Transcriptome Analysis and Physiological Response to Salinity Stress in Adzuki Bean (Vigna angularis) at the Seedling Stage

Adzuki bean (<i>Vigna angularis</i> (Willd.) Ohwi & H. Ohashi) is a significant crop for its applications in both traditional medicine and nutritional diets in China. However, there remains a paucity of exploration employing an RNA-seq approach to investigate the molecular response mechanisms of the species under salinity stress. In this study, Jin Xiao Dou 6 (JXD6) adzuki bean cultivar was subjected to 0 mmol/L (CK), 32.5 mmol/L, and 65.0 mmol/L NaCl treatments to preliminarily characterize salinity-induced alterations in plant height, chloroplast pigment contents, leaf surface humidity and temperature, H₂O₂ and O₂^- accumulation, activities of antioxidative enzymes, and transcriptome profiles. Under increasing NaCl concentrations, the plant height of JXD6 seedlings was progressively inhibited. Conversely, the unifoliate leaves exhibited elevated leaf surface temperature, increased contents of chlorophyll a, total chlorophyll and carotenoids, enhanced accumulation of O₂^-, as well as heightened activities of superoxide dismutase, peroxidase, and catalase. Transcriptome profile analyses suggested that a total of 363 and 858 differentially expressed genes were obtained in the unifoliate leaves of adzuki bean seedlings treated with 32.5 mmol/L and 65.0 mmol/L NaCl groups, respectively. The up-regulated genes were mainly enriched in the spliceosome pathway, while the down-regulated genes were mainly enriched in pathways of plant hormone signal transduction, plant-pathogen interaction, and the MAPK signaling pathway in plants. These results provide new insight into exploring the response mechanisms of adzuki beans to salinity stress via transcriptome analyses.