Cold injury is a major environmental stress affecting the growth and yield of crops. Brassinosteroids (BRs) and salicylic acid (SA) play important roles in plant cold tolerance. However, whether or how BR signaling interacts with the SA signaling pathway in response to cold stress is still unknown. Here, we identified an SA methyltransferase, TaSAMT1 that converts SA to methyl SA (MeSA) and confers freezing tolerance in wheat (Triticum aestivum). TaSAMT1 overexpression greatly enhanced wheat freezing tolerance, with plants accumulating more MeSA and less SA, whereas Tasamt1 knockout lines were sensitive to freezing stress and accumulated less MeSA and more SA. Spraying plants with MeSA conferred freezing tolerance to Tasamt1 mutants, but SA did not. We revealed that BRASSINAZOLE-RESISTANT 1 (TaBZR1) directly binds to the TaSAMT1 promoter and induces its transcription. Moreover, TaBZR1 interacts with the histone acetyltransferase TaHAG1, which potentiates TaSAMT1 expression via increased histone acetylation and modulates the SA pathway during freezing stress. Additionally, overexpression of TaBZR1 or TaHAG1 altered TaSAMT1 expression and improved freezing tolerance. Our results demonstrate a key regulatory node that connects the BR and SA pathways in the plant cold stress response. The regulatory factors or genes identified could be effective targets for the genetic improvement of freezing tolerance in crops.

Drought is a major global challenge in agriculture that decreases crop production. γ-Aminobutyric acid (GABA) interfaces with drought stress in plants; however, a mechanistic understanding of the interaction between GABA accumulation and drought response remains to be established. Here we showed the potassium/proton exchanger TaNHX2 functions as a positive regulator in drought resistance in wheat by mediating cross-talk between the stomatal aperture and GABA accumulation. TaNHX2 interacted with glutamate decarboxylase TaGAD1, a key enzyme that synthesizes GABA from glutamate. Furthermore, TaNHX2 targeted the C-terminal auto-inhibitory domain of TaGAD1, enhanced its activity, and promoted GABA accumulation under drought stress. Consistent with this, the tanhx2 and tagad1 mutants showed reduced drought tolerance, and transgenic wheat with enhanced TaNHX2 expression had a yield advantage under water deficit without growth penalty. These results shed light on the plant stomatal movement mechanism under drought stress and the TaNHX2-TaGAD1 module may be harnessed for amelioration of negative environmental effects in wheat as well as other crops.

Low temperature at the seedling stage adversely affects sorghum growth and development and limits its geographical distribution. APETALA2/Ethylene-Responsive transcription factors (AP2/ERFs), one of the largest transcription factor families in plants, play essential roles in growth, development, and responses to abiotic stresses. However, the roles of AP2/ERF genes in cold tolerance in sorghum and the mechanisms underlying their effects remain largely unknown. Here, transcriptome sequencing (RNA-seq) was performed on the leaves of sorghum seedlings before and after cold treatment. Several candidate genes for cold tolerance and regulation pathways involved in “photosynthesis” under cold stress were identified via Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment. Additionally, the AP2/ERF family gene SbERF027, a novel regulator of cold tolerance, was functionally identified through a comprehensive analysis. The expression of SbERF027 was high in seedlings and panicles, and its expression was induced by low temperature; the cold-induced expression level of SbERF027 was markedly higher in cold-tolerant accession SZ7 than in cold-sensitive accession Z-5. SbERF027 was detected in the nucleus under both normal and cold stress conditions. In addition, the cold tolerance of SbERF027-overexpressing lines was higher than that of wild-type plants; while the cold tolerance of lines with SbERF027 silenced via virus-induced gene silencing (VIGS) was significantly lower than that of wild-type plants. Further research demonstrated that SNP-911 of the promoter was essential for enhancing cold tolerance by mediating SbERF027 expression. This study lays a theoretical foundation for dissecting the mechanism of cold tolerance in sorghum and has implications for the breeding and genetic improvement of cold-tolerant sorghum.

Wheat (Triticum aestivum L.) is a major food crop that is severely affected by salt stress, resulting in significant yield losses. Glutamic acid decarboxylase (GAD) catalyzes the irreversible conversion of glutamic acid to γ-aminobutyric acid (GABA) and plays key roles in plant growth, development, and stress responses. However, the GAD gene family in hexaploid wheat and its role in salt tolerance remain poorly understood. In this study, the wheat GAD gene family was systematically identified. Genome-wide analysis revealed seven TaGAD genes with 19 gene copies. A Ka/Ks ratio < 1 indicates strong evolutionary conservation of this family. All TaGAD proteins contain a conserved Glu-decarb-GAD domain with similar motif composition and structural organization. Promoter analysis showed enrichment of stress-responsive cis-elements. Expression profiling demonstrated tissue-specific patterns, with several TaGAD genes significantly induced under salt stress. CRISPR/Cas9-mediated knockout of TaGAD1 led to markedly reduced salt tolerance, accompanied by decreased GABA content and GAD activity, reduced activities of antioxidant enzymes (SOD, POD, and CAT), and excessive accumulation of reactive oxygen species (ROS). These results demonstrate that TaGAD1 positively regulates salt tolerance in wheat through GABA-mediated ROS homeostasis. This study provides a systematic characterization of the wheat TaGAD gene family in the context of salt stress, laying a theoretical foundation for understanding GABA-mediated tolerance mechanisms and identifying TaGAD1 as a potential molecular breeding target for improving salt tolerance in wheat.

Drought stress severely constrains wheat ( Triticum aestivum L.) growth and productivity. Here, we identify the histone deacetylase TaHDA1 as a negative regulator of drought tolerance in wheat. We demonstrate that TaHDA1 interacts with and deacetylates the L‐glutamate decarboxylase TaGAD1 at lysine 493, promoting its ubiquitination‐dependent degradation and thereby suppressing γ‐aminobutyric acid (GABA) accumulation. Loss of TaHDA1 function enhances TaGAD1 stability, increases GABA levels, and confers markedly improved drought tolerance, along with elevated grain GABA content. Integrated multi‐omics analyses further reveal that TaHDA1 globally modulates H3K9 acetylation to orchestrate drought‐responsive transcriptional programs. Notably, tahda1 ‐ko mutants show a slight reduction in grain size under normal conditions, but maintain stable yield under drought stress. Our findings uncover a dual mechanism by which TaHDA1 integrates non‐histone and histone deacetylation to balance growth and stress adaptation, providing a promising target for breeding drought‐resilient and nutritionally enhanced wheat varieties.