水稻苗期耐冷基因qCTS11的图位克隆与功能分析

Rice is a kind of low-temperature-sensitive plant, and low temperature is one of major abiotic stresses resulting in yield loss of rice, especially Indica rice. Therefore, the study of cold tolerance in rice is of great significance for food security in China. Compared to Indica rice, Japonica is more resistant to cold stress, so it is a feasible way to improve the cold tolerance of Indica rice through using low-temperature resistant genes from Japonica rice. However, the genetic basis of nature variation of rice subspecies and its molecular mechanism have been still unknown, which limits the application of molecular breeding for low temperature tolerance in Indica rice. Recently we have mapped a major QTL controlling cold-tolerance of rice seedlings on rice chromosome 11, named qCTS11, in genetic population crossed between two varieties form different subspecies. Moreover, the near-isogenic line of qCTS11 has been constructed through backcrossing. On these bases, we intend to clone the gene of qCTS11 by map-based cloning and then analyze the functions of the gene and the pathway involving qCTS11. The expected results are that the gene for qCTS11 is expected to be cloned, that the function and the regulatory network of qCTS11 will be discovered. They will serve as prelude towards understanding the genetic bases of rice cold tolerance. The excellent allele of qCTS11 identified by association analysis will be used for molecular breeding of cold-tolerant in Indica rice.

水稻是低温敏感植物，低温冷害是造成水稻（特别是籼稻）减产的主要逆境之一，开展水稻耐冷性研究对保障我国粮食安全有着重要意义。与籼稻相比，粳稻耐冷性强，利用粳稻的耐冷基因资源改良籼稻的耐冷性是一条可行的途径。但是，由于籼稻和粳稻耐冷性差异的遗传基础和分子机理目前还不清楚，制约了分子育种手段在籼稻耐冷性改良育种过程中的应用。在前期研究中，本课题组利用籼/粳遗传群体定位到1个来自于粳稻的苗期耐冷主效QTL-qCTS11，并通过多次回交构建得到该QTL的近等基因系。本项目拟利用近等基因系对qCTS11进行基因克隆，并对该基因进行功能分析和网络调控研究。预期结果不仅可以揭示籼粳耐冷多样性的遗传基础，还可以从粳稻中挖掘到优秀的耐冷基因，为籼稻耐冷分子育种提供基因资源。

水稻是我国主要粮食作物，也是低温敏感植物，低温冷害常常造成水稻（尤其籼稻品种）减产。普遍上粳稻品种比籼稻品种具备较强的耐冷性，可为籼稻的耐低温育种提供基因资源，然而亚种间的耐冷性差异的遗传机制知之甚少。为此，本课题组利用籼粳亚种遗传群体，图位克隆到了一个控制籼粳苗期耐冷性差异的QTL-qCTS11，该基因编码CYP450，定位于内质网上，受低温等逆境诱导表达；编码蛋白可以代谢茉莉酸活性成分，从而通过JAZ-ICE1-DREB1途径负调控水稻耐受性。该基因在籼粳稻之间有序列上的分化，其单倍型可以划分籼粳两大类；该基因受到地理纬度相关环境因子例如低温的选择，分布于高纬度的温粳具备特有的保守单倍型，其耐冷性最强。该QTL的克隆与功能分析，解析了茉莉酸与水稻亚种间耐冷性差异的关联，所克隆的等位基因为水稻尤其籼稻育种提供了基因资源。