密穗型高粱稻GLR大穗与密穗性状主效QTLs的定位和克隆分析

Increasing the grain number per spike in rice is the successful strategy and developing direction for super high-yielding rice breeding. Creating elite germplasms with large panicle and cloning panicle-related genes are of great importance for scientific research and breeding practice. An elite variant GLR was found primarily by injecting genomic DNA of sorghum into indica rice 9311 through Spike-Stalk Injection Method (SIM). Compared to the recipient 9311, the grain number per spike of GLR increased from 242 to 393, the grain density from 9.77 to 18.31, and has a higher seed setting rate. The genetic diversity between GLR and 9311 was about 8.07%, and a lot of single-nucleotide polymorphisms (SNPs) and structural variations (SVs) were identified in GLR relative to 9311. We cloned and compared the panicle-related genes between GLR and 9311, and found that a few sequence variations in DEP3, D1 and Gn1a. On these basis, focusing on the characters of large and dense panicle, we will carry out series of experiments including the comparative genomic analysis between GLR and 9311 genome, fine mapping and gene clone of grain number per panicle and panicle density in the F2 population crossed between GLR and Hua Hang 31, and the BC3F2 population with the Hua Hang 31 as the recurrent parent, and preliminary analysis of gene function, which would provide new genes for super high-yielding rice breeding.

增加每穗粒数是超高产育种的成功策略与发展方向，创制优异大穗种质、克隆相关基因，具有十分重要的科学意义与应用价值。本课题组转移高粱基因组DNA获得一大穗变异系：“密穗型高粱稻GLR”。相对受体9311，GLR每穗粒数由242粒增加到393粒，穗着粒密度由9.77增加到18.31，而且结实率更高。初步的分子标记分析发现两者间遗传多样性为8.07%，基因组序列比较发现两者存在大量单核苷酸与结构变异，克隆比较两者间穗粒数相关基因发现其中DEP3、D1和Gn1a这 3个基因存在序列变异。本项目拟在此基础上围绕GLR大穗、密穗性状，深入开展GLR与9311比较基因组分析，GLR与华航31的F2、BC3F2群体穗粒数和着粒密度主效QTLs的精细定位、克隆，以及转基因功能初步验证等研究，为超高产育种提供新的基因资源。

增加每穗粒数是超高产育种的成功策略与发展方向，创制优异大穗种质、克隆相关基因具有十分重要的科学意义与应用价值。本课题组转移高粱基因组DNA获得一大穗变异系“密穗型高粱稻GLR”，相对受体9311，GLR每穗粒数由242粒增加到393粒，穗着粒密度由9.77增加到18.31，而且结实率更高。在此基础上，我们开展了GLR中重要产量性状的QTL定位，基因克隆和基因的遗传效应分析。共鉴定到36个与水稻产量性状相关的QTL区间，其中一个主效QTL区间（chr8: 24.76-26.05 Mb）同时关联到粒长、叶宽等8个性状（平均LOD>69.95，表型贡献率>44.54%），另一个主效QTL区间（chr4: 30.47-31.81 Mb）同时关联到粒长、叶宽和籽粒长宽比（平均LOD>22.56，表型贡献率>17.66%）；克隆测序和基因定量分析等表明GLR中IPA1和NAL1基因的等位变异是导致GLR性状变异的主效关键基因；以9311为遗传背景的单片段代换系的产量相关性状比较数据表明来源于GLR中的IPA1等位基因可以使叶宽平均增加28.85%，穗粒数平均增加36.01%，NAL1等位基因可以使叶宽平均增加31.34%，穗粒数平均增加8.29%。本研究为超高产水稻育种提供了新的基因资源和分子模块。