Search

The primary root is the basic component of the root system and plays a key role in early seedling growth in rice. Its growth is easily affected by environmental cues, such as salt stress. Abscisic acid (ABA) plays an essential role in root development, but the molecular mechanism underlying ABA-regulated root growth in response to salt stress remains poorly understood. In this study, we report that salt stress inhibits primary root elongation and promotes primary root swelling. Moreover, salt stress induces the expression of ABA-responsive genes and ABA accumulation in the primary root, revealing that ABA plays an essential role in salt-modulated root growth. Transgenic lines of OsSAPK10-OE and OsABIL2-OE , which constitutively express OsSAPK10 or OsABIL2 , with enhanced or attenuated ABA signaling, show increased and decreased sensitivity to salt, correspondingly. Microscopic analysis indicates that salt and ABA inhibits cell proliferation and promotes cell expansion in the root apical meristem. Transcriptome analysis showed that ABA induces the expression of E genes. Further investigations indicate that ABA exerts these effects largely through ABA signaling. Thus, our findings deepen our understanding of the role of ABA in controlling primary root growth in response to salt stress, and this knowledge can be used by breeders to cultivate rice varieties suitable for saline-alkali land.XPANSIN genes. Further investigations indicate that ABA exerts these effects largely through ABA signaling. Thus, our findings deepen our understanding of the role of ABA in controlling primary root growth in response to salt stress, and this knowledge can be used by breeders to cultivate rice varieties suitable for saline-alkali land.

The plasma membrane NADPH Oxidase-derived ROS as signaling molecules play crucial roles in salt stress response. As the motor organelle of cells, mitochondria are also important for salt tolerance. However, the possible interaction between NADPH Oxidase-derived ROS and mitochondria is not well studied. Here, a transgenic Arabidopsis expressing mitochondrial matrix-targeted pH-sensitive indicator cpYFP was used to monitor the pH dynamics in root cells under salt stress. A significant alkalization in mitochondria was observed when the root was exposed to NaCl or KCl, but not osmotic stress such as isotonic mannitol. Interestingly, when pretreated with the NADPH Oxidase inhibitor DPI, the mitochondrial alkalization in root cells was largely abolished. Genetic evidence further showed that salt-induced mitochondrial alkalization was significantly reduced in the loss of function mutant atrbohF . Pretreatment with endocytosis-related inhibitor PAO or TyrA23, which inhibited the ROS accumulation under salt treatment, almost abolished this effect. Furthermore, [Ca 2+ ] cyt increase might also play important roles by affecting ROS generation to mediate salt-induced mitochondrial alkalization as indicated by treatment with plasma membrane Ca 2+ channel inhibitor LaCl 3 and mitochondrial Ca 2+ uniporter inhibitor Ruthenium Red. Together, these results suggest that the plasma membrane NADPH Oxidase-derived ROS promote the mitochondrial alkalization under salt treatment, providing a possible link between different cellular compartments under salt stress.

Key Message: NADPH oxidase-mediated H 2 O 2 maintains proline concentration under NaCl stress through regulating its biosynthesis and degradation, conferring salt tolerance to wheat plants. Considerable attention has been paid to the specific role of hydrogen peroxide (H 2 O 2 ) in plant stress responses. Here, using microscopic, pharmacological and biochemical approaches, we explored H 2 O 2 production and its roles in redox control under salt stress in wheat roots. Exogenous H 2 O 2 pretreatment decreased salt-induced lipid peroxidation, while increased proline content in wheat roots. Salt stress led to a transient increase in NADPH oxidase activity accompanied by accumulation of H 2 O 2 and proline in roots. The elevated proline accumulation in the presence of NaCl was significantly suppressed by diphenyleneiodonium, an inhibitor of NADPH oxidase, and dimethylthiourea, a scavenger of H 2 O 2 . The rate-limiting enzyme involved in proline biosynthesis, Δ 1 -pyrroline-5-carboxylate synthetase (P5CS), was induced by NaCl, whereas the house-keeping enzyme in proline degradation, proline dehydrogenase (ProDH), was inhibited. After 6 h, the activity of P5CS increased by 1.5-fold, whereas ProDH decreased by 13.9%. The levels of these enzymes, however, were restored by NADPH oxidase inhibitor or H 2 O 2 scavenger. After treatment with H 2 O 2 , the effects of diphenyleneiodonium and or dimethylthiourea on proline content and activities of P5CS and ProDH were reversed. These results suggested that NADPH oxidase-mediated H 2 O 2 alleviates oxidative damage induced by salt stress through regulating proline biosynthesis and degradation.

Soybean is an economically important plant, and its production is affected in soils with high salinity levels. It is important to understand the adaptive mechanisms through which plants overcome this kind of stress and to identify potential genes for improving abiotic stress tolerance. RNA-Seq data of two Glycine max cultivars, a drought-sensitive (C08) and a tolerant (Conquista), subjected to different periods of salt stress were analyzed. The transcript expression profile was obtained using a transcriptogram approach, comparing both cultivars and different times of treatment. After 4 h of salt stress, Conquista cultivar had 1400 differentially expressed genes, 647 induced and 753 repressed. Comparative expression revealed that 719 genes share the same pattern of induction or repression between both cultivars. Among them, 393 genes were up- and 326 down-regulated. Salt stress also modified the expression of 54 isoforms of miRNAs in Conquista, by the maturation of 39 different pre-miRNAs. The predicted targets for 12 of those mature miRNAs also have matches with 15 differentially expressed genes from our analyses. We found genes involved in important pathways related to stress adaptation. Genes from both ABA and BR signaling pathways were modulated, with possible crosstalk between them, and with a likely post-transcriptional regulation by miRNAs. Genes related to ethylene biosynthesis, DNA repair, and plastid translation process were those that could be regulated by miRNA.

Auxin controls multiple aspects of plant growth and development. However, its role in stress responses remains poorly understood. Auxin acts on the transcriptional regulation of target genes, mainly through Auxin Response Factors ( ARF ). This study focuses on the involvement of SlARF4 in tomato tolerance to salinity and osmotic stress. Using a reverse genetic approach, we found that the antisense down-regulation of SlARF4 promotes root development and density, increases soluble sugars content and maintains chlorophyll content at high levels under stress conditions. Furthermore, ARF4 -as displayed higher tolerance to salt and osmotic stress through reduced stomatal conductance coupled with increased leaf relative water content and Abscisic acid (ABA) content under normal and stressful conditions. This increase in ABA content was correlated with the activation of ABA biosynthesis genes and the repression of ABA catabolism genes. Cu/ZnSOD and mdhar genes were up-regulated in ARF4 -as plants which can result in a better tolerance to salt and osmotic stress. A CRISPR/Cas9 induced SlARF4 mutant showed similar growth and stomatal responses as ARF4 -as plants, which suggest that arf4-cr can tolerate salt and osmotic stresses. Our data support the involvement of ARF4 as a key factor in tomato tolerance to salt and osmotic stresses and confirm the use of CRISPR technology as an efficient tool for functional reverse genetics studies.

Listeria monocytogenes causes the severe foodborne illness listeriosis and survives in food-associated environments due to its high stress tolerance. A data assembly and analysis protocol for microbial growth experiments was compiled to elucidate the strain variability of L. monocytogenes stress tolerance. The protocol includes measurement of growth ability under stress (step 1), selection of a suitable method for growth parameter calculation (step 2), comparison of growth patterns between strains (step 3), and biological interpretation of the discovered differences (step 4). In step 1, L. monocytogenes strains ( n  = 388) of various serovars and origins grown on media with 9.0% NaCl were measured using a Bioscreen C microbiology reader. Technical variability of the growth measurements was assessed and eliminated. In step 2, the growth parameters determined by Gompertz, modified-Gompertz, logistic, and Richards models and model-free splines were compared, illustrating differences in the suitability of these methods to describe the experimental data. In step 3, hierarchical clustering was used to describe the NaCl tolerance of L. monocytogenes measured by strain-specific variation in growth ability; tolerant strains had higher growth rates and maximum optical densities and shorter lag phases than susceptible strains. The spline parameter area under the curve best classified "poor," "average," and "good" growers. In step 4, the tested L. monocytogenes lineage I strains (serovars 4b and 1/2b) proved to be significantly more tolerant toward 9.0% NaCl than lineage II strains (serovars 1/2a, 1/2c, and 3a). Our protocol provides systematic tools to gain comparable data for investigating strain-specific variation of bacterial growth under stress. IMPORTANCE The pathogen Listeria monocytogenes causes the foodborne disease listeriosis, which can be fatal in immunocompromised individuals. L. monocytogenes tolerates several environmental stressors and can persist in food-processing environments and grow in foodstuffs despite traditional control measures such as high salt content. Nonetheless, L. monocytogenes strains differ in their ability to withstand stressors. Elucidating the intraspecies strain variability of L. monocytogenes stress tolerance is crucial for the identification of particularly tolerant strains. To enhance reliable identification of variability in bacterial stress tolerance phenotypes, we compiled a large-scale protocol for the entire data assembly and analysis of microbial growth experiments, providing a systematic approach and checklist for experiments on strain-specific growth ability. Our study illustrated the diversity and strain-specific variation of L. monocytogenes stress tolerance with an unprecedented scope and discovered biologically relevant serovar- and lineage-dependent phenotypes of NaCl tolerance., (Copyright © 2020 American Society for Microbiology.)

