调控水稻灌浆期耐热相关基因表达的DNA甲基化关键位点挖掘

Several waves of rice output were related to double-season rice yields, and high temperature climate at rice milky stage is a main natural calamity limiting rice yield on the major double-season growing area in China. Therefore, breeding new cultivars with good quality and high temperature tolerant traits become a basic countermeasure for double-season rice productivity, but the trait of rice resistanting to high-temperature is regulated by multiple genes. Therefore, the uppermost task is to improve the breeding efficiency on breeding rice cultivars with the heat-resistant traits, and clone effective functional gene for high temperature tolerant rice. In our previous study, full-length cDNA sequences of the 54 genes related to rice responding to high temperature were cloned. The further study result showed that the different display genes were not only origin from heat-tolerant rice but also from heat-sensitive rice, but showed significant different in gene expression under high temperature conditions, and the partial differentially expressed gene showed DNA methylation, which was accorded with the characteristics of epigenetic. In this project, the relationship between rice heat-tolerant traits and the key locus of methylation (demethylation) locus in the different display genes will be further analyzed, and the epigenetic function on the key methylation (demethylation) locus in the genes would be confirmed by transgene. The result would be able to provide effective functional genes for and be beneficial to accelerating breeding new cultivars with high temperature tolerant traits.

我国稻谷总产量的几次大波动都与双季早稻的减产密切相关，灌浆期高温热害是造成我国水稻主产区双季早稻减产的重要自然灾害，加快选育灌浆期耐热性强的优良新品种是双季早稻生产中应对高温热害的根本性对策。水稻灌浆期耐热性受多基因控制，为尽快提高水稻灌浆期耐热性育种的成效，挖掘有效的功能基因已成为当务之急。本项目组前期研究克隆了54个与水稻灌浆期耐热相关基因的全长cDNA序列；这些基因既存在于耐热水稻也存在于热敏感水稻，而在气温升高条件下却呈现显著的相对表达差异；DNA双链溶解曲线显示这些基因存在DNA甲基化现象。为此，本申请项目拟进一步论证水稻灌浆期耐热性与差异表达基因的甲基化和去甲基化之间的关系，明确调控水稻灌浆期耐热相关基因表达的甲基化和去甲基化关键位点，并验证其表观调控功能，研究结果可为水稻灌浆期耐热性育种提供有效的功能基因，从而促进早稻灌浆期耐热性强的优良新品种的选育。

水稻灌浆期是高温热害的敏感期之一，水稻灌浆期耐热性存在极显著的基因型差异；研究表明，夜间高温是危害水稻籽粒灌浆充实，导致籽粒粒重下降、稻米品质变劣，是直接危害水稻生产的主要气候因子。本项目在前期研究的基础上，利用全基因组甲基化测序技术分别分析了水稻灌浆期耐热近等基因系耐热与热敏感纯系应答灌浆期夜间高温的全基因组胞嘧啶位点甲基化情况，比较了耐热与热敏感纯系基因组被高温诱导产生的差异甲基化或去甲基化区域及其所在的基因，深入揭示了灌浆期夜间高温诱导耐热与热敏感纯系的基因组DNA甲基化和去甲基化的区域，以及这些区域与所在基因部件的关系，阐明了基因的甲基化和去甲基化与水稻耐热性的相关性；结合项目的转录组和蛋白质组研究结果，我们筛查出来了1个水稻应答灌浆期高温的关键甲基化基因，并进一步通过基因克隆、遗传转化和转基因水稻的灌浆期耐热性评价，验证了该关键甲基化基因调控水稻灌浆期耐热性的效应，结果表明该目的基因参与调控水稻的籽粒灌浆充实过程。已在Environmental and Experimental Botany、Journal of Agricultural and Food Chemistry、Proteomics、中国水稻科学等国内外权威学术期刊发表论文4篇（均标注基金资助），其中SCI论文3篇，产生了重要的学术影响；已获授权国家专利1件，培养博士2名、硕士2名，取得了良好的社会效益。