREB, AtRD22, AtRD29A, and AtRD29B were significantly reduced in these lines, suggesting that SbWRKY34 functions to negatively regulate drought resistance in A. thaliana., Competing Interests: Declaration of competing interest The authors declare no conflict of interest related to this study., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

As the only evergreen relict species in the desert environment of western China, Ammopiptanthus mongolicus (Leguminosae) roots is colonized with dark septate endophytes (DSE), but the potential of DSE to alleviate the adverse effects of drought on seedling roots remains uncertain. This study examined the effects of DSE on root growth, physiology and transcriptome of A. mongolicus under drought stress. Drought drastically reduced root biomass by 47.7%, while all DSE strains established positive symbiosis with A.mongolicus, with G.hyphopodioides having the most pronounced promoting effect. Inoculation with G. hyphopodioides alleviated drought stress injury by increasing CAT activity, AsA content and soluble sugar content in the roots, with a significant reduction in MDA accumulation by 97.7%. G. hyphopodioides also significantly increased zeatin and brassinosteroid contents, which in turn regulated the root structure and increased root activity, resulting in a 208.6% increase in root biomass. Transcriptome analysis screened 1246 differentially expressed genes (542 up-regulated and 704 down-regulated) between G. hyphopodioides inoculation under drought treatment, mainly associated with phenylpropanoid biosynthesis, ascorbic acid and aldehyde metabolism, hormone synthesis and signalling, sucrose and starch metabolism, and vitamin B6 metabolism, and further investigated and identified key potential genes and transcription factors (DREB, ERF, NAC, MYB, C2H2). These findings reveal the physiological and molecular mechanisms by which DSE symbiosis improves the drought resistance of A. mongolicus seedlings, providing valuable guidance on the use of DSE resources to promote ecological construction and production of desert plants., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Cinnamyl alcohol dehydrogenase (CAD) is a crucial enzyme in the final stage of lignin monomer biosynthesis. This study focuses on the CAD gene family within Gossypium hirsutum . Through comprehensive genomic analysis, we identified 29 GhiCAD genes within the Gossypium hirsutum genome using a bioinformatics approach. Phylogenetic analysis revealed that the GhiCAD family can be categorized into four subgroups, which are closest to the evolutionary relationship with Arabidopsis thaliana . There are multiple cis -acting elements on the promoters of GhiCAD genes associated with abiotic stress responses. Some GhiCAD genes demonstrated high expression in various tissues like root, leaf, and sepal, as well as in fiber and ovule at different developmental stages (10 days post anthesis (DPA), 15 DPA, 20 DPA, 25 DPA). The transcript levels of GhiCAD23 were notably elevated when exposed to PEG treatment and drought stress (DS). GhiCAD23 is also co-expressed with many known drought response genes, suggesting its involvement in the plant's reaction to DS. Employing virus-induced gene silencing (VIGS) technology to silence the GhiCAD23 gene, it was found that silencing GhiCAD23 reduced the tolerance of cotton to DS. Under DS, the relative leaf water content, superoxide dismutase (SOD), and catalase (CAT) enzyme activities of the GhiCAD23 -silenced cotton plants were decreased by 31.84%, 30.22% and 14.19%, respectively, while malondialdehyde (MDA) was increased by 72.16% compared with the control cohort. Drought promotes the accumulation of lignin, and it was found that silencing the GhiCAD23 reduces lignin accumulation in cotton under DS. The analysis of phenotypic and physiological indicators indicates that GhiCAD23 is vital in cotton's resistance to DS. This investigation provides an important reference for future comprehensive exploration of the GhiCAD23 gene's function in cotton's DS response mechanism., Competing Interests: The authors declare that they have no competing interests., (© 2024 Zhang et al.)

Strawberries (Fragaria x ananassa) are valued worldwide for their aroma among other quality traits. Pyruvate decarboxylase (PDC) is a key enzyme in aroma, initiating the conversion of pyruvate into acetaldehyde. This process produces precursors for esters and aromatic compounds that enhance strawberry aroma. Additionally, alcohol acyltransferases (AATs) are essential for catalyzing acyl group transfers, further enriching fruit aroma diversity. However, strawberries are highly vulnerable to drought, which affects product quality. Plant root-associated fungi offer a novel approach to mitigate water deficiency stress. This study investigates the effect of Antarctic fungal inoculation on the gene expression of FaPDC, and the FaAAT gene family, related to the accumulation of volatile organic compounds (VOCs) in strawberries. Fruits of fungi-inoculated plants under drought stress showed significant changes in gene expression, leading to increased total volatile ester production, primarily in acetate esters, which are important for strawberry aroma. These findings underscore the role of Antarctic fungi in modulating the metabolic pathway of volatile esters by inducing the expression of FaPDC and FaAAT genes. Beyond elucidating the molecular mechanisms underlying aromatic compound biosynthesis in fruits, this study highlights the potential of Antarctic microorganisms as valuable tools to restore and maintain the sensory attributes of agricultural products under water deficiency stress., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

