Impact of antibiosis in the rhizosphere on pathogenicity gene activation and biocontrol of bacterial-mediated solanaceous plant diseases

由于针对某些疾病的化学控制措施无效，以及公众对环境中使用化学物质的关注，人们对植物病原体的生物控制越来越感兴趣。已经证明，几种根际细菌，如假单胞菌，可以在体外或受控条件下利用抗生素控制植物病原菌的数量，这涉及到抗菌代谢产物的产生。然而，土壤条件下的抗菌效率仍然是不同的，这解释了为什么只有少数产生抗微生物代谢物的根际细菌菌株被商业化。更好地了解植物根际微生物的动态和抗生素的原位作用将有利于假单胞菌的大规模使用。用于生物防治。茄科植物物种，主要是土豆和番茄，对加拿大经济很重要。这些作物受到许多病原体的攻击，造成了重大的经济损失。在这里，我建议研究定制的抗菌代谢产物对假单胞菌产生的影响。接种对影响茄科植物的两种重要细菌病原菌：引起马铃薯赤霉病的链霉菌和密歇根棒状杆菌亚种的防病效果。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，它对植物的定殖和细菌病原体的感染的影响，以及它对茄子病害的保护作用。具体目标是：1)鉴定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细菌性病害防治的影响。2)研究根际细菌抗菌代谢产物的产生对霉菌和密歇根霉菌的致病力和毒力基因激活的影响。评估抗微生物代谢物的产生是否可以在根际持续一段时间，并确定这是否可以抑制病原菌的致病性和毒力基因的激活，这是控制茄科植物病害的一个有趣的途径。

An increased interest in biocontrol of plant pathogens has been fuelled by ineffective chemical control measures against certain diseases and public concern over the use of chemicals in the environment. It has been demonstrated that several rhizobacteria, such as Pseudomonas spp., can control plant pathogen populations under in vitro or controlled conditions using antibiosis, which involves the production of antimicrobial metabolites. However, the efficiency of antibiosis under soil conditions is still variable, explaining why only few antimicrobial metabolite-producing rhizobacterial strains have been commercialized. A better understanding of the microbial dynamics in the rhizosphere of plants and in situ action of antibiosis would favour large-scale use of Pseudomonas spp. for biocontrol. Solanaceous plant species, mainly potato and tomato, are important to the Canadian economy. These crops are attacked by numerous pathogens causing important economic losses. Here, I propose to study the impact of tailored antimicrobial metabolite producing Pseudomonas spp. inoculations on disease protection against two important bacterial plant pathogens affecting Solanaceae: Streptomyces scabies causing common scab of potato and Clavibacter michiganensis subsp. michiganensis 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, its effect on the colonization and infection of plants by bacterial pathogens, and the protection it offers against Solanaceous diseases. Specific goals are to: 1) Characterize the transcriptional activity associated with Pseudomonas spp. antimicrobial metabolite production in the rhizosphere of potato and tomato and its impact on controlling bacterial plant diseases. 2) Study the impact of rhizobacterial antimicrobial metabolite production on pathogenicity and virulence gene activation in S. scabies and C. m. michiganensis. Assessing if antimicrobial metabolite production can be sustained over time in the rhizosphere and determining if this can repress pathogenicity and virulence gene activation in pathogens represents an interesting avenue to control Solanaceous plant diseases.