西瓜噬酸菌(Acidovorax citrulli)pilO基因的功能研究

Functional Characterization of the pilO Gene of Acidovorax citrulli

细菌性果斑病是全世界范围内瓜类生产中的重要病害,其病原菌是西瓜噬酸菌(Acidovorax citrulli).细菌Tpye-IV菌毛的生物合成及功能由十几个基因参与调控,pilO是其中的一个基因.运用同源重组的方法,构建了西瓜噬酸菌AAC-3菌株Type IV菌毛结构蛋白编码基因pilO的功能缺失突变体菌株ΔpilO,对突变体的生长能力、运动能力、生物薄膜形成能力及致病力等进行了测定,同时对菌体形态进行观察.透射电镜观察结果显示突变体菌株不能形成菌毛.ΔpilO突变体菌株的生长基本不受影响,但是其运动能力显著下降,生物薄膜形成能力降低80%,致病力与野生型菌株相比下降了55%.本研究结果表明pilO基因在病原菌Type IV菌毛形成及其运动性和致病力等方面发挥重要作用.

Bacterial fruit blotch of melons caused by Acidovorax citrulli is a world-wide disease of cucurbit production.The biogenesis and function of bacterial type-IV pili is controlled by more than 10 genes,one of which is pilO.Specific disruption of the pilO gene from A.citrulli strain AAC-3 was achieved through homologous recombination.Transmission electron microscope observation shows that theΔpilO mutant strain could not form type-IV pili.The ΔpilO mutant strain growth is basically not affected,but the motility ability is decreased significantly.Disruption of pilOin A.citrulli causes a 80% reduction in biofilm formation and a 55% decrease in disease efficacy.These results suggests that pilO may be one of the key genes involved in type-IV pili conformation and pilO plays an important role in biofilm formation and pathogenicity of A.citrulli.