Drought is the primary factor limiting rice production in ecosystems. Wild rice rhizosphere bacteria possess the potential to assist in the stress resistance of cultivated rice. This study examines the impact of wild rice rhizosphere bacteria on cultivated rice under drought conditions. From the rhizosphere soil of wild rice, 20 potential drought-resistant strains were isolated. Subsequent to the screening, the most effective strain b3, was identified as Enterobacter ludwigii. Pot experiments were conducted on the cultivated Changbai 9 rice. It was found that inoculation with the E. ludwigii b3 strain improved the drought resistance of the rice, promotion of rice growth (shoot height increased by 13.47 %), increased chlorophyll content (chlorophyll a, chlorophyll b and carotenoid increased by 168.74 %, 130.68 % and 87.89 %), improved antioxidant system (content of glutathione was increased by 60.35 %), and accumulation of osmotic regulation substances (soluble sugar and soluble protein increased by 70.36 % and 142.03 %). Furthermore, E. ludwigii b3 had a transformative effect on the rhizosphere bacterial community of cultivated rice, increasing its abundance and diversity while simultaneously recruiting beneficial rhizosphere bacteria, resulting in a more complex community. Additionally, E. ludwigii b3 acted directly and indirectly on cultivated rice through its metabolites (organic acids, amino acids, flavonoids and other substances), which helped alleviate drought stress. In conclusion, the E. ludwigii b3 shows promise as a drought-resistant strain and has the potential to improve the growth and productivity of cultivated rice in arid agricultural ecosystems. This study represents the first investigation of E. ludwigii in the rhizosphere of wild rice under drought conditions on cultivated rice., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Inc.)

While humic substances (HS) are recognized for their role in enhancing plant growth under abiotic stress by modulating hormonal and redox metabolisms, a key question remains: how do HS influence the microbiota associated with plants? This study hypothesizes that the effects of HS extend beyond plant physiology, impacting the plant-associated bacterial community. To explore this, we investigated the combined and individual impacts of HS and osmotic stress on tomato plant physiology and root endophytic communities. Tomatoes were grown within a sterile hydroponic system, which allowed the experiment to focus on seed-transmitted endophytic bacteria. Moreover, sequencing the 16S-ITS-23S region of the rrn operon (~4,500 bp) in a metabarcoding assay using the PNA-chr11 clamp nearly eliminated the reads assigned to Solanum lycopersicum and allowed the species-level identification of these communities. Our findings revealed that HS, osmotic stress, and their combined application induce changes in bacterial endophytic communities. Osmotic stress led to reduced plant growth and a decrease in Bradyrhizobium sp., while the application of HS under osmotic stress resulted in increased tomato growth, accompanied by an increase in Frigoribacterium sp., Roseateles sp., and Hymenobacter sp., along with a decrease in Sphingomonas sp. Finally, HS application under non-stress conditions did not affect plant growth but did alter the endophytic community, increasing Hymenobacter sp. and decreasing Sphingomonas sp. This study enhances the understanding of plant-endophyte interactions under stress and HS application, highlighting the significance of the vertically transmitted core microbiome in tomato roots and suggesting new insights into the mode of action of HS that was used as a biostimulant., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Lengrand, Dubois, Pesenti, Debode and Legrève.)

As a crucial forage grass, Leymus chinensis plays significant roles in soil and water conservation owing to its robust stress resistance. However, the underlying molecular mechanisms of its stress tolerance remain unclear. In this study, a novel gene, designated as LcASR (Abiotic Stress Resistance in Leymus chinensis), imparting resilience to both high light and drought, was identified. Under normal growth conditions, heterologous overexpression of LcASR in Arabidopsis (HO lines) showed no significant difference in appearance compared to wild-type. Nevertheless, HO lines accumulate significantly higher chlorophyll content during the dark-to-light transition compared to the wild-type, indicating that the LcASR protein participates in chlorophyll synthesis during chloroplast development. Meanwhile, transgenic Arabidopsis and L. chinensis plants exhibited resistance to abiotic stresses such as high light and drought. Photosystem complexes analysis revealed that LHCII proteins remained stable within their respective complexes during high light stress. We hypothesize that LcASR may play a role in fine tuning of chlorophyll synthesis to enable plant adaptation to diverse stress conditions. Moreover, overexpression of LcASR in L. chinensis led to agronomically valuable traits such as deeper green color, higher biomass accumulation, prolonged withering period, and extended grazing durations. This study uncovers a novel gene in L. chinensis that enhances forage yield and provides valuable genetic resources for sheepgrass breeding., (© 2024 Society for Experimental Biology and John Wiley & Sons Ltd.)

Phoebe species constitute a large portion of subtropical forestry, which are key players in biomass resources. However, abiotic stresses such as drought stress severely limit the growth and development of P. bournei, and even lead to its death. It has been shown that basic helix-loop-helix (bHLH) as the second largest transcription factor family plays essential roles in response to multiple stresses in plants. However, little information of bHLH family is available in P. bournei. In this study, 130 PbbHLHs were identified and classified into 24 subfamilies. Then, the bHLH domain, conserved motifs and gene structures, evolutionary patterns and protein structural features were probed. The expression levels of 17 PbbHLHs were differentially induced by PEG and ABA by RT-qPCR analysis, indicating that they may be involved in drought stress response. Characterization of the drought candidate gene PbbHLH74 showed that it was transcriptionally active and localized in the nucleus. Heterologous transformation of PbbHLH74 into yeast improved cellular tolerance to drought stress. Meanwhile, overexpression of PbbHLH74 in Arabidopsis showed higher seed germination, plant biomass and expression levels of stress-related genes under drought conditions. Through the hairy root technique, overexpression of PbbHLH74 in P. bournei improved drought tolerance by enhancing root development and expression levels of genes involved in ABA-dependent and ROS scavenging pathways. Moreover, PbbHLH74 might positively regulate the expression of PbPOD by Y1H and dual-luciferase reporter assays. Overall, these results elucidated the structure and evolution of the PbbHLH family, in which PbbHLH74 could be applied to molecular assisted breeding for drought tolerance in P. bournei., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Bacillus velezensis S141 helps soybean establish specific symbiosis with strains of Bradyrhizobium diazoefficiens to form larger nodules and improve nitrogen fixation efficiency. In this study, we found that the dry weight of soybean roots increased significantly in the presence of S141 alone under drought conditions. Hence, S141 improved the root growth of soybean under limited water supply conditions. S141 can produce some auxin, which might be involved in the improved nodulation. Inactivating IPyAD of S141, which is required for auxin biosynthesis, did not alter the beneficial effects of S141, suggesting that the root growth was independent of auxin produced by S141. Under drought conditions, soybean exhibited some responses to resist osmotic and oxidative stresses; however, S141 was relevant to none of these responses. Although the mechanism remains unclear, S141 might produce some substances that stimulate the root growth of soybean under drought conditions., (© The Author(s) 2024. Published by Oxford University Press on behalf of Japan Society for Bioscience, Biotechnology, and Agrochemistry.)

