SOS2-AFP2 module regulates seed germination by inducing ABI5 degradation in response to salt stress in Arabidopsis.

Soil salinity pose a significant challenge to global agriculture, threatening crop yields and food security. Understanding the salt tolerance mechanisms of plants is crucial for improving their survival under salt stress. AFP2, a negative regulator of ABA signaling, has been shown to play a crucial role in salt stress tolerance during seed germination. Mutations in AFP2 gene lead to increased sensitivity to salt stress. However, the underline mechanisms by which AFP2 regulates seed germination under salt stress remain elusive. In this study, we identified a protein interaction between AFP2 and SOS2, a Ser/Thr protein kinase known to play a critical role in salt stress response. Using a combination of genetic, biochemical, and physiological approaches, we investigated the role of the SOS2-AFP2 module in regulating seed germination under salt stress. Our findings reveal that SOS2 physically interacts with AFP2 and stabilizes it, leading to the degradation of the ABI5 protein, a negative transcription factor in seed germination under salt stress. This study sheds light on previously unknown connections within salt stress and ABA signaling, paving the way for novel strategies to enhance plant resilience against environmental challenges.

CO2 Response Screen in Grass Brachypodium Reveals Key Role of a MAP Kinase in CO2-Triggered Stomatal Closure.

Plants respond to increased CO2 concentrations through stomatal closure, which can contribute to increased water use efficiency. Grasses display faster stomatal responses than eudicots due to dumbbell-shaped guard cells flanked by subsidiary cells working in opposition. However, forward genetic screening for stomatal CO2 signal transduction mutants in grasses has yet to be reported. The grass model Brachypodium distachyon is closely related to agronomically important cereal crops, sharing largely collinear genomes. To gain insights into CO2 control mechanisms of stomatal movements in grasses, we developed an unbiased forward genetic screen with an EMS-mutagenized Brachypodium distachyon M5 generation population using infrared imaging to identify plants with altered leaf temperatures at elevated CO2. Among isolated mutants, a "chill1" mutant exhibited cooler leaf temperatures than wildtype Bd21-3 parent control plants after exposure to increased [CO2]. chill1 plants showed strongly impaired high CO2-induced stomatal closure despite retaining a robust abscisic acid-induced stomatal closing response. Through bulked segregant whole-genome-sequencing analyses followed by analyses of further backcrossed F4 generation plants and generation and characterization of sodium-azide and CRISPR-cas9 mutants, chill1 was mapped to a protein kinase, Mitogen-Activated Protein Kinase 5 (BdMPK5). The chill1 mutation impaired BdMPK5 protein-mediated CO2/HCO3- sensing together with the High Temperature 1 (HT1) Raf-like kinase in vitro. Furthermore, AlphaFold2-directed structural modeling predicted that the identified BdMPK5-D90N chill1 mutant residue is located at the interface of BdMPK5 with the BdHT1 Raf-like kinase. BdMPK5 is a key signaling component that mediates CO2-induced stomatal movements and is proposed to function as a component of the primary CO2 sensor in grasses.

Emerging multiple function of B-RAFs in plants.

Recent studies have revealed that B-subgroup rapidly accelerated fibrosarcoma (RAF) kinases have pivotal roles in hormone signaling and stress responses across a wide range of organisms. In this forum, I explore their evolution and diverse signaling pathways, highlighting the significance of B-RAF kinases in plant growth and plant-environment interactions while discussing open questions for future research.

Role of Abscisic Acid, Reactive Oxygen Species, and Ca2+ Signaling in Hydrotropism-Drought Avoidance-Associated Response of Roots.

