Joosten M H, Cozijnsen T J, De Wit P J
Department of Phytopathology, Wageningen Agricultural University, The Netherlands.
Nature. 1994 Jan 27;367(6461):384-6. doi: 10.1038/367384a0.
Host genotype specificity in interactions between biotrophic pathogens and plants in most cases complies with the gene-for-gene model; success or failure of infection is determined by absence or presence of complementary genes, avirulence and resistance genes, in the pathogen and host plant, respectively. Resistance, expressed by the induction of a hypersensitive response in the host, is envisaged to be based on recognition of the pathogen, mediated through direct interaction between products of pathogen avirulence genes (the so-called race-specific elicitors) and receptors in the host plant, the putative products of resistance genes. The interaction between the biotrophic fungus Cladosporium fulvum and its only host, tomato (Lycopersicon esculentum), is a well-established model system for studying fungus-plant gene-for-gene relationships. Here we report the isolation of race-specific elicitor AVR4 of C. fulvum and the cloning of its encoding avirulence gene. We present evidence that, in nature, a single base-pair change in this avirulence gene leads to virulence of races previously avirulent on tomato genotypes carrying the complementary Cf4 resistance gene.
在大多数情况下，活体营养型病原体与植物之间相互作用的宿主基因型特异性符合基因对基因模型；感染的成功或失败分别由病原体和宿主植物中互补基因、无毒基因和抗性基因的缺失或存在决定。宿主中通过超敏反应诱导所表现出的抗性，被认为是基于对病原体的识别，这种识别是通过病原体无毒基因产物（所谓的小种特异性激发子）与宿主植物中抗性基因的假定产物受体之间的直接相互作用介导的。活体营养型真菌番茄叶霉与其唯一宿主番茄（Lycopersicon esculentum）之间的相互作用，是研究真菌 - 植物基因对基因关系的一个成熟的模型系统。在此，我们报告了番茄叶霉小种特异性激发子AVR4的分离及其编码无毒基因的克隆。我们提供的证据表明，在自然条件下，该无毒基因中的单个碱基对变化会导致以前对携带互补Cf4抗性基因的番茄基因型无毒的小种产生毒性。
