Identification, evolution, and expression analysis of OsBSK gene family in Oryza sativa Japonica

Background: As an essential component of the BR (brassinosteroid) signaling pathway, BSK (BR-signalling kinases) plays a vital role in plant growth, development, and stress regulation. There have been sporadic reports on the functions of members of this family in monocotyledonous model plant rice, but few reports have been reported on the phylogenetic analysis and gene expression profiling of the family genes. Results: In this study, a total of 6 OsBSK members were identified at the genomic level by bioinformatics methods, distributed on four rice chromosomes. Through the evolution analysis of 74 BSK proteins from 22 species, it was found that BSKs originated from higher plants, were highly conserved, and could be divided into six subgroups. Among them, OsBSKs belonged to four subgroups or two significant groups. OsBSK family gene promoters contained a large number of light, abscisic acid (ABA), and methyl jasmonate (MeJA) response-related elements. At the same time, the qRT-PCR test also showed that the genes of this family were involved in response to a variety of hormones, biotic and abiotic stress treatments, and expression patterns of the family gene can be roughly divided into two categories, which were similar to the tissue expression patterns of genes in different growth stages. OsBSK1-1, OsBSK1-2, and OsBSK3 were mostly up-regulated. OsBSK2, OsBSK4, and OsBSK5 were mostly down-regulated or had little change in expression. Conclusions: This study revealed the origin and evolution of the BSK family and the farm-out of BSKs in rice growth, development, and stress response. It provides the theoretical reference for in-depth analysis of BR hormone, signal transduction, and molecular breeding design for resistance.