Identification and expression analysis of R2R3-MYB gene family in Begonia masoniana

【Objective】 Identification and analysis of the R2R3-MYB gene family in Begonia masoniana was conducted，and the expression patterns of the R2R3-MYB gene family members in different growth stages of leaf spots and non-leaf spot regions was detected，providing theoretical reference for understanding the molecular regulatory mechanisms underlying leaf spot formation in B. masoniana，as well as for leaf color improvement and new variety breeding. 【Method】 Using leaves from 3 key growth and development periods of B. masoniana as experimental materials，with Arabidopsis thaliana R2R3-MYB family proteins as reference sequences，members of the R2R3-MYB gene family from the B. masoniana genome database were identified using bioinformatics methods. Then predicted and analyzed their physicochemical properties，chromosomal localization，phylogenetic relationships，gene structures，conserved motifs and promoter cis-acting elements. Additionally，examined the expression patterns of 7 BmaMYBs genes in the leaf spot region and non-leaf spot region during 3 growth and development periods of B. masoniana through real-time fluorescence quantitative PCR. 【Result】 A total of 110 members of the R2R3-MYB gene family were identified from the genome of B. masoniana. These gene family members had amino acid quantity ranging from 128 to 870，molecular weights ranging from 14660.85 to 97435.93 Da，and theoretical isoelectric points（pI）ranging from 4.92 to 10.10. There were great differences among the members，with most being unstable hydrophobic proteins，and all of them located in the nucleus. The 110 R2R3-MYB family genes were distributed across all 15 chromosomes，with some genes concentrated on the same chromosome forming gene clusters. BmaMYBs contained 0-10 introns；approximately 94% of the members contained Motif 1， Motif 2 and Motif 3；and the promoter regions of R2R3-MYB gene family members contained a large number of lightresponsive elements. During leaf development，BmaMYB10，BmaMYB18，BmaMYB38，BmaMYB53，BmaMYB97，BmaMYB99 and BmaMYB109 genes were expressed in both leaf spot and non-leaf spot regions；relative expression level of the BmaMYB53 gene in the leaf spot region was as high as 19.41 to 131.99 times compared to that in non-leaf spot region. 【Conclusion】 In the genome of B. masoniana，110 members of the R2R3-MYB gene family are identified. The relative expression level difference between the leaf spot region and non-leaf spot region is the greatest for BmaMYB53 gene，suggesting that this gene is a key regulator in the formation of leaf spots in B. masoniana.