Clavibacter michiganensis subsp. michiganensis (Cmm) causes bacterial wilt and canker in tomato, producing important economic losses worldwide. Its virulence has been related to several putative virulence factors present on a chromosomal pathogenicity island and on plasmids pCM1 and pCM2, in strain NCPPB382. We genotypically characterized a collection of Cmm isolates from the main greenhouse tomato‐producing areas of Argentina by BOX‐PCR fingerprinting and screened for the presence of genes and plasmids involved in pathogenicity by PCR. In addition, we evaluated in vitro cellulolytic activity and virulence in planta of selected strains. BOX‐PCR fingerprinting clustered strains into four groups. Group II was dominant and included the most virulent strains, while Group III was the smallest and had the least virulent strains. All local strains exhibited similar cellulolytic activity. Most of the examined strains carry two plasmids of similar size to those of NCPPB382, although there were strains with one or three plasmids. By PCR amplification of repA, pCM1 was detected only in strains belonging to Group III, which includes local strains closely related to reference strain NCPPB382. All analysed pathogenicity genes were widespread among strains, and so in strains belonging to Groups I and II, celA found on pCM1 in NCPPB382 could be found in the chromosome or in plasmids other than pCM1. This study contributes to a better understanding of the diversity of Cmm genetic profiles and virulence of strains present in Argentina. Such information could be useful for the selection of strains for screening of host resistance and development of resistant tomato varieties.

中文翻译：

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毒力和pCM1质粒的携带与密歇根氏杆菌亚种菌株的BOX-PCR指纹类型有关。导致阿根廷番茄萎缩和萎缩的密歇根州

密歇根州棒状杆菌亚种。密歇根州（Cmm）在番茄中引起细菌枯萎和溃疡病，在全球范围内造成重要的经济损失。其毒力与NCPPB382菌株中染色体致病性岛以及质粒pCM1和pCM2上存在的几种推定毒力因子有关。我们通过BOX-PCR指纹图谱对阿根廷主要温室番茄产区的Cmm分离物进行了基因分型，并通过PCR筛选了与致病性有关的基因和质粒的存在。此外，我们评估了所选菌株在植物体内的体外纤维素分解活性和毒力。BOX-PCR指纹图谱将菌株分为四组。第二组占主导地位，包括最强毒株，而第三组最小，毒力最低。所有本地菌株均表现出相似的纤维素分解活性。尽管有些菌株带有一个或三个质粒，但大多数检测的菌株带有两个大小与NCPPB382相似的质粒。通过PCR扩增repA，pCM1仅在属于III组的菌株中检测到，其中包括与参考菌株NCPPB382紧密相关的局部菌株。所有分析的致病基因均在菌株中广泛分布，因此在属于I和II组的菌株中，NCPPB382中pCM1上发现的celA可以在染色体或pCM1以外的质粒中找到。这项研究有助于更好地了解阿根廷存在的Cmm基因型的多样性和菌株的毒力。这样的信息对于筛选用于筛选宿主抗性的菌株和开发抗性番茄品种可能有用。