The impact of climate change on agricultural production is apparent due to declining irrigation water availability vis-à-vis rising drought stress, particularly affecting summer crops. Growing evidence suggests that zinc (Zn) supplementation may serve as a potential drought stress management strategy in agriculture. Field studies were conducted using soybean (Glycine max var. Saba) as a model crop to test whether foliar application of zinc oxide nanoparticles (ZnO-NPs) or conventional Zn fertilizer (ZnSO 4 ) would mitigate drought-related water stress and improve soybean yield. Each fertilizer was foliar applied twice at a two-week interval during the flowering stage. Experiments were concurrently conducted under non-drought conditions (70% field capacity) for comparison. Results showed drought significantly reduced relative water content, chlorophyll-a, and chlorophyll-b in untreated control plants by 35.7%, 47.7%, and 41.4%, respectively, compared to non-drought conditions (p < 0.05). Under drought conditions, ZnO-NPs (200 mg Zn/L) led to 33.1% and 20.7% increase in chlorophyll-a and chlorophyll-b levels, respectively, compared to ZnSO 4 at 400 mg Zn/L. Likewise, catalase, peroxidase and superoxide dismutase activities increased by 62.6%, 39.5% and 28.5%, respectively, with ZnO-NPs (200 mg Zn/L) under drought compared to non-drought conditions. Proline was significantly increased under drought but was remarkably suppressed (~ 54% lower) with ZnO-NPs (200 mg Zn/L) treatment. More importantly, the highest seed yield was observed with ZnO-NPs (200 mg Zn/L) treatment under drought (39% higher than untreated control) and non-drought (79.4% higher than control) conditions. Overall, the findings suggest that ZnO-NPs could promote seed yield in soybean under drought stress via increased antioxidant activities, increased relative water content, decreased stress-related proline content, and increased photosynthetic pigments. It is recommended that foliar application of 200 mg Zn/L as ZnO-NPs could serve as an effective drought stress management strategy to improve soybean yield., Competing Interests: Declarations Competing interests The authors declare no competing interests., (© 2024. The Author(s).)

Drought stress is a major threat leading to global plant and crop losses in the context of the climate change crisis. Brassinosteroids (BRs) are plant steroid hormones, and the BR signaling mechanism in plant development has been well elucidated. Nevertheless, the specific mechanisms of BR signaling in drought stress are still unclear. Here, we identify a novel Arabidopsis gene, BRZ INSENSITIVE LONG HYPOCOTYL 9 (BIL9), which promotes plant growth via BR signaling. Overexpression of BIL9 enhances drought and mannitol stress resistance and increases the expression of drought-responsive genes. BIL9 protein is induced by dehydration and interacts with the HD-Zip IV transcription factor HOMEODOMAIN GLABROUS 11 (HDG11), which is known to promote plant resistance to drought stress, in vitro and in vivo. BIL9 enhanced the transcriptional activity of HDG11 for drought-stress-resistant genes. BIL9 is a novel BR signaling factor that enhances both plant growth and plant drought resistance., (© The Author(s) 2024. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site–for further information please contact journals.permissions@oup.com.)

Early stress detection of crops requires a thorough understanding of the signals showing the very first symptoms of the alterations in the photosynthetic light reactions. Detection of the activation of the regulated heat dissipation mechanism is crucial to complement passively induced fluorescence to resolve ambuiguities in energy partitioning. Using leaf spectroscopy, we evaluated the capability of pigment spectral unmixing to calculate the fluorescence quantum efficiency (FQE) and simultaneously retrieve fast absorption changes in a drought and nitrogen deficiency experiment with tomato. In addition, active fluorescence measurements and pigment analyses of xanthophylls, carotenes and chlorophylls were conducted. We observed notable responses in noninvasive proximal sensing-retrieved FQE values under stress, but as expected, these alone were not enough to identify the constraints in photosynthetic efficiency. Reflectance-based detection of the 535-nm peak absorption change was able to complement FQE and indicate the activation of regulated heat dissipation for both stress treatments under growing light conditions. However, further complexity in the light harvesting energy regulation needs to be accounted for when considering additional light stress. Our results underscore the potential of complementary in vivo quantitative spectroscopy-based products in the early and nondestructive stress diagnosis of plants, marking the path for further applications., (© 2024 The Author(s). New Phytologist © 2024 New Phytologist Foundation.)