Plant roots exert hydrotropism in response to moisture gradients to avoid drought stress. The regulatory mechanism underlying hydrotropism involves novel regulators such as MIZ1 and GNOM/MIZ2 as well as abscisic acid (ABA), reactive oxygen species (ROS), and Ca2+ signaling. ABA, ROS, and Ca2+ signaling are also involved in plant responses to drought stress. Although the mechanism of moisture gradient perception remains largely unknown, the sensory apparatus has been reported to reside in the root elongation zone rather than in the root cap. In Arabidopsis roots, hydrotropism is mediated by the action of MIZ1 and ABA in the cortex of the elongation zone, the accumulation of ROS at the root curvature, and the variation in the cytosolic Ca2+ concentration in the entire root tip including the root cap and stele of the elongation zone. Moreover, root exposure to moisture gradients has been proposed to cause asymmetric ABA distribution or Ca2+ signaling, leading to the induction of the hydrotropic response. A comprehensive and detailed analysis of hydrotropism regulators and their signaling network in relation to the tissues required for their function is apparently crucial for understanding the mechanisms unique to root hydrotropism. Here, referring to studies on plant responses to drought stress, we summarize the recent findings relating to the role of ABA, ROS, and Ca2+ signaling in hydrotropism, discuss their functional sites and plausible networks, and raise some questions that need to be answered in future studies.

Elevated CO2 induce alterations in the hormonal regulation of stomata in drought stressed tomato seedlings.

The atmospheric CO2 level is rising, and the consequent climate change is causing an increase in drought events. Furthermore, the CO2 level is known to induce changes in the physiological responses to stress in plants. Exogenous melatonin is suggested to play roles in the response of plants to abiotic stresses, including drought. We investigated physiological drought stress responses at ambient and elevated CO2 levels (aCO2 and eCO2) of melatonin-treated and untreated tomato plants, aiming to link effects of water use efficiency of photosynthesis at (WUELeaf) and stomatal conductance (gs) with the hormonal regulation of stomata. Tomatoes grown at eCO2 had reduced water use of both irrigated and drought stressed plants during the progression of drought at the whole plant level. This was also reflected in a CO2-affected increase in WUELeaf at eCO2 across irrigated and drought-stressed plants. These CO2-induced effects were mediated through stomatal closing and reductions in stomatal pore area rather than stomatal density or size. Abscisic acid (ABA) and its conjugated form, ABA glucose ester (ABA-GE), increased at drought stress in aCO2, while only ABA-GE increased at eCO2. Contrary, salicylic acid (SA) increased to a greater magnitude at drought stress in eCO2 than aCO2. Melatonin treatment showed no effects on the stomatal regulation. Our findings imply that eCO2 changes in the balance of hormonal effectors in stomatal regulation during drought, shifting from it ABA to SA regulation, suggesting to consider stomatal reactions at eCO2 in a perspective of a hormonal interplay rather than only ABA.

Integrated anatomical structure, physiological, and transcriptomic analyses to identify differential cold tolerance responses of Ziziphus jujuba mill. 'Yueguang' and its autotetraploid 'Hongguang'.

Cold stress is a limiting stress factor that limits plant distribution and development; however, polyploid plants have specific characteristics such as higher resistance to abiotic stress, especially cold stress, that allow them to overcome this challenge. The cultivated cultivar Ziziphus jujuba Mill. 'Yueguang' (YG) and its autotetraploid counterpart 'Hongguang' (HG) exhibit differential cold tolerance. However, the underlying molecular mechanism and methods to enhance their cold tolerance remain unknown. Anatomical structure and physiological analysis indicated YG had a higher wood bark ratio, and xylem ratio under cold treatment compared to HG. However, the half-lethal temperature (LT50), cortex ratio, and malondialdehyde (MDA) content were significantly decreased in YG than HG, which indicated YG was cold tolerant than HG. Transcriptome analysis showed that 2084, 1725, 2888, and 2934 differentially expressed genes (DEGs) were identified in HC vs YC, H20 vs Y20, Y20 vs YC, and H20 vs HC treatment, respectively. Meanwhile, KEGG enrichment analysis of DEGs showed that several metabolic pathways, primarily plant hormone signal transduction and the MAPK signaling pathway, were involved in the differential regulation of cold tolerance between YG and HG. Furthermore, exogenous abscisic acid (ABA) and brassinolide (BR) treatments could improve their cold tolerance through increased SOD and POD activities, decreased relative electrical conductivity, and MDA content. All of these findings suggested that plant hormone signal transduction, particularly ABA and BR, might have an important role in the regulation of differential cold tolerance between YG and HG, laying the foundation for further improving cold tolerance in jujube and examining the molecular mechanisms underlying differences in cold tolerance among different ploidy cultivars.

