大果黄花梨自交亲和性变异机制研究

Mutational analysis of self-compatible mutant of Daguohuanghua (Pyrus pyrifolia)

梨品种大果黄花由黄花芽变而来。田间授粉试验表明,黄花梨自花授粉结实率仅为1.5%,属于梨自交不亲和性品种;而大果黄花自花授粉的结实率高达60.0%,属于自交亲和性品种;相互授粉时,黄花×大果黄花组合的坐果率达70.0%,为杂交亲和,但反交时坐果率为1.0%,表现为杂交不亲和。荧光显微镜观察这些组合授粉后花柱内花粉管生长情况,也得到相同的结果。这些结果表明,两品种雌蕊的自交不亲和性性状正常。进一步鉴定出了黄花和大果黄花是基于S-RNase基因的S-基因型,发现两者均含有S1-RNase和S2-RNase基因;而且两品种的这1对雌蕊S-RNase基因均特异性地在花柱中表达,表达量没有明显差异,表明大果黄花和黄花的雌蕊S-RNase基因并无差异。由此推断:大果黄花的自交亲和性突变,是由于花粉自交不亲和性功能丧失,从而表现出自花授粉能够结实。

Daguohuanghua （D） is a sport from Huanghua （H）. Field pollination showed that H had a fruit set percentage of 1.5% on self-pollination displaying typical self-incompatibility （ SI）, while 60% of selfed flower of D set fruits showing self-compatibility （SC）. When pollinated with D pollen, 70% of H flower set fruit displaying cross-compatibility. Reciprocally, only 1% of D flower set fruit exhibiting cross-incompatibility. After inspection of pollen tube growth in style under fluorescent microscope, it were observed that many pollen tubes of D grew down to the base of both H and D style, whereas those of H were arrested at the upper part of D and H style, identical to the field pollination results. Further molecular S-genotyping revealed that both H and D possess S1 -RNase and S2-RNase behave similarly at the transcriptional level, indicating that D performed normally as H did in SI response on the stylar part. These results implied that a pollen SI function loss might be the cause of SC mutation in D.