Genome-wide analysis and expression profiles of the StR2R3-MYB transcription factor superfamily in potato (Solanum tuberosum L.)

MYB transcription factors comprise one of the largest families in plant kingdom, which play a variety of functions in plant developmental processes and defence responses, the R2R3-MYB members are the predominant form found in higher plants. In the present study, a total of 111 StR2R3-MYB transcription factors were identified and further phylogenetically classified into 31 subfamilies, as supported by highly conserved gene structures and motifs. Collinearity analysis showed that the segmental duplication events played a crucial role in the expansion of StR2R3-MYB gene family. Synteny analysis indicated that 37 and 13 StR2R3-MYB genes were orthologous to Arabidopsis and wheat (Triticum aestivum), respectively, and these gene pairs have evolved under strong purifying selection. RNA-seq data from different tissues and abiotic stresses revealed tissue-preferential and abiotic stress-responsive StR2R3-MYB genes. We further analyzed StR2R3-MYB genes might be involved in anthocyanin biosynthesis and drought stress by using RNA-seq data of pigmented tetraploid potato cultivars and drought-sensitive and -tolerant tetraploid potato cultivars under drought stress, respectively. Moreover, EAR motifs were found in 21 StR2R3-MYB proteins and 446 pairs of proteins were predicted to interact with 21 EAR motif-containing StR2R3-MYB proteins by constructing the interaction network with medium confidence (0.4). Additionally, Gene Ontology (GO) analysis of the 21 EAR motif-containing StR2R3-MYB proteins was performed to further investigate their functions. This work will facilitate future biologically functional studies of potato StR2R3-MYB transcription factors and enrich the knowledge of MYB superfamily genes in plant species.