辣椒R2R3-MYB转录因子家族的全基因组鉴定与比较进化分析

Genome-wide Identification and Comparative Evolutionary Analysis of the R2R3-MYB Transcription Factor Gene Family in Pepper

MYB转录因子作为植物中最大的转录因子家族之一,参与植物的生长、代谢、抵御生物和非生物胁迫等多种生理生化过程。R2R3-MYB是MYB转录因子家族的主要存在形式。辣椒是具有重要经济价值的蔬菜作物,其R2R3-MYB转录因子缺乏系统的研究。从一年生辣椒(Capsicum annuum)、浆果状辣椒(C.baccatum)和中国辣椒(C.chinense)基因组中分别鉴定出94、92和94个R2R3-MYB基因,基于系统发育关系将其分为28个亚族。共线性分析表明,3种辣椒间存在73组直系同源R2R3-MYB基因,一年生辣椒、浆果状辣椒和中国辣椒分别存在5、4和2个特有的R2R3-MYB基因。鉴定出12对重复基因,其中8对是串联重复基因,它们在3种辣椒分化前就已经存在。比较基因组学分析表明,在辣椒进化过程中同源R2R3-MYB转录因子发生了功能分化。组织表达分析表明,辣椒R2R3-MYB基因主要有3种表达特征:在根、叶、茎和花中均高表达,如Ca MYB13/Cb MYB12/CcMYB13;仅在花中高表达,如Ca MYB93/Cb MYB86/Cc MYB12;仅在根中高表达,如Ca MYB48/Cb MYB47/Cc MYB51。研究结果为深入揭示R2R3-MYB转录因子在辣椒生长发育中的生物学功能奠定了基础。

As one of the largest transcription factor(TF)families in plants,MYB TFs are involved in various physiological and biochemical processes,such as plant growth,metabolism,and response to various biotic and abiotic stresses.R2R3-MYB is the main form of MYB TFs in higher plants.Pepper is a vegetable crop with important economic value,but the R2R3-MYB TF family has not been systematically studied in pepper.In this study,94 CaMYB,92 CbMYB,and 94 CcMYB TFs genes were identified with comparative genomic analysis in Capsicum annuum,C.baccatum,and C.chinense,respectively.These genes were categorized into 28 subfamilies.Collinearity analysis indicated that there were 73 groups of orthologous R2R3-MYB genes among three pepper species.There were five,four,and two unique R2R3-MYB genes in C.annuum,C.baccatum,and C.chinense,respectively.In addition,we identified 12 pairs of duplicated genes,and eight of which are tandemly repeated genes,which already existed before the divergence of three pepper species.Comparative genomics analysis suggested that the homologous R2R3-MYB TFs underwent functionally divergence during the evolution of pepper.Analysis on the expression profile showed that R2R3-MYB genes were expressed in three major patterns:high expression in roots,leaves,stems,and flowers,such as Ca MYB13/CbMYB12/-CcMYB13;high expression in flowers,such as CaMYB93/Cb MYB86/CcMYB12;high expression in roots,such as CaMYB48/Cb MYB47/CcMYB51.These results lay a foundation for further study on the biological functions of R2R3-MYB TFs in the growth and development of pepper.