Competition in mesic sites and drought stress combined with short growing seasons in drier sites are key environmental factors along macroclimatic aridity gradients. They impose a triangular trade-off for local adaptation. However, as experiments have rarely disentangled their effects on plant fitness, uncertainty remained whether mesic populations are indeed better competitors and drier populations better adapted to drought stress and short season length. Aridity differs also at microclimatic scale between north (more mesic) and south (more arid) exposed hill-slopes. Little is known whether local adaptation occurs among exposures and whether south exposures harbor conspecifics better adapted to drier climates that could provide adaptive reservoirs under climate change. We sampled two Mediterranean annuals ( Brachypodium hybridum, Hedypnois rhagadioloides ) in 15 sites along a macroclimatic aridity gradient (89-926 mm rainfall) on corresponding north and south exposures. In a large greenhouse experiment, we measured their fitness under drought stress, competition, and short vs. long growing seasons. Along the macroclimatic gradient, mesic populations were better competitors under benign conditions. Drier populations performed no better under drought stress per se but coped better with the short growing seasons typical for drier macroclimates. At microclimatic scale, north exposure plants were slightly better competitors in H. rhagadioloides; in B. hybridum , south exposure plants coped better with drought under short season length. We demonstrate that local adaptation to drier macroclimates is trading-off with competitive ability under benign conditions and vice-versa. Drought escape via short life-cycles was the primary adaptation to drier macroclimates, suggesting that intensified drought stress within the growing season under climate change challenges arid and mesic populations alike. Moreover, the drier microclimates at south exposures exhibited some potential as nearby reservoirs of drier-adapted genotypes. This potential needs further investigation, yet may assist populations to persist under climate change and lessen the need for long-distance migration., Competing Interests: The authors declare no conflicts of interest., (© 2024 The Author(s). Ecology and Evolution published by John Wiley & Sons Ltd.)

When plants respond to drought stress, dynamic cellular changes occur, accompanied by alterations in gene expression, which often act through trans-regulation. However, the detection of trans-acting genetic variants and networks of genes is challenged by the large number of genes and markers. Using a tensor decomposition method, we identify trans-acting expression quantitative trait loci (trans-eQTLs) linked to gene modules, rather than individual genes, which were associated with maize drought response. Module-to-trait association analysis demonstrates that half of the modules were relevant to drought-related traits. Genome-wide association studies of the expression patterns of each module identify 286 trans-eQTLs linked to drought-responsive modules, the majority of which cannot be detected based on individual gene expression. Notably, the trans-eQTLs located in the regions selected during maize improvement tend towards relatively strong selection. We further prioritize the genes that affected the transcriptional regulation of multiple genes in trans, as exemplified by two transcription factor genes. Our analyses highlight that multidimensional reduction could facilitate the identification of trans-acting variations in gene expression in response to dynamic environments and serve as a promising technique for high-order data processing in future crop breeding., Competing Interests: Declaration of Competing Interest All authors declare no competing financial interests., (Copyright © 2024. Published by Elsevier Ltd.)

Drought is the most significant abiotic stress that impedes agroforestry development. In nature, drought tolerance also depends on the ability to compensate after water restoration. Dark septate endophytes (DSEs) are believed to enhance plant tolerance in drought environments. However, the compensatory mechanisms of DSEs for rehydration after drought stress have not been reported. To assess the drought tolerance and compensatory capacity of DSEs, the following DSEs were investigated in this study using solid-liquid screening and potting tests under different drought gradients, rehydration conditions, and field water-holding capacities: Stagonosporopsis lupini , Microsphaeropsis cytisi , Macrophomina pseudophaseolina , Paraphoma radicina , Alternaria alstroemeriae , Alternaria tellustris , and Papulaspora equi . The results showed that M. pseudophaseolina reached the maximum diameter for plate growth in only 4 d. In a liquid shaker, the biomass of S. lupini peaked after rehydration. The Mantel heatmap indicated that lipid metabolites were significantly expressed in M. pseudophaseolina and S. lupini under drought stress. Correlations between drought tolerance indexes and amino acid metabolites increased dramatically in both DSEs after rehydration. Moreover, in rehydration after drought, the treatments inoculated with M. pseudophaseolina and S. lupini showed significant increases in root weight of 20.36% and 23.82%, respectively, compared with the uninoculated treatment.

Introduction: Mitochondria are essential organelles in eukaryotic cells, producing ATP through the electron transport chain to supply energy for cellular activities. Beyond energy production, mitochondria play crucial roles in cellular signaling, stress responses, and the regulation of reactive oxygen species. In plants, mitochondria are one of the keys to responding to environmental stresses which can significantly affect crop productivity, particularly in crops like wheat. RNA editing, a post-transcriptional RNA modification process in mitochondria, is linked to regulating these stress responses., Methods: This study explores RNA editing patterns in the nad9 gene of wheat drought-tolerant (Giza168) and drought-sensitive (Gemmiza10) wheat cultivars under drought stress to understand plant adaptation mechanisms. RNA-seq data for these cultivars were analyzed using CLC Genomic Workbench to identify RNA editing sites in the nad9 gene, examining subsequent amino acid changes and predicting secondary structure modifications. These RNA editing sites were validated using qRT-PCR on drought-treated seedlings at 0, 2, and 12 hours post-treatment. Protein models were generated using AlphaFold, with functional predictions and structure verification conducted using various bioinformatics tools to investigate the effect of RNA editing on protein level., Results: The results showed significant RNA editing events, especially C-to-T conversions, in the nad9 gene across different drought exposure times. Giza168 had 22 editing sites, while Gemmiza10 had 19, with several showing significant differences between control and stress conditions. RNA editing influenced the NAD9 protein's secondary structure, particularly beta sheets, and 3D modeling highlighted the structural impacts of these edits. The N-terminal region of NAD9 contained important regulatory motifs, suggesting a complex regulatory environment., Discussion: This study reveals key editing sites that differ between drought-tolerant and sensitive wheat cultivars, impacting NAD9 protein structures and highlighting the role of RNA editing in enhancing drought resilience. Additionally, the study suggests potential regulatory mechanisms, including phosphorylation and ubiquitination that influence mitochondrial stability and function., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Mohamed, Ramadan, Amer, Morsy, Mohamed, Said, Alnufaei, Ibrahim, Hassanein and Eissa.)

