水稻耐盐主效QTLqRKC1的图位克隆与功能分析

Rice is a salt susceptible crop, and salt damage is one of the most severe adversity harm affecting the growth and development of rice. Through excavating salt-tolerant genes of rice and using them in molecular breeding, the progress of salt-tolerant breeding in rice could be accelerated, and the affection to rice arising from salt harm could be alleviated. At earlier stage, this project has detected a new main effective QTL (qRKC1) for salt tolerance about the K+ content in root at the middle and later periods of rice growth period. We have fine mapped it and got its candidate gene. .This project plans to complete the map-based cloning of qRKC1 based on the previous research. Targeted editing of the qRKC1 will be performed using the CRISPR/Cas9 technology, and its functions under the salt stress will be verified combining the overexpression. The RNA-seq will be used to analyze its regulatory network. Functional molecular marker of qRKC1 will be developed to perform the assisted selection of salt tolerance. This project is aimed at solving the salt-tolerant function of qRKC1, obtaining the new salt-tolerant materials of rice through the marker-assisted selection (MAS). This project could provide the clue to uncover the molecular mechanism of salt-tolerance in rice, and also could establish the theoretical and material basis for breeding the new salt-tolerant rice varieties through the molecular breeding methods.

水稻是一种对盐敏感的作物，盐害是影响水稻生长发育最为严重的逆境危害之一。挖掘水稻耐盐基因，利用其进行耐盐分子育种，可以加快水稻耐盐育种的进程，从而减轻盐害对水稻生产的影响。本项目前期检测到了一个与水稻生育中后期根K+含量有关的主效QTL qRKC1，并完成了精细定位，获得了候选基因。. 本项目拟在前期研究的基础上，对qRKC1的候选基因进行图位克隆；利用CRISPR/Cas9技术定点编辑qRKC1，结合过量表达验证其在盐胁迫下的功能；通过转录组测序（RNA-seq）分析其调控网络；开发qRKC1的功能性分子标记，进行耐盐辅助选择。本项目旨在解析qRKC1在盐胁迫下的功能，通过标记辅助选择获得耐盐水稻新材料，为揭示水稻耐盐的分子机制提供线索，为利用分子育种手段培育耐盐水稻新品种奠定理论和材料基础。

水稻是世界上主要的粮食作物，也是一种对盐较为敏感的作物，盐害是水稻生长发育中影响最为严重的逆境危害之一。实践证明，选育和利用耐盐品种是解决水稻盐害问题最经济有效的办法，而发掘和利用耐盐基因进行分子育种则可以加快耐盐品种培育的速度。因此，必须加快鉴定和应用水稻耐盐相关基因，特别是挖掘生育中后期的耐盐基因，应用于育种实践，才能提高选育耐盐品种的效率和准确性。本项目前期利用盐敏感的水稻品种东农425 和耐盐品种长白10 杂交衍生的RIL群体，在田间盐碱胁迫试验条件下，定位到了1个耐盐主效QTL qRKC1。本项目在此基础上，进一步通过候选基因分析确定了其候选基因。完成了qRKC1候选基因的克隆，构建了过表达和敲除载体，成功进行了水稻遗传转化和亚细胞定位。通过转基因功能验证，证实qRKC1可以通过调控Na+、K+的积累来调控水稻的耐盐性。qRKC1可以使盐胁迫下水稻抽穗期提前，每株穗数和千粒重增加，进而增加水稻产量。利用qRKC1的功能性分子标记，在东农425×长白10衍生的回交群体中进行辅助选择，筛选出6个耐盐性较强、农艺性状与东农425相近的株系。本项目为解析qRKC1的耐盐性机制，今后更加深入地研究和利用qRKC1进行水稻耐盐性育种奠定了基础。