CBR1调控水稻碳氮平衡和抗旱性的分子机理研究

干旱引起植物的各种应激反应，然而碳氮平衡是否参与调控水稻干旱响应以及维持碳氮代谢稳态的分子机制尚不清楚。本申请鉴定到一个干旱胁迫超敏感突变体cbr1。与野生型相比，突变体源器官中的总氮含量降低，非结构性碳水化合物含量以及碳氮比（C/N）显著增加。库器官中许多碳氮转运相关基因的表达下调，总氮含量增加，而C/N显著降低。利用BC1F2群体将CBR1精细定位在57kb的区间内，该候选基因为一个调控碳氮平衡的新基因。在此基础上，拟开展基因的互补、过表达、CRISPR-Cas9敲除、GUS、GFP、原位杂交、RNA-seq、ChIP-seq及酵母筛库等，并结合定量PCR、Western、酵母单杂和双杂、体内BiFC和体外pull down验证，在表型、细胞、转录及蛋白水平上对基因功能进行深入研究，解析CBR1的分子作用机制，丰富水稻响应干旱胁迫的基因调控网络，为培育抗旱水稻新品种提供理论和材料基础。

Drought stress triggers various plant responses, however, it was not clear whether C/N balance was involved in the regulation of drought response in rice and the molecular mechanisms of maintaining the coordination of carbon and nitrogen metabolism remain elusive. In this application, a highly drought-sensitive mutant cbr1 was identified. A comparison between wild type rice (WT) and cbr1 mutant showed that total N content was decreased, but total non-structural carbohydrate and C/N ratio were markedly increased in the cbr1 source leaves. The abundance of the transcript generated by a number of genes encoding components of C and N transports were lower in cbr1 than in WT plants’ sink tissues, while the total N content and C/N ratio were, respectively, markedly increased and decreased. By using the BC1F2 population, the CBR1 was fine mapped in an interval of 57kb. The candidate gene is a new gene in regulating C/N balance. On the basis, we will carry out the study to further conduct the CBR1 gene function analysis to ascertain the molecular mechanism and enrich the gene regulatory network of the drought response by the experiments of the gene function complementation, over expression, CRISPR-Cas9 knock-out, GUS, GFP, fluorescent in Situ Hybridization, RNA-seq analysis, ChIP-seq analysis and yeast library screening combined with the qRT-PCR, Western, yeast one-hybrid, yeast two-hybrid, BiFC and pull down test on the level of the phenotype, cell, transcription and protein. Therefore, this research will lay the theoretical and material basis of molecular design breeding for new rice varieties with enhanced drought tolerance.