Drought tolerance varies among different peanut ( Arachis hypogaea L.) cultivars. Here, drought responses of two cultivars, Huayu 22 (HY22) with drought tolerance and Fuhua 18 (FH18) with drought sensitivity, were compared at the morphological, physiological, biochemical, photosynthetic, and transcriptional levels. Drought stress caused wilting and curling of leaves, bending of stems, and water loss in both cultivars. There was an increase in malondialdehyde (MDA) content under prolonged drought stress, more so in FH18. But the levels of reactive oxygen species (H 2 O 2 ) and lipid peroxidation were low in HY22. The activities of superoxide dismutase (SOD), peroxidase (POD), and glutathione reductase (GR) were considerably elevated, corresponding with rapid increases in the accumulation of soluble proteins, soluble sugars, and proline. Transcriptional sequencing showed gene expression varied seriously in HY22, which was upregulated in both stems of two cultivars, though downregulation was less pronounced in HY22. KEGG pathway analysis revealed significant enrichment in four leaf and six stem pathways. Additionally, core genes relating to photosynthesis, carbon fixation, proline synthesis, and sucrose and starch synthesis pathways were identified by correlation analysis. Those gene expressions were variously upregulated in stems of two cultivars, especially in HY22, giving a novel view of the shoot as a whole participating in stress response.

The abscisic acid (ABA) signalling pathway plays a crucial role in plants' response to drought stress. In this study, we aimed to characterize the impact of an ABA signalling module, which consisted of TaPYL9 and its downstream partners in Triticum aestivum, on plant drought adaptation. Our results showed that TaPYL9 protein contains conserved motifs and targets plasma membrane and nucleus after being sorted by the endoplasmic reticulum. In addition, TaPYL9 transcripts in both roots and leaves were significantly upregulated in response to drought stress. We conducted glucuronidase (GUS) histochemical staining analysis for transgenic plants carrying a truncated TaPYL9 promoter, which suggested that cis-elements associate with ABA and drought response, such as ABRE, DRE and recognition sites MYB and MYC, regulating the gene transcription under drought conditions. Using protein interaction assays (i.e., yeast two-hybrid, bimolecular fluorescence complementation (BiFC), co-immunoprecipitation (Co-IP) and in vitro pull-down), we demonstrated interactions between the intermediate segment of TaPYL9, the intermediate segment of TaPP2C6, the N-terminus of TaSnRK2.8 and the C-terminus of the transcription factor TabZIP1 in wheat, indicating the involvement of TaPYL9 in the constitution of an ABA signalling module, namely TaPYL9/TaPP2C6/TaSnRK2.8/TabZIP1. Transgene analysis revealed that TaPYL9, TaSnRK2.8 and TabZIP1 positively regulated drought response, while TaPP2C6 negatively regulated it, and that these genes were closely associated with the regulation of stomata movement, osmolyte accumulation and ROS homeostasis. Electrophoretic mobility shift (EMSA) and transcriptioal activation assays indicated that TabZIP1 interacted promoters of TaP5CS2, TaSLAC1-1 and TaCAT2 and activated transcription of these genes, which regulated proline biosynthesis, stomata movement and ROS scavenging upon drought signalling, respectively. Furthermore, we found that the transcripts of TaPYL9 and stress-responsive genes were positively correlated with yields in wheat cultivars under field drought conditions. Altogether, our findings suggest that the TaPYL9-involved signalling pathway significantly regulates drought response by modulating osmotic stress-associated physiological processes in T. aestivum., (© 2024 The Author(s). Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.)

Nitrogen is a critical nutrient vital for crop growth. However, our current understanding of nitrogen use efficiency (NUE) under drought remains inadequate. To delve into the molecular mechanisms underlying NUE under drought, a transcriptome and physiological co-expression analysis was performed in rice, which is particularly sensitive to drought. We conducted a pot experiment using rice grown under normal irrigation, mild drought stress, and severe drought stress. Compared to the normal treatment, drought stress led to a significant reduction in NUE across growth stages, with decreases ranging from 2.18% to 31.67%. Totals of 4,424 and 2,452 genes were identified as NUE-related DEGs that showed differential expressions (DEGs) and significantly correlated with NUE (NUE-related) under drought in the vegetative and reproductive stages, respectively. Interestingly, five genes involved in nitrogen metabolism were found in the overlapped genes of these two sets. Furthermore, the two sets of NUE-related DEGs were enriched in glyoxylate and dicarboxylate metabolism, as well as carbon fixation in photosynthetic organisms. Several genes in these two pathways were identified as hub genes in the two sets of NUE-related DEGs. This study offers new insights into the molecular mechanism of rice NUE under drought in agricultural practices and provides potential genes for breeding drought-resistant crops with high NUE., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Wang, Zhang, Qiao, Zheng, Hou and Shi.)