OsJAZ10 negatively modulates the drought tolerance by integrating hormone signaling with systemic electrical activity in rice.

Jasmonic acid (JA) plays crucial functions in plant stress response, and the synergistic interaction between JA and abscisic acid (ABA) signaling is implicated to help plants adapt to environmental challenges, whereas the underlying molecular mechanism still needs to be revealed. Here, we report that OsJAZ10, a repressor in the JA signaling, represses rice drought tolerance via inhibition of JA and ABA biosynthesis. Function loss of OsJAZ10 markedly enhances, while overexpression of OsJAZ10ΔJas reduces rice drought tolerance. The osjaz10 mutant is more sensitive to exogenous ABA and MeJA, and produces higher levels of ABA and JA after drought treatment, indicating OsJAZ10 represses the biosynthesis of these two hormones. Mechanistic study demonstrated that OsJAZ10 physically interacts with OsMYC2. Transient transcriptional regulation assays showed that OsMYC2 activates the expression of ABA-biosynthetic gene OsNCED2, JA-biosynthetic gene OsAOC, and drought-responsive genes OsRAB21 and OsLEA3, while OsJAZ10 prevents OsMYC2 transactivation of these genes. Further, the electrophoretic mobility shift assay (EMSA) confirmed that OsMYC2 directly binds to the promoters of OsNCED2 and OsRAB21. Electrical activity has been proposed to activate JA biosynthesis. Interestingly, OsJAZ10 inhibits the propagation of osmotic stress-elicited systemic electrical signals, indicated by the significantly increased PEG-elicited slow wave potentials (SWPs) in osjaz10 mutant, which is in accordance with the elevated JA levels. Collectively, our findings establish that OsJAZ10 functions as a negative regulator in rice drought tolerance by repressing JA and ABA biosynthesis, and reveal an important mechanism that plants integrate electrical events with hormone signaling to enhance the adaption to environmental stress.

Zonal Chemical Signal Pathways Mediating Floral Induction in Apple.

Phytohormones that trigger or repress flower meristem development in apple buds are thought to be locally emitted from adjacent plant tissues, including leaves and fruitlets. The presence of fruitlets is known to inhibit adjacent buds from forming flowers and thus fruits. The resulting absence of fruitlets the following season restores flower-promoting signalling to the new buds. The cycle can lead to a biennial bearing behaviour of alternating crop loads in a branch or tree. The hormonal stimuli that elicit flowering is typically referred to as the floral induction (FI) phase in bud meristem development. To determine the metabolic pathways activated in FI, young trees of the cultivar 'Ruby Matilda' were subjected to zonal crop load treatments imposed to two leaders of bi-axis trees in the 2020/2021 season. Buds were collected over the expected FI phase, which is within 60 DAFB. Metabolomics profiling was undertaken to determine the differentially expressed pathways and key signalling molecules associated with FI in the leader and at tree level. Pronounced metabolic differences were observed in trees and leaders with high return bloom with significant increases in compounds belonging to the cytokinin, abscisic acid (ABA), phenylpropanoid and flavanol chemical classes. The presence of cytokinins, namely adenosine, inosine and related derivatives, as well as ABA phytohormones, provides further insight into the chemical intervention opportunities for future crop load management strategies via plant growth regulators.

Abscisic acid induces PpeKIL1 to terminate fruit growth and promote fruit abortion in peach (Prunus persica).

