摘 要 ：MYB转录因子家族是植物重要的转录因子家族之一，其成员在植物的生长、发育、细胞壁形成及胁迫反应等多方面发挥重要作用。从白桦(Betula platyphylla Suk.)中鉴定了17条MYB家族基因，与拟南芥家族基因进行系统进化分析结果表明，17个白桦MYB基因分属不同亚家族的不同亚类，其中10条属于1R/4R型亚家族，其余7条属于2R型亚家族。BplMYB13与已知的次生细胞壁合成相关基因AtMYB46聚为一组，BplMYB15和BplMYB26分别与胁迫响应和非生物胁迫应答相关MYB聚为一组，BplMYB23与硫代葡萄糖苷合成相关MYB聚为一组，BplMYB9、21和22与苯丙烷生物合成相关MYB聚为一组。利用Real time RT-PCR分析白桦MYB家族基因在白桦形成层和木质部组织一个生长季不同发育时期及人工弯曲处理6h的表达模式。结果显示17个MYB基因在5月中旬至7月中旬白桦形成层活动旺盛,木质部迅速形成期表达量较高，其中BpMYB13在全生长季形成层和新生木质部中都有较高的表达水平，推测该基因与次生细胞壁的形成相关；在白桦茎干人工弯曲处理6 h时，与直立木和对应木相比，14条基因在应拉木中上调表达；与直立木相比，7条基因在对应木中上调表达。说明这些基因对人工弯曲处理和重力刺激具有应答反应，可能在白桦木质部发育和响应外力刺激等过程的生理变化中起重要作用。
Abstract:The MYB transcription factor family is one of the important plant transcription factor family members, and they have the key function on the growth, development, cell wall biosynthesis and stress response in plant. We obtained the total of 17MYB genes, and by phylogenetic analysis, 17 MYB genes of birch belong to different subfamilies and groups. Among these genes, 10 MYBs belong to the 1R/4R subfamilies, and 7 MYBs belong to the 2R subfamily. BplMYB13 is homologous to the AtMYB46 which functions in the secondary cell wall biosynthesis. BplMYB15 and BplMYB26 belong to the group which involved in the stress response. BplMYB23 is homologous to the AtMYBs involved in the glucosinolate biosynthesis. BplMYB9, 21 and 22 have homologous with the AtMYBs functioned in phenylpropanoid biosynthesis. The expression patterns analysis among the development stages of the growth season and the tension wood and opposite wood bended for 6 h, and the normal wood were performed by real time RT-PCR. 17 MYB genes had the peak express levels from the middle of May to the middle of July, and the BplMYB13 maintained the high express levels among all the growth season in the cambium and xylem. The BplMYB13 may play the role in the cambium and xylem development. After 6 h bending, 14 MYBs were up-regulated in the tension wood compare with the opposite wood or normal wood, and 7 MYBs were increased expressed in the opposite wood than those in the normal wood. Therefore, these genes response to the artificial bending and play key roles in the physiology change during the xylem development response to the bending stress.