Background: Cotton serves as a primary source of natural fibers crucial for the textile industry. However, environmental elements such as drought have posed challenges to cotton cultivation, resulting in adverse impacts on both production and fiber quality. Improving cotton's resilience to drought could mitigate yield losses and foster the expansion of cotton farming. Rab7 protein, widely present in organisms, controls the degradation and recycling of cargo, and has a potential role in biotic and abiotic tolerance. However, comprehensive exploration of the Rab7 gene family in Gossypium remains scarce., Results: Herein, we identified a total of 10, 10, 20, and 20 Rab7 genes through genome-wide analysis in Gossypium arboreum, Gossypium raimondii, Gossypium hirsutum, and Gossypium barbadense, respectively. Collinearity analysis unveiled the pivotal role of whole genome or segmental duplication events in the expansion of GhRab7s. Study of gene architecture, conserved protein motifs, and domains suggested the conservation of structure and function throughout evolution. Exploration of cis-regulatory elements revealed the responsiveness of GhRab7 genes to abiotic stress, corroborated by transcriptome analysis under diverse environmental stresses. Notably, the greatly induced expression of GhRab7B3-A under drought treatment prompted us to investigate its function through virus-induced gene silencing (VIGS) assays. Silencing GhRab7B3-A led to exacerbated dehydration and wilting compared with the control. Additionally, inhibition of stomatal closure, antioxidant enzyme activities and expression patterns of genes responsive to abiotic stress were observed in GhRab7B3-A silenced plants., Conclusions: This study sheds light on Rab7 members in cotton, identifies a gene linked to drought stress, and paves the way for additional investigation of Rab7 genes associated with drought stress tolerance., (© 2024. The Author(s).)

Environmental stress significantly affects plant growth and productivity. The effects of drought stress on plants are reflected primarily in enzyme activity, membrane systems, and cell-water loss. Here, the Kelch repeat F-box (KFB) protein family in tomato was systematically identified and analysed. Using bioinformatics, we identified 37 SlKFB family members in the tomato genome and analysed their protein structure, phylogenetic relationships, chromosome distribution, and expression under drought or biotic-stress conditions. Transcriptome data revealed that SlKFB members exhibit differential responses to drought stress, with significant differences in SlKFB16 and SlKFB34 expression. Functional analysis revealed that SlKFB16 functions in the cytoplasm and SlKFB34 in the nucleus and cytoplasm. Under drought stress, SlKFB16 and SlKFB34-silencing significantly reduced reactive oxygen species scavenging and resistance to drought stress. These findings provide a reference for further studies of the mechanisms of SlKFB16 and SlKFB34 in drought stress in tomato as well as a foundation for enhancing their resistance to drought stress., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

Actin cytoskeleton and reactive oxygen species are principal determinants of root hair polarity and tip growth. Loss of function in RESPIRATORY BURST OXIDASE HOMOLOG C/ROOT HAIR DEFECTIVE 2 (AtRBOHC/RHD2), an NADPH oxidase emitting superoxide to the apoplast, and in ACTIN 2, a vegetative actin isovariant, in rhd2-1 and der1-3 mutants, respectively, lead to similar defects in root hair formation and elongation Since early endosome-mediated polar localization of AtRBOHC/RHD2 depends on actin cytoskeleton, comparing the proteome-wide consequences of both mutations might be of eminent interest. Therefore, we employed a differential proteomic analysis of Arabidopsis rhd2-1 and der1-3 mutants. Both mutants exhibited substantial alterations in abundances of stress-related proteins. Notably, plasma membrane (PM)-localized PIP aquaporins showed contrasting abundance patterns in the mutants compared to wild-types. Drought-responsive proteins were mostly downregulated in rhd2-1 but upregulated in der1-3. Proteomic data suggest that opposite to der1-3, altered vesicular transport in rhd2-1 mutant likely contributes to the deregulation of PM-localized proteins, including PIPs. Moreover, lattice light sheet microscopy revealed reduced actin dynamics in rhd2-1 roots, a finding contrasting with previous reports on der1-3 mutant. Phenotypic experiments demonstrated a drought stress susceptibility in rhd2-1 and resistance in der1-3. Thus, mutations in AtRBOHC/RHD2 and ACTIN2 cause similar root hair defects, but they differently affect the actin cytoskeleton and vesicular transport. Reduced actin dynamics in rhd2-1 mutant is accompanied by alteration of vesicular transport proteins abundance, likely leading to altered protein delivery to PM, including aquaporins, thereby significantly affecting drought stress responses., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

ABA-insensitive 5 (ABI5) belongs to the basic leucine zipper class of transcription factors and is named for being the fifth identified Arabidopsis mutant unresponsive to ABA. To understand the influence of ABI5 in its active state on downstream gene expression and plant growth and development, we overexpressed the full-length ABI5 (A.t.MX-4) and the active forms of ABI5 with deleted transcriptional repression domains (A.t.MX-1, A.t.MX-2, and A.t.MX-3). Compared with the wild type, A.t.MX-1, A.t.MX-2, and A.t.MX-3 exhibited an increase in rosette leaf number and size, earlier flowering, increased thousand-seed weight, and significantly enhanced drought resistance. Thirty-five upregulated/downregulated proteins in the A.t.MX-1 were identified by proteomic analysis, and these proteins were involved in ABA biosynthesis and degradation, abiotic stress, fatty acid synthesis, and energy metabolism. These proteins participate in the regulation of plant drought resistance, flowering timing, and seed size at the levels of transcription and post-translational modification., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier GmbH. All rights reserved.)