Extraterrestrial environments encompass physicochemical conditions and habitats that are unknown on Earth, such as perchlorate-rich brines that can be at least temporarily stable on the martian surface. To better understand the potential for life in these cold briny environments, we determined the maximum salt concentrations suitable for growth (MSCg) of six different chloride and perchlorate salts at 25°C and 4°C for the extremotolerant cold- and salt-adapted bacterial strain Planococcus halocryophilus . Growth was measured through colony-forming unit (CFU) counts, while cellular and colonial phenotypic stress responses were observed through visible light, fluorescence, and scanning electron microscopy. Our data show the following: (1) The tolerance to high salt concentrations can be increased through a stepwise inoculation toward higher concentrations. (2) Ion-specific factors are more relevant for the growth limitation of P. halocryophilus in saline solutions than single physicochemical parameters like ionic strength or water activity. (3) P. halocryophilus shows the highest microbial sodium perchlorate tolerance described so far. However, (4) MSCg values are higher for all chlorides compared to perchlorates. (5) The MSCg for calcium chloride was increased by lowering the temperature from 25°C to 4°C, while sodium- and magnesium-containing salts can be tolerated at 25°C to higher concentrations than at 4°C. (6) Depending on salt type and concentration, P. halocryophilus cells show distinct phenotypic stress responses such as novel types of colony morphology on agar plates and biofilm-like cell clustering, encrustation, and development of intercellular nanofilaments. This study, taken in context with previous work on the survival of extremophiles in Mars-like environments, suggests that high-concentrated perchlorate brines on Mars might not be habitable to any present organism on Earth, but extremophilic microorganisms might be able to evolve thriving in such environments.

Transgenerational plasticity in plants enables rapid adaptation to environmental changes, allowing organisms and their offspring to adapt to the environment without altering their underlying DNA. In this study, we investigated the transgenerational plasticity in salinity tolerance of rice plants using a reciprocal transplant experimental strategy. Our aim was to assess whether non-genetic environment-induced phenotypic modifications and transgenerational salinity affect the salinity tolerance of progeny while excluding nuclear genomic factors for two generations. Using salt-tolerant and salt-sensitive rice genotypes, we observed that the parentally salt-stressed salt-sensitive genotype displayed greater growth performance, photosynthetic activity, yield performance, and transcriptional responses than the parentally non-stressed salt-sensitive plants under salt stress conditions. Surprisingly, salt stress-exposed salt-tolerant progeny did not exhibit as much salinity tolerance as salt stress-exposed salt-sensitive progeny under salt stress. Our findings indicate that the phenotypes of offspring plants differed based on the environment experienced by their ancestors, resulting in heritable transgenerational phenotypic modifications in salt-sensitive genotypes via maternal effects. These results elucidated the mechanisms underlying transgenerational plasticity in salinity tolerance, providing valuable insights into how plants respond to changing environmental conditions. [ABSTRACT FROM AUTHOR]

Matricaria chamomilla (Asteraceae), commonly known as chamomile can tolerate freezing temperatures and grows in many soil types. This plant is found on all continents and has significant medicinal value. There are more than 120 chemicals detected in chamomile flowers, with the majority found in the essential oil. In this study, M. chamomilla was given the NaCl stress of 0 mM, 1 mM, 100 mM, and 150 mM concentrations This study was the first to assess the efficacy of German chamomile upon exposure to salt stress hence plant particles that had been dried and powdered were analyzed using, phytochemical tests, Fourier Transform Infrared and UV–Vis spectroscopy, thin layer chromatography, fluorescence recovery after photobleaching assay, antibacterial and antioxidant activity. The characterization and results of these activities show amazing results which enhance their antibacterial property with an increased zone of inhibition when the samples of salt stress of the above-given concentrations were compared to the control samples. More graph analysis indicates an effective impact of salt stress on the phytoconstituents of M. chamomilla. Other than that, there was a clear flower induction upon salt stress, as a variety of compounds are regarded as essential to the biological functions of chamomile flowers according to the phytoconstituent screening which can be further used in the cosmetic industry, pharmaceutical industry, and all other fields as well for various application as a nano-drug or bio-drug. Due to this, this plant became essential for plant biotechnology research. [ABSTRACT FROM AUTHOR]

Excess soil salinity significantly impairs plant growth and development. Our previous reports demonstrated that the core circadian clock oscillator GIGANTEA (GI) negatively regulates salt stress tolerance by sequestering the SALT OVERLY SENSITIVE (SOS) 2 kinase, an essential component of the SOS pathway. Salt stress induces calcium‐dependent cytoplasmic GI degradation, resulting in activation of the SOS pathway; however, the precise molecular mechanism governing GI degradation during salt stress remains enigmatic. Here, we demonstrate that salt‐induced calcium signals promote the cytoplasmic partitioning of CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1), leading to the 26S proteasome‐dependent degradation of GI exclusively in the roots. Salt stress‐induced calcium signals accelerate the cytoplasmic localization of COP1 in the root cells, which targets GI for 26S proteasomal degradation. Align with this, the interaction between COP1 and GI is only observed in the roots, not the shoots, under salt‐stress conditions. Notably, the gi‐201 cop1‐4 double mutant shows an enhanced tolerance to salt stress similar to gi‐201, indicating that GI is epistatic to COP1 under salt‐stress conditions. Taken together, our study provides critical insights into the molecular mechanisms governing the COP1‐mediated proteasomal degradation of GI for salt stress tolerance, raising new possibilities for developing salt‐tolerant crops. Summary statement: Salt‐induced Ca2+ signal triggers E3 ubiquitin ligase CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1) dependent proteasomal degradation of cytosolic GIGANTEA (GI) in the roots under salt‐stress conditions. Consequently, COP1‐regulated GI degradation positively regulates salt stress tolerance in Arabidopsis thaliana. [ABSTRACT FROM AUTHOR]

Plant JASMONATE ZIM‐DOMAIN (JAZ) genes play crucial roles in regulating the biosynthesis of specialized metabolites and stressful responses. However, understanding of JAZs controlling these biological processes lags due to numerous JAZ copies. Here, we found that two leaf‐specific CwJAZ4/9 genes from Curcuma wenyujin are strongly induced by methyl‐jasmonate (MeJA) and negatively correlated with terpenoid biosynthesis. Yeast two‐hybrid, luciferase complementation imaging and in vitro pull‐down assays confirmed that CwJAZ4/9 proteins interact with CwMYC2 to form the CwJAZ4/9‐CwMYC2 regulatory cascade. Furthermore, transgenic hairy roots showed that CwJAZ4/9 acts as repressors of MeJA‐induced terpenoid biosynthesis by inhibiting the terpenoid pathway and jasmonate response, thus reducing terpenoid accumulation. In addition, we revealed that CwJAZ4/9 decreases salt sensitivity and sustains the growth of hairy roots under salt stress by suppressing the salt‐mediated jasmonate responses. Transcriptome analysis for MeJA‐mediated transgenic hairy root lines further confirmed that CwJAZ4/9 negatively regulates the terpenoid pathway genes and massively alters the expression of genes related to salt stress signaling and responses, and crosstalks of multiple phytohormones. Altogether, our results establish a genetic framework to understand how CwJAZ4/9 inhibits terpenoid biosynthesis and confers salt tolerance, which provides a potential strategy for producing high‐value pharmaceutical terpenoids and improving resistant C. wenyujin varieties by a genetic approach. Summary statement: CwJAZ4/9 interacts with CwMYC2 and negatively regulates MeJA‐induced terpenoid biosynthesis by inhibiting jasmonate response in Curcuma wenyujin. Meanwhile, CwJAZ4/9 can confer salt tolerance and sustain hairy root growth by weakening the salt‐mediated JA response and upregulating the expression of stress‐responsive genes. [ABSTRACT FROM AUTHOR]

CLE proteins are a class of signalling factors involved in plant growth and abiotic stress response. They play crucial roles in processes such as cell differentiation, chlorophyll synthesis and abscisic acid (ABA) signal transduction. However, the function of the CLE genes in Sorghum bicolor remains unclear. In this study, 42 sorghum CLE genes were identified, and their evolutionary relationship, gene structure, amino acid sequence and homologous genes were analysed. We also examined the expression levels of CLE genes under various treatment conditions. Transcriptome data showed that there were significant differences in the expression patterns of 42 CLE genes in different tissues and organs. It is worth noting that SbCLE39 is mainly highly expressed in sorghum roots. At the same time, the expression of SbCLE39 decreased significantly under salt and ABA treatment. Compared with wild‐type yeast cells (EV), yeast cells with high expression of SbCLE39 had lower tolerance to salt stress. In addition, the excessive accumulation of ABA caused by external application of SbCLE39p reduced the salt tolerance of sorghum. These findings suggest that SbCLE39 negatively regulates the salt tolerance of sorghum. These results lay a foundation for revealing the mechanism of CLE genes regulating the salt tolerance of sorghum and are of great significance for the cultivation of salt‐tolerant crops. [ABSTRACT FROM AUTHOR]