Abnormal pollination from chance events or hybridization between species leads to unusual embryo development, resulting in fruit abortion. To elucidate the mechanism underlying fruit abortion, we conducted a comprehensive analysis of the transcriptome and hormone profiles in aborting fruits (AF) derived from an interspecific cross between the peach cultivar 'Huangjinmi 3' and the Prunus mume cultivar 'Jiangmei', as well as in normal-seeded fruits (NF) resulting from an intraspecific cross of 'Huangjinmi 3' with the 'Manyuanhong' peach cultivars. Growth of AF was inhibited during the exponential growth phase, with up-regulation of oxidative stress related genes and down-regulation of DNA replication and cell cycle genes. Accumulation of the tissue growth-related hormones auxin and cytokinin was reduced in AF, while levels of the growth inhibiting hormone abscisic acid (ABA) were higher compared to NF. The increased ABA concentration aligned with down-regulation of the ABA catabolism gene CYP707A2, which encodes abscisic acid 8'-hydroxylase. Correlation analysis showed ABA could explain the maximum proportion of differently expressed genes between NF and AF. We also showed that expression of KIRA1-LIKE1 (PpeKIL1), a peach ortholog of the Arabidopsis KIRA1 gene, was up-regulated in AF. PpeKIL1 promotes senescence or delays normal growth in tobacco and Arabidopsis, and its promoter activity increases with exogenous ABA treatment. Our study demonstrates a candidate mechanism where ABA induces expression of PpeKIL1, which further blocks normal fruit growth and triggers fruit abscission.

Protein kinase FaSnRK2.6 phosphorylates transcription factor FabHLH3 to regulate anthocyanin homeostasis during strawberry fruit ripening.

Strawberry (Fragaria×ananassa) is a model plant for studying non-climacteric fruit ripening regulated by abscisic acid (ABA). However, the signaling of ABA in the regulation of fruit coloration is not fully understood. Here, a transcription factor FabHLH3 key to fruit coloration is identified by yeast two hybrid library screening using FaSnRK2.6 as a bait, an ABA core signaling component negative to ripening. Indeed, this interaction is also confirmed by firefly luciferase complementation assay and pull-down assay. RT-qPCR and Western blotting analysis confirm FabHLH3 is expressed ubiquitously in strawberry and stably during fruit development. Manipulating both FabHLH3 and FaSnRK2.6 expression by overexpression and interference demonstrates that FabHLH3 and FaSnRK2.6 promote and inhibit strawberry fruit coloration, respectively, using the marker gene FaUFGT, key to anthocyanin biosynthesis. FaSnRK2.6 can phosphorylate FabHLH3, which promotes FaUFGT expression by the directly binding to its promoter. The phosphorylation inhibits the binding of FabHLH3 to FaUFGT promoter, consequently suppressing FaUFGT expression. Altogether, FaSnRK2.6, a negative kinase in ripening, interacts with and phosphorylates FabHLH3 to suppress FaUFGT expression. With the increase of ABA content in strawberry fruit ripening, the expression of FaSnRK2.6 decreased, which released FabHLH3 transcription activity and enhanced FaUFGT expression, finally promoting the coloration. Thus, our findings fill a gap how FaSnRK2.6 negatively regulates strawberry fruit coloration and ripening by FabHLH3.

The metabolism of amino acids, AsA and abscisic acid induced by strigolactone participates in chilling tolerance in postharvest zucchini fruit.

Zucchini fruit are notably susceptible to chilling injury when stored at low temperatures. The purpose of this experimental investigation was to assess the influence of strigolactone (ST) (5 µmol L-1) on mitigating chilling injury and the metabolic changes in amino acids, ascorbic acid, and abscisic acid in zucchini fruit stored at 4°C. Research findings demonstrated that ST-treated zucchini fruit displayed a significantly higher tolerance to chilling stress compared to the control group. Postharvest ST treatment led to a decrease in weight loss, accompanied by reduced levels of malondialdehyde and relative ion leakage compared to the untreated group. ST immersion significantly boosted the metabolic pathways associated with proline and arginine, affecting both the enzymatic reactions and gene expressions, thus cumulatively increasing the internal concentrations of these amino acids in zucchini fruit. Zucchini treated with ST exhibited an increased concentration of γ-aminobutyric acid (GABA) as a result of augmented activities and elevated transcriptional levels of glutamate decarboxylase (GAD), GABA transaminase (GAT), and succinate semialdehyde dehydrogenase (SSD). In the ST-treated sample, the elevated enzymatic activities and enhanced gene expressions within the ascorbic acid (AsA) biosynthesis pathway worked together to sustain AsA accumulation. The application of ST resulted in a rise in abscisic acid (ABA) concentration, which correspondingly correlated with the induction of both activities and gene expression levels of crucial enzymes involved in ABA metabolism. Our findings revealed that submerging zucchini fruit in ST could be a highly effective strategy for boosting their chilling tolerance. The alleviation in chilling injury induced by ST may be attributed to the modulation of proline, arginine, GABA, AsA and ABA metabolism.