The globally changing climatic condition is increasing the incidences of drought in several parts of the world. This is predicted and already shown to not only impact plant growth and flower development, but also plant-pollinator interactions and the pollination success of entomophilous plants. However, there is a large gap in our understanding of how drought affects the different flowers and pollen transfer among flowers in sexually polymorphic species. Here, we evaluated in monoecious Styrian oil pumpkin, and separately for female and male flowers, the responses of drought stress on flower production, petal size, nectar, floral scent and visitation by bumblebee pollinators. Drought stress adversely affected all floral traits studied, except floral scent. Although both flower sexes were adversely affected by drought stress, the effects were more severe on female flowers, with most of the female flowers even aborted before opening. The drought had negative effects on floral visitation by the pollinators, which generally preferred female flowers. Overall, our study highlights that the two flower sexes of a monoecious plant species are differently affected by drought stress and calls for further investigations to better understand the cues used by the pollinators to discriminate against male flowers and against flowers of drought-stressed plants., (© 2024 The Author(s). New Phytologist © 2024 New Phytologist Foundation.)

Background: Codonopsis pilosula (Campanulaceae) is a traditional herbal plant that is widely used in China, and the drought stress during the seedling stage directly affects the quality, ultimately impacting its yield. However, the molecular mechanisms underlying the drought resistance of C . pilosula seedlings remain unclear., Method: Herein, we conducted extensive comparative transcriptome and physiological studies on two distinct C. pilosula cultivar (G1 and W1) seedlings subjected to a 4-day drought treatment., Results: Our findings revealed that cultivar G1 exhibited enhanced retention of proline and chlorophyll, alongside a marked elevation in peroxidase activity, coupled with diminished levels of malondialdehyde and reduced leaf relative electrolyte leakage compared with cultivar W1. This suggested that cultivar G1 had relatively higher protective enzyme activity and ROS quenching capacity. We discerned a total of 21,535 expressed genes and identified 4,192 differentially expressed genes (DEGs) by RNA sequencing (RNA-seq). Our analysis revealed that 1,764 DEGs unique to G1 underwent thorough annotation and functional categorization utilizing diverse databases. Under drought conditions, the DEGs in G1 were predominantly linked to starch and sucrose metabolic pathways, plant hormone signaling, and glutathione metabolism. Notably, the drought-responsive genes in G1 were heavily implicated in hormonal modulation, such as ABA receptor3-like gene ( PYL9 ), regulation by transcription factors ( KAN4 , BHLH80 , ERF1B ), and orchestration of drought-responsive gene expression. These results suggest that cultivar G1 possesses stronger stress tolerance and can better adapt to drought growing conditions. The congruence between qRT-PCR validation and RNA-seq data for 15 DEGs further substantiated our findings., Conclusion: Our research provides novel insights into the physiological adaptations of C. pilosula to arid conditions and lays the groundwork for the development of new, drought-tolerant C. pilosula cultivars., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Wang, Chen, Liu, Guo, Liang, Dong, Dong, Cheng and Chen.)

Background: Precision phenotyping of short-term transpiration response to environmental conditions and transpiration patterns throughout wheat development enables a better understanding of specific trait compositions that lead to improved transpiration efficiency. Transpiration and related traits were evaluated in a set of 79 winter wheat lines using the custom-built "DroughtSpotter XXL" facility. The 120 l plant growth containers implemented in this phenotyping platform enable gravimetric quantification of water use in real-time under semi-controlled, yet field-like conditions across the entire crop life cycle., Results: The resulting high-resolution data enabled identification of significant developmental stage-specific variation for genotype rankings in transpiration efficiency. In addition, for all examined genotypes we identified the genotype-specific breakpoint in transpiration in response to increasing vapour pressure deficit, with breakpoints ranging between 2.75 and 4.1 kPa., Conclusion: Continuous monitoring of transpiration efficiency and diurnal transpiration patterns enables identification of hidden, heritable genotypic variation for transpiration traits relevant for wheat under drought stress. Since the unique experimental setup mimics field-like growth conditions, the results of this study have good transferability to field conditions., (© 2024. The Author(s).)

Drought stress severely impedes plant growth, development, and yield. Therefore, it is critical to uncover the genetic mechanisms underlying drought resistance to ensure future food security. To identify the genetic controls of these responses in Sorghum, an agriculturally and economically important grain crop, an interspecific recombinant inbred line (RIL) population was established by crossing a domesticated inbred line of Sorghum bicolor (TX7000) with its wild relative, Sorghum propinquum. This RIL population was evaluated under drought conditions, allowing for the identification of quantitative trait loci (QTL) that contribute to drought resistance. We detected eight QTL in the drought population that explain a significant portion of the observed variation for four traits (height, aboveground biomass, relative water content, and leaf temperature/transpiration). The allelic effects of, and the candidate genes within, these QTL emphasize: (1) the influence of domestication on drought-responsive phenotypes, such as height and aboveground biomass, and (2) how control of water uptake and/or loss can be driven by species-specific plant architecture. Our findings shed light on the interconnected roles of shoot and root responses in drought resistance as it relates to regulation of water uptake and/or loss, while the detected allelic effects demonstrate how maintenance of grain production and yield under drought is a likely result of domestication-derived drought tolerance., (© 2024 The Author(s). Plant Biology published by John Wiley & Sons Ltd on behalf of German Society for Plant Sciences, Royal Botanical Society of the Netherlands.)

