梭梭HaNAC转录因子响应荒漠地表高温胁迫的分子机制研究

NAC is a family of plant-specific transcription factors playing an important role in plant growth and development. As an important constructive species in desert environment of high temperature in northwestern China, Haloxylon. ammodendron is an ideal material for studying adversity-stress molecular mechanism of plants in addition to its significant ecological value. Revolving round the core scientific problem “molecular mechanism of eremophytes in response to high surface temperature” in the high surface temperature environment of northern Xinjiang desert, in view of the low survival rate of H. ammodendron seedlings and shoots under high temperature stress, the proposed project will focus on the functions of such representative transcription factors as HaNAC3, HaNAC12 and HaNAC38 out of NAC family of H. ammodendron in response to high temperature stress, the upstream proteins regulating their responses to high temperature stress, and interactions between NAC-family transcription factors and between them and the other proteins with H. ammodendron germplasm materials of high surface temperature resistant. The project aims to determine the role 3 NAC genes of H. ammodendron germplasm plays under high temperature stress on desert surface, explain their regulation network under high temperature stress, analyze molecular mechanism of NAC transcription factors of H. ammodendron in response to high-temperature stress on desert surface and the differences and similarities in those molecular mechanisms. The research results would be of important theory and application value in understanding comprehensively of the molecular mechanism of H. ammodendron in response to high temperature stress on desert surface, improving the survival rate of H. ammodendron seedlings and shoots, and speeding up the natural and artificial regeneration of such population.

NAC 是植物特有的转录因子，在植物生长发育中具有重要作用，梭梭是分布在我国西北荒漠高温环境中的重要建群物种，不仅具有重要的生态价值，还是研究植物抗逆分子机制的理想材料。本项目将围绕“荒漠植物应对地表高温的分子机制”这一核心科学问题，以新疆北部荒漠地表高温为环境背景，针对梭梭幼苗和幼株在高温胁迫下存活率低的问题，利用耐地表高温梭梭种质材料，重点研究梭梭NAC家族中响应高温胁迫的代表性转录因子HaNAC3、HaNAC12和HaNAC38的功能、调控其应答高温胁迫的上游蛋白、彼此间以及与其他蛋白的互作关系。明确梭梭3个NAC基因在应对荒漠地表高温胁迫中的作用，解析其在高温胁迫下的调控网络，分析梭梭 NAC 转录因子参与应对地表层高温胁迫的分子机制及其异同。研究结果将对全面了解梭梭应对地表层高温胁迫的分子机制、提高梭梭幼苗和幼株成活率、加快其种群自然和人工更新具有重要理论和应用价值。

项目利用耐地表高温梭梭种质材料，重点研究梭梭NAC家族中响应高温胁迫的代表性转录因HaNAC3、HaNAC12和 HaNAC38的功能、调控其应答高温胁迫的上游蛋白、彼此间以及与其他蛋白的互作关系。采用染色体步移法克隆了梭梭HaNAC3、HaNAC12、HaNAC38的启动子，均含有大量干旱、脱水、盐、热激等逆境响应元件，HaNAC38还含有高转录水平的元件，进一步克隆了启动子的上游调控蛋白HaDREB2A、HaDREB2C可与脱水响应元件DRE结合，HaHSFA8、HaHSFB2a、HaHSFA2c可与热激元件HSE结合。HaNAC3、HaNAC12、HaNAC38均定位于细胞核，具有转录自激活活性，转录激活域在C端。HaNAC3/12/42都能够与核心序列CGT[G/A]结合，HaNAC38可以与TTGCGT核心序列结合。酵母体内HaNAC3/12可与HaNAC42形成异源二聚体，HaNAC38可与HaNAC20，HaNAC42形成异源二聚体，HaNAC42还能够与HaNAC2形成异源二聚体。HaNAC2、HaNAC3基因提高了烟草对高温、干旱和盐胁迫的抵抗能力。HaNAC12、HaNAC38基因提高了拟南芥对高温、干旱和盐胁迫的抵抗能力。HaNAC3基因主要通过烟草根部代谢来抵御干旱胁迫，主要途径有苯丙素生物合成和谷胱甘肽代谢等；HaNAC3基因在烟草的叶片中通过上调植物激素信号转导和谷胱甘肽代谢等通路来抵御高温。HaNAC12可在逆境条件下维持拟南芥生殖生长，其在生殖生长中的作用还需进一步研究。项目研究了梭梭HaNAC3、HaNAC12、HaNAC38应对干旱、高温胁迫中的作用，解析其在高温胁迫下的调控网络，分析了彼此间响应逆境的分子机制及其异同。研究结果将对全面了解梭梭应对逆境胁迫的分子机制具有重要理论和应用价值。