水稻结实率杂种优势负向超显性位点的功能研究与利用

结实率是每穗实粒数的重要组分，对杂交稻产量有直接影响。结实率杂种优势的负向超显性位点导致杂合子结实率低于亲本，其功能解析为阐明杂种优势机制和进一步提高杂交稻产量提供切入点。前期工作创建了珍汕97×明恢63永久F2、F2群体和双向导入系，基于三年田间结实率数据和对应超高密度遗传连锁图，在51个遗传bin中检测到负向超显性效应，导致杂种育性降低，也说明杂交稻汕优63的结实率还有提高空间。本研究以三次田间试验重复鉴定到的三个负向超显性位点为研究对象，将其效应分解为花粉和胚囊育性，克隆并解析其遗传效应和杂合背景下的功能，阐明其调控结实率杂种优势的机制。在此基础上利用606份水稻种质和已构建的16个F2群体鉴定三个位点的育种价值，评价优良等位基因和单倍型组合在杂交稻结实率性状改良中的潜力。研究结果将增进对杂种不育和杂种优势机制的理解，同时为杂交育种和提高水稻产量开拓思路，在理论和应用上有重要意义。

As a major determinant of grains per panicle, decrease in seed setting rate affects yield in hybrids significantly. The loci showing negative overdominance in heterosis for fertility lead to reduced seed setting rate in heterozygote relative to its parents, which provide insight into yield improvement and mechanisms with respect to heterosis.. Previously, we have constructed an immortalized F2 population, an F2 population, and reciprocal introgressive lines derived from the cross between Zhenshan 97 and Minghui 63. Based on data of hybrid spikelet fertility from three replicated field trials and the corresponding ultra-high density genetic maps, significant negative overdominance effects were detected in 51 bins, leading to reduced fertility in hybrids. Therefore, there is still room for improvement in seed setting rate of Shanyou 63.. In this study, we plan to fine map three loci exhibiting negative overdominance in hybrid fertility, regulating pollen and embryo-sac development, respectively, both of which are repeatedly detected in field experiments. Genetic effect and functional characterization of the three loci in hybrid seed setting will be investigated, in order to determine the mechanism regulating heterosis for fertility. In addition, we plan to investigate natural variations of these identified loci and their values in genetic improvement in hybrid fertility, on the basis of 606 rice materials and 16 constructed F2 populations. These results will provide direct evidence in understanding the biological mechanisms underlying hybrid sterility and hybrid vigor, and they may also aid in heterosis breeding and improving seed setting rate in hybrids theoretically and practically.