PDF(Pubmed)
Abstract：
Clavibacter michiganensis is a Gram-positive bacterium that causes bacterial canker and wilting in host plants like tomato. Two major virulence genes encoding a cellulase (celA) and a putative serine protease (pat-1) have been reported. Here we show that Nicotiana benthamiana, a commonly used model plant for studying molecular plant-pathogen interactions, is a surrogate host of C. michiganensis and C. capsici. When a low concentration of two Clavibacter species, C. michiganensis and C. capsici, were infiltrated into N. benthamiana leaves, they caused blister-like lesions closely associated with cell death and the generation of reactive oxygen species and proliferated significantly like a pathogenic bacterium. By contrast, they did not cause any disease symptoms in N. tabacum leaves. The celA and pat-1 mutants of C. michiganensis still caused blister-like lesions and cankers like the wild-type strain. When a high concentration of two Clavibacter species and two mutant strains were infiltrated into N. benthamiana leaves, all of them caused strong and rapid necrosis. However, only C. michiganensis strains, including the celA and pat-1 mutants, caused wilting symptoms when it was injected into stems. When two Clavibacter species and two mutants were infiltrated into N. tabacum leaves at the high concentration, they (except for the pat-1 mutant) caused a strong hypersensitive response. These results indicate that C. michiganensis causes blister-like lesions, canker, and wilting in N. benthamiana, and celA and pat-1 genes are not necessary for the development of these symptoms. Overall, N. benthamiana is a surrogate host of Clavibacter species, and their novel virulence factors are responsible for disease development in this plant.
摘要：
MichiganensisClavibacter是一种革兰氏阳性细菌，可在番茄等寄主植物中引起细菌性溃疡和枯萎。已经报道了编码纤维素酶（celA）和推定的丝氨酸蛋白酶（pat-1）的两个主要毒力基因。这里我们展示了Nicotianabenthamiana，一种用于研究分子植物-病原体相互作用的常用模型植物，是密歇根州C.capsici和C.的替代宿主。当两个Clavibacter物种的浓度较低时，C.密歇根和辣椒，渗入了N.benthamiana的叶子，它们引起与细胞死亡和活性氧的产生密切相关的水泡样病变，并像致病菌一样显著增殖。相比之下,它们在烟草叶中没有引起任何疾病症状。密歇根C.的celA和pat-1突变体仍然像野生型菌株一样引起水泡样病变和溃疡。当高浓度的两种Clavibacter种和两种突变菌株渗入N.benthamiana叶片时，所有这些都导致强烈而迅速的坏死。然而,只有C.michiganensis菌株，包括celA和pat-1突变体,当它被注射到茎中时引起了枯萎的症状。当两种Clavibacter物种和两种突变体以高浓度渗入烟草叶片时，它们（除了pat-1突变体）引起强烈的过敏反应。这些结果表明，密西根草引起水疱样病变，溃疡,在N.benthamiana枯萎，celA和pat-1基因对于这些症状的发展不是必需的。总的来说,N.benthamiana是Clavibacter物种的替代宿主，和他们的新的毒力因子负责该植物的疾病发展。