Genome-wide characterization of Remorin gene family and their responsive expression to abiotic stresses and plant hormone in Brassica napus.

KEY MESSAGE: Remorin proteins could be positively related to salt and osmotic stress resistance in rapeseed. Remorins (REMs) play a crucial role in adaptations to adverse environments. However, their roles in abiotic stress and phytohormone responses in oil crops are still largely unknown. In this study, we identified 47 BnaREM genes in the B.napus genome. Phylogenetic relationship and synteny analysis revealed that they were categorized into 5 distinct groups and have gone through 55 segmental duplication events under purifying selection. Gene structure and conserved domains analysis demonstrated that they were highly conserved and all BnaREMs contained a conserved Remorin_C domain, with a variable N-terminal region. Promoter sequence analysis showed that BnaREM gene promoters contained various hormones and stress-related cis-acting elements. Transcriptome data from BrassicaEDB database exhibited that all BnaREMs were ubiquitously expressed in buds, stamens, inflorescences, young leaves, mature leaves, roots, stems, seeds, silique pericarps, embryos and seed coats. The qRT-PCR analysis indicated that most of them were responsive to ABA, salt and osmotic treatments. Further mutant complementary experiments revealed that the expression of BnaREM1.3-4C-1 in the Arabidopsis rem1.3 mutant restored the retarded growth phenotype and the ability to resistance to salt and osmotic stresses. Our findings provide fundamental information on the structure and evolutionary relationship of the BnaREM family genes in rapeseed, and reveal the potential function of BnaREM1.3-4C-1 in stress and hormone response.

Molecular Mechanism of Exogenous ABA to Enhance UV-B Resistance in Rhododendron chrysanthum Pall. by Modulating Flavonoid Accumulation.

With the depletion of the ozone layer, the intensity of ultraviolet B (UV-B) radiation reaching the Earth's surface increases, which in turn causes significant stress to plants and affects all aspects of plant growth and development. The aim of this study was to investigate the mechanism of response to UV-B radiation in the endemic species of Rhododendron chrysanthum Pall. (R. chrysanthum) in the Changbai Mountains and to study how exogenous ABA regulates the response of R. chrysanthum to UV-B stress. The results of chlorophyll fluorescence images and OJIP kinetic curves showed that UV-B radiation damaged the PSII photosystem of R. chrysanthum, and exogenous ABA could alleviate this damage to some extent. A total of 2148 metabolites were detected by metabolomics, of which flavonoids accounted for the highest number (487, or 22.67%). KEGG enrichment analysis of flavonoids that showed differential accumulation by UV-B radiation and exogenous ABA revealed that flavonoid biosynthesis and flavone and flavonol biosynthesis were significantly altered. GO analysis showed that most of the DEGs produced after UV-B radiation and exogenous ABA were distributed in the cellular process, cellular anatomical entity, and catalytic activity. Network analysis of key DFs and DEGs associated with flavonoid synthesis identified key flavonoids (isorhamnetin-3-O-gallate and dihydromyricetin) and genes (TRINITY_DN2213_c0_g1_i4-A1) that promote the resistance of R. chrysanthum to UV-B stress. In addition, multiple transcription factor families were found to be involved in the regulation of the flavonoid synthesis pathway under UV-B stress. Overall, R. chrysanthum actively responded to UV-B stress by regulating changes in flavonoids, especially flavones and flavonols, while exogenous ABA further enhanced its resistance to UV-B stress. The experimental results not only provide a new perspective for understanding the molecular mechanism of the response to UV-B stress in the R. chrysanthum, but also provide a valuable theoretical basis for future research and application in improving plant adversity tolerance.

Differential Transcription Profiling Reveals the MicroRNAs Involved in Alleviating Damage to Photosynthesis under Drought Stress during the Grain Filling Stage in Wheat.

