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SUMMARY: Extracellular ATP (eATP) is a key signaling molecule that plays a pivotal role in plant growth and defense responses. The receptor P2K1 is responsible for perceiving eATP and initiating its signaling cascade. However, the signal transduction mechanisms downstream of P2K1 activation remain incompletely understood. We conducted a comprehensive analysis of the P2K1 interactome using co‐immunoprecipitation‐coupled tandem mass spectrometry, leading to the identification of 121 candidate proteins interacting with P2K1. In silico analysis narrowed down the candidates to 47 proteins, including Ca2+‐binding proteins, ion transport‐related proteins, and receptor kinases. To investigate their involvement in eATP signaling, we employed a screening strategy based on changes in gene expression in response to eATP in mutants of the identified interactors. This screening revealed several Ca2+‐dependent protein kinases (CPKs) that significantly affected the expression of eATP‐responsive genes, suggesting their potential roles in eATP signaling. Notably, CPK28 and CPK6 showed physical interactions with P2K1 both in yeast and plant systems. Calcium influx and gene expression studies demonstrated that CPK28 perturbed eATP‐induced Ca2+ mobilization and some early transcriptional responses. Overexpression of CPK28 resulted in an antagonistic physiological response to P2K1‐mediated eATP signaling during both plant growth and defense responses to the necrotrophic pathogen Botrytis cinerea. Our findings highlight CPK28, among other CPKs, as a modulator of P2K1‐mediated eATP signaling, providing valuable insights into the coordination of eATP signaling in plant growth and immunity. Significance Statement: In the last two decades, extracellular ATP has become a pivotal signaling element in animal physiology and plant biology. Recognized for its role in plant growth and defense, the purinergic signal of eATP is well‐established. Despite some identified interactors of the eATP receptor P2K1, a comprehensive understanding of purinergic signaling has been hindered by the lack of a P2K1 interactome. Our study successfully generated this interactomics dataset, shedding light on eATP‐mediated signaling and revealing a key player, CPK28, a Ca2+‐dependent protein kinase. [ABSTRACT FROM AUTHOR]

SUMMARY: Senescence is a highly regulated process driven by developmental age and environmental factors. Although leaf senescence is accelerated by nitrogen (N) deficiency, the underlying physiological and molecular mechanisms are largely unknown. Here, we reveal that BBX14, a previously uncharacterized BBX‐type transcription factor in Arabidopsis, is crucial for N starvation‐induced leaf senescence. We find that inhibiting BBX14 by artificial miRNA (amiRNA) accelerates senescence during N starvation and in darkness, while BBX14 overexpression (BBX14‐OX) delays it, identifying BBX14 as a negative regulator of N starvation‐ and dark‐induced senescence. During N starvation, nitrate and amino acids like glutamic acid, glutamine, aspartic acid, and asparagine were highly retained in BBX14‐OX leaves compared to the wild type. Transcriptome analysis showed a large number of senescence‐associated genes (SAGs) to be differentially expressed between BBX14‐OX and wild‐type plants, including ETHYLENE INSENSITIVE3 (EIN3) which regulates N signaling and leaf senescence. Chromatin immunoprecipitation (ChIP) showed that BBX14 directly regulates EIN3 transcription. Furthermore, we revealed the upstream transcriptional cascade of BBX14. By yeast one‐hybrid screen and ChIP, we found that MYB44, a stress‐responsive MYB transcription factor, directly binds to the promoter of BBX14 and activates its expression. In addition, Phytochrome Interacting Factor 4 (PIF4) binds to the promoter of BBX14 to repress BBX14 transcription. Thus, BBX14 functions as a negative regulator of N starvation‐induced senescence through EIN3 and is directly regulated by PIF4 and MYB44. Significance Statement: Senescence is a well‐controlled nutrient‐recovery process in plants occurring during age‐dependent development and under environmental stress. Here, we demonstrate that transcription factor BBX14 functions as a negative regulator of leaf senescence in Arabidopsis thaliana in darkness and during nitrogen limitation. [ABSTRACT FROM AUTHOR]

Phosphorus (P) is an essential macronutrient for plant growth. The roots are the main organ for nutrient and water absorption in plants, and they adapt to low-P soils by altering their architecture for enhancing absorption of inorganic phosphate (Pi). This review summarizes the physiological and molecular mechanisms underlying the developmental responses of roots to Pi starvation, including the primary root, lateral root, root hair, and root growth angle, in the dicot model plant Arabidopsis thaliana and the monocot model plant rice (Oryza sativa). The importance of different root traits and genes for breeding P-efficient roots in rice varieties for Pi-deficient soils are also discussed, which we hope will benefit the genetic improvement of Pi uptake, Pi-use efficiency, and crop yields. [ABSTRACT FROM AUTHOR]

