杨树MYB家族转录因子调节植物干旱胁迫反应的分子机制研究

As an important woody species, Poplar (Populus) possesses typical resources and the ecological effects for us human being, and it is likely to be affected by drought stress on the growth and development. In the Poplar genome, the MYB transcription factors are belonged to one largest gene family, but the biological function of vast majority remain unknown. Based on the poplar transcriptome sequencing results under abiotic stresses, a Poplar R2R3-type MYB transcription factor, which could respond to drought stress, temporarily named it as PtrRDF1 by us, was screened out. According to our current research results, presumably the transcription factor is likely to involve in abscisic acid (ABA) signaling to mediate plant drought tolerance. In the molecular level, however, the function of the transcription factor is still not clear, the potential regulation targets and activation sites need to be experimentally confirmed. Therefore, to apply for the project we intend to further refine PtrRDF1 expression pattern in detail under different stresses, and the methods of modern molecular biology, biochemistry and others could be utilized for identifying the gene regulation target or site and participating in the molecular mechanism of drought stress regulation on multiple levels. The results contributed by the project could be expected to lead to a R2R3-type MYB transcription factor cloning initially from Poplar genome, and revealing the function and mechanism of its responding to drought stress and playing a role of transcriptional regulation in plant.

杨树(Populus)是一种具备典型资源和生态效应的木本植物，干旱会对其生长发育造成较大影响。其基因组编码的MYB家族转录因子成员众多，但其中绝大多数生物学功能未知。我们利用非生胁迫下的杨树转录组测序，筛选出一个R2R3型MYB家族转录因子，响应干旱胁迫诱导，暂命名其为PtrRDF1。据我们目前的研究，推测该转录因子很可能以参与植物脱落酸(ABA)信号调控的方式介导植物的干旱耐受反应。但是，分子水平上该转录因子的功能仍不清楚，其潜在的调控靶标和激活位点亟待实验证实。为此，申请项目拟进一步细化PtrRDF1非生胁迫下的表达模式，并采用现代分子生物学、生物化学等方法和技术多角度鉴定该基因的调控靶标或作用位点，揭示其参与干旱胁迫调控的分子机制。项目研究成果可望首次从杨树中克隆该MYB家族转录因子，搞清其响应干旱胁迫、发挥转录调节的基因功能和分子机制，从而为杨树逆境功能基因组学研究提供基础。

杨树是我国林业的主要栽培树种。随时代发展和气候变迁，一方面国内外对林木原材的需求日益增加，另一方面外界气候环境等条件时常严重损害林业生产。例如，干旱、盐碱等导致杨树种植减产，成为威胁我国林业和生态安全的主要不利因素。着眼未来，必需加快以杨树为主要对象的分子生物学和基因组学领域的应用基础研究，揭示其中作用机制，为从根本上增强杨树等林木树种抵御干旱等逆境提供重要基础。在植物抵御和适应外部环境条件过程中，转录调控是决定基因表达和分子功能的关键环节。MYB基因是植物大型转录因子基因家族中的重要代表，并且该基因家族成员在植物生长、发育和抵御逆境等方面均具有重要的调节功能。但是在杨树为代表的木本植物中，该基因家族成员的调节功能和作用机制还远未被揭示。本项目首先克隆了杨树中重要的R2R3-MYB转录因子PtrMYB94等基因，并对其在植物中调节干旱等胁迫的功能和作用机制进行了深入探究。结果表明，PtrMYB94能够介导植物内源脱落酸激素信号正向调节植物对干旱胁迫的适应性。依托项目资源，为研究生和本科生多人的培养提供了重要支撑。研究结果先后发表重要论文四篇。总之，在基金的资助下，项目有力支撑了人才培养，研究结果为深入揭示杨树MYB因子参与调节干旱、盐碱等环境胁迫的功能和作用机制提供了重要证据，并为深入开展杨树林木抵抗干旱胁迫等方面的基础及应用研究提供了参考和基因材料。