Mutagenesis of all eight avr genes in Xanthomonas camplestris pv. campestris had no detected effect on pathogenicity, but one avr gene affected race specificity
Mutagenesis of all eight avr genes in Xanthomonas camplestris pv. campestris had no detected effect on pathogenicity, but one avr gene affected race specificity
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DOI：
10.1094/mpmi-18-1306
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发表时间：
2005-12-01
影响因子：
3.5
通讯作者：
Gabriel, DW
中科院分区：
文献类型：
--
作者：
Castañeda, A;Reddy, JD;Gabriel, DW
采用抑制减法杂交（SSH）技术对十字花科植物系统性黑腐病病原菌黄单胞菌进行了基因鉴定。油菜病菌528(T)在十字花科植物叶斑病的非系统性病原菌中缺失。armoraciae 417。在已发表的528(T)基因组（NC-003902）中鉴定出的八个推测的avr基因中，528(T)特有的DNA片段是Xcc2109。对所有8个528(T) avr基因位点进行了单独和顺序缺失、插入突变或两者同时缺失，但没有观察到任何avr突变组合的致病性变化，包括8个avr基因全部缺失的菌株。然而，影响Xcc2109位点的插入或缺失突变体对佛罗里达芥菜（一种油菜弧菌pv）失去了毒性（即变得有毒性）。Campestris种族决定，差异寄主。克隆了注释的Xcc2109开放阅读框，发现它没有功能。一个包含Xcc2109的更长的基因被克隆出来，在这里被命名为avrXccFM，并被发现与Xcc2109突变体互补，并赋予另外两个野生型葡萄球菌pv无毒。因此改变了他们的种族。佛罗里达芥对携带avrXccFM的528 T菌株的抗性在叶片上没有发生典型的超敏反应（hypersensitive response， HR），尽管在幼苗上观察到维管性的超敏反应（hypersensitive response， HR）。
Suppression subtractive hybridization (SSH) was used to identify genes present in the systemic crucifer black rot pathogen Xanthomonas campestris pv. campestris 528(T) but missing from the nonsystemic crucifer leaf spot pathogen, X. campestris pv. armoraciae 417. Among the DNA fragments unique to 528(T) was Xcc2109, one of eight putative avr genes identified in the published 528(T) genome (NC-003902). Individual and sequential deletion, insertion mutations, or both of all eight 528(T) avr gene loci were made, but no change in pathogenicity was observed with any combination of avr mutations, including a strain with all eight avr genes deleted. However, insertion or deletion mutants affecting the Xcc2109 locus lost avirulence (i.e., became virulent) on Florida Mustard, an X. campestris pv. campestris race-determining, differential host. The Xcc2109 open reading frame as annotated was cloned and found to be nonfunctional. A longer gene, encompassing Xcc2109 and here designated avrXccFM, was cloned and found to complement the Xcc2109 mutants and to confer avirulence to two additional wild-type X. campestris pv. campestris strains, thereby changing their races. Resistance in Florida Mustard to 528 T strains carrying avrXccFM occurred without a typical hypersensitive response (HR) on leaves, although a vascular HR was observed in seedlings.