Under salt stress, plants are forced to take up and accumulate large amounts of sodium (Na+) and chloride (Cl−). Although most studies have focused on the toxic effects of Na+ on plants, Cl− stress is also very important. This study aimed to clarify physiological mechanisms underpinning growth contrasts in canola varieties with different salt tolerance. In hydroponic experiments, 150 mM Na+, Cl− and NaCl were applied to salt-tolerant and sensitive canola varieties. Both NaCl and Na+ treatments inhibited seedling growth. NaCl caused the strongest damage to both canola varieties, and stress damage was more severe at high concentrations of Na+ than Cl−. High Cl− promoted the uptake of ions (potassium K+, calcium Ca2+) and induced antioxidant defence. Salt-tolerant varieties were able to mitigate ion toxicity by maintaining lower Na+ content in the root system for a short period of time, and elevating magnesium Mg2+ content, Mg2+/Na+ ratio, and antioxidant enzyme activity to improve photosynthetic capacity. They subsequently re-established new K+/Na+ and Ca2+/Na+ balances to improve their salt tolerance. High concentrations of Cl salts caused less damage to seedlings than NaCl and Na salts, and Cl− also had a positive role in inducing oxidative stress and responsive antioxidant defence in the short term. Both sodium chloride and sodium salt treatments inhibited the growth of canola seedlings. Sodium chloride imposed the most damage, and chloride salts the least. Under treatment with sodium chloride and sodium salt, the canola variety Huayouza 62 grew best, by maintaining lower sodium content in the root system, higher magnesium content, and a greater ratio of magnesium to sodium to improve photosynthetic capacity. Chloride salts had a positive role in inducing oxidative stress and responsive antioxidant defence in canola seedlings. [ABSTRACT FROM AUTHOR]

Salt stress inhibits plant growth and affects the biosynthesis of its secondary metabolites. Flavonoids are natural compounds that possess many important biological activities, playing a significant role in the medicinal activity of Eucommia ulmoides (E. ulmoides). To investigate the mechanism by which salt stress affects the biosynthesis of flavonoids in E. ulmoides , a comprehensive analysis of metabolomics and transcriptomics was conducted. The results indicated that salt stress led to the wilting and darkening of E. ulmoides leaves, accompanied by a decrease in chlorophyll levels, and significantly induced malondialdehyde (MDA) and relative electrical conductivity. During salt stress, most metabolites in the flavonoid biosynthesis pathway of E. ulmoides were upregulated, indicating that flavonoid biosynthesis is likely the main induced pathway under salt stress. Among them, secondary metabolites such as 6-Hydroxyluteolin and Quercetin are likely key metabolites induced by salt stress. The correlation analysis of transcriptomics and metabolomics revealed that EuSHT is a hub gene induced by salt stress, promoting the production of flavonoids such as 6-Hydroxyluteolin. The co-expression network showed a strong positive correlation between EuSHT and the biosynthesis of 6-Hydroxyluteolin and Quercetin, while it exhibited a negative correlation with Catechin biosynthesis. The branches leading to Luteolin and Dihydroquercetin are likely the main pathways for flavonoid compound biosynthesis in the plant stress response during salt stress. The results of this study provided a preliminary mechanism of secondary metabolites such as flavonoids in the medicinal plant E. ulmoides induced by salt stress and provided new theoretical support for discussing the mechanism of plant stress response. It also provided useful information for subsequent exploration of resistance genes in E. ulmoides. [ABSTRACT FROM AUTHOR]

Soil is indispensable for agricultural production but has been seriously polluted by cadmium and salt in recent years. Many crops are suffering from this, including rapeseed, the third largest global oilseed crop. However, genes simultaneously related to both cadmium and salt stress have not been extensively reported yet. In this study, BnaA10.WRKY75 was screened from previous RNA-seq data related to cadmium and salt stress and further analyses including sequence comparison, GUS staining, transformation and qRT-PCR were conducted to confirm its function. GUS staining and qRT-PCR results indicated BnaA10.WRKY75 was induced by CdCl2 and NaCl treatment. Sequence analysis suggested BnaA10.WRKY75 belongs to Group IIc of the WRKY gene family and transient expression assay showed it was a nuclear localized transcription factor. BnaA10.WRKY75-overexpressing Arabidopsis and rapeseed plants accumulated more H2O2 and O2− and were more sensitive to CdCl2 and NaCl treatment compared with untransformed plants, which may be caused by the downregulation of BnaC03.CAT2. Our study reported that BnaA10.WRKY75 increases sensitivity to cadmium and salt stress by disrupting the balance of reactive oxygen species both in Arabidopsis and rapeseed. The results support the further understanding of the mechanisms underlying cadmium and salt tolerance and provide BnaA10.WRKY75 as a valuable gene for rapeseed abiotic stress breeding. [ABSTRACT FROM AUTHOR]

• The Blue Bonnet 76 (BB76) rice cultivar is more susceptible to salt stress than the Sakha Super 300 (SS300) cultivar. • The tolerance of SS300 owes to more reduced leaf Na+ owing partially to enhanced OsHKT1;5 in the root. • BB76 accumulated 9-fold more proline than SS300. • The susceptibility of BB76 is probably due to utilization of more energy for osmolyte synthesis. Salt stress remains a global problem affecting agricultural production, and the elucidation of stress tolerance mechanisms in crops, such as rice, can provide essential information to breeders to generate improved cultivars capable of withstanding environmental challenges. Therefore, this study aimed to evaluate the tolerance mechanisms of two rice cultivars with different salinity tolerance. The rice cultivars, Sakha Super 300 (SS300, tolerant) and Blue Bonnet 76 (BB76, sensitive), were subjected to 0 and 100 mM NaCl (control and salt stress, respectively) for 14 days. Subsequently, growth indices (dry weight and plant length), physiological parameters (Na+ and K + concentrations, secondary metabolites, enzyme activities, and chlorophyll and carotenoid concentrations), and the expression of Na+ and K + transport-coding genes were determined. The results showed that the dry weight (DW) of SS300 was not significantly altered by salt stress, whereas that of BB76 decreased by 1.8 folds. The leaf Na+ concentration in SS300 (15.3 mg/g DW) was less than that of BB76 (23.7 mg/g DW), whereas the ratio of Na+/ K + was significantly higher in BB76 than in SS300 leaves. The leaf proline concentration of BB76 was 23-fold that of control and 9-fold that of SS300, whereas total flavonoid increased only in the leaves of SS300 (38 % increase). Regarding antioxidant enzyme activities, peroxidase (POD) significantly declined (2.7-fold) in the leaves of BB76 but remained unchanged in SS300. Regarding gene expression, there was 21- and 10-fold upregulation of OsHKT1;5 expression in the roots of SS300 and BB76, respectively, whereas root OsAKT1 and OsHAK7 were induced only in SS300 (2.3 and 2-fold induction, respectively). These results suggest that the susceptibility of BB76 to salt stress is likely attributed to the utilization of more energy for osmolyte synthesis, and reduced antioxidants and Na+ and K + regulation. [ABSTRACT FROM AUTHOR]

SUMMARY: Salinity is frequently mentioned as a major constraint in worldwide agricultural production. Lint percentage (LP) is a crucial yield‐component in cotton lint production. While the genetic factors affect cotton yield in saline soils are still unclear. Here, we employed a recombinant inbred line population in upland cotton (Gossypium hirsutum L.) and investigated the effects of salt stress on five yield and yield component traits, including seed cotton yield per plant, lint yield per plant, boll number per plant, boll weight, and LP. Between three datasets of salt stress (E1), normal growth (E2), and the difference values dataset of salt stress and normal conditions (D‐value), 87, 82, and 55 quantitative trait loci (QTL) were detectable, respectively. In total, five QTL (qLY‐Chr6‐2, qBNP‐Chr4‐1, qBNP‐Chr12‐1, qBNP‐Chr15‐5, qLP‐Chr19‐2) detected in both in E1 and D‐value were salt related QTL, and three stable QTL (qLP‐Chr5‐3, qLP‐Chr13‐1, qBW‐Chr5‐5) were detected both in E1 and E2 across 3 years. Silencing of nine genes within a stable QTL (qLP‐Chr5‐3) highly expressed in fiber developmental stages increased LP and decreased fiber length (FL), indicating that multiple minor‐effect genes clustered on Chromosome 5 regulate LP and FL. Additionally, the difference in LP caused by Gh_A05G3226 is mainly in transcription level rather than in the sequence difference. Moreover, silencing of salt related gene (GhDAAT) within qBNP‐Chr4‐1 decreased salt tolerance in cotton. Our findings shed light on the regulatory mechanisms underlining cotton salt tolerance and fiber initiation. Significance Statement: Our study provided important gene resources for salt tolerance improvement of cotton, and shed light on the regulatory mechanisms underlining plant salt tolerance. [ABSTRACT FROM AUTHOR]

Premise: Salt tolerance has rarely been investigated regionally in the neotropics and even more rarely in Orchidaceae, one of the largest families. Therefore, investigating local adaptation to salt spray and its physiological basis in Epidendrum fulgens, a neotropical orchid species, brings important new insights. Methods: We assessed the degree of salt tolerance in E. fulgens by testing whether coastal populations are more tolerant to salt, which could point to local adaptation. To understand the physiological basis of such salt tolerance, we exposed wild‐collected individuals to salt spray for 60 days, then measured leaf expansion, osmotic potential, sodium leaf concentration, chlorophyll leaf index, chlorophyll fluorescence, relative growth rate, and pressure–volume curves. Results: There is no local adaptation to salt spray since both inland and coastal plants have a high tolerance to salt stress. This tolerance is explained by the ability to tolerate high concentrations of salt in leaf tissues, which is related to the high succulence displayed by this species. Conclusions: We showed an unprecedented salt tolerance level for an orchid species, highlighting our limited knowledge of that trait beyond the traditional studied groups. Another interesting finding is that salt tolerance in E. fulgens is linked to succulence, is widespread, and is not the result of local adaptation. We suggest that E. fulgens and its allied species could be an interesting group to explore the evolution of important traits related to tolerance to salt stress, like succulence. [ABSTRACT FROM AUTHOR]