Grain filling is a critical process for improving crop production under adverse conditions caused by climate change. Here, using a quantitative method, we quantified post-anthesis source-sink relationships of a large dataset to assess the contribution of remobilized pre-anthesis assimilates to grain growth for both biomass and nitrogen. The dataset came from 13 years of semi-controlled field experimentation, in which six bread wheat genotypes were grown at plot scale under contrasting temperature, water, and nitrogen regimes. On average, grain biomass was ~10% higher than post-anthesis above-ground biomass accumulation across regimes and genotypes. Overall, the estimated relative contribution (%) of remobilized assimilates to grain biomass became increasingly significant with increasing stress intensity, ranging from virtually nil to 100%. This percentage was altered more by water and nitrogen regimes than by temperature, indicating the greater impact of water or nitrogen regimes relative to high temperatures under our experimental conditions. Relationships between grain nitrogen demand and post-anthesis nitrogen uptake were generally insensitive to environmental conditions, as there was always significant remobilization of nitrogen from vegetative organs, which helped to stabilize the amount of grain nitrogen. Moreover, variations in the relative contribution of remobilized assimilates with environmental variables were genotype dependent. Our analysis provides an overall picture of post-anthesis source-sink relationships and pre-anthesis assimilate contributions to grain filling across (non-)environmental factors, and highlights that designing wheat adaptation to climate change should account for complex multifactor interactions., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Society for Experimental Biology.)

Fibrillins (FBNs), highly conserved plastid lipid-associated proteins (PAPs), play a crucial role in plant physiology. These proteins, encoded by nuclear genes, are prevalent in the plastoglobules (PGs) of chloroplasts. FBNs are indispensable for maintaining plastid stability, promoting plant growth and development, and enhancing stress responses. The conserved PAP domain of FBNs was found across a wide range of photosynthetic organisms, from plants and cyanobacteria. FBN families are classified into 12 distinct groups/clades, with the 12th group uniquely present in algal-fungal symbiosis. This mini review delves into the structural attributes, phylogenetic classification, genomic features, protein-protein interactions, and functional roles of FBNs in plants, with a special focus on their effectiveness in mitigating abiotic stresses, particularly drought stress., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 El-Sappah, Li, Yan, Zhu, Huang, Zhu, Chen, El-Tarabily and AbuQamar.)

Ubiquitination plays important roles in modulating the abiotic stress tolerance of plants. Drought seriously restricts agricultural production, but how ubiquitination participates in regulating drought tolerance remains largely unknown. Here, we identified a drought-inducible gene, MYB30-INTERACTING E3 LIGASE 1 (GhMIEL1), which encodes a RING E3 ubiquitin ligase in cotton (Gossypium hirsutum). GhMIEL1 was strongly induced by polyethylene glycol (PEG-6000) and the phytohormone abscisic acid (ABA). Overexpression and knockdown of GhMIEL1 in cotton substantially enhanced and reduced drought tolerance, respectively. GhMIEL1 interacted with the MYB transcription factor GhMYB66 and could ubiquitinate and degrade it in vitro. GhMYB66 directly bound to the LONELY GUY 5 (GhLOG5) promoter, a gene encoding cytokinin riboside 5'-monophosphate phosphoribohydrolase, to repress its transcription. Overexpression of GhMIEL1 and silencing of GhMYB66 altered the homeostasis of cytokinin of plant roots, increased total root length and number of root tips, and enhanced plant drought tolerance. Conversely, silencing GhLOG5 decreased total root length and number of root tips and reduced plant drought tolerance. Our studies reveal that the GhMIEL1-GhMYB66-GhLOG5 module positively regulates drought tolerance in cotton, which deepens our understanding of plant ubiquitination-mediated drought tolerance and provides insights for improving drought tolerance., (© The Author(s) 2024. Published by Oxford University Press on behalf of American Society of Plant Biologists. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Main Conclusion: TaZAT8-5B, a C2H2 zinc finger protein transcription factor, positively regulates drought tolerance in transgenic Arabidopsis. It promotes root growth under drought stress via the Aux/IAA-ARF module in the auxin signaling pathway. C2H2 zinc finger proteins (C2H2-ZFPs) represent the largest but relatively unexplored family of transcription factors in plants. This is particularly evident in wheat, where the functions of only a few C2H2-ZFP genes have been confirmed. In this study, we identified a novel C2H2-ZFP gene, TaZAT8-5B. This gene shows high expression in roots and flowers and is significantly induced by heat, drought, and salt stress. Under drought stress, overexpressing TaZAT8-5B in Arabidopsis resulted in increased proline content and superoxide dismutase (SOD) activity in leaves. It also led to reduced stomatal aperture and water loss, while inducing the expression of P5CS1, RD29A, and DREB1A. Consequently, it alleviated drought stress-induced malondialdehyde (MDA) accumulation and improved drought tolerance. Additionally, TaZAT8-5B promoted lateral root initiation under mannitol stress and enhanced both lateral and primary root growth under long-term drought stress. Moreover, TaZAT8-5B was induced by indole-3-acetic acid (IAA). Overexpressing TaZAT8-5B under drought stress significantly inhibited the expression of auxin signaling negative regulatory genes IAA12 and IAA14. Conversely, downstream genes (ARF7, LBD16, LBD18, and CDKA1) of IAA14 and IAA12 were upregulated in TaZAT8-5B overexpressing plants compared to wild-type (WT) plants. These findings suggest that TaZAT8-5B regulates root growth and development under drought stress via the Aux/IAA-ARF module in the auxin signaling pathway. In summary, this study elucidates the role of TaZAT8-5B in enhancing drought tolerance and its involvement in root growth and development through the auxin signaling pathway. These findings offer new insights into the functional analysis of homologous genes of TaZAT8-5B, particularly in Gramineae species., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)