Genome-wide identification and characterization of Subtilisin-like Serine protease encoding genes in Vigna radiata L. Wilczek.

Subtilisin-like serine proteases (SBTs) are serine proteolytic enzymes that play various roles in plant growth, function and stress responses. Vigna glabrescens, a wild relative of mungbean known to be a potential donor of photo- and thermoperiod insensitivity, was characterized for thermotolerance through reproductive biology and gene expression profiling. Whole-genome sequencing of this species has not yet been performed; hence, genome-wide analysis of this species has not been explored. In the present study, a systematic analysis of SBT-encoding genes in the V. radiata (Vradi_SBT) genome was conducted, with a focus on their response during flower development under different temperature regimes, such as optimum temperature, heat and cold stresses, in Vigna radiata and a wild relative, Vigna glabrescens. Thirty-eight Vradi_SBT genes were identified in the V. radiata genome and were further grouped into five distinct subgroups. The key domain of the SBT peptidase, "peptidase_S8_53," was found in all 38 Vradi_SBT proteins, while 28 of them contained the "peptidase_S8" domain. Additionally, 30 of these proteins contained a maximum of 10 motifs. A total of 22 orthologous genes were identified in Arabidopsis thaliana, whereas paralogous gene pairs were detected as tandemly duplicated genes with V. unguiculata. Cis-acting element analysis revealed that these genes presented more stress-responsive promoter sequences than the other promoters. Furthermore, Vradi_SBT-1.9 was found significantly upregulated under both high- and low-temperature stresses. This study provides insights into SBT-encoding genes and their possible role in flower development and thermotolerance in Vigna species.