Background: Salt is an important factor that affects crop productivity. Plant hexokinases (HXKs) are key enzymes in the glycolytic pathway and sugar signaling transduction pathways of plants. In previous studies, we identified and confirmed the roles of GmHXK2 in salt tolerance. Results: In this study, we analyzed the tissue-specific expression of GmHXK2 at different growth stages throughout the plant's life cycle. The results showed that GmHXK2 was expressed significantly in all tissues at vegetative stages, including germination and seedling. However, no expression was detected in the pods, and there was little expression in flowers during the later mature period. Arabidopsis plants overexpressing the GmHXK2 (OE) had more lateral roots. The OE seedlings also produced higher levels of auxin and ascorbic acid (AsA). Additionally, the expression levels of genes PMM, YUC4/YUC6/YUC8, and PIN/LAX1,LAX3, which are involved respectively in the synthesis of AsA and auxin, as well as polar auxin transport, were upregulated in OE plants. This upregulation occurred specifically under exogenous glucose treatment. AtHKT1, AtSOS1, and AtNHX1 were up-regulated in OE plants under salt stress, suggesting that GmHXK2 may modulate salt tolerance by maintaining ion balance within the cells and alleviating damage caused by salt stress. Additionally, we further confirmed the interaction between GmHXK2 and the protein GmPMM through yeast two-hybridization and bimolecular fluorescence complementation assays, respectively. Conclusion: The expression of GmHXK2 gene in plants is organ-specific and developmental stage specific. GmHXK2 not only regulates the synthesis of AsA and the synthesis and distribution of auxin, but also promotes root elongation and induces lateral root formation, potentially enhancing soil water absorption. This study reveals the crosstalk between sugar signaling and hormone signaling in plants, where GmHXK2 acts as a glucose sensor through its interaction with GmPMM, and sheds light on the molecular mechanism by which GmHXK2 gene is involved in salt tolerance in plants. [ABSTRACT FROM AUTHOR]

Biotic stresses caused by bacterial and fungal pathogens damage crops; identifying treatments that enhance disease resistance provides important information for understanding plant defenses and sustainable agriculture. Salt stress affects crop yields worldwide; however, studies have focused on the toxic sodium ion, leaving the effects of the chloride ion unclear. In this study, we found that irrigation with a combination of chloride salts (MgCl2, CaCl2, and KCl) suppressed the cell death phenotype of the ceramide kinase mutant acd5. Chloride salt pre-irrigation also significantly limited the cell death caused by Pseudomonas syringae pv maculicola infection and inhibited the multiplication of this bacterial pathogen in a mechanism partially dependent on the salicylic acid pathway. Moreover, chloride salt preirrigation improved plant defenses against the fungal pathogen challenge, confining the lesion area caused by Botrytis cinerea infection. Furthermore, the growth of herbivorous larvae of Spodoptera exigua was retarded by feeding on chloride salt irrigated plants. Thus, our data suggest that treatment with Clincreases broad spectrum resistance to biotic challenges. [ABSTRACT FROM AUTHOR]

The holly Ilex dabieshanensis K. Yao & M. B. Deng, a tree endemic to the Dabieshan Mountains region in China, is a commonly used landscaping plant. Like other crops, its growth is affected by salt stress. The molecular mechanism underlying salt tolerance in holly is still unclear. In this study, we used NaCl treatment and RNA sequencing (RNA-seq) at different times to identify the salt stress response genes of holly. A total of 4775 differentially expressed genes (DEGs) were identified. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of the DEGs obtained at different salt treatment times (3, 6, 9, 12, and 24 h), as compared to control (ck, 0 h), showed that plant hormone signal transduction and carotenoid biosynthesis were highly enriched. The mechanism by which holly responds to salt stress involves many plant hormones, among which the accumulation of abscisic acid (ABA) and its signal transduction may play an important role. In addition, ion homeostasis, osmotic metabolism, accumulation of antioxidant enzymes and nonenzymatic antioxidant compounds, and transcription factors jointly regulate the physiological balance in holly, providing important guarantees for its growth and development under conditions of salt stress. These results lay the foundation for studying the molecular mechanisms of salt tolerance in holly and for the selection of salt-tolerant varieties. [ABSTRACT FROM AUTHOR]

This study aimed to analyze the effects of salt stress on the growth physiology and plant-cell ultrastructure of Isatis indigotica Fort. (I. indigotica) to evaluate its adaptability under salt stress. The effects of different concentrations of salt (NaCl; 0, 25, and 300 mmol·L−1) on the agronomic traits, activities of related enzymes, ion balance, and mesophyll-cell ultrastructure of I. indigotica were studied in a controlled pot experiment. Results showed that compared with those of the control group, the aerial-part fresh weight, underground fresh weight, tiller number, root length, root diameter, plant height, and leaf area of salt-stressed I. indigotica increased at 25 mmol·L−1 and then decreased at 300 mmol·L−1. The changes in levels of superoxide dismutase, peroxidase, ascorbate peroxidase, and catalase showed a similar trend, with significant differences compared with control group. Salt stress altered the ion balance of I. indigotica, resulting in a significant increase in Na+ content and a significant decrease in K+ content. The contents of Ca2+ and Mg2+ changed to varying degrees. The analysis of the microstructure of the root showed that under salt treatment, the epidermal cells of the root significantly thickened and the diameter of the xylem decreased. The results of ultrastructural analysis of mesophylls showed that salt stress can cause cell-membrane contraction, cell-gap enlargement, disorder in the structures of chloroplasts and mitochondria, and an increase in the number of osmiophilic particles. These changes were aggravated by the increase in NaCl concentration. This study reveals the response of I. indigotica to salt stress and provides a basis for further study on the salt-tolerance mechanism of I. indigotica. [ABSTRACT FROM AUTHOR]

Salt stress is a major abiotic stress that affects the growth of Reaumuria soongorica and many psammophytes in the desert areas of Northwest China. However, various Plant Growth-Promoting Rhizobacteria (PGPR) have been known to play an important role in promoting plant growth and alleviating the damaging effects of salt stress. In this study, three PGPR strains belonging to Bacillaceae were isolated from the rhizosphere of Reaumuria soongorica by morphological and molecular identification. All isolated strains exhibited capabilities of producing IAA, solubilizing phosphate, and fixing nitrogen, and were able to tolerate high levels of NaCl stress, up to 8-12%. The results of the pot-based experiment showed that salt (400 mM NaCl) stress inhibited Reaumuria soongorica seedlings' growth performance as well as biomass production, but after inoculation with strains P2, S37, and S40, the plant's height significantly increased by 26.87, 17.59, and 13.36%, respectively (p < 0.05), and both aboveground and root fresh weight significantly increased by more than 2 times compared to NaCl treatment. Additionally, inoculation with P2, S37, and S40 strains increased the content of photosynthetic pigments, proline, and soluble protein in Reaumuria soongorica seedlings under NaCl stress, while reducing the content of malondialdehyde and soluble sugars. Metabolomic analysis showed that strain S40 induces Reaumuria soongorica seedling leaves metabolome reprogramming to regulate cell metabolism, including plant hormone signal transduction and phenylalanine, tyrosine, and tryptophan biosynthesis pathways. Under NaCl stress, inoculation with strain S40 upregulated differential metabolites in plant hormone signal transduction pathways including plant hormones such as auxins (IAA), cytokinins, and jasmonic acid. The results indicate that inoculation with Bacillaceae can promote the growth of Reaumuria soongorica seedlings under NaCl stress and enhance salt tolerance by increasing the content of photosynthetic pigments, accumulating osmoregulatory substances, regulating plant hormone levels This study contributes to the enrichment of PGPR strains capable of promoting the growth of desert plants and has significant implications for the psammophytes growth and development in desert regions, as well as the effective utilization and transformation of saline-alkali lands. [ABSTRACT FROM AUTHOR]

Summary: Most splicing factors are extensively phosphorylated but their physiological functions in plant salt resistance are still elusive.We found that phosphorylation by SnRK1 kinase is essential for SRRM1L nuclear speckle formation and its splicing factor activity in plant cells. In Arabidopsis, loss‐of‐function of SRRM1L leads to the occurrence of alternative pre‐mRNA splicing events and compromises plant resistance to salt stress.In Arabidopsis srrm1l mutant line, we identified an intron‐retention Nuclear factor Y subunit A 10 (NFYA10) mRNA variant by RNA‐Seq and found phosphorylation‐dependent RNA‐binding of SRRM1L is indispensable for its alternative splicing activity. In the wild‐type Arabidopsis, salt stress can activate SnRK1 to phosphorylate SRRM1L, triggering enrichment of functional NFYA10.1 variant to enhance plant salt resistance. By contrast, the Arabidopsis srrm1l mutant accumulates nonfunctional NFYA10.3 variant, sensitizing plants to salt stress.In summary, this work deciphered the molecular mechanisms and physiological functions of SnRK1‐SRRM1L‐NFYA10 module, shedding light on a regulatory pathway to fine‐tune plant adaptation to abiotic stress at the post‐transcriptional and post‐translational levels. [ABSTRACT FROM AUTHOR]

