Dissertation Research: Population Genetics of a Plant Disease Resistance Gene: Cf-2 in Natural Populations of L. pimpinellifolium

[73082] [qh]植物抗病基因参与识别入侵的病原体，是近十年来研究的热点。最终鉴定出少数抗性基因，主要是在作物植物中。然而，人们对自然种群中抗性基因的进化知之甚少。该项目将重点关注Cf-2的进化，这是在非作物物种中发现的少数抗性基因之一。本研究将对番茄的亲缘植物番茄（Lycopersicon pimpinellifolium）野生群体中Cf-2基因的等位基因多样性进行调查，以确定群体内和群体间的多样性水平。本文将从Cf-2等位基因间的遗传关系、地理位置、抗性表型和自然选择的影响等方面对这种遗传变异进行分析。这些分析将揭示塑造Cf-2进化的微观进化过程。植物抗性基因提供了一个独特的机会来研究选择和其他群体水平的过程如何在分子水平上影响一个重要的生态性状。传统上，由于缺乏对特定基因及其功能的了解，在这一水平上对适应的研究受到阻碍。因此，抗性基因成为阐明分子适应进化动力学的理想候选者。此外，了解抗性基因功能和进化的机制对作物系统及其威胁害虫的持续管理非常重要。

0073082Schaal & CaicedoPlant disease resistance genes, involved in the recognition of invading pathogens, have been a subject of intense research in the past decade. This has culminated in the identification of a handful of resistance genes, mostly in crop plants. However, little is known about the evolution of resistance genes in natural populations. This project will focus on the evolution of Cf-2, one of the few resistance genes to have been identified in a noncrop species. Allelic diversity of the Cf-2 gene in wild populations of Lycopersicon pimpinellifolium, a close relative of the tomato, will be surveyed to establish levels of within- and between-population diversity. This genetic variation will be analyzed with respect to the geneological relationships among Cf-2 alleles, geographical location, resistance phenotype, and the effects of natural selection. These analyses will reveal the microevolutionary processes that have shaped Cf-2's evolution.Plant resistance genes offer a unique opportunity to study how selection and other population-level processes affect an ecologically important trait at the molecular level. The study of adaptation at this level has traditionally been hindered by lack of knowledge of specific genes and their functions. Resistance genes thus emerge as ideal candidates to elucidate the evolutionary dynamics of molecular adaptation. Furthermore, knowledge of the mechanisms underlying resistance gene function and evolution is important for the continuing management of crop systems and the pests which threaten them.