Characterization of the MYB Gene Family in the Chinese White Pear (Pyrus bretschneideri) and Comparison with Arabidopsis thaliana

The MYB superfamily as transcription factors is large, and functionally diverse in plants. To date, although several MYB genes have been characterized to regulate diverse processes including secondary metabolism, development, and stress responses in Arabidopsis, the MYB family has not yet been identified in the Chinese white pear (Pyrus bretschneideri) and their functions remain rather unclear. In this study, we provided a genome-wide identification and analysis to explicitly explore the detail information about MYB family in pear. Through analysis of gene structures, chromosome locations, conserved domains, phylogeny, and expression patterns, R2R3-MYB (PbrMYB) family was analyzed emphatically. Meanwhile, to predicted their functions, a comparative genomic analysis with Arabidopsis was performed. The result of phylogenetic analysis showed that most characterized R2R3-MYB genes which possess similar functions are clustered in the same subgroup, together with the identification of orthologs by synteny analysis. This strongly indicated the functional conservation among subgroups of MYB genes. WGD (Whole genome duplications) played critical roles in the expansion of the R2R3-MYB gene family in pear, and most of the duplicated MYB gene pairs were dated back to the recent whole-genome. Through the analysis of transcriptome data, the expression levels of MYB genes were widely different, which revealed that MYB genes play various roles in pear development and indicative of a divergence in function. The whole genome wide characterization of  MYB gene family in pear establish a solid foundation for future comprehensive functional analysis of PbrMYBs.

Keywords: Pear (Pyrus bretschneideri); MYB gene family; gene structures , function divergence; expression pattern.