Identification of Xylella fastidiosa antivirulence genes:: Hemagglutinin adhesins contribute to X-fastidiosa biofilm maturation and colonization and attenuate virulence
Identification of Xylella fastidiosa antivirulence genes:: Hemagglutinin adhesins contribute to X-fastidiosa biofilm maturation and colonization and attenuate virulence
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DOI：
10.1094/mpmi-18-0856
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发表时间：
2005-08-01
影响因子：
3.5
通讯作者：
Kirkpatrick, BC
中科院分区：
文献类型：
--
作者：
Guilhabert, MR;Kirkpatrick, BC
丛枝木霉是一种革兰氏阴性、木质部受限的细菌，是几种重要的植物病害的病原菌，包括皮尔斯病(PD)和柑橘斑叶黄化病(CVC)。直到最近，无法转化或产生条斑病菌转座子突变体一直是鉴定条斑病菌介导病原菌与植物相互作用的基因的主要障碍。构建了条斑病菌的随机转座子(Tn5)文库，并筛选出比野生型葡萄更严重的症状和更早死亡(高病毒)的突变体。在此筛选中发现的7个超强毒力突变体的移动速度更快，达到了比葡萄野生型更高的种群。这些结果表明，丛枝杆菌对植物的毒力是减弱的，运动在丛枝杆菌毒力中起着重要作用。突变的基因被测序，之前没有一个被描述为抗毒力基因，尽管其中六个基因与其他生物中已知功能的基因相似。一个转座子插入使血凝素粘附素基因(PD2118)失活，我们将其命名为HxfA。构建了第二个可能的枯萎病菌血凝素基因PD1792(HxfB)的另一个突变体，对这些突变体的进一步鉴定表明，枯萎病菌血凝素介导了枯萎病菌细胞之间的接触，导致木质部导管内的克隆形成和生物膜成熟。
Xylella fastidosa, a gram-negative, xylem-limited bacterium, is the causal agent of several economically important plant diseases, including Pierce's disease (PD) and citrus variegated chlorosis (CVC). Until recently, the inability to transform or produce transposon mutants of X. fastidosa had been a major impediment to identifying X. fastidosa genes that mediate pathogen and plant interactions. A random transposon (Tn5) library of X. fastidosa was constructed and screened for mutants showing more severe symptoms and earlier grapevine death (hyperviru- lence) than did vines infected with the wild type. Seven hypervirulent mutants identified in this screen moved faster and reached higher populations than the wild type in grapevines. These results suggest that X. fastidosa attenuates its virulence in planta and that movement is important in X. fastidosa virulence. The mutated genes were sequenced and none had been described previously as anti-virulence genes, although six of them showed similarity with genes of known functions in other organisms. One transposon insertion inactivated a hemagglutinin adhesin gene (PD2118), which we named HxfA. Another mutant in a second putative X. fastidosa hemagglutinin gene, PD1792 (HxfB), was constructed, and further characterization of these hxf mutants suggests that X. fastidosa hemagglutinins mediate contact between X. fastidosa cells, which results in colony formation and biofilm maturation within the xylem vessels.