Identification and in silico evaluation of bHLH genes in the Sesamum indicum genome: Growth regulation and stress dealing specially through the metal ions homeostasis and flavonoid biosynthesis

Abstract A multitude of plant developmental processes, metal ion homeostasis, stimuli responses as well as flavonols biosynthesis pathways are regulated by basic helix-loop-helix (bHLH) transcription factors. Despite the importance of this gene family, there is no comprehensive study of bHLH genes in the significant oil crop sesame. Here, 130 sesame bHLH genes have been distinguished via a genome-wide analysis, which were grouped into the 21 clades based on the phylogenetic relationships. The 11 duplicated gene pairs were distinguished in the sesame bHLH family, suffering purifying selection. Based on the promoter analysis, 11 and 35 SinbHLHs have been detected to be engaged in the metal ion homeostasis and anthocyanin biosynthesis systems, respectively. According to the proteins interaction, FRU, ILR3, PIF3 and TT8 proteins were detected as the significant interacting bHLHs with the MYB, RGA, CRY1 and bZIP proteins, which can regulate stress coping, iron ion homeostasis and anthocyanin biosynthesis during the sesame life cycle. Tissue-specific expression analysis revealed 77 SinbHLH genes that can adjust the sesame growth/development. The stress-induced expression profiling of SinbHLHs also suggested the extensive involvement of these genes during the sesame stimuli coping. Regarding to our assessments, some candidate SinbHLHs were found to be engaged in regulation of the sesame growth and stress tolerance through the metal ions homeostasis and secondary metabolites biosynthesis. A systematic evaluation of the regulatory bHLHs can provide valuable insights into these important biological pathways and may be informative for improvement of the significant oil crop sesame.