Stahl E A, Dwyer G, Mauricio R, Kreitman M, Bergelson J
Committee on Genetics, University of Chicago, Illinois 60637, USA.
Nature. 1999 Aug 12;400(6745):667-71. doi: 10.1038/23260.
The co-evolutionary 'arms race' is a widely accepted model for the evolution of host-pathogen interactions. This model predicts that variation for disease resistance will be transient, and that host populations generally will be monomorphic at disease-resistance (R-gene) loci. However, plant populations show considerable polymorphism at R-gene loci involved in pathogen recognition. Here we have tested the arms-race model in Arabidopsis thaliana by analysing sequences flanking Rpm1, a gene conferring the ability to recognize Pseudomonas pathogens carrying AvrRpm1 or AvrB. We reject the arms-race hypothesis: resistance and susceptibility alleles at this locus have co-existed for millions of years. To account for the age of alleles and the relative levels of polymorphism within allelic classes, we use coalescence theory to model the long-term accumulation of nucleotide polymorphism in the context of the short-term ecological dynamics of disease resistance. This analysis supports a 'trench warfare' hypothesis, in which advances and retreats of resistance-allele frequency maintain variation for disease resistance as a dynamic polymorphism.
共同进化的“军备竞赛”是宿主-病原体相互作用进化的一个被广泛接受的模型。该模型预测，抗病性的变异将是短暂的，并且宿主群体在抗病性（R基因）位点通常是单态的。然而，植物群体在参与病原体识别的R基因位点表现出相当大的多态性。在这里，我们通过分析Rpm1基因侧翼序列来测试拟南芥中的军备竞赛模型，Rpm1基因赋予识别携带AvrRpm1或AvrB的假单胞菌病原体的能力。我们拒绝军备竞赛假说：该位点的抗性和敏感等位基因已经共存了数百万年。为了解释等位基因的年龄和等位基因类群内多态性的相对水平，我们使用合并理论在抗病性短期生态动态的背景下对核苷酸多态性的长期积累进行建模。该分析支持“堑壕战”假说，即抗性等位基因频率的上升和下降将抗病性变异维持为一种动态多态性。
