A multilocus sequence analysis of Xanthomonas campestris reveals a complex structure within crucifer-attacking pathovars of this species
A multilocus sequence analysis of Xanthomonas campestris reveals a complex structure within crucifer-attacking pathovars of this species
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DOI：
10.1016/j.syapm.2010.09.001
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发表时间：
2011-04-01
影响因子：
3.4
通讯作者：
Manceau, C.
中科院分区：
文献类型：
--
作者：
Fargier, E.;Saux, M. Fischer-Le;Manceau, C.
先前对油菜黄单胞菌的分类定义了六种引起十字花科植物疾病的病原菌（aberrans, armoraciae, barbareae, campestris， canae和raphani）。然而，对一系列菌株和不同宿主的致病性测定只确定了三种症状：黑腐病、叶斑病和细菌性枯萎病。这些发现提出了分配给不同病原体或症状表型的菌株之间的遗传相关性的问题。本文通过对42株菌株的多位点序列分析，解决了这一问题。8个位点均呈多态性，具有较高的遗传多样性；共鉴定出23种序列类型，其中16种是唯一的。所有引起黑腐病的菌株（异常病原菌和campestris）在遗传上接近，但分成两组。仅发现3个克隆复合物，均在病原菌内。经基因组测序的菌株756C与疾病症状提示的拉法尼病原菌的关系得到了证实，尽管这组菌株具有特别的多态性。属barbareae和canae的菌株亲缘关系密切，但与campestris不同。从splittree分析的单个基因系统发育和网络结构之间的明显不一致推断，有证据表明该物种内部存在管家基因的遗传交换。本研究表明，高遗传多样性来源于重组和点突变积累。然而，由于对十字花科寄主的差异适应，X. campestris仍然是一个克隆进化的物种。(C) 2010 Elsevier GmbH版权所有。
Previous classification of Xanthomonas campestris has defined six pathovars (aberrans, armoraciae, barbareae, campestris, incanae, and raphani) that cause diseases on cruciferous plants. However, pathogenicity assays with a range of strains and different hosts identifies only three types of symptom: black rot, leaf spot and bacterial blight. These findings raise the question of the genetic relatedness between strains assigned to different pathovars or symptom phenotypes. Here we have addressed this issue by multi-locus sequence analysis of 42 strains. The X. campestris species was polymorphic at the 8 loci analysed and had a high genetic diversity; 23 sequence types were identified of which 16 were unique. All strains that induce black rot (pathovars aberrans and campestris) were genetically close but split in two groups. Only three clonal complexes were found, all within pathovar campestris. The assignment of the genome-sequenced strain 756C to pathovar raphani suggested from disease symptoms was confirmed, although this group of strains was particularly polymorphic. Strains belonging to pathovars barbareae and incanae were closely related, but distinct from pathovar campestris. There is evidence of genetic exchanges of housekeeping genes within this species as deduced from a clear incongruence between individual gene phylogenies and from network structures from SplitsTree analysis. Overall this study showed that the high genetic diversity derived equally from recombination and point mutation accumulation. However, X. campestris remains a species with a clonal evolution driven by a differential adaptation to cruciferous hosts. (C) 2010 Elsevier GmbH. All rights reserved.