Molecular mechanisms involved in Pseudomonas biocontrol

土壤中自然存在的一些细菌能够抑制真菌引起植物疾病的能力。由于这些细菌不会引起人类或其他动物的疾病，它们代表了化学农药的环保替代品。菌核菌（Sclerotinia sclerotiorum）是一种真菌，对油菜和其他400多种作物造成毁灭性的损失。de Kievit实验室正在进行的工作重点是一种细菌，即绿假单胞菌菌株PA23，它能够控制菌核菌的生长并保护油菜免受这种真菌引起的疾病。到目前为止，生物防治细菌作为农用化学品替代品的能力尚未充分发挥其潜力。抑制化合物表达的波动和引入的生物体未能在给定的生态位中建立自己是导致性能不佳的两个因素。为了使生物防治剂取得成功，我们必须了解疾病抑制所需化合物的性质以及控制其表达的因素。在我们提出的研究中，我们将研究基因表达的重要调控因子PtrA如何控制PA23中抗生素和酶的产生。由于其他几种细菌含有ptra样基因，包括导致人类疾病的细菌，我们的发现有望产生深远的影响。细菌接种剂应对食草捕食者的能力对细菌在环境中的生存至关重要。因此，我们将研究菌株PA23如何与取食细菌的蛔虫秀丽隐杆线虫相互作用。这些研究将提供有关细菌-捕食者相互作用的重要信息。

Some bacteria naturally present in soil are able to inhibit the ability of fungi to cause disease in plants. As these bacteria do not cause disease in humans or other animals, they represent an environmentally friendly alternative to chemical pesticides. Sclerotinia sclerotiorum is a fungus that causes devastating losses in canola as well as over 400 other crop species. Work ongoing in the de Kievit laboratory is focused on a bacterium, Pseudomonas chlororaphis strain PA23 that it is able to control the growth of S. sclerotiorum and protect canola from the disease caused by this fungus. So far, the ability of biocontrol bacteria to act as substitutes for agrochemicals has not reached its full potential. Fluctuations in the expression of inhibitory compounds and failure of the introduced organism to establish itself in a given niche are two factors underlying poor performance. For biocontrol agents to be successful, we must understand the nature of the compound(s) required for disease inhibition as well as factors controlling their expression. In the research proposed, we will study how an essential regulator of gene expression, called PtrA, controls production of antibiotics and enzymes in PA23. Because several other bacteria contain ptrA-like genes, including bacteria that cause disease in humans, our findings are expected to have far-reaching implications. The ability of bacterial inoculants to cope with grazing predators is important for bacterial survival in the environment. Therefore, we will investigate how strain PA23 interacts with the bacterial-feeding roundworm, Caenorhabditis elegans. These studies will provide important information regarding bacteria-predator interactions.