A review of target gene specificity of flavonoid R2R3-MYB transcription factors and a discussion of factors contributing to the target gene selectivity  

作　　者：Yunsong LAI Huanxiu LI Masumi YAMAGISHI 

机构地区：[1]Institute of Pomology and Olericulture, Siehuan Agricultural University, Chengdu 611130, China [2]Research Faculty of Agriculture, Hokkaido University, Kita-Ku, Sapporo 060-8589, Japan

出　　处：《Frontiers in Biology》2013年第6期577-598,共22页生物学前沿（英文版）

摘　　要：Flavonoid biosynthetic genes are often coordinately regulated in a temporal manner during flower or fruit development, resulting in specific accumulation profiles of flavonoid compounds. R2R3-MYB-type transcription factors （TFs） ＂recruit＂ a set of biosynthetic genes to produce flavonoids, and, therefore, R2R3-MYBs are responsible for the coordinated expression of structural genes. Although a wealth of information regarding the identified and functionally characterized R2R3-MYBs that are involved in flavonoid accumulation is available to date, this is the first review on the global regulation of MYB factors in the flavonoid pathway. The data presented in this review demonstrate that anthocyanin, flavone/flavonol/3-deoxyflavonoid （FFD）, proanthocyanidin （PA）, and isoflavonoid are independently regulated by different subgroups of R2R3-MYBs. Furthermore, FFD-specific R2R3-MYBs have a preference for early biosynthetic genes （EBGs） as their target genes; anthocyanin-specific R2R3-MYBs from dicot species essentially regulate late biosynthetic genes （LBGs）; the remaining R2R3-MYBs have a wider range of target gene specificity. To elucidate the nature of the differential target gene specificity between R2R3-MYBs, we analyzed the DNA binding domain （also termed the MYB-domain） of R2R3-MYBs and the distribution of the recognition cis-elements. We identified four conserved amino acid residues located in or just before helix-3 of dicot anthocyanin R2R3-MYBs that might account for the different recognition DNA sequence and subsequently the different target gene specificity to the remaining R2R3-MYB TFs.Flavonoid biosynthetic genes are often coordinately regulated in a temporal manner during flower or fruit development, resulting in specific accumulation profiles of flavonoid compounds. R2R3-MYB-type transcription factors （TFs） ＂recruit＂ a set of biosynthetic genes to produce flavonoids, and, therefore, R2R3-MYBs are responsible for the coordinated expression of structural genes. Although a wealth of information regarding the identified and functionally characterized R2R3-MYBs that are involved in flavonoid accumulation is available to date, this is the first review on the global regulation of MYB factors in the flavonoid pathway. The data presented in this review demonstrate that anthocyanin, flavone/flavonol/3-deoxyflavonoid （FFD）, proanthocyanidin （PA）, and isoflavonoid are independently regulated by different subgroups of R2R3-MYBs. Furthermore, FFD-specific R2R3-MYBs have a preference for early biosynthetic genes （EBGs） as their target genes; anthocyanin-specific R2R3-MYBs from dicot species essentially regulate late biosynthetic genes （LBGs）; the remaining R2R3-MYBs have a wider range of target gene specificity. To elucidate the nature of the differential target gene specificity between R2R3-MYBs, we analyzed the DNA binding domain （also termed the MYB-domain） of R2R3-MYBs and the distribution of the recognition cis-elements. We identified four conserved amino acid residues located in or just before helix-3 of dicot anthocyanin R2R3-MYBs that might account for the different recognition DNA sequence and subsequently the different target gene specificity to the remaining R2R3-MYB TFs.

关 键 词：MYB CIS-ELEMENT DNA-binding domain flavonoid transcription factor target gene specificity 

分 类 号：Q943[生物学—植物学] Q946.8