While soybean (Glycine max L.) provides the most important source of vegetable oil and protein, it is sensitive to salinity, which seriously endangers the yield and quality during soybean production. The application of Plant Growth‐Promoting Rhizobacteria (PGPR) to improve salt tolerance for plant is currently gaining increasing attention. Streptomycetes are a major group of PGPR. However, to date, few streptomycetes has been successfully developed and applied to promote salt tolerance in soybean. Here, we discovered a novel PGPR strain, Streptomyces lasalocidi JCM 3373T, from 36 strains of streptomycetes via assays of their capacity to alleviate salt stress in soybean. Microscopic observation showed that S. lasalocidi JCM 3373T does not colonise soybean roots. Chemical analysis confirmed that S. lasalocidi JCM 3373T secretes indole‐3‐carboxaldehyde (ICA1d). Importantly, IAC1d inoculation alleviates salt stress in soybean and modulates its root architecture by regulating the expression of stress‐responsive genes GmVSP, GmPHD2 and GmWRKY54 and root growth‐related genes GmPIN1a, GmPIN2a, GmYUCCA5 and GmYUCCA6. Taken together, the novel PGPR strain, S. lasalocidi JCM 3373T, alleviates salt stress and improves root architecture in soybean by secreting ICA1d. Our findings provide novel clues for the development of new microbial inoculant and the improvement of crop productivity under salt stress. Summary statement: Streptomyces lasalocidi JCM 3373T, selected from 36 species of streptomycetes, alleviates salt tolerance and shapes root architecture by secreting a metabolite‐indole‐3‐carboxaldehyde in soybean. [ABSTRACT FROM AUTHOR]

Due to their immobility and possession of underground parts, plants have evolved various mechanisms to endure and adapt to abiotic stresses such as extreme temperatures, drought, and salinity. However, the contribution of long noncoding RNAs (lncRNAs) to different abiotic stresses and distinct rice seedling parts remains largely uncharacterized beyond the protein-coding gene (PCG) layer. Using transcriptomics and bioinformatics methods, we systematically identified lncRNAs and characterized their expression patterns in the roots and shoots of wild type (WT) and ososca1.1 (reduced hyperosmolality-induced [Ca2+]i increase in rice) seedlings under hyperosmolarity and salt stresses. Here, 2937 candidate lncRNAs were identified in rice seedlings, with intergenic lncRNAs representing the largest category. Although the detectable sequence conservation of lncRNAs was low, we observed that lncRNAs had more orthologs within the Oryza. By comparing WT and ososca1.1, the transcription level of OsOSCA1.1-related lncRNAs in roots was greatly enhanced in the face of hyperosmolality stress. Regarding regulation mode, the co-expression network revealed connections between trans-regulated lncRNAs and their target PCGs related to OsOSCA1.1 and its mediation of hyperosmolality stress sensing. Interestingly, compared to PCGs, the expression of lncRNAs in roots was more sensitive to hyperosmolarity stress than to salt stress. Furthermore, OsOSCA1.1-related hyperosmolarity stress-responsive lncRNAs were enriched in roots, and their potential cis-regulated genes were associated with transcriptional regulation and signaling transduction. Not to be ignored, we identified a motif-conserved and hyperosmolarity stress-activated lncRNA gene (OSlncRNA), speculating on its origin and evolutionary history in Oryza. In summary, we provide a global perspective and a lncRNA resource to understand hyperosmolality stress sensing in rice roots, which helps to decode the complex molecular networks involved in plant sensing and adaptation to stressful environments. [ABSTRACT FROM AUTHOR]

MOCA1 encodes the last key glucuronosyltransferase for ionic stress sensor glycosyl inositol phosphoryl-ceramide (GIPCs) biosynthesis in Arabidopsis, which indicates that the MOCA gene family play important role in plant tolerance to salt stress. However, the isolation and function of MOCAs in staple crops have not been reported and the downstream targets of MOCAs in salt stress tolerance signalling pathway are not clear. In this study, we identified 110 MOCA genes in wheat which were classified into five clades and they differed in gene structure, protein length, conserved motifs and expression profiles in different tissues and under salt stress. TaMOCA1 was selected for further functional study in response to salt stress. TaMOCA1 was rapidly induced by NaCl treatment. The 35S::TaMOCA1-GFP construction showed the cell nucleus and cytoplasm location in wheat protoplast. TaMOCA1 over-expressing Arabidopsis seedlings formed longer primary roots and more lateral roots than the wild type ones under 50 mM NaCl treatment. The over-expressing Arabidopsis had higher expression levels of HKT1, but lower expression levels of NHX1 and SOS genes than the wild type. Also, the transgenic plants had higher SOD activity and lower MDA content than the wild Arabidopsis seedling under salt stress. These results may indicate that TaMOCA1 increases salt stress tolerance through decreasing Na+ loading from the xylem parenchyma cells to the xylem via SOS1 and HKT1, hence lowering root-to-shoot delivery of Na+ and superior antioxidant ability. All these results lay a foundation for further functional study of MOCAs in wheat. [ABSTRACT FROM AUTHOR]

Soil salinization is a major abiotic stress factor that negatively impacts plant growth, development, and crop yield, severely limiting agricultural production and economic development. Cotton, a key cash crop, is commonly cultivated as a pioneer crop in regions with saline-alkali soil due to its relatively strong tolerance to salt. This characteristic renders it a valuable subject for investigating the molecular mechanisms underlying plant salt tolerance and for identifying genes that confer salt tolerance. In this study, focus was placed on examining a salt-tolerant variety, E991, and a salt-sensitive variety, ZM24. A combined analysis of transcriptomic data from these cotton varieties led to the identification of potential salt stress-responsive genes within the glutathione S-transferase (GST) family. These versatile enzyme proteins, prevalent in animals, plants, and microorganisms, were demonstrated to be involved in various abiotic stress responses. Our findings indicate that suppressing GhGSTF9 in cotton led to a notably salt-sensitive phenotype, whereas heterologous overexpression in Arabidopsis plants decreases the accumulation of reactive oxygen species under salt stress, thereby enhancing salt stress tolerance. This suggests that GhGSTF9 serves as a positive regulator in cotton's response to salt stress. These results offer new target genes for developing salt-tolerant cotton varieties. [ABSTRACT FROM AUTHOR]

p-Coumaric acid (p-CA) is a phenolic compound that plays a crucial role in mediating multiple signaling pathways. It serves as a defense strategy against plant wounding and is also presumed to play a role in plant development and lignin biosynthesis. This study aimed to investigate the physiological and ionomic effect of p-CA on chia seedlings under salt stress. To this end, chia seedlings were supplemented with Nitrosol® containing 100 μM of p-CA, 100 of mM NaCI, and their combined (100 mM NaCI + 100 μM p-CA) solutions in 2-day intervals for a period of 14 days along with a control containing Nitrosol® only. The treatment of chia seedlings with 100 mM of NaCI decreased their growth parameters and the content of the majority of the essential macro-elements (K, P, Ca, and Mg), except for that of sodium (Na). The simultaneous application of p-CA and a salt stress treatment (p-CA + NaCI) alleviated the effect of salt stress on chia seedlings' shoots, and this was indicated by the increase in chia biomass. Furthermore, this combined treatment significantly enhanced the levels of the essential microelements Mg and Ca. In summary, this brief report is built on the foundational work of our previous study, which demonstrated that p-CA promotes growth in chia seedlings via activation of O2−. In this brief report, we further show that p-CA not only promotes growth but also mitigates the effects of salt stress on chia seedlings. This mitigation effect may result from the presence of Mg and Ca, which are vital nutrients involved in regulating metabolic pathways, enzyme activity, and amino acid synthesis. [ABSTRACT FROM AUTHOR]

The climate-driven challenges facing Earth necessitate a comprehensive understanding of the mechanisms facilitating plant resilience to environmental stressors. This review delves into the crucial role of ubiquitin-like modifiers, particularly focusing on ATG8-mediated autophagy, in bolstering plant tolerance to salt stress. Synthesising recent research, we unveil the multifaceted contributions of ATG8 to plant adaptation mechanisms amidst salt stress conditions, including stomatal regulation, photosynthetic efficiency, osmotic adjustment, and antioxidant defence. Furthermore, we elucidate the interconnectedness of autophagy with key phytohormone signalling pathways, advocating for further exploration into their molecular mechanisms. Our findings underscore the significance of understanding molecular mechanisms underlying ubiquitin-based protein degradation systems and autophagy in salt stress tolerance, offering valuable insights for designing innovative strategies to improve crop productivity and ensure global food security amidst increasing soil salinisation. By harnessing the potential of autophagy and other molecular mechanisms, we can foster sustainable agricultural practices and develop stress-tolerant crops resilient to salt stress. [ABSTRACT FROM AUTHOR]

(1) Background: Soil salinity is one of the major abiotic stresses that limits plant growth and production. However, the response patterns of plant growth and carbon metabolism to salt stress are still unclear. (2) Methods: We measured the relative growth rate, non-structural carbohydrate (NSC) concentrations and pool size across organs, the leaf mass area (LMA), root-to-shoot ratio, midday leaf water potential (Ψmd), and photosynthetic characteristics of elm seedlings planted in the field under different salt stress intensities and durations. (3) Results: Salt stress can reduce the photosynthesis rate, stomatal conductance, and Ψmd and inhibit the growth of elm species. LMA increased with the degree and duration of salt stress, indicating an increase in leaf carbon investment to resist salt stress. The root-to-shoot ratio decreased under salt stress to reduce salt absorption by the roots. In the early stage of stress, the concentrations of starch and total NSCs in all organs increased to improve stress resistance and the survival of plants. In the late stage of stress, the concentration of NSCs in the root decreased, which could restrict root growth and water uptake. The relationships between NSC concentration and growth in different organs were contrasting. Meanwhile, the pool size of NSCs had a more significant impact on growth than their concentration. Moreover, the pool size of NSCs in below-ground organs is more closely related to growth than that of above-ground organs. (4) Conclusions: Our research elucidates the carbon allocation mechanism across organs under different salt stress intensities and durations, providing theoretical support for understanding the relationship between tree growth and carbon storage under salt stress. [ABSTRACT FROM AUTHOR]

