稗草耐低氮的分子机理及其育种利用研究

The genus Echinochloa includes numerous problematic weeds (barnyard grasses) worldwide that are able to tolerate a wide range of environmental stresses. Understanding molecular mechanisms of environmental adaption and identification of essential stress tolerant genes in barnyard grasses will provide important theoretical basis and gene recourses for crop improvement. Nitrogen is required in greater quantities by crop than any of the other essential nutrients. The development of new varieties of rice with high nitrogen use efficiency is one of the important ways to increase rice yield. We will mainly use genomics and transcriptomics approaches in this project based on our barnyard grass genome sequences and 150 genomes re-sequenced. This project study the molecular genetic basis of low nitrogen tolerance through comparing the genome sequences of barnyard grasses with different abilities of low nitrogen tolerance, explore the gene regulation mechanisms under low nitrogen stress through transcriptomics analysis, and identify low nitrogen tolerant genes in barnyard grasses. Furthermore, we investigate the conservative and specific mechanisms of low nitrogen tolerance in barnyard grasses compared with rice. These results will provide key genes for breeding new varieties of rice with high nitrogen use efficiency.

稗草是世界性恶性杂草，具有很强的环境适应性，对稗草环境适应性分子机理的解析及关键基因的挖掘，将为作物改良提供重要的理论基础与基因资源。氮素是植物营养需要量最大的矿质元素，培育氮肥高效吸收和利用的品种是提高水稻产量的重要途径之一。本项目以稗草为研究对象，利用申请者所在实验室已有基础（稗草基因组数据及150份重测序数据），以基因组学和转录组学分析为主要手段，通过比较具有不同低氮胁迫耐性的稗草基因组，揭示稗草耐低氮胁迫的分子遗传基础；通过对低氮胁迫下稗草转录组的分析，探究稗草低氮胁迫下基因表达调控机制，挖掘稗草耐低氮关键基因；同时与水稻进行比较分析，阐明稗草响应低氮胁迫机制的保守性和独特性，为培育氮高效利用水稻品种提供重要基因资源。

稗草（Echinochloa spp.）是世界上最严重的农田杂草之一，具有很强的环境适应性。研究其环境适应性分子机制，可为水稻分子育种提供重要基因资源。本项目（1）基于稗草E. crus-galli和E. oryzicola叶绿体基因组，开发稗草分子标记，并在200多份稗草材料中对其中一个标记进行了检测，结果表明该分子标记有助于稗草种类鉴定；（2）基于前期已有稗草E. crus-galli基因组序列及其拼接，进一步优化了其拼接及注释，稗草E. crus-galli基因组Scaffold N50达到1.8Mb，包含10万左右的蛋白编码基因，并发现了稗草以基因簇的形式适应环境的分子机制；（3）测定了稗草E. crus-galli在低氮胁迫处理前后的转录组，分析了其差异表达基因，结果显示稗草中显著上调基因大部分在水稻中有同源基因，表明两者在响应低氮胁迫分子机制的保守性，同时发现了32个稗草特异基因显著上调，这些结果为水稻耐低氮分子育种提供了重要基因资源。该项目发表标注论文2篇。