Plasma membrane (PM) proton-translocating adenosine triphosphatase (H+-ATPase) is a pivotal enzyme for plant growth and development that acts as a primary transporter and is activated by phosphorylation of the penultimate residue, threonine, at the C-terminus. Small Auxin-Up RNA family proteins maintain the phosphorylation level via inhibiting dephosphorylation of the residue by protein phosphatase 2C-D clade. Photosynthetically active radiation activates PM H+-ATPase via phosphorylation in mesophyll cells of Arabidopsis thaliana , and phosphorylation of PM H+-ATPase depends on photosynthesis and photosynthesis-related sugar supplementation, such as sucrose, fructose and glucose. However, the molecular mechanism and physiological role of photosynthesis-dependent PM H+-ATPase activation are still unknown. Analysis using sugar analogs, such as palatinose, turanose and 2-deoxy glucose, revealed that sucrose metabolites and products of glycolysis such as pyruvate induce phosphorylation of PM H+-ATPase. Transcriptome analysis showed that the novel isoform of the Small Auxin-Up RNA genes, SAUR30 , is upregulated in a light- and sucrose-dependent manner. Time-course analyses of sucrose supplementation showed that the phosphorylation level of PM H+-ATPase increased within 10 min, but the expression level of SAUR30 increased later than 10 min. The results suggest that two temporal regulations may participate in the regulation of PM H+-ATPase. Interestingly, a 15NO3− uptake assay in leaves showed that light increases 15NO3− uptake and that increment of 15NO3− uptake depends on PM H+-ATPase activity. The results opened the possibility of the physiological role of photosynthesis-dependent PM H+-ATPase activation in the uptake of NO3−. We speculate that PM H+-ATPase may connect photosynthesis and nitrogen metabolism in leaves. [ABSTRACT FROM AUTHOR]

Plants activate a myriad of signaling cascades to tailor adaptive responses under environmental stresses, such as salinity. While the roles of exogenous karrikins (KARs) in salt stress mitigation are well comprehended, genetic evidence of KAR signaling during salinity responses in plants remains unresolved. Here, we explore the functions of the possible KAR receptor KARRIKIN-INSENSITIVE2 (KAI2) in Arabidopsis thaliana tolerance to salt stress by investigating comparative responses of wild-type (WT) and kai2 -mutant plants under a gradient of NaCl. Defects in KAI2 functions resulted in delayed and inhibited cotyledon opening in kai2 seeds compared with WT seeds, suggesting that KAI2 played an important role in enhancing seed germination under salinity. Salt-stressed kai2 plants displayed more phenotypic aberrations, biomass reduction, water loss and oxidative damage than WT plants. kai2 shoots accumulated significantly more Na+ and thus had a lower K+/Na+ ratio, than WT, indicating severe ion toxicity in salt-stressed kai2 plants. Accordingly, kai2 plants displayed a lower expression of genes associated with Na+ homeostasis, such as SALT OVERLY SENSITIVE (SOS) 1, SOS2, HIGH-AFFINITY POTASSIUM TRANSPORTER 1;1 (HKT1;1) and CATION–HYDROGEN EXCHANGER 1 (NHX1) than WT plants. WT plants maintained a better glutathione level, glutathione-related redox status and antioxidant enzyme activities relative to kai2 plants, implying KAI2's function in oxidative stress mitigation in response to salinity. kai2 shoots had lower expression levels of genes involved in the biosynthesis of strigolactones (SLs), salicylic acid and jasmonic acid and the signaling of abscisic acid and SLs than those of WT plants, indicating interactive functions of KAI2 signaling with other hormone signaling in modulating plant responses to salinity. Collectively, these results underpin the likely roles of KAI2 in the alleviation of salinity effects in plants by regulating several physiological and biochemical mechanisms involved in ionic and osmotic balance, oxidative stress tolerance and hormonal crosstalk. [ABSTRACT FROM AUTHOR]