Modern Solanum melongena varieties have been developed to improve the content of phenolics, sugars, and nutritionally relevant minerals in fruit. However, fruit composition might be altered due to abiotic stresses like salinity. Physiological and fruit quality traits were evaluated in four eggplant landraces under usual irrigation and moderately salty irrigation conditions (80 mM NaCl). Growing parameters measured included root length, leaf surface, and fresh weight, while fruit composition traits included sugars, phenolics, and mineral content determinations. Few differences were observed for agronomic traits, probably due to the mild tolerance of eggplant to salinity. Some varieties showed signs of salt tolerance like an increase in primary root length to overcome salt stress. Glucose was the metabolite more affected by the salt treatment in the fruit, while phenolic compounds and other metabolites studied were not altered. Significant differences were observed in the main minerals Na, K, Ca, P, and Mg, both between genotypes and treatments. Although salinity produced changes in some physiological and developmental traits, the composition of the fruit was not significantly modified for the accessions tested. Mineral, sugar, and phenolic contents were not particularly altered in unripe fruits, indicating tolerance of eggplant varieties to salinity in terms of fruit quality. [ABSTRACT FROM AUTHOR]

Tomato production in the Canary Islands has significantly decreased in recent years due to the presence of parasites and pathogens, poor-quality irrigation water, lack of infrastructure modernization, and increased competition. To address this issue, local varieties with better agro-climatic adaptation and organoleptic characteristics have been cultivated. These varieties show their maximum potential under an agro-ecological cultivation system, where the beneficial micro-organisms of the rhizosphere (in general) and mycorrhizal fungi (in particular) have a positive influence on their development, especially when the plants are subjected to biotic or abiotic stresses. Irrigation water in Canary Islands tomato cultivation comes from groundwater sources with moderate levels of sodium and chlorides or sodium and bicarbonates. This study evaluated the response of mycorrizal plants of the local tomato variety "Manzana Negra" under abiotic stress conditions due to the presence of chlorides and bicarbonates. Two tests were carried out with mycorrhizal and non-mycorrhizal plants. In the first one, 0, 75, and 150 mM NaCl solutions were applied. In the second, the nutrient solution was enriched with sodium bicarbonate at doses of 0, 2.5, 5, 7.5, 10, and 12.5 mM. Presence of native mycorrhizae improved the growth and nutrition of plants affected by irrigation with saline and alkaline water containing chloride and sodium carbonate. Symbiosis produced statistically significant increases in all plant-development-related variables (stem length and diameter; fresh and dry weight) in all bicarbonate concentrations. However, the results with the application of sodium chloride do not seem to indicate a positive interaction in most of the analytical parameters at 150 mM NaCl concentration. The mycorrhizal inoculation with local fungi can be interesting in the production of seedlings of this tomato variety in situations of moderate salinity, especially under bicarbonate stress conditions. [ABSTRACT FROM AUTHOR]

The combination of high or low temperatures and high salt may cause significant harm to the yield, quality, and overall productivity of forage pea crops. The germination process, a crucial phase in the life cycle of forage peas, may be greatly influenced by varying temperature and salinity conditions. To comprehend the influence of these elements on the germination of forage peas, one must use many tactics, including the choice of resilient forage pea cultivars. The experiment aimed to evaluate the response of four forage pea cultivars (Arda, Ozkaynak, Taskent, and Tore) caused by various temperature (10 °C, 15 °C, and 20 °C) and salt (0, 5, 10, 15, and 20 dS m−1) conditions at the germination stage using multivariate analysis and machine learning methods. An observation of statistical significance (p < 0.01) was made regarding the variations between genotypes, temperature–salt levels, and the interaction of the observed factors: germination percentage (GP), shoot length (SL), root length (RL), fresh weight (FW), and dry weight (DW). The cultivar Tore had the best values for SL (1.63 cm), RL (5.38 cm), FW (1.10 g), and DW (0.13 g) among all the cultivars. On the other hand, the Ozkaynak cultivar had the highest value for GP (89.13%). The values of all of the parameters that were investigated decreased as the salt level rose, whereas the values increased when the temperature level increased. As a result, the Tore cultivar exhibited the highest values for shoot length, root length, fresh weight, and dry weight variables when exposed to a maximum temperature of 20 °C and a saline level of 0 dS m−1. It was determined that temperature treatment of fodder peas can reduce salt stress if kept at optimum levels. The effects of temperature and salt treatments on the germination data of several fodder pea cultivars were analyzed and predicted. Three distinct machine learning algorithms were used to create predictions. Based on R2 (0.899), MSE (5.344), MAPE (6.953), and MAD (4.125) measures, the MARS model predicted germination power (GP) better. The GPC model performed better in predicting shoot length (R2 = 0.922, MSE = 0.602, MAPE = 11.850, and MAD = 0.326) and root length (R2 = 0.900, MSE = 0.719, MAPE = 12.673, and MAD = 0.554), whereas the Xgboost model performed better in estimating fresh weight (R2 = 0.966, MSE = 0.130, MAPE = 11.635, and MAD = 0.090) and dry weight (R2 = 0.895, MSE = 0.021, MAPE = 12.395, and MAD = 0.013). The results of the research show that the techniques and analyses used can estimate stress tolerance, susceptibility levels, and other plant parameters, making it a cost-effective and reliable way to quickly and accurately study forage peas and related species. [ABSTRACT FROM AUTHOR]

Potassium is an essential mineral nutrient for citrus growth and stress response. In this study, the HAK/KUP/KT gene family was identified from the genome of trifoliate orange (Poncirus trifoliata). The physical and chemical properties, chromosomal location, gene structure, evolutionary relationship, conserved motifs, and tissue expression characteristics were analyzed. The expression characteristics under low potassium and salt stress were analyzed by fluorescence quantitative PCR. The function of PtKUP10 was investigated by heterologous expression in Arabidopsis thaliana. The results showed that at least 18 PtKUPs were distributed in seven chromosomes. Phylogenetic analysis showed that four PtKUPs clustered in clade I, which mediated the high-affinity potassium absorption. Gene expression analysis showed that four PtKUPs were highly expressed in root, seven PtKUPs were up-regulated by low potassium stress, and nine PtKUPs were up-regulated by salt stress. The cis-acting elements on the promoter of PtKUPs were predominantly involved in stress and hormone responses. Overexpression of PtKUP10 in Arabidopsis thaliana could enhance salt tolerance by accumulating more potassium in the shoot and reducing sodium content in the shoots and roots. These results indicated that PtKUPs play important roles in potassium absorption and salt stress response, and PtKUP10 might enhance salt tolerance by maintaining potassium and sodium homeostasis. [ABSTRACT FROM AUTHOR]

NAC (NAM, ATAF1/2, and CUC2) transcription factors regulate plant growth and development and response to various stresses. However, there is still limited insight into the NAC family in Chimonanthus praecox. This study performed a genome-wide characterization of the NAC transcription factor family members in C. praecox. A total of 105 NAC family members were identified from the C. praecox genome. The phylogenetic tree categorized the CpNACs into nine groups and the accuracy of this classification was confirmed by the analysis results of conserved motifs, conserved domain, and gene structure. Cis-acting element analysis revealed that the promoters of CpNACs were abundant in elements responsive to various hormones and stresses, implying the functional diversity and complexity of CpNACs. Furthermore, we investigated the function of the CpNAC30. The expression level of CpNAC30 could be significantly induced by abiotic stress and the CpNAC30 was the highest expressed in mature leaves of C. praecox. Overexpression of CpNAC30 reduced salt stress tolerance of transgenic Arabidopsis. Nevertheless, the drought stress tolerance of transgenic plants was enhanced. This study lays a foundation for further understanding the function of CpNACs genes and provides insights for abiotic stress tolerance breeding of C. praecox and other woody plants. [ABSTRACT FROM AUTHOR]

Leucine-rich repeat extensin (LRX) is involved in the regulation of crucial cellular processes, such as cell wall growth and development, as well as signaling. However, the presence of the LRX gene family in Brassica rapa (B. rapa) has not been previously reported. This study identified 17 BrLRXs within the Brassica rapa genome by bioinformatic analysis, and these genes were distributed on seven chromosomes. Phylogenetic and covariance analyses indicate that BrLRXs can be categorized into two distinct branches: the trophic branch and the reproductive branch, with a close relationship observed between BrLRXs and AtLRXs. According to cis-acting element analysis, this gene family is rich in hormone-responsive and stress-responsive elements such as drought-inducibility, abscisic acid, methyl jasmonate, and gibberellic acid responsive elements, suggesting a potential role in abiotic stress response. Transcriptomic, proteomic, and RT-qPCR analyses demonstrated significant up-regulation of BrLRX2 and BrLRX6 under salt stress, while BrLRX3, BrLRX6, and BrLRX8 were significantly down-regulated under osmotic stress. Our analysis of the protein tertiary structure predicts a strong association between LRX proteins and RALF. Protein–protein interaction prediction revealed that LRX interacts with the RALF protein and the receptor FER, which have been previously reported to jointly regulate plant stress responses. We propose that BrLRX6 and BrLRX8 are implicated in osmotic stress, while BrLRX2 and BrLRX6 are involved in the modulation of salt stress. [ABSTRACT FROM AUTHOR]

