ABA合成关键基因Nced介导陆稻根系发育调控的功能研究

Developing drought tolerance (DT) rice varieties is regarded as the main strategy to reduce the drought injury losses and expand adaptability of rice, which is vital for food security in China. In our pervious study, a lateral root development related gene Nced in upland rice was identified using a large amount of genomics data. Preliminary results showed that Nced can promote the synthesis of ABA and then regulate the root development in upland rice while the detailed function of Nced in root development remains to be clarified. This study plan to analyze the root development and drought tolerance phenotype of Nced-overexpressed and Nced-knockoff transgenic rice for clarify Nced biology function. Expression pattern and promoter (ProNced::GUS) activity of Nced in different tissues and responding to drought stress will be analyzed. Enzyme activity of different Nced protein from upland and lowland rice will be tested to explicit Nced catalytic characteristic in upland rice. Cytology analysis of transgenic rice root under different hormone and drought treatment will be performed for further study, which would uncover the effect of the maintenance and differentiation of stem cells in the root meristems mediated by Nced and the relationship between Nced and the root growth plasticity. All the result will help us to study the roles of rice root development mediated by Nced in drought tolerance and terrestrial adaptations.

培育抗旱水稻，是降低旱灾危害和增加水稻适应性的重要手段，对我国粮食生产至关重要。课题组前期利用水/陆稻群体比较基因组学分析筛选到一个调节陆稻根系发育相关基因（Nced），并初步证明Nced可能通过调节脱落酸（ABA）合成进而调控陆稻根系发育，但其如何介导根系发育功能尚不明确。本研究拟通过对Nced敲除突变体和超表达转基因植株进行ABA水平、根系发育和抗旱性评价等表型分析，明确Nced的生物学功能；通过荧光定量PCR和启动子活性分析，研究Nced基因的时空表达规律和响应旱胁迫表达模式；利用酶活试验分析不同基因型Nced蛋白酶的活性，进一步明确水/陆稻Nced催化特性；结合不同激素和旱胁迫下转基因植株根系的细胞学观察，深入解析Nced在陆稻根分生组织干细胞的维持与分化中的作用，研究Nced调节旱胁迫诱导的根系可塑性，进而探讨Nced介导的根系发育调控对响应旱胁迫及陆生适应性的贡献。

培育抗旱水稻，是降低旱灾危害和增加水稻适应性的重要手段，对我国粮食生产至关重要。本研究验证了陆稻根系发育相关基因（Nced）通过调节脱落酸（ABA）合成进而调控陆稻根系发育功能，通过基因定点编辑证明了单个碱基造成了Nced基因功能的分化。开发了该基因的CAPs分子标记，获得了抗旱性提高的携带T型Nced的近等基因型；进而探讨了Nced介导的根系发育调控对响应旱胁迫及陆生适应性的贡献。本项目进一步证明了OsTb2调控的分蘖减少和Nced调控的根系发育是共同提高根冠比的重要途径，为陆稻陆生适应性进化提供了重要依据。研究结果以文章和发明专利进行体现，目前已发表文章2篇，申请发明专利1项。本项目阶段性成果将为解析陆稻适应性进化机制和抗旱育种提供理论依据和技术支撑。