To explore the possible novel microRNA (miRNA) regulatory pathways in Zhengmai 1860, a newly cultivated drought-tolerant wheat (Triticum aestivum L.) cultivar, miRNA transcriptome sequencing of the flag leaves of Zhengmai 1860, drought-sensitive variety Zhoumai 18, and drought-resistant variety Bainong 207 was performed during the grain filling stage. We also observed changes in the chloroplast ultrastructure, phytohormone levels, and antioxidant- and photosynthesis-related physiological indicators in three wheat varieties. The results showed that the flag leaves of the drought-tolerant variety Zhengmai 1860 had higher chlorophyll contents and net photosynthetic rates than those of Zhoumai 18 under drought stress during the grain filling stage; in addition, the chloroplast structure was more complete. However, there was no significant difference between Zhengmai 1860 and Bainong 207. MiRNA transcriptome analysis revealed that the differential expression of the miRNAs and mRNAs exhibited variable specificity. The KEGG pathway enrichment results indicated that most of the genes were enriched in the MAPK signaling pathway, plant hormone signal transduction, photosynthetic antennae protein, and amino acid and carbohydrate metabolism. In the drought-tolerant cultivar Zhengmai 1860, tae-miR408 was targeted to regulate the allene oxide synthase (AOS) gene, inhibit its expression, reduce the AOS content, and decrease the synthesis of jasmonic acid (JA) and abscisic acid (ABA). The results of this study suggest that Zhengmai 1860 could improve the photosynthetic performance of flag leaves by inhibiting the expression of genes involved in the JA pathway through miRNAs under drought conditions. Moreover, multiple miRNAs may target chlorophyll, antioxidant enzymes, phytohormone signal transduction, and other related pathways; thus, it is possible to provide a more theoretical basis for wheat molecular breeding.

Demographic differences in access to health/therapeutic services over first year of the pandemic: a SPARK COVID-19 impact survey analysis.

Introduction: This analysis examined changes in services received and service recovery one-year post-pandemic compared to pre-pandemic levels in children with ASD aged between 19 months and 17 years in various subgroups based on factors such as age, income, race/ethnicity, geographic location, and sex. Methods: An online, parent report survey was completed by the parents of children with ASD in the SPARK study cohort (N = 6,393). Descriptive statistics, chi-square analyses, and Spearman correlations were performed to study associations between various factors and service access, pre-pandemic and one-year, post-pandemic. Results: One year after pandemic, the lag in service recovery in children with ASD was greatest for PT/OT services followed by SLT. ABA services only recovered in half of the subgroups. In contrast, SES fully recovered and MH and MED services superseded pre-pandemic levels. Across majority of the timepoints, younger children received more SLT, PT/OT, and ABA services whereas older children received more SES, MH, and MED services. Higher income families accessed more SES, SLT, and ABA whereas lower income families received more MH services. White families received less SLT compared to non-white families. Hispanic families received more SLT services compared to non-Hispanic families. Compared to rural families, urban families received more ABA services at baseline which also recovered one year after the pandemic. Certain counterintuitive findings may be attributed to home/remote schooling leading to reduced access to related services. Conclusions: Future research and policy changes are needed to address the American healthcare vulnerabilities when serving children with ASD by enhancing the diversity of healthcare formats for continued service access during future pandemics and other similar crises.

The ZmbHLH47-ZmSnRK2.9 Module Promotes Drought Tolerance in Maize.

Drought stress globally poses a significant threat to maize (Zea mays L.) productivity and the underlying molecular mechanisms of drought tolerance remain elusive. In this study, we characterized ZmbHLH47, a basic helix-loop-helix (bHLH) transcription factor, as a positive regulator of drought tolerance in maize. ZmbHLH47 expression was notably induced by both drought stress and abscisic acid (ABA). Transgenic plants overexpressing ZmbHLH47 displayed elevated drought tolerance and ABA responsiveness, while the zmbhlh47 mutant exhibited increased drought sensitivity and reduced ABA sensitivity. Mechanistically, it was revealed that ZmbHLH47 could directly bind to the promoter of ZmSnRK2.9 gene, a member of the subgroup III SnRK2 kinases, activating its expression. Furthermore, ZmSnRK2.9-overexpressing plants exhibited enhanced ABA sensitivity and drought tolerance, whereas the zmsnrk2.9 mutant displayed a decreased sensitivity to both. Notably, overexpressing ZmbHLH47 in the zmsnrk2.9 mutant closely resembled the zmsnrk2.9 mutant, indicating the importance of the ZmbHLH47-ZmSnRK2.9 module in ABA response and drought tolerance. These findings provided valuable insights and a potential genetic resource for enhancing the environmental adaptability of maize.