Salinity stress, an ever-present challenge in agriculture and environmental sciences, poses a formidable hurdle for plant growth and productivity in saline-prone regions worldwide. Therefore, this study aimed to explore the effectiveness of trehalose and mannitol induce salt resistance in wheat seedlings. Wheat grains of the commercial variety Sakha 94 were divided into three groups : a group that was pre-soaked in 10 mM trehalose, another group was soaked in 10 mM mannitol, and the last was soaked in distilled water for 1 hour, then the pre soaked grains cultivated in sandy soil, each treatment was divided into two groups, one of which was irrigated with 150 mM NaCl and the other was irrigated with tap water. The results showed that phenols content in wheat seedlings increased and flavonoids reduced due to salt stress. Trehalose and mannitol cause slight increase in total phenols content while total flavonoids were elevated highy in salt-stressed seedlings. Furthermore, Trehalose or mannitol reduced salt-induced lipid peroxidation. Salt stress increases antioxidant enzyme activities of guaiacol peroxidase (G-POX), ascorbate peroxidase (APX), and catalase (CAT) in wheat seedlings, while polyphenol oxidase (PPO) unchanged. Trehalose and mannitol treatments caused an increase in APX, and CAT activities, whereas G-POX not altered but PPO activity were decreased under salt stress conditions. Molecular docking confirmed the interaction of Trehalose or mannitol with peroxidase and ascorbic peroxidase enzymes. Phenyl alanine ammonia layase (PAL) activity was increased in salt-stressed seedlings. We can conclude that pre-soaking of wheat grains in 10 mM trehalose or mannitol improves salinity stress tolerance by enhancing antioxidant defense enzyme and/or phenol biosynthesis, with docking identifying interactions with G-POX, CAT, APX, and PPO. [ABSTRACT FROM AUTHOR]

Salt stress is a well-known abiotic constraint that hampers crop productivity, affecting more than 424 million hectares of topsoil worldwide. Applying plant growth regulators externally has proven effective in enhancing crop resilience to salt stress. Previous metabolomics studies revealed an accumulation of Valine-Threonine-Isoleucine-Aspartic acid (VTID) in salt-stressed maize seedlings, suggesting its potential to assist maize adaptation to salt stress. To explore the effectiveness of VTID in enhancing salt tolerance in maize, 10 nM VTID was applied to salt-stressed maize seedlings. The results showed a remarkable 152.29% increase in plant height and a 122.40% increase in fresh weight compared to salt-stressed seedlings. Moreover, the addition of VTID enhanced the activity of antioxidant enzymes, specifically superoxide dismutase (SOD) and catalase (CAT), while reducing the level of malondialdehyde (MDA), a marker of oxidative stress. Additionally, VTID supplementation resulted in a significant increase in osmoregulatory substances such as proline. Metabolomic analysis revealed substantial changes in the metabolite profile of maize seedlings when treated with VTID during salt stress. Differential metabolites (DMs) analysis revealed that the identified DMs primarily belonged to lipids and lipid-like molecules. The receiver operating characteristic curve and linear regression analysis determined a correlation between isodolichantoside and the height of maize seedlings under salt-stress conditions. In conclusion, these findings validate that VTID effectively regulates tolerance in maize seedlings and offers valuable insights into the potential of short peptides for mitigating salt stress. [ABSTRACT FROM AUTHOR]

Triose phosphate utilization (TPU) limitation is one of the three biochemical limitations of photosynthetic CO2 assimilation rate in C3 plants. Under TPU limitation, abrupt and large transitions in light intensity cause damped oscillations in photosynthesis. When plants are salt-stressed, photosynthesis is often down-regulated particularly under dynamic light intensity, but how salt stress affects TPU-related dynamic photosynthesis is still unknown. To elucidate this, tomato (Solanum lycopersicum) was grown with and without sodium chloride (NaCl, 100 mM) stress for 13 d. Under high CO2 partial pressure, rapid increases in light intensity caused profound photosynthetic oscillations. Salt stress reduced photosynthetic oscillations in leaves initially under both low- and high-light conditions and reduced the duration of oscillations by about 2 min. Besides, salt stress increased the threshold for CO2 partial pressure at which oscillations occurred. Salt stress increased TPU capacity without affecting Rubisco carboxylation and electron transport capacity, indicating the up-regulation of end-product synthesis capacity in photosynthesis. Thus salt stress may reduce photosynthetic oscillations by decreasing leaf internal CO2 partial pressure and/or increasing TPU capacity. Our results provide new insights into how salt stress modulates dynamic photosynthesis as controlled by CO2 availability and end-product synthesis. [ABSTRACT FROM AUTHOR]

The cultivated Echinochloa frumentacea (Roxb.) Link and Echinochloa crusgalli (L.) Beauv. var. mitis (Pursh) Peter are two valuable grass species that are widely used in improving saline-alkali soil. Here we conducted a pot experiment combined with roots morphological analysis to investigate the adaptability of grass roots to saline stress environments, with cultivated E. frumentacea and E. crusgalli being subjected to salt treatments of 0 (CK), 100, 220, and 340 mmoL·L-. Results indicated that E. frumentacea had longer primary roots with fewer root hairs and lower local branching density than E. crusgalli, with the root volume of E. frumentacea being 1.43 times greater than that of E. crusgalli. The aboveground biomass of both grasses decreased significantly (p < 0.05) with increasing salt concentrations, whereas the root-to-shoot ratio exhibited the opposite trend, suggesting the preferential allocation of photosynthetic products to the roots under salt stress. The total length, surface area, and tip number of fine roots and the growth of coarse roots (d > 2.00 mm) showed significant differences (p < 0.05) between the two grass species. Different concentrations of salt stress had inconsistent effects on the biomass and radial growth of roots for grasses. The cultivated E. frumentacea seems to adopt an adapt strategy of gradually increasing its root thickness, root hairs, and root density under increasing salt stress. E. crusgalli, on the other hand, employed a strategy of increasing root length, maintaining uniform thickness, and developing root hairs. [ABSTRACT FROM AUTHOR]

Amaranth species are C4 plants that are rich in betalains, and they are tolerant to salinity stress. A small family of plant-specific TCP transcription factors are involved in the response to salt stress. However, it has not been investigated whether amaranth TCP1 is involved in salt stress. We elucidated that the growth and physiology of amaranth were affected by salt concentrations of 50–200 mmol·L−1 NaCl. The data showed that shoot and root growth was inhibited at 200 mmol·L−1, while it was promoted at 50 mmol·L−1. Meanwhile, the plants also showed physiological responses, which indicated salt-induced injuries and adaptation to the salt stress. Moreover, AtrTCP1 promoted Arabidopsis seed germination. The germination rate of wild-type (WT) and 35S::AtrTCP1-GUS Arabidopsis seeds reached around 92% by the seventh day and 94.5% by the second day under normal conditions, respectively. With 150 mmol·L−1 NaCl treatment, the germination rate of the WT and 35S::AtrTCP1-GUS plant seeds was 27.0% by the seventh day and 93.0% by the fourth day, respectively. Under salt stress, the transformed 35S::AtrTCP1 plants bloomed when they grew 21.8 leaves after 16.2 days of treatment, which was earlier than the WT plants. The transformed Arabidopsis plants flowered early to resist salt stress. These results reveal amaranth's growth and physiological responses to salt stress, and provide valuable information on the AtrTCP1 gene. [ABSTRACT FROM AUTHOR]

Salinity stress is a type of abiotic stress which negatively affects the signaling pathways and cellular compartments of plants. Melatonin (MT) has been found to be a bioactive compound that can mitigate these adverse effects, which makes it necessary to understand the function of MT and its role in salt stress. During this study, plants were treated exogenously with 100 µM of MT for 7 days and subjected to 200 mM of salt stress, and samples were collected after 1 and 7 days for different indicators and transcriptome analysis. The results showed that salt reduced chlorophyll contents and damaged the chloroplast structure, which was confirmed by the downregulation of key genes involved in the photosynthesis pathway after transcriptome analysis and qRT-PCR confirmation. Meanwhile, MT increased the chlorophyll contents, reduced the electrolyte leakage, and protected the chloroplast structure during salt stress by upregulating several photosynthesis pathway genes. MT also decreased the H2O2 level and increased the ascorbic acid contents and APX activity by upregulating genes involved in the ascorbic acid pathway during salt stress, as confirmed by the transcriptome and qRT-PCR analyses. Transcriptome profiling also showed that 321 and 441 DEGs were expressed after 1 and 7 days of treatment, respectively. The KEGG enrichment analysis showed that 76 DEGs were involved in the photosynthesis pathway, while 35 DEGs were involved in the ascorbic acid metabolism pathway, respectively. These results suggest that the exogenous application of MT in plants provides important insight into understanding MT-induced stress-responsive mechanisms and protecting Brassica campestris against salt stress by regulating the photosynthesis and ascorbic acid pathway genes. [ABSTRACT FROM AUTHOR]

