Yanan Chen

Salt stress severely limits rapeseed growth and productivity, with varietal differences in tolerance, yet the molecular responses remain poorly understood. In this study, we compared the physiological and transcriptomic responses of a salt-tolerant cultivar ‘ZY821’, and a salt-sensitive cultivar ‘HS3’ under salt stress. Physiological analysis confirmed that ‘ZY821’ exhibited significantly higher plant height, shoot and root biomass, chlorophyll content, and SOD and CAT activities, while accumulating lower level of H₂O₂ under salt stress compared to ‘HS3’. Transcriptome analysis revealed 1542 and 2348 differentially expressed genes (DEGs) in ‘ZY821’ and ‘HS3’ under salt stress, respectively. A formal genotype × treatment interaction analysis further identified 1011 genes with genotype-dependent salt responses. GO and KEGG enrichment analyses indicated that upregulated genes in ‘ZY821’ were primarily associated with environmental sensing, starch and sucrose metabolism, and phenylpropanoid biosynthesis, whereas downregulated genes involved lipid metabolism. In contrast, ‘HS3’ exhibited broad upregulation of ribosome-related genes and downregulation of secondary metabolism and glutathione-mediated redox pathways. Analysis of transcription factors (TFs) identified 569 differentially expressed TFs under salt stress. Basic characterization revealed that three candidate TFs (BnaERF106, BnaNFYA6, and BnaCOL13) localized to the nucleus, with BnaERF106 exhibiting transcriptional activation activity. BnaERF106 and BnaNFYA6 were downregulated in both cultivars under salt stress, while BnaCOL13 showed contrasting gene expression patterns. Heterologous expression of BnaERF106 and BnaCOL13 reduced yeast salt tolerance, consistent with a possible negative regulatory role that requires validation in plants. Collectively, these findings provide a candidate gene resource and testable hypotheses for future functional validation.

Soil salinization severely limits forage crop productivity, yet the regulatory networks that govern salt stress adaptation in alfalfa, a moderately salt-tolerant leguminous forage, remain largely unexplored. Here, we examined the physiological and transcriptomic dynamics of alfalfa leaves under 200 mM NaCl stress across three time points. Salt stress induced a progressive elevation of the Na⁺/K⁺ ratio, biphasic activation of antioxidant enzymes and concurrent accumulation of malondialdehyde. Time-course RNA-seq analysis identified 3631 differentially expressed genes (DEGs) and 132 core salt-responsive transcription factors (TFs). Pathway and functional annotation analyses indicated that these DEGs were prominently involved in cell wall biogenesis, redox homeostasis, and the carotenoid biosynthesis pathway, with carotenoid accumulation strongly activated under salt stress. Using weighted gene co-expression network analysis (WGCNA), nine distinct co-expression clusters were constructed. Notably, the brown module, which showed a positive correlation with Na⁺ accumulation and the Na⁺/K⁺ ratio, was significantly enriched in the plant hormone signal transduction pathway, within which 72.7% of the enriched genes belonged to the TIFY family. Among them, a core hub gene, MsTIFY11B, was isolated for functional characterization. Subcellular localization demonstrated that MsTIFY11B is exclusively localized to the nucleus. Heterologous expression in yeast showed that MsTIFY11B overexpression enhanced tolerance to salinity and alkalinity, whereas it conferred negligible protection against mannitol-induced drought stress. Taken together, our findings provide a comprehensive temporal framework of the alfalfa transcriptomic response to salinity and suggest that MsTIFY11B may contribute to salt–alkali tolerance, making it a promising candidate for further functional characterization and potential application in the development of stress-adapted alfalfa varieties.

The dehydration response element binding protein (DREB) family of the AP2/ERF superfamily functions as a key regulatory component in plant adaptation to water-deficit conditions. However, studies on the DREB A4 subfamily in poplar (Populus trichocarpa) are insufficient. In this study, members of the DREB A4 subgroup in poplar were identified and analyzed via bioinformatic analysis. A pCAMBIA-2300-PtrDREB4 expression vector was constructed and transformed into Arabidopsis, followed by phenotypic analysis of transgenic plant in response to drought stress. A total number of 29 DREB A4 members were identified in the poplar genome. Synteny analysis revealed that 19 gene pairs went through segmental duplication at least 12.84 million years ago. Their promoter regions were enriched with cis-elements related to stress resistance, hormone regulation, and growth and development. Upstream regulator analysis of poplar DREB A4 genes identified 425 transcription factor genes, which belonged to 39 families. Gene expression analysis demonstrated distinct expression patterns of DREB A4 genes in leaves, roots and stems with a notable response to drought stress. Ectopic expression of PtrDREB4 in yeast and Arabidopsis increased the drought tolerance of transformants, indicating the positive role of PtrDREB4 in response to drought stress. These findings collectively established a theoretical foundation for further functional exploration of DREB A4 genes in poplar.