ZmASR1 negatively regulates drought stress tolerance in maize.

Abscisic acid-, stress-, and ripening-induced (ASR) proteins in plants play a significant role in plant response to diverse abiotic stresses. However, the functions of ASR genes in maize remain unclear. In the present study, we identified a novel drought-induced ASR gene in maize (ZmASR1) and functionally characterized its role in mediating drought tolerance. The transcription of ZmASR1 was upregulated under drought stress and abscisic acid (ABA) treatment, and the ZmASR1 protein was observed to exhibit nuclear and cytoplasmic localization. Moreover, ZmASR1 knockout lines generated with the CRISPR-Cas9 system showed lower ROS accumulation, higher ABA content, and a higher degree of stomatal closure than wild-type plants, leading to higher drought tolerance. Transcriptome sequencing data indicated that the significantly differentially expressed genes in the drought treatment group were mainly enriched in ABA signal transduction, antioxidant defense, and photosynthetic pathway. Taken together, the findings suggest that ZmASR1 negatively regulates drought tolerance and represents a candidate gene for genetic manipulation of drought resistance in maize.

A soybean bZIP transcription factor is involved in submergence resistance.

Although the functions of basic leucine zipper (bZIP) family transcription factors in the regulation of various abiotic stresses are beginning to be unveiled, the precise roles of bZIP proteins in plants coping with submergence stress remain unclear. Here we identified a bZIP gene GmbZIP71-4 from soybean, which localized in the nucleus. The GmbZIP71-4 over-expressed tabocco line showed reduced submergence resistance due to the decreased abscisic acid (ABA) content. GO and KEGG pathway analysis based on chromatin immunoprecipitation assay sequencing (ChIP-seq) indicated that the differences expressed genes between submergence treatment and control groups were specially enriched in plant hormone signal transduction items, especially those in response to ABA. Electrophoretic mobility shift assays (EMSA) demonstrated that GmbZIP71-4 bound to the promoter of GmABF2 gene, which is consistent with the ChIP-qPCR results. GmbZIP71-4 function as a negative regulator of soybean in responding to submergence stress through manipulating ABA signaling pathway. This findings will set a solid foundation for the understanding of submergence resistance in plants.

Novel nucleus-localized GRAM protein encoding OsGRAM57 gene enhances salt tolerance through ABA-dependent pathway and modulated carbohydrate metabolism.

GRAM (Glucosyltransferases-like GTPase activators and Myotubularin) domain-encoding proteins play pivotal roles in plant growth and responses to biotic stresses. Yet, their influence on abiotic stress responses has remained enigmatic. This study unveils a novel nucleus-localized OsGRAM57, a GRAM protein-encoding gene and its profound regulatory functions in enhancing salt stress tolerance using Arabidopsis thaliana as a model plant. OsGRAM57-OEX (OsGRAM57-OEX) lines displayed significant enhancement in salt tolerance, modulated physiological, biochemical, K+/Na+ ratios, and enzymatic indices as compared to their wild-type (WT). Furthermore, OsGRAM57-OEX seedlings demonstrate increased levels of endogenous abscisic acid (ABA) and other phytohormones, while metabolic profiling revealed enhanced carbohydrate metabolism. Delving into the ABA signaling pathway, OsGRAM57 emerged as a central regulator, orchestrating the expression of genes crucial for salt stress responses, carbohydrate metabolism, and ABA signaling. The observed interactions with target genes and transactivation assays provided additional support for OsGRAM57's pivotal role. These findings underscore OsGRAM57's positive influence on the ABA pathway and affirm its capacity to enhance salt tolerance through an ABA-dependent pathway and fine-tuned carbohydrate metabolism. In summary, this new study reveals the previously undiscovered regulatory roles of OsGRAM57 in Arabidopsis abiotic stress responses, offering promising ways for strengthening plant resilience in the face of adverse environmental conditions.