Characterization,expression and phylogenetic study of R2R3-MYB genes in orchid

cDNA fragments representing 21 R2R3-MYB genes were isolated by RT-PCR from the Dendrobiumorchid hybrid Woo Leng. Six full-length cDNA clones were obtained from a flower cDNA library, four of which, DwMYB1, DwMYB2, DwMYB8 and DwMYB10, represent typical plant R2R3-MYB genes. The conceptual DwMYB4 protein is truncated at the C-terminal region and contains the R2 repeat and the N-terminal half of the R3 repeat (R2R3). DwMYB4 expression is restricted to flowers. DwMYB9 contains an 8 amino acid N-terminal deletion in the R2 repeat (R2R3) and is expressed at high levels in mature flower and inflorescence, but at very low levels in young flower buds. DwMYB8 and DwMYB10 show similar expression patterns and share very high sequence similarity in the N-terminal part of the MYB domain. Analysis of amino acid substitution indicated that the pattern and type of substitution between Arabidopsis and maize are quite different. Maize may have more conserved substitution in the MYB^BRH domain than Arabidopsis.     

拟南芥R2R3-MYB类转录因子在环境胁迫中的作用

MYB转录因子是植物转录因子中最大的家族之一,以含有保守的MYB结构域为共同特征,分为三个亚族（R1／2-MYB、R2R3-MYB和R1R2R3-MYB）,其中含有两个MYB结构域的R2R3-MYB成员最多,广泛参与植物次生代谢调控、细胞形态发生、胁迫应答、分生组织形成及细胞周期控制等。近年来,R2R3-MYB在植物逆境胁迫中的作用引起了广泛关注,本文综述了拟南芥R2R3-MYB蛋白在环境胁迫响应中作用的研究进展。     

拟南芥R2R3-MYB家族第22亚族的结构与功能

拟南芥R2R3-MYB转录因子在拟南芥生长发育、代谢及响应生物和非生物胁迫的调控网络中具有重要作用。根据保守的氨基酸序列,R2R3-MYB转录因子被分为25个亚族,其中第22亚族包含AtMYB44、AtMYB77、AtMYB73和AtMYB70 4个基因,主要响应生物和非生物胁迫。文章从基因功能的相似性、基因表达的一致性和基因结构的保守性3方面综述了第22亚族的4个基因,并综合讨论了其在结构与功能上的冗余性和多样性。     

An extensive analysis of R2R3-MYB regulatory genes from Fagus crenata

Using pairs of degenerate primers, we conducted a polymerase chain reaction to amplify the partial R2R3 domains of a majority of the R2R3-MYB family genes from Fagus crenata and identified a total of 85 independent gene fragments. By phylogenetic analysis of the deduced amino acid sequences, we found that many of the beech genes clustered with members from Arabidopsis, suggesting that these members represent beech orthologs of Arabidopsis. Some of the orthologous relationships became more evident when the complete gene structures were compared. Further, a large number of genes formed an additional and expanding cluster, independent from the other subgroups. These members were further compared with the Populus and Vitis family genes. In the epidermal cell fate clade, expansion of the beech family genes was comparable with those of the Populus and Vitis families, but the number of genes present in every subclade fluctuated extensively. Beech genes were abundant in the general flavonoid pathway regulation and TT2-related subclades; no beech gene was included in the anthocyanin-related subclade. Further analysis of the newly amplified regulatory genes to elucidate their functions may clarify the role of these genes in the evolution of plant species.     

ZmMYB31, a R2R3-MYB transcription factor in maize,positively regulates the expression of CBF genes and enhances resistance to chilling and oxidative stress

Molecular Biology Reports - Maize (Zea mays L.) is an important model plant with an important role in agriculture and national economies all over the world. The optimum growth temperature of maize...