Dissertation Research: Mechanisms Maintaining Variation for Disease Resistance at Rpm1 in Arabidopsis thaliana

植物种类一般表现出抗病变异。这一惊人的观察结果表明，一种相反力量的平衡作用于维持抗病变异。由于疾病带来的成本会促使种群产生更强的抵抗力，因此为了解释观察到的变异，应该进行一种与抵抗力增强相反的权衡。在模式植物拟南芥中，一种对立力量的平衡维持了抗病基因Rpm1的分子变异。拟议的研究将调查种群内抗病变异的起源和决定因素。高通量方法将允许对印第安纳州和密歇根州当地种群的数百个拟南螺旋体个体进行基因分型。分析将测量Rpm1与附近遗传标记之间的关联。较小的联合将支持人口内部的平衡，而较大的联合将支持由于不同力量占主导地位的人口之间的迁移而产生的平衡。近年来，拟南芥抗病研究得到了广泛的关注，本文提出的生态和进化研究将对该系统的分子遗传学研究起到补充作用。必须了解植物抗病性，以促进作物病害管理，评估种植策略和预测病害对天然植物种群和杂草的影响。此外，植物的抗病性可以与动物的免疫进行比较，以便更全面地了解病原体对宿主物种施加的压力。这个项目延续了Kreitman对果蝇的研究，在种群遗传理论和经验数据的界面上。拟南芥Rpm1是平衡选择维持分子变异的一个强有力的例子。对Rpm1的持续研究将有助于阐明形成遗传变异和变化的模式和过程。最后，本研究将继续发展拟南芥作为重要的群体遗传学新模式生物。可以说，没有其他模式生物能像拟南芥一样，与生态学和遗传学相互作用，这两个领域都是拟南芥生物学的成熟领域。

Kreitman 9800957 Plant species generally exhibit variation for resistance to disease. This striking observation implies that a balance of opposing forces acts to maintain variation for disease resistance. Since the cost imposed by disease would drive populations toward increased resistance, a trade-off should oppose increased resistance to account for the observed variation. In the model plant species Arabidopsis thaliana, a balance of opposing forces maintains molecular variation at disease resistance gene Rpm1. The proposed research will investigate the origin and determinants of variation for disease resistance within populations. High through-put methods will allow genotyping of hundreds of A. thaliana individuals from local populations in Indiana and Michigan. Analyses will measure associations between Rpm1 and nearby genetic markers. Little association would support a balance within populations, while greater association would support a balance due to migration among populations where different forces dominate. Arabidopsis disease resistance has come under intense study recently, and the ecological and evolutionary work proposed here will complement molecular genetic work on this system. Plant disease resistance must be understood to facilitate the management of disease in crops, for assessing planting strategies and predicting the impact of disease in natural plant populations and weeds. Furthermore, plant disease resistance can be compared with the animal immunity for a more general understanding of the pressures pathogens place on host species. This project continues in the vein of Kreitman's work on the fruit fly Drosophila, at the interface between population genetic theory and empirical data. Arabidopsis Rpm1 is a strong example of balancing selection maintaining molecular variation. Continuing study of Rpm1 will help elucidate the patterns and processes shaping genetic variation and change. Finally, the proposed work continues to develop Arabidopsis as an important new model organism for population genetics. Arguably, no other model organism affords as much potential for interplay with ecology and genetics, both well-established fields in Arabidopsis biology.