枇杷自交（不）亲和强度差异的分子机制研究

The cultivars are various in loquat（Eriobotrya japonica Lindl.）, which has the intensity difference of gametophytic self-incompatibility that is a key problem in cultivation. They are the effective approaches to resolve the problem that planting with pollination tree according to the different S-genotype and breeding the self-compatibility cultivars. However, This is the main bottleneck of the plan that identification of S-genotype and clarification of molecular mechanism of the intensity difference of self-incompatibility. Therefore, on the basis of prophase research work, it is carried out that identification of S-genotype and the intensity difference of self-incompatibility. Furthermore, the molecular mechanism of the intensity difference of self-incompatibility is systematically researched from four aspects, including mutations and abnormal expression of S-RNase and SFB gene, competition effect of pollen, and accumulation of non-functional gene. Simultaneously, it is noticed that the hereditary character and interaction of S-RNase and SFB gene on the basis of identification of S-genotype. The purpose of this study is to reveal the S-genotype of the cultivars, and to reveal the hereditary character and the molecular basis of the intensity difference of gametophytic self-incompatibility, which can not only contribute to a better understanding of molecular mechanism of the mutation of self-incompatibility in loquat, but also contribute to a better scientific basis for genetic breeding and the choice of pollination tree in cultivation.

枇杷为典型的配子体型自交不亲和性植物，品种繁多且自交不亲和强度各异，是其生产栽培需要解决的难题之一，配植不同S基因型的授粉树，和开发自交亲和品种是解决这一难题的两条有效途径，而鉴定各品种的S基因型和阐明自交（不）亲和强度差异的分子机制是其实施的瓶颈所在。因此，在前期研究工作的基础上，本项目拟开展各品种自交（不）亲和强度的差异鉴定和S基因型鉴定，从花柱S-RNase和花粉SFB基因的变异、或异常表达，花粉的'竞争作用'，和无功能基因的累积四个方面全面系统的对枇杷的自交（不）亲和强度差异的分子机制进行研究，同时关注花柱S-RNase基因和花粉SFB基因的交互作用和遗传特性，以明确各主栽品种的S基因型，阐明枇杷自交（不）亲和强度差异的分子基础和S基因遗传特性，为深入认识枇杷自交（不）亲和变异的分子机制，及遗传育种和生产栽培授粉树的选择提供科学依据。

枇杷为典型的配子体型自交不亲和性植物，品种繁多且自交不亲和强度各异，是其生产栽培需要解决的难题之一，配植不同S 基因型的授粉树，和开发自交亲和品种是解决这一难题的两条有效途径，而鉴定各品种的S 基因型和阐明自交（不）亲和强度差异的分子机制是其实施的瓶颈所在。因此，本项目开展了各品种自交（不）亲和强度的差异鉴定和S 基因型鉴定，从花柱S-RNase 和花粉SFB 基因的变异、或异常表达，花粉的‘竞争作用’，和无功能基因的累积四个方面全面系统的对枇杷的自交（不）亲和强度差异的分子机制进行研究，同时关注花柱S-RNase 基因和花粉SFB 基因的交互作用和遗传特性。结果表明，经鉴定参试材料中获自交不亲和、半亲和、及亲和品种或株系分别为11份、16份和 34份，获21个枇杷属新S-RNase，10个新SFB 基因，鉴定了67份参试材料S-RNase和SFB基因型。高通量测序显示，自交不亲和、半亲和，及亲和品种的显著差异表达基因的数目是213个，其中上调表达数量是143个，下调表达基因数量是70个，GO 和KEGG注释分类表明，涉及核糖核酸蛋白酶活性、信号转导机制、核糖核酸酶T2家族基因及活性、氨基酸运输和代谢、RNA降解及转录等相关基因，其相互授粉九个组合F1代S-RNase基因与SFB基因遗传分布与理论不符，综合差异表达基因深度挖掘分析表明，‘凯红’携带的S2-RNase基因表达异常，GO 和KEGG注释表明其与磷酸二酯键水解生物学过程密切相关，此外，S6-RNase基因推导氨基酸序列分析结果表明，在C5区下游有8个氨基酸的插入，这可能使S6-RNase失活。综合分析表明造成‘大五星’、‘黄蜜’和‘凯红’自交不亲和程度不同的原因是共同携带的S2-RNase表达有差异，同时携带S6-RNase的品种或株系则表现为半亲和，未发现‘花粉竞争’和无功能基因累积作用对自交不亲和程度造成影响。研究结果为阐明枇杷自交（不）亲和强度差异的分子基础和S 基因遗传特性，为深入认识枇杷自交（不）亲和变异的分子机制，及遗传育种和生产栽培授粉树的选择提供了科学依据，具有重要的理论价值和潜在的实践意义。