Objective This study employs transcriptomic techniques to investigate the molecular mechanisms underlying salt tolerance in P. vaginatum, with the aim of providing theoretical support for the development of salt-tolerant crops.

Method In this study, the salt-tolerant genotype sealsle2000 and salt-sensitive genotype 17USA-45 were used as experimental materials to measure physiological index changes under salt stress at different time points. RNA-seq technology was employed for transcriptome sequencing, and bioinformatics methods were applied to analyze differentially expressed genes (DEGs).

Result Under salt stress, the decrease in Pn, Gs and SPAD, as well as the increase in RLF in sealsle2000, were significantly lower than those in 17USA-45. Under 1 day of salt stress, 6876 and 6017 DEG were identified in sealsle2000 and 17USA-45, respectively. Under 3 days of salt stress, 4457 and 5536 DEGs were detected in sealsle2000 and 17USA-45, respectively. Analysis suggested that the AP2 transcription factor gene family may play a central role in the response to salt stress. KEGG and GO enrichment analyses revealed that both genotypes were commonly enriched in pathways related to starch and sucrose metabolism, carbon metabolism, and photosynthetic components. sealsle2000 was specifically enriched in pathways associated with brassinolide biosynthesis, salt stress response, and mannitol response. In contrast, 17USA-45 was specifically enriched in pathways related to phenylpropanoid biosynthesis and the NAD(P)H dehydrogenase complex. qRT-PCR validation confirmed the high reliability of the RNA-seq data obtained in this study.

Conclusion This study revealed that the salt-tolerant genotype of P. vaginatum is specifically enriched in the brassinosteroid biosynthesis pathway, negative regulation of ethylene-activated signaling pathway, and response to mannitol, providing valuable insights into the molecular mechanisms underlying salt tolerance in P. vaginatum.