Antúnez-Lamas María, Cabrera-Ordóñez Ezequiel, López-Solanilla Emilia, Raposo Rosa, Trelles-Salazar Oswaldo, Rodríguez-Moreno Andrés, Rodríguez-Palenzuela Pablo
Departamento de Biotecnología, Universidad Politécnica de Madrid, E.T.S. Ingenieros Agrónomos, CBGP, Centro de Biotecnología y Genómica de Plantas, Avda Complutense S/N, E-28040 Madrid, Spain.
CIFOR, Instituto Nacional Investigaciones Agrarias (INIA), C. Coruña km 7.5, 28040 Madrid, Spain.
Microbiology (Reading). 2009 Feb;155(Pt 2):434-442. doi: 10.1099/mic.0.022244-0.
Dickeya dadantii 3937 (ex Erwinia chrysanthemi), a member of the Enterobacteriaceae, causes soft rot in many economically important crops. A successful pathogen has to reach the interior of the plant in order to cause disease. To study the role of motility and chemotaxis in the pathogenicity of D. dadantii 3937, genes involved in the chemotactic signal transduction system (cheW, cheB, cheY and cheZ) and in the structure of the flagellar motor (motA) were mutagenized. All the mutant strains grew like the wild-type in culture media, and the production and secretion of pectolytic enzymes was not affected. As expected, the swimming ability of the mutant strains was reduced with respect to the wild-type: motA (94%), cheY (80%), cheW (74%), cheB (54%) and cheZ (48%). The virulence of the mutant strains was analysed in chicory, Saintpaulia and potato. The mutant strains were also tested for their capability to enter into Arabidopsis leaves. All the mutants showed a significant decrease of virulence in certain hosts; however, the degree of virulence reduction varied depending on the virulence assay. The ability to penetrate Arabidopsis leaves was impaired in all the mutants, whereas the capacity to colonize potato tubers after artificial inoculation was affected in only two mutant strains. In general, the virulence of the mutants could be ranked as motA<cheY<cheB=cheW<cheZ, which correlated with the degree to which swimming was affected. These results clearly indicate that motility plays an important role in the pathogenicity of this bacterium.
胡萝卜软腐果胶杆菌3937（原菊欧文氏菌）是肠杆菌科的一员，可在许多具有重要经济价值的作物上引发软腐病。一种成功的病原体必须进入植物内部才能引发病害。为了研究运动性和趋化性在胡萝卜软腐果胶杆菌3937致病性中的作用，对趋化信号转导系统（cheW、cheB、cheY和cheZ）以及鞭毛马达结构（motA）中涉及的基因进行了诱变。所有突变菌株在培养基中的生长情况与野生型相似，且果胶酶的产生和分泌未受影响。正如预期的那样，突变菌株的游动能力相对于野生型有所降低：motA（降低94%）、cheY（降低80%）、cheW（降低74%）、cheB（降低54%）和cheZ（降低48%）。在菊苣、非洲紫罗兰和马铃薯中分析了突变菌株的毒力。还测试了突变菌株进入拟南芥叶片的能力。所有突变体在某些宿主中均表现出毒力显著下降；然而，毒力降低的程度因毒力测定方法而异。所有突变体穿透拟南芥叶片的能力均受损，而人工接种后在马铃薯块茎上定殖的能力仅在两个突变菌株中受到影响。总体而言，突变体的毒力可排序为motA＜cheY＜cheB = cheW＜cheZ，这与游动受影响的程度相关。这些结果清楚地表明运动性在这种细菌的致病性中起重要作用。
