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

由于对某些疾病的化学防治措施无效以及公众对在环境中使用化学品的关注，对植物病原体生物防治的兴趣日益增加。已经证明，几种根际细菌，如假单胞菌属，可以在体外或受控条件下使用包括产生抗微生物代谢物的微生物作用来控制植物病原体种群。然而，在土壤条件下的固氮效率仍然是可变的，这解释了为什么只有少数产生抗菌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动态和假单胞菌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，主要是马铃薯和番茄，对加拿大经济很重要。这些作物受到许多病原体的侵袭，造成重大的经济损失。在这里，我建议研究定制的抗菌代谢产物产生假单胞菌的影响。接种对影响茄科的两种重要细菌性植物病原体的病害保护：引起马铃薯普通疮痂病的疥疮链霉菌和Clavibacter michiganensis subsp.引起番茄青枯病和溃疡病的Michiganensis。本研究的总体目标是在分子水平上了解植物病原菌在根际的作用方式，它对细菌病原体定殖和感染植物的影响，以及它对茄科疾病的保护作用。具体目标是：1）表征与假单胞菌属相关的转录活性。马铃薯和番茄根际抗菌代谢产物的产生及其对控制细菌性植物病害的影响。2)研究了根际细菌抗菌代谢产物的产生对S. scabies和C. M. Michiganensis。评估是否抗菌代谢产物的生产可以持续一段时间在根际，并确定这是否可以抑制病原体的致病性和毒力基因的激活代表了一个有趣的途径，以控制茄科植物疾病。

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.