Molecular characterization of bacterial antibiosis in the rhizosphere and its impact on Solanaceous plant diseases

由于公众对在环境中使用化学杀虫剂以及对某些疾病的化学控制措施不力的担忧，人们对植物病原体的生物控制越来越感兴趣。已有的研究表明，几种拮抗假单胞菌均具有较强的抗菌活性。可以在体外或受控条件下使用抗生素控制植物病原菌种群。然而，土壤中的抗菌效率仍然是可变的，这解释了为什么只有很少的抗菌素代谢产物产生假单胞菌。菌株已被商业化为生物杀虫剂。在此，我们建议用马铃薯和番茄这两种茄科植物来研究产生抗菌代谢产物的假单胞菌的效果。接种两种重要的植物细菌病原菌：引起马铃薯赤霉病的链霉菌(Streptomyces scabiei，SS)和密歇根棒状杆菌亚种。引起番茄青枯病和溃烂病的密歇根病菌。这项研究的总体目标是在分子水平上了解抗生素如何在根际发挥作用，它如何影响SS和CMM的转录，它对植物定殖和病原体侵染的影响，以及它如何防御疾病。假单胞菌属(Passomonas spp.本实验室已分离出吩嗪-1-羧酸(PCA)、2，4-二乙酰间苯三酚(DAPG)和氰化氢(HCN)等抗菌代谢产物。不能产生抗微生物代谢产物的这些菌株的基因敲除也已经开发出来。这些生物将被用来解决以下具体目标：1)表征与假单胞菌相关的转录活性。马铃薯和番茄根际抑菌代谢产物的产生及其对植物病害防治的影响。2)研究抗菌代谢产物的产生对SS和CMM转录的影响。3)确定在茄科植物中，抗菌代谢产物的产生除了抗菌作用外，是否还能引发诱导的系统抗性(ISR)。这项创新工作应该有助于更好地理解假单胞菌介导的抗生素在土壤条件下是如何运作的，以及它如何有助于茄科植物的疾病保护。

An increased interest in biocontrol of plant pathogens has been fuelled by public concern over the use of chemical pesticides in the environment and ineffective chemical control measures against certain diseases. It has been demonstrated that several antagonistic Pseudomonas spp. can control plant pathogen populations under in vitro or controlled conditions using antibiosis. However, the efficiency of antibiosis in soil is still variable, explaining why only few antimicrobial metabolite-producing Pseudomonas spp. strains have been commercialized as biopesticides. Here, it is proposed that two Solanaceous plant species, potato and tomato, be used to study the effect of tailored antimicrobial metabolite-producing Pseudomonas spp. inoculations against two important bacterial plant pathogens: Streptomyces scabiei (Ss) causing common scab of potato and Clavibacter michiganensis subsp. michiganensis (Cmm) causing bacterial wilt and canker of tomato. The general goal of this research is to understand, at the molecular level, how antibiosis operates in the rhizosphere, how it affects the transcriptomics of Ss and Cmm, its effect on colonization and infection of plants by pathogens, and how it can protect against diseases. A collection of Pseudomonas spp. producing antimicrobial metabolites such as phenazine-1-carboxylic acid (PCA), 2,4-diacetylphloroglucinol (DAPG) and hydrogen cyanide (HCN) has been isolated in our laboratory. Knockouts of these strains, incapable of producing the antimicrobial metabolites, have also been developed. These organisms will be used to address the following specific goals: 1) Characterize the transcriptional activity associated with Pseudomonas spp. antimicrobial metabolite production in the rhizosphere of potato and tomato and its impact on controlling plant diseases. 2) Study the impact of antimicrobial metabolite production on Ss and Cmm transcriptomics. 3) Determine if antimicrobial metabolite production can, in addition to antibiosis, trigger induced systemic resistance (ISR) in Solanaceae. This innovative work should lead to a better understanding of how Pseudomonas spp.-mediated antibiosis operates under soil conditions and how it can contribute to disease protection in Solanaceae.