水稻应答灌浆期夜间高温的miRNA鉴定及其调控的基因转录网络分析

The heat-tolerant trait of rice is regulated by polygenes, which is difficult to gather into one rice cultivar by traditional breeding way. Therefore, in order to responding to high-temperature climate, it is the necessary to improve the breeding efficiency by excavating effective gene and elucidating the molecular mechanism of rice responding to high-temperature stress. In our previous study, the gene transcript network and the key genes in the network of rice responding to high night temperature at milky stage were successfully constructed by comparative transcriptomics. But the reason why the key genes in the network were showed differentially expressed in the heat-tolerant and -sensitive rice under high-night temperature stress, compared to normal nature conditions and the key genes were regulated by what kind of factors, however, is poorly unstood. Aims to find the key microRNA which regulate the key gene(s) expression in the network, and to provide "new" gene(s) for heat-tolerant rice cultivar breeding, this study would identify the microRNA in rice respoding to high night temperature and further study the regulating relationship among the key genes ,the target genes of the microRNAs and the microRNAs, which would be benefited to improve and perfect the gene network based on microRNA and mRNA level, and provide new gene(s) for breeding heat-tolerant rice and research foundation on the melocular mechanism of rice response to high night temperature stress at milky stage.

水稻灌浆期耐热性受多基因调控，难以通过常规育种途径育成对夜温升高钝感的优良新品种，因而亟待挖掘有效基因元件、弄清水稻应答灌浆期夜间高温的分子机制，进而提高育种成效以应对气候变暖。本团队前期研究已构建了水稻应答灌浆期夜间高温的基因转录调控网络、明确了网络中的关键节点基因，揭示了关键节点基因在夜间高温及常温条件下呈现差异表达。然而其为什么呈现差异表达？是什么因子在调控其表达？亟待进一步探明。本项目拟从基因表达的上游调控因子miRNA入手，通过鉴定耐热性近等基因系应答灌浆期夜间高温和常温条件的差异表达miRNA并预测其靶基因、比较靶基因与关键节点基因的功能，确定调控基因转录网络的关键miRNA，分析关键miRNA及其靶基因表达量与耐热性的关联性，建立基于miRNA和mRNA的基因调控网络，从而为培育灌浆期对夜温升高钝感的新品种提供基因元件、为进一步深入揭示水稻灌浆期耐夜间高温的分子机制奠定基础。

水稻灌浆期耐热性受多基因调控，难以通过常规育种途径育成对夜温升高钝感的优良新品 种，因而亟待挖掘有效基因元件、弄清水稻应答灌浆期夜间高温的分子机制，进而提高育种成效以应对气候变暖。前期研究中，我们以一对近等基因系耐热水稻纯系XN0437T和热敏感水稻纯系XN0437为材料，构建了水稻应答灌浆期夜间高温的基因转录调控网络、明确了网络中的关键节点基因，揭示了关键节点基因在夜间高温及常温条件下呈现差异表达。本研究从基因表达的上游调控因子microRNA（miRNA）入手，鉴定耐热性近等基因系耐热水稻纯系XN0437T和热敏感水稻纯系XN0437应答灌浆期夜间高温和常温条件的差异表达miRNA并预测其靶基因、比较靶基因与关键节点基因的功能，确定调控基因转录网络的关键miRNA，分析了关键miRNA及其靶基因表达量与耐热性的关联性，建立基于miRNA和mRNA的基因调控网络。研究结果深入阐明了参与调控水稻应答灌浆期夜间高温的关键miRNA，建立了miRNA调控的基因转录网络，丰富了人们从分子水平对水稻耐热性的分子机理的了解。为进一步深入揭示水稻灌浆期耐夜间高温的分子机制奠定基础。通过本项目的实施，申请国家专利1件，项目组在国际期刊《Environmental and Experimental Botany》、《Journal of Agricultural and Food Chemistry》和《Genes》发表SCI论文3篇；培养博士2名，硕士1名。项目组完成了原定研究计划的全部科学研究任务。