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

植物抗病基因参与了入侵病原体的识别，在过去十年中一直是一个密集的研究主题。这最终确定了少数抗性基因，主要是在农作物中。然而，人们对自然种群中抗性基因的进化知之甚少。这个项目将集中在CF-2的进化上，这是在非作物物种中发现的为数不多的抗性基因之一。我们将调查番茄近缘野生群体中Cf-2基因的等位基因多样性，以确定群体内和群体间的多样性水平。这种遗传变异将从Cf-2等位基因之间的遗传关系、地理位置、抗性表型和自然选择的影响等方面进行分析。这些分析将揭示形成CF-2‘S进化的微进化过程。植物抗性基因为在分子水平上研究选择和其他群体水平的过程如何影响生态重要性状提供了一个独特的机会。传统上，由于缺乏对特定基因及其功能的了解，在这一层面上的适应研究一直受到阻碍。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，对抗性基因功能和进化的潜在机制的了解对于继续管理作物系统和威胁作物系统的害虫是重要的。

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.