Objective Transcriptomic techniques were applied to investigate the molecular mechanisms underlying the salt tolerance of Paspalum vaginatum.

Method Physiological index changes in the salt-tolerant sealsle2000 and the salt-sensitive 17USA-45 under salt-stress were determined. RNA-seq technology was employed for transcriptome sequencing, and bioinformatics methods for analysis on differentially expressed genes (DEGs).

Result  Under salt-stress, the decreases in P_n, G_s, and SPAD as well as the increase in RLF of sealsle2000 were significantly lower than those of 17USA-45. Transcriptome analysis revealed that after 1 and 3 days of salt stress, 6876 and 6017 DEGs were identified in sealsle2000, respectively, while 4457 and 5536 DEGs were identified in 17USA-45. An analysis suggested that the AP2 transcription factor gene family in P. vaginatum might play a pivotal 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. Sealsle 2000 was specifically enriched in the pathways associated with brassinolide biosynthesis, salt-stress response, and mannitol response. In contrast, 17USA-45 was enhanced in the pathways associated with phenylpropanoid biosynthesis and the NAD(P)H dehydrogenase complex. A qRT-PCR validation confirmed the high reliability of the RNA-seq data obtained in this study.

Conclusion  The salt-tolerant genotype of P. vaginatum was found to be specifically enriched in the brassinosteroid biosynthesis pathway, negative regulation of ethylene-activated signaling pathway, and response to mannitol.