Molecular mechanisms involved in Pseudomonas biocontrol

土壤中自然存在的一些细菌能够抑制真菌在植物中致病的能力。由于这些细菌不会引起人类或其他动物的疾病，它们是化学杀虫剂的一种环境友好的替代品。核盘菌是一种对油菜和其他400多种作物造成毁灭性损失的真菌。De Kievit实验室正在进行的工作重点是一种细菌--绿假单胞菌PA23，它能够控制菌核葡萄球菌的生长，并保护油菜免受这种真菌引起的疾病的侵袭。到目前为止，生防菌作为农用化学品替代品的能力还没有完全发挥出来。抑制化合物表达的波动和引入的有机体未能在给定的利基环境中站稳脚跟，是导致业绩不佳的两个因素。为了使生防剂取得成功，我们必须了解抑制疾病所需的化合物(S)的性质以及控制其表达的因素。在这项拟议的研究中，我们将研究一种称为PtrA的基因表达的基本调节因子如何控制PA23中抗生素和酶的产生。由于其他几种细菌含有类似ptrA的基因，包括导致人类疾病的细菌，我们的发现预计将具有深远的影响。细菌接种剂应对捕食性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PA23菌株如何与食细菌的线虫--秀丽线虫相互作用。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.