梭梭幼苗HaNACs响应干旱胁迫的分子调控机理研究

NAC transcription factors imply important roles in plants’ developmental events and regulation of abiotic stresses. Reported literature show that most NAC genes belong to stress-responsive NAC group, SNAC. Haloxylon ammondendron, an endangered typical super-xerophytic C4 plant that widely distributed in desert area. Seedlings of Haloxylon ammondendron can maitain normal growth under 100 mm rainfall and it is also the constructive edificators in desert. However, the molecular mechanisms of HaNACs in Haloxylon ammondendron seedlings in response to drought stress remained obscure. In this project, all the drought - responsive NAC family members and their promoter sequences will be isolated by RNA-SEQ and homology-based cloning. Functional characterization of these HaNACs will be tested and verified by over-expression and RNAi method in Arabidopsis thaliana. Genes related to HaNACs in transgene plants will be verified by digital gene expression (DGE) profiling analysis and yeast one hybrid system. Based on the above analyses, regulatory networks of HaNACs as well as their roles in photosynthesis regulation will be constructed. Transpiration and morphological structure changes will also be illustrated..This research will give a clear explanation of the molecular mechanism that how Haloxylon ammondendron saplings dealing with drought stress in a systematic and dynamical way.

NAC转录因子对植物形态发生和非生物胁迫具有重要调节作用，大多数旱胁迫响应NAC属于SNAC组。梭梭为濒危、超旱生C4小乔木，在降雨量不足100mm的生境中能够正常生长，是荒漠优势建群种，特别是其幼苗抗旱能力超强。梭梭幼苗的HaNACs对旱胁迫响应调控的分子机理是一个重要的科学问题，亟待探索研究。.项目拟以同化枝初生期梭梭幼苗为材料，克隆全部旱胁迫响应HaNACs成员并分析其序列结构特征，构建过表达和RNAi抑制表达载体，转化拟南芥验证基因功能，并用数字表达谱分析和酵母单、双杂交等方法筛选与HaNACs有互作用关系的调控基因，构建基于HaNACs的基因调控网络，确定转基因植株HaNACs对光合、蒸腾作用以及与抗旱相关性状发生的调控作用，揭示梭梭幼苗HaNACs响应干旱胁迫的调控机理，为阐明C4植物NAC和苗期梭梭对旱胁迫分子调控机理提供理论依据，研究成果具有重要的应用价值。

梭梭（Haloxylon ammodendron）为濒危超旱生小乔木，具有超强的抗旱、耐盐碱能力；其幼苗抗逆分子调控机理研究结果将对农作物抗旱遗传改良研究起到重要的理论支撑作用。本项目以梭梭幼苗、拟南芥等为研究材料，以梭梭NAC转录因子编码基因研究为切入点，从基因克隆、遗传转化、转基因株系抗逆形态、生理、生化指标检测、逆境应答关键基因表达模式鉴定和表达谱分析等方面进行了研究，初步搞清了梭梭NAC1响应干旱胁迫的分子调控机制。.首先，从梭梭幼苗转录组测序数据中鉴定得到49个NAC家族成员，其中17个具有NAM结构域，并包含与模式植物类似的5个保守区和核定位信号序列（PRDRKYPN）。 .其次，构建了pCAMBIA1302-GFP-HaNAC1表达载体，在烟草和拟南芥中确定了HaNAC1的核定位信号，并在酵母中证明HaNAC1具有转录激活活性。在拟南芥中异源表达HaNAC1基因获得3个阳性株系，通过pull-down，co-ip和BiFC等实验证明HaNAC1与AtNAC32发生直接相互作用，互作产生的信号可能导致NCED1等6个逆境应答关键基因表达量上调，致使ABA、IAA等内源激素含量上升，从而使植株表现出矮化、早花等适应性表型以应答干旱胁迫。.第三，项目还以马铃薯为材料，证明了HaNAC1在提高抗旱性的同时提高了产量，并初步探究了生理和分子调控机制；创制并筛选出4个性状表现优良的基因工程材料，具有原始创新性。.本项目在国内核心期刊上发表研究论文7篇，SCI收录期刊论文1篇（影响因子3.4），培养硕士研究生2人，青年科技骨干人才3人；已圆满完成了计划研究任务，取得了创新性强、应用前景广阔的研究成果。