Rhizobia, which enter into symbiosis with legumes, can also interact with non-legumes and promote plant growth. In this paper, we explored the effects of nickel (Ni, 200 µM) on Arabidopsis thaliana (Col-0) inoculated with plant growth-promoting (PGP) rhizobia nodulating ultramafic Anthyllis vulneraria. The isolated PGP strains tolerant to Ni were identified as Rhizobium sp. and Bradyrhizobium sp. The isolates highly differed in their PGP abilities and Ni resistance. Without Ni-stress, the plants inoculated with most isolates grew better and had higher photosynthetic efficiency than non-inoculated controls. Nickel treatment increased Ni concentration in inoculated plants. Plant growth, leaf anatomy, chloroplast ultrastructure, efficiency of photosynthesis, and antioxidant defense system activity were significantly impaired by Ni, however, the majority of these effects were diminished in plants inoculated with the most effective PGP rhizobia. Real-time PCR revealed an increased expression level of genes involved in auxin and gibberellin biosynthesis in the inoculated, Ni-treated plants, and this may have improved shoot and root growth after inoculation with effective isolates. Our results also suggest a positive correlation between Ni-stress parameters and antioxidant defense system activity, and also between the effectiveness of photosynthesis and plant growth parameters. We showed that the selected rhizobia, naturally nodulating Anthyllis on Ni-rich ultramafic soils can promote Arabidopsis growth and increase plant tolerance to Ni by improving different physiological and biochemical mechanisms. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide is a signalling molecule with a well‐established impact on both plant and animal physiology. Intense investigation into the regulation of autophagy by sulfide in Arabidopsis thaliana has revealed that the post‐translational modification of persulfidation/S‐sulfhydration plays a key role. In this review focused on plants, we discuss the nature of the sulfide molecule involved in the regulation of autophagy, the final outcome of this modification and the persulfidated autophagy proteins identified so far. A detailed outline of the actual knowledge of the regulation mechanism of the autophagy‐related proteins ATG4a and ATG18a from Arabidopsis by sulfide is also included. This information will be instrumental for furthering research on the regulation of autophagy by sulfide. [ABSTRACT FROM AUTHOR]

Microplastics have garnered global attention due to their potential ecological risks. Research shows micro/nano-plastics pollution has adverse effects on plant growth, development, and physiological characteristics. However, the mechanisms underlying these effects remain unclear. The study examined the effects of polystyrene micro/nano-plastics with varying sizes and concentrations on different physiological and biochemical markers of A. thaliana. The indicators assessed include seed viability, growth, chlorophyll content, accumulation of root reactive oxygen species, and root exudates. Using fluorescence labeling, we investigated the absorption and translocation processes of micro/nano-plastics in A. thaliana. We also performed transcriptomic analysis to better understand the particular mechanisms of micro/nano-plastics. It indicated that micro/nano-plastics had an adverse effect on seed germination, especially under high concentration and small particle size treatments. This effect diminished with prolonged exposure. High concentrations at 50 nm and 100 nm treatment groups significantly inhibited the growth. Conversely, low concentrations of 1000 nm had a promoting effect. Exposure to micro/nano-plastics potentially resulted in decreased chlorophyll content, the accumulation of H 2 O 2 in roots, and stimulated root secretion of oxalic acid. Through transcriptomic analysis, the gene expression linked to micro/nano-plastic treatments of varying sizes enriched multiple metabolic pathways, impacting plant growth, development, environmental adaptation, metabolism, pigment synthesis, and stress response. [Display omitted] • Polystyrene micro/nanoplastics impact Arabidopsis thaliana physiology & biochemistry. • Low-concentration of 1000 nm polystyrene micro/nanoplastics promoted A. thaliana growth. • A. thaliana 's absorption & accumulation polystyrene micro/nanoplastics from 50–1000 nm. • Polystyrene micro/nanoplastics' size impacts gene expression in A. thaliana leaves & roots. [ABSTRACT FROM AUTHOR]

The results of assessing the primary dormancy, greatly important for adaptation, of seeds of A. thaliana plants from northern natural populations are presented. The temperature history of the maternal plant during the period of seed maturation was found to control the germination of seed progeny. The dependence of the transcriptional activity of the FT gene in plant pods on temperature history of the maternal plant was identified: the activity was found to be higher at a colder temperature (16°C) compared to warmer conditions. For DOG1, a similar relationship is true only for some populations that include both late-flowering and relatively early-flowering plants. This is likely due to the fact that the latest ecotypes of A.thaliana have special regulatory mechanisms of the physiological functions of DOG1. It was shown that, in a cold climate, seeds of the majority of A. thaliana plants experience deeper dormancy at a high temperature (22°C), which ensures their germination in autumn and flowering in spring, after the end of vernalization. Nevertheless, a portion of seeds was found to be able to germinate at 22°C, possibly suggesting a mixture of alternative strategies of the life cycle of A. thaliana plants in the Karelian populations. In some populations, both winter and summer annuals are present, which creates an adaptive potential for the species to survive in a harsh and unstable environment in the northern periphery of the range of the species. [ABSTRACT FROM AUTHOR]

