Diversification of Self-incompatibility Alleles in the Rosaceae

两个远亲的植物科，茄科(土豆科)和蔷薇科(玫瑰科)使用相同的分子方法拒绝自体花粉。这个项目将研究蔷薇科植物自交不亲和(S-)基因座的多样性，以检验关于S-等位基因在这两个家族中进化差异的假说。初步数据表明，蔷薇科植物中的等位基因非常年轻，并且在所研究的两个亚科中存在不重叠的等位基因组。这与茄科植物缺乏周转和古老的等位基因形成了鲜明的对比。该项目将确定这些差异是否普遍存在于已采样的蔷薇科种群中，并评估平衡和非平衡假设以解释科水平的差异。该项目还将使用序列和基因结构信息来确定在这两个家族中使用RNase进行自交不亲和是由于共同的祖先还是平行进化。涉及自我非我识别的基因座表现出已知的最高水平的遗传变异性。例如开花植物、真菌和克隆海洋无脊椎动物的自交不亲和性基因座，以及人类和其他脊椎动物的抗病主要组织相容性基因座(MHC)。极端的变异性是由作用于这些基因的选择类型造成的，通常被称为平衡选择。了解这些基因的进化对许多领域都很重要。首先，与使用其他基因相比，更大的时间变异深度允许历史推断追溯到更早的时间。其次，对这些基因多样化模式的分析提供了有关驱动它们进化的选择性力量的信息。第三，在分子水平上对选择模式的检查提供了对自我识别的分子基础方面的洞察，这些方面目前还知之甚少。

Two distantly related plant families, the Solanaceae (potato family) and Rosaceae (rose family) use the same molecular method to reject self pollen. This project will examine diversification at the self incompatibility (S-) locus in the Rosaceae to test hypotheses about differences in S-allele evolution in the two families. Preliminary data indicate that alleles in the Rosaceae are quite young and that non-overlapping sets of alleles occur in the two subfamilies investigated. This stands in stark contrast to the lack of turnover and ancient alleles seen in the Solanaceae. This project will determine if these differences generally hold or are peculiar to the groups of Rosaceae that have been sampled and evaluate equilibrium and non-equilibrium hypotheses to explain family-level differences. This project will also use sequence and gene structure information to determine whether use RNases for self incompatibility in these two families is due to common ancestry or parallel evolution. Loci involved in self-nonself recognition exhibit the highest levels of genetic variability known. Examples include the self-incompatibility loci of flowering plants, fungi, and clonal marine invertebrates, and the disease fighting major histocompatiblity loci (MHC) of humans and other vertebrates. Extreme variability is due to the types of selection, generally called balancing selection, that act on such genes. Understanding the evolution these genes is important for many fields. First, the much greater time depth of variation allows historical inference that reaches farther back in time than is possible when using other genes. Second, analysis of diversification patterns at these genes provides information on the selective forces that drive their evolution. Third, examination of patterns of selection at the molecular level provides insight into as yet poorly understood aspects of the molecular basis of self recognition.