梭梭幼苗应对荒漠干旱和地表层高温胁迫的分子机制以及优异品系的创制

H. ammodendron is a dominant shrubby or subarboreal perennial. The desert flora, which consists of H. ammodendron, is the most widely distributed vegetation type of our country's deserts. H. ammodendron plays important roles in the maintenance of the structure and function of the ecosystems of our country's deserts, reducing wind speed and ameliorating the desert microclimate, thus facilitating the settlement and growth of other desert plants. Due to jamming, groundwater level declining, inadequate soil moisture, soil salinization, and soil crust, etc, the distribution areas of H. ammodendron in China decreased rapidly in the 1960s and 1970s. Desert drought and high desert surface temperature stresses have been recognized as the major limiting factors that hinder survival rates of H. ammodendron seedlings or transplanting seedlings. In this project, using desert drought and high desert surface temperature resistant lines as materials as well as by transcriptomics, breeding and tissue culture technologies, we hope firstly to reveal the molecular mechanism of H. ammodendron responding to desert drought and high desert surface temperature stresses; secondly to excavate special adverse factor resistant genes; and thirdly to establish breeding technology system of resisting adverse factors and to create elite germplasm and materials. These studies will be helpful to provide not only instructions for the high efficient regulation, improvement and enhancement of adversity resistance of forests and crops, but also scientific foundations for large-scale ecologic recovering and reconstruction of H. ammodendron forests in northwest region of China.

梭梭是我国西北荒漠区珍贵的植物资源，也是固沙造林面积最大的树种，在维护区域生态平衡和促进国民经济发展中起着重要作用。上世纪因持续垦荒、过度放牧和采伐等，新疆梭梭分布面积大量萎缩，荒漠化面积加剧。如何加快梭梭林的恢复与营建工作已成为该地区风沙治理和生态建设工程的重点课题。但在梭梭林的恢复与营建工作中荒漠干旱和地表层高温胁迫成为制约其天然更新幼苗、直播苗和移栽苗成活率提升的关键因子。本项目拟采用筛选获得的苗期抗旱和耐地表层高温胁迫梭梭株系为材料，运用转录组学、育种等技术，①初步揭示其应对干旱、地表层高温胁迫的分子机制及其异同；②挖掘其特有的抗逆基因；③建立抗逆育种技术体系，创制优异抗逆新种质和新品系。其结果不仅可为新疆乃至西北荒漠区梭梭林恢复重建提供理论和实践指导以及优异材料，推进荒漠区生态治理进程；而且可为高效调控、改良农林作物的抗逆特性提供借鉴；还可为我国农林作物基因工程提供重要基因资源。

本项目以筛选获得的苗期抗旱和耐地表高温胁迫梭梭株系为材料，分别进行干旱和模拟地表层高温胁迫后梭梭一年生苗同化枝和根部的转录组测序。对测序结果分析表明：梭梭根和同化枝在应对干旱胁迫时即有类似的代谢通路也存在组织特异性的应对反应，且根对干旱胁迫更加敏感、更持久。在地表层高温胁迫中，同化枝可持续响应地表层高温胁迫，并在不同时间启动不同机制以应对胁迫，而根响应地表层高温胁迫慢于同化枝，且发生显著变化的代谢通路有限。 从梭梭中克隆了数十条基因序列，目前，已克隆基因44个，其中HaNAC基因序列24个，内参基因8个，DREB基因2个 ，14-3-3蛋白基因9个，热激转录因子HSFA 基因1个。通过荧光定量分析和转基因功能分析明确了与干旱和耐地表层高温胁迫相关的NAC基因6个，14-3-3蛋白基因3个 ，1个HSFA 基因。建立了以土壤含水量3%和地表层高温55℃的一年生梭梭幼苗抗逆育种培育技术体系；目前已筛选获得耐旱、耐地表高温、高生长量的梭梭新品系3份。本项目初步揭示梭梭幼苗应对荒漠干旱和地表层高温胁迫生态制约因子的分子机制，克隆与耐逆性密切相关的关键基因，建立梭梭抗逆育种技术体系，创制优异新品系，不仅为荒漠区梭梭林恢复重建工作提供理论依据和实践指导，而且使人们对梭梭在进化过程中所形成的抵御逆境的高效机制有更深入的了解，也为抗逆基因工程提供重要基因资源。