Genome-wide identification, structural analysis, and expression profiles of the BZR gene family in tomato

BRASSINAZOLE-RESISTANT (BZR) genes are a family that has transcription factors that are particular to plants and are involved in the signal transduction of brassinosteroids. This study identified nine BZR genes in tomato using a computational approach. BZRs are hydrophilic proteins mostly located in the nucleus. The most common secondary structure of BZRs is random coil. The number of introns contained in the BZR family genes is between 1 and 9, and these genes are distributed in a disarrayed fashion across the chromosomes, while there were two pairs of duplicated gene fragments. Forty-four cis-elements were identified in the region of the gene promoter, all of which were associated with plant hormones, tissue specific expression, response to stress, and light response. The genes in this family mainly responded to plant hormones such as gibberellin, salicylic acid, abscisic acid, auxin, and methyl jasmonate (MeJa). Analysis of the expression profile demonstrated that SlBZR gene expression was significantly different in tissues and organs at different developmental stages of tomato, and some genes had tissue specific expression. The results of qRT-PCR demonstrated that all genes in the BZR family were involved in stress response (200 mmol/L SA, 200 mmol/L ABA, and 4 °C). The results lay the foundation to further study the functions of tomato BZR genes.