Department of Plant Pathology, University of Florida, Gainesville, Florida, USA.
Southwest Research and Education Center, University of Florida, Immokalee, Florida, USA.
Appl Environ Microbiol. 2018 Jun 18;84(13). doi: 10.1128/AEM.00136-18. Print 2018 Jul 1.
Recombination is a major driver of evolution in bacterial populations, because it can spread and combine independently evolved beneficial mutations. Recombinant lineages of bacterial pathogens of plants are typically associated with the colonization of novel hosts and the emergence of new diseases. Here we show that recombination between evolutionarily and phenotypically distinct plant-pathogenic lineages generated recombinant lineages with unique combinations of pathogenicity and virulence factors. and are two closely related lineages causing bacterial spot disease on tomato and pepper worldwide. We sequenced the genomes of atypical strains collected from tomato in Nigeria and observed recombination in the type III secretion system and effector genes, which showed alleles from both and Wider horizontal gene transfer was indicated by the fact that the lipopolysaccharide cluster of one strain was most similar to that of a distantly related pathogen of barley. This strain and others have experienced extensive genomewide homologous recombination, and both species exhibited dynamic open pangenomes. Variation in effector gene repertoires within and between species must be taken into consideration when one is breeding tomatoes for disease resistance. Resistance breeding strategies that target specific effectors must consider possibly dramatic variation in bacterial spot populations across global production regions, as illustrated by the recombinant strains observed here. The pathogens that cause bacterial spot of tomato and pepper are extensively studied models of plant-microbe interactions and cause problematic disease worldwide. Atypical bacterial spot strains collected from tomato in Nigeria, and other strains from Italy, India, and Florida, showed evidence of genomewide recombination that generated genetically distinct pathogenic lineages. The strains from Nigeria and Italy were found to have a mix of type III secretion system genes from and , as well as effectors from These genes and effectors are important in the establishment of disease, and effectors are common targets of resistance breeding. Our findings point to global diversity in the genomes of bacterial spot pathogens, which is likely to affect the host-pathogen interaction and influence management decisions.
重组是细菌种群进化的主要驱动力，因为它可以独立传播和组合独立进化的有益突变。植物病原菌的重组谱系通常与新宿主的定殖和新疾病的出现有关。在这里，我们表明，植物病原性谱系之间的进化和表型上的重组产生了具有独特致病性和毒力因子组合的重组谱系。 和 是两种密切相关的谱系，导致全球番茄和辣椒的细菌性斑点病。我们对从尼日利亚番茄中收集的非典型菌株的基因组进行了测序，并观察到 III 型分泌系统和效应基因的重组，这些基因显示了来自 和 的等位基因。一个菌株的脂多糖簇与远缘大麦病原菌的脂多糖簇最为相似，这表明存在广泛的水平基因转移。事实上，一个菌株的脂多糖簇与远缘大麦病原菌的脂多糖簇最为相似，这表明存在广泛的水平基因转移。一个菌株的脂多糖簇与远缘大麦病原菌的脂多糖簇最为相似，这表明存在广泛的水平基因转移。一个菌株的脂多糖簇与远缘大麦病原菌的脂多糖簇最为相似，这表明存在广泛的水平基因转移。一个菌株的脂多糖簇与远缘大麦病原菌的脂多糖簇最为相似，这表明存在广泛的水平基因转移。一个菌株的脂多糖簇与远缘大麦病原菌的脂多糖簇最为相似，这表明存在广泛的水平基因转移。一个菌株的脂多糖簇与远缘大麦病原菌的脂多糖簇最为相似，这表明存在广泛的水平基因转移。一个菌株的脂多糖簇与远缘大麦病原菌的脂多糖簇最为相似，这表明存在广泛的水平基因转移。一个菌株的脂多糖簇与远缘大麦病原菌的脂多糖簇最为相似，这表明存在广泛的水平基因转移。一个菌株的脂多糖簇与远缘大麦病原菌的脂多糖簇最为相似，这表明存在广泛的水平基因转移。一个菌株的脂多糖簇与远缘大麦病原菌的脂多糖簇最为相似，这表明存在广泛的水平基因转移。一个菌株的脂多糖簇与远缘大麦病原菌的脂多糖簇最为相似，这表明存在广泛的水平基因转移。一个菌株的脂多糖簇与远缘大麦病原菌的脂多糖簇最为相似，这表明存在广泛的水平基因转移。一个菌株的脂多糖簇与远缘大麦病原菌的脂多糖簇最为相似，这表明存在广泛的水平基因转移。一个菌株的脂多糖簇与远缘大麦病原菌的脂多糖簇最为相似，这表明存在广泛的水平基因转移。一个菌株的脂多糖簇与远缘大麦病原菌的脂多糖簇最为相似，这表明存在广泛的水平基因转移。
重组谱系的遗传多样性和独特的组合可能会影响它们与番茄宿主的相互作用，并可能导致不同的疾病表型。
