Amplification generates modular diversity at an avirulence locus in the pathogen Phytophthora
Amplification generates modular diversity at an avirulence locus in the pathogen Phytophthora
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DOI：
10.1101/gr.5193806
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发表时间：
2006-07-01
期刊：
影响因子：
7
通讯作者：
Govers, Francine
中科院分区：
文献类型：
--
作者：
Jiang, Rays H. Y.;Weide, Rob;Govers, Francine
晚疫病病原体致病疫霉（Phytophthora infestans）因其快速适应以规避由植物抗性（R）基因介导的检测而臭名昭著。我们进行了比较基因组杂交芯片（阵列CGH）在近全基因组调查，以确定基因组重排有关的毒力的变化。发现了6个拷贝数变异的位点，其中之一涉及与先前鉴定的位点共定位的扩增，该位点与R基因R3 b、R10或R11组合赋予无毒力。除了阵列CGH，我们使用了三个独立的方法来寻找候选基因在Avr 3b-Avr 10-Avr 11位点：定位克隆，cDNA-AFLP分析，和Affytron阵列表达谱。这产生了一个候选物pi3.4，其编码具有转录因子特征性调节结构域的1956个氨基酸的蛋白质。扩增仅限于全长基因的3'端，但扩增的拷贝仍含有调节蛋白的标志。序列比较表明，扩增可以产生模块多样性，并通过不等交换协助组装新的全长基因。致病疫霉田间分离株的分析表明，p13.4扩增与无毒力相关;在R3 b、R10和R11植物上有毒性的分离株缺乏扩增的基因簇。疫霉属谱系中3.4的祖先状态是全长单拷贝基因。然而，在致病疫霉中，pi3.4是一个动态基因，它被扩增并转移到其他位置。模块多样性可能是病原体快速适应环境变化的一种新机制。
The destructive late blight pathogen Phytophthora infestans is notorious for its rapid adaptation to circumvent detection mediated by plant resistance ( R) genes. We performed comparative genomic hybridization on microarrays (array-CGH) in a near genome-wide survey to identify genome rearrangements related to changes in virulence. Six loci with copy number variation were found, one of which involves an amplification colocalizing with a previously identified locus that confers avirulence in combination with either R gene R3b, R10, or R11. Besides array-CGH, we used three independent approaches to find candidate genes at the Avr3b-Avr10-Avr11 locus: positional cloning, cDNA-AFLP analysis, and Affymetrix array expression profiling. This resulted in one candidate, pi3.4, that encodes a protein of 1956 amino acids with regulatory domains characteristic for transcription factors. Amplification is restricted to the 3' end of the full-length gene but the amplified copies still contain the hallmarks of a regulatory protein. Sequence comparison showed that the amplification may generate modular diversity and assist in the assembly of novel full-length genes via unequal crossing-over. Analyses of P. infestans field isolates revealed that the pi3.4 amplification correlates with avirulence; isolates virulent on R3b, R10, and R11 plants lack the amplified gene cluster. The ancestral state of 3.4 in the Phytophthora lineage is a full-length, single-copy gene. In P. infestans, however, pi3.4 is a dynamic gene that is amplified and has moved to other locations. Modular diversity could be a novel mechanism for pathogens to quickly adapt to changes in the environment.