水稻结实率调控基因SS1的克隆及分子机制解析

结实率是影响水稻产量的主要因素之一，水稻低结实率导致单株实粒数下降，产量降低。在前期工作中，从日本晴和清香糯杂交、回交构建的BC2F6群体中检测到一个控制结实率的主效QTL位点qSS-1。本研究进一步利用由BC2F6杂合单株自交获得的BC2F7家系进行精细定位，将控制结实率的候选基因定位在1号染色体991 bp的区间。该区间只有1个预测基因，因此确定为候选基因，命名为SS1。对近等基因系的定位区间DNA序列比较发现高结实率近等基因系NIL22H中有34 bp的插入片段，位于该基因第一内含子。通过转基因互补验证，初步证明SS1是控制水稻结实率的新基因。组织学观察表明SS1主要影响花药绒毡层降解和花粉壁结构。SS1主要在水稻幼穗中表达，编码蛋白定位于细胞核内。在此基础上，本研究将继续开展敲除、超表达等转基因验证，互作蛋白筛选和单倍型分析，深入阐明SS1调控水稻结实率的分子机制和育种应用潜力。

Seed setting rate is one of the main factors affecting rice yield. The low seed setting rate of rice resulted in the decrease of filled grain number and finally decreased the yield per plant. In the previous work, a major QTL-qSS-1, controlling seed setting rate, was detected from BC2F6 population constructed by crossing and back-crossing between Nipponbare and Qingxiangnuo. In this study, we further used the BC2F7 lines generated by self-crossing of heterozygous individuals in BC2F6 population for fine mapping, and finally the candidate gene controlling seed setting rate was mapped within the interval of 991 bp on chromosome 1. There was only one predicted gene in this region, so it was identified as the candidate gene and named SS1. The comparison of DNA sequences in the mapped region between near isogenic lines revealed that 34 bp DNA fragment was inserted into the first intron of SS1 in the high seed setting rate near isogenic line NIL22H. Through transgenic complementary verification, we preliminarily proved that SS1 is a newly identified gene that controls seed setting rate in rice. Histological observation showed that SS1 mainly affected the degradation of anther tapetum and pollen wall structure. SS1 is mainly expressed in young panicle, and its protein is located in the nucleus. Based on these results, transgenic validation by knock out or overexpression of SS1, interacting protein screening and haplotype analysis will be conducted to further elucidate the molecular mechanism of SS1 in regulating seed setting rate and its application potential in rice breeding.