Heavy metal pollution of soil has become a serious global concern in recent years. In particular, cadmium (Cd) contamination is a ubiquitous environmental problem among heavy metals. Iris lactea var. chinensis is a perennial herb with significant ecological and industrial value. It is known for its good cadmium tolerance and cadmium enrichment capabilities; thus, it is considered an important plant for the restoration of cadmium-contaminated soil. Previous studies have shown that the cysteine-rich gene, IlCDT1 isolated from I. lactea conferred tolerance to Cd stress in yeast and Arabidopsis thaliana. However, the molecular mechanism of its regulation is poorly understood to date. In the current study, we screened and identified the transcription factor IlNF-YC6 that regulates IlCDT1 using yeast one-hybrid assay (Y1H). Overexpression of IlNF-YC6 conferred a significant tolerance to Cd stress in A. thaliana. Furthermore, the detection of physiological markers and transcriptome analysis revealed that IlNF-YC6 might increase plant tolerance to Cd stress primarily by improving plant detoxification ability and antioxidant capacity. Overall, our study would provide a genetic resource for candidate gene selection that might enhance plant tolerance to Cd contamination in soil or groundwater and subsequently lowering Cd absorption in the future. [Display omitted] • Upstream regulators IlNF-YC6 of IlCDT1 identified by yeast one-hybrid. • IlNF-YC6 is up-regulated by cadmium stress and interacts with CCAAT element. • Overexpression IlNF-YC6 in A. thaliana significantly increased cadmium tolerance. • RNA-seq data demonstrates that I1NF-YC6 can enhance cadmium tolerance in plants by activating IlCDT1 expression. [ABSTRACT FROM AUTHOR]

Casein kinase CK2 is a highly conserved serine/threonine protein kinase and exists in all eukaryotes. It has been demonstrated to be widely involved in the biological processes of plants. The CK2 holoenzyme is a heterotetramer consisting of two catalytic subunits (α and/or α′) and two regulatory subunits (β). CK2 in plants is generally encoded by multiple genes, with monomeric and oligomeric forms present in the tissue. Various subunit genes of CK2 have been cloned and characterized from Arabidopsis thaliana , tobacco, maize, wheat, tomato, and other plants. This paper reviews the structural features of CK2, provides a clear classification of its physiological functions and mechanisms of action, and elaborates on the regulation of CK2 activity to provide a knowledge base for subsequent studies of CK2 in plants. [ABSTRACT FROM AUTHOR]

Fluorine (F) is a highly reactive and non-biodegradable pollutant widely present in the environment, which has seriously threatened ecosystems and human health. To date, no fluorescent probes have been reported to visually observe the accumulation of excess fluoride ions in living plants and animals, which severely limits the study of the toxic effects of fluoride ions in biological chains. In this work, we designed and synthesized a new deep-red emission fluorescent probe NRF for detecting the accumulation of F− in living animals and plants. Exploiting F-induced cleavage of the silicon-oxygen bond, the probe NRF exhibited remarkable fluorescence changes from weak to strong. In addition, this probe displayed some significant advantages in detecting F−, including excellent selectivity, good photostability, and low biological toxicity. Furthermore, its favorable properties for detecting F− were successfully demonstrated in HeLa cells and zebrafish. Notably, utilizing the robust probe NRF , visualization of F− accumulation in acute F− toxicity model and the roots of Arabidopsis thaliana tissues had been achieved. This study shows that NRF can be used as an effective tool to detect excess F− in living cells, animals and plants, and provides a method for elucidating the toxicity mechanism of fluoride in physiological and pathological processes. [Display omitted] • We have developed a new deep-red emission fluorescent probe (NRF) for the detection of F− in living organisms. • The probe NRF was successfully applied to high-contrast imaging of F− in HeLa cells and zebrafish. • The unique probe NRF was used effectively to visualize F− in a mouse model of acute F− toxicity. • The accumulation of F− in the roots of Arabidopsis thaliana can be effectively observed using the novel probe NRF. [ABSTRACT FROM AUTHOR]