Background: Members of the ACR gene family are commonly involved in various physiological processes, including amino acidmetabolismand stress responses. In recent decades, significant progress has been made in the study of ACR genes in plants. However, little is known about their characteristics and function in maize. Methods: In this study, ACR genes were identified from the maize genome, and their molecular characteristics, gene structure, gene evolution, gene collinearity analysis, cis-acting elements were analyzed. qRT-PCR technology was used to verify the expression patterns of the ZmACR gene family in different tissues under salt stress. In addition, Ectopic expression technique of ZmACR5 in Arabidopsis thaliana was utilized to identify its role in response to salt stress. Results: A total of 28 ZmACR genes were identified, and their molecular characteristics were extensively described. Two gene pairs arising from segmented replication events were detected in maize, and 18 collinear gene pairs were detected between maize and 3 other species. Through phylogenetic analysis, three subgroups were revealed, demonstrating distinct divergence between monocotyledonous and dicotyledonous plants. Analysis of ZmACR cis-acting elements revealed the optional involvement of ZmACR genes in light response, hormone response and stress resistance. Expression analysis of 8 ZmACR genes under salt treatment clearly revealed their role in the response to salt stress. Ectopic overexpression of ZmACR5 in Arabidopsis notably reduced salt tolerance compared to that of the wild type under salt treatment, suggesting that ZmACR5 has a negative role in the response to salt stress. Conclusion: Taken together, these findings confirmed the involvement of ZmACR genes in regulating salt stress and contributed significantly to our understanding of the molecular function of ACR genes in maize, facilitating further research in this field. [ABSTRACT FROM AUTHOR]

Soil salinization poses a significant threat to agricultural productivity, necessitating innovative agronomic strategies to mitigate its impact. This study focuses on improving salt stress resistance in tomato plants through the application of silicon (Si) in roots. A greenhouse experiment was carried out under normal conditions (control, and 1 and 4 mM Si) and under salinity stress (salt control, and 1 and 4 mM Si). Various parameters were analyzed in leaves and roots. Under normal conditions, tomato plants grown in non-saline conditions exhibited some toxicity when exposed to Na2SiO3. As for the experiments under salt stress conditions, Si mitigated oxidative damage, preserving root cell membrane integrity. The concentration of malondialdehyde was reduced by 69.5%, that of proline was reduced by 56.4% and there was a 57.6% decrease in catalase activity for tomato plants treated with 1 mM Si under salt stress. Furthermore, Fe uptake and distribution, under salt conditions, increased from 91 to 123 mg kg−1, the same concentration as that obtained for the normal control. In all cases, the lower dose produced better results under normal conditions than the 4 mM dose. In summary, this research provides a potential application of Si in non-fertigated crop systems through a radicular pathway. [ABSTRACT FROM AUTHOR]

Polyploid plants often exhibit enhanced stress tolerance. Switchgrass is a perennial rhizomatous bunchgrass that is considered ideal for cultivation in marginal lands, including sites with saline soil. In this study, we investigated the physiological responses and transcriptome changes in the octoploid and tetraploid of switchgrass (Panicum virgatum L. 'Alamo') under salt stress. We found that autoploid 8× switchgrass had enhanced salt tolerance compared with the amphidiploid 4× precursor, as indicated by physiological and phenotypic traits. Octoploids had increased salt tolerance by significant changes to the osmoregulatory and antioxidant systems. The salt-treated 8× Alamo plants showed greater potassium (K+) accumulation and an increase in the K+/Na+ ratio. Root transcriptome analysis for octoploid and tetraploid plants with or without salt stress revealed that 302 upregulated and 546 downregulated differentially expressed genes were enriched in genes involved in plant hormone signal transduction pathways and were specifically associated with the auxin, cytokinin, abscisic acid, and ethylene pathways. Weighted gene co-expression network analysis (WGCNA) detected four significant salt stress-related modules. This study explored the changes in the osmoregulatory system, inorganic ions, antioxidant enzyme system, and the root transcriptome in response to salt stress in 8× and 4× Alamo switchgrass. The results enhance knowledge of the salt tolerance of artificially induced homologous polyploid plants and provide experimental and sequencing data to aid research on the short-term adaptability and breeding of salt-tolerant biofuel plants. [ABSTRACT FROM AUTHOR]

Pectin is a structural polysaccharide and a major component of plant cell walls. Pectate lyases are a class of enzymes that degrade demethylated pectin by cleaving the α-1,4-glycosidic bond, and they play an important role in plant growth and development. Currently, little is known about the PL gene family members and their involvement in salt stress in potato. In this study, we utilized bioinformatics to identify members of the potato pectate lyase gene family and analyzed their gene and amino acid sequence characteristics. The results showed that a total of 27 members of the pectate lyase gene family were identified in potato. Phylogenetic tree analysis revealed that these genes were divided into eight groups. Analysis of their promoters indicated that several members' promoter regions contained a significant number of hormone and stress response elements. Further, we found that several members responded positively to salt treatment under single salt and mixed salt stress. Since StPL18 exhibited a consistent expression pattern under both single and mixed salt stress conditions, its subcellular localization was determined. The results indicated that StPL18 is localized in the endoplasmic reticulum membrane. The results will establish a foundation for analyzing the functions of potato pectate lyase family members and their expression under salt stress. [ABSTRACT FROM AUTHOR]

The SAUR (small auxin-up RNA) family constitutes a category of genes that promptly respond to the hormone auxin and play a pivotal role in diverse biological processes encompassing plant growth and the response to abiotic stress. Santalum album L., a semi-parasitic evergreen tree, is renowned for its economically valuable essential oils, positioning it among the most prized tree species. In this study, a meticulous identification and comprehensive analysis of 43 SAUR genes was conducted within S. album. Based on phylogenetic relationships, the SaSAUR genes were systematically categorized into five groups. A collinearity analysis revealed intriguing insights, disclosing 14 segmental duplications and 9 tandem duplications within the SaSAUR genes, emphasizing the pivotal role of duplication in the expansion of this gene family. Noteworthy variations in the expression levels of SaSAUR genes were observed by delving into the SaSAUR transcriptome data from various tissues, including leaves, roots, and heartwood, as well as under salt-stress conditions. Notably, SaSAUR08 and SaSAUR13 were significantly upregulated in heartwood compared with roots and leaves, while SaSAUR18 was markedly more expressed in roots compared with heartwood and leaves. Furthermore, SaSAUR27 and SaSAUR28 were found to respond closely to salt stress, hinting at their potential involvement in the salt-stress response mechanism. This research offers a comprehensive investigation of SAUR genes in S. album and establishes a foundation for future exploration of the SAUR gene family, particularly its relation to growth and salt-stress responses. [ABSTRACT FROM AUTHOR]

As a potential crop in saline-alkali land, the growth of switchgrass could also be threatened by salt stress. Promoting the growth of switchgrass under salt stress by humic acid has great significance in the utilization of saline-alkali land. In this study, a pot experiment was arranged to investigate the responses of photosynthetic and physicochemical characteristics of switchgrass to HA under salt stress. Results showed that humic acid increased the photosynthetic function of switchgrass and enhanced plant height by 41.1% and dry weight by 26.9% under salt stress. Correlation analysis showed that the membrane aquaporin gene PvPIP1, malondialdehyde, ascorbate peroxidase, abscisic acid, polyamine, and jasmonic acid were important factors affecting the photosynthetic function of switchgrass in this study. Meanwhile, HA reduced the content of malondialdehyde, indicating the alleviation of the membrane damage caused by salt stress. On the other hand, HA upregulated the relative expression of the PvPIP1 gene and activated ascorbate peroxidase, abscisic acid, polyamine, and jasmonic acid in switchgrass to resist salt stress. These improved the membrane stability and promoted the photosynthetic activity of switchgrass to enhance the plant's tolerance against salt stress and growth. Results from this study are helpful to the efficient growing of switchgrass and the sustainable development of saline-alkali land. [ABSTRACT FROM AUTHOR]

As the most abundant form of methylation modification in messenger RNA (mRNA), the distribution of N6‐methyladenosine (m6A) has been preliminarily revealed in herbaceous plants under salt stress, but its function and mechanism in woody plants were still unknown. Here, we showed that global m6A levels increased during poplar response to salt stress. Methylated RNA immunoprecipitation sequencing (MeRIP‐seq) revealed that m6A significantly enriched in the coding sequence region and 3′‐untranslated regions in poplar, by recognising the conserved motifs, AGACU, GGACA and UGUAG. A large number of differential m6A transcripts have been identified, and some have been proved involving in salt response and plant growth and development. Further combined analysis of MeRIP‐seq and RNA‐seq revealed that the m6A hypermethylated and enrich in the CDS region preferred to positively regulate expression abundance. Writer inhibitor, 3‐deazaneplanocin A treatment increased the sensitivity of poplar to salt stress by reducing mRNA stability to regulate the expression of salt‐responsive transcripts PagMYB48, PagGT2, PagNAC2, PagGPX8 and PagARF2. Furthermore, we verified that the methyltransferase PagFIP37 plays a positively role in the response of poplar to salt stress, overexpressed lines have stronger salt tolerance, while RNAi lines were more sensitive to salt, which relied on regulating mRNA stability in an m6A manner of salt‐responsive transcripts PagMYB48, PagGT2, PagNAC2, PagGPX8 and PagARF2. Collectively, these results revealed the regulatory role of m6A methylation in poplar response to salt stress, and revealed the importance and mechanism of m6A methylation in the response of woody plants to salt stress for the first time. Summary statement: We revealed the regulatory role of m6A methylation in poplar response to salt stress, and revealed the importance and mechanism of m6A methylation in the response of woody plants to salt stress for the first time. [ABSTRACT FROM AUTHOR]