Genome-wide identification and expression analysis of SBP-box gene family in Sorghum bicolor L.

SQUAMOSA PROMOTER BINDING PROTEIN-box (SBP-box) family genes encoding plant-specific transcription factors are involved in many aspects of crop genetic improvement such as yield, plant-type and stress-resistance. The SBP-box gene family have important practical applications. In this study, 18 SBP-box genes were identified from the reference genome of sorghum (Sorghum bicolor L.) using bioinformatics. These genes distributed on nine chromosomes while eight of them located in the segmental duplication region. Phylogenetic reconstruction resulted in six subfamilies of SBP-box genes, among which SbSBP12, SbSBP3 and SbSBP15 are orthologous to ZmLG1, ZmTGA1 and ZmUB2/3 in corn, respectively. RNA-seq data analysis indicated that SbSBP-box genes show the highest expression level in primordial inflorescences. Moreover, SbSBP9 and SbSBP17 exhibited a tissue specific expression in primordial inflorescences. The expression levels of SbSBP5, SbSBP8 and SbSBP18 were increased in response to exogenous ABA and PEG,indicating that SbSBP-box genes are involved in the defense response against abiotic stresses in sorghum. This research provides references for cloning important genes in SbSBP-box gene family. Genes identified in this study could be considered as candidate genes for genetic improvement of sorghum.