Comprehensive analysis of the MYB transcription factor gene family in Morus alba

Background The V-myb myeloblastosis viral oncogene homolog (MYB) family of proteins is large, containing functionally diverse transcription factors. However, MYBs in Morus are still poorly annotated and a comprehensive functional analysis of these transcription factors is lacking. Results In the present study, a genome-wide identification of MYBs in Morus alba was performed . In total 166 MaMYB s were identified, including 103 R2R3-MYB s and four 3R-MaMYB s. Comprehensive analyses, including the phylogenetic analysis with putative functional annotation, motif and structure analysis, gene structure organization, promoter analysis, chromosomal localization, and syntenic relationships of R2R3-MaMYB s and 3R-MaMYB s, provided primary characterization for these MaMYB s. R2R3-MaMYB s covered the subgroups reported for R2R3-MYB s in Arabidopsis and Populus, and had two Morus -specific subgroups, indicating the high retention of MYBs in Morus . Motif analysis revealed high conservative residues at the start and end of each helix and residues consisting of the third helix in R2 and R3 repeats. Thirteen intron/exon patterns (a–m) were summarized, and the intron/exon pattern of two introns with phase numbers of 0 and 2 was the prevalent pattern for R2R3-MaMYB s. Various cis-elements in promoter regions were identified, and were mainly related to light response, development, phytohormone response, and abiotic and biotic stress response and secondary metabolite production. Expression patterns of R2R3-MaMYB s in different organs showed that MaMYBs involved in secondary cell wall components and stress responsiveness were preferentially expressed in roots or stems . R2R3-MaMYB s involved in flavonoid biosynthesis and anthocyanin accumulation were identified and characterized based on functional annotation and correlation of their expression levels with anthocyanin contents. Conclusion Based on a comprehensive analysis, this work provided functional annotation for R2R3-MYBs and an informative reference for further functional dissection of MYBs in Morus .