Genome structure impacts molecular evolution at the AvrLm1 avirulence locus of the plant pathogen Leptosphaeria maculans
Genome structure impacts molecular evolution at the AvrLm1 avirulence locus of the plant pathogen Leptosphaeria maculans
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DOI：
10.1111/j.1462-2920.2007.01408.x
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发表时间：
2007-12-01
影响因子：
5.1
通讯作者：
Rouxel, Thierry
中科院分区：
文献类型：
--
作者：
Gout, Lilian;Kuhn, Marie Line;Rouxel, Thierry
斑点细球腔菌（Leptosphaeria maculans）是一种能引起油菜茎溃疡病的真菌，它与寄主植物之间存在基因对基因的互作。它有能力快速适应含有新型抗性基因的品种施加的选择压力，最近法国种群AvrLm 1位点3年的毒力进化就证明了这一点。AvrLm1无毒基因最近被克隆，并被证明是一个269 kb的非编码，异染色质样区域内的独奏基因。在这里，我们描述了一个无毒和两个毒力菌株的AvrLm1基因组区域的测序，以探讨在AvrLm1基因座的毒力进化的分子基础。对于这些强毒分离株，毒力的获得与跨越AvrLm1的染色体片段的260 kb缺失有关，并且缺失断点相同或相似。在来自法国、澳大利亚和墨西哥的460个分离株中，类似的大缺失在> 90%的强毒分离株中明显。缺失断点也强烈保守，在大多数的毒力分离株，这导致了一个独特的缺失事件，导致avrLm1毒力的假设已经扩散到病原体种群。这些数据最终表明，逆转录转座子是基因组进化和适应新的选择压力在L。斑点。
Leptosphaeria maculans, a dothideomycete fungus causing stem canker on oilseed rape, develops gene-for-gene interactions with its host plants. It has the ability to rapidly adapt to selection pressure exerted by cultivars harbouring novel resistance genes as exemplified recently by the 3-year evolution towards virulence at the AvrLm1 locus in French populations. The AvrLm1 avirulence gene was recently cloned and shown to be a solo gene within a 269 kb non-coding, heterochromatin-like region. Here we describe the sequencing of the AvrLm1 genomic region in one avirulent and two virulent isolates to investigate the molecular basis of evolution towards virulence at the AvrLm1 locus. For these virulent isolates, the gain of virulence was linked to a 260 kb deletion of a chromosomal segment spanning AvrLm1 and deletion breakpoints were identical or similar. Among the 460 isolates analysed from France, Australia and Mexico, a similar large deletion was apparent in > 90% of the virulent isolates. Deletion breakpoints were also strongly conserved in most of the virulent isolates, which led to the hypothesis that a unique deletion event leading to the avrLm1 virulence has diffused in pathogen populations. These data finally suggest that retrotransposons are key drivers in genome evolution and adaptation to novel selection pressure in L. maculans.