Biocontrol of bacterial canker/wilt of tomato (Lycopersicum esculentum) caused by Clavibacter michiganensis subsp. michiganensis with rhizobacteria

密歇根锁杆菌亚种。摘要密歇根菌（Cmm）是引起番茄青枯病和溃疡病的病原菌，在世界范围内造成了巨大的经济损失。近十年来，对番茄青枯病的研究主要集中在流行病学方面，而生物防治方面的研究很少。人们对番茄的有机生产越来越感兴趣，生物防治与这种方法是相容的。本研究的目的是筛选植物根际中对Cmm具有拮抗作用的细菌，并研究它们对番茄抗Cmm的保护作用。我们建议从根际土壤和植物根系样品中分离根附生细菌和内生细菌。然后筛选这些分离物对Cmm的活性。在这方面的第一个小努力发现了四种具有抗cmm活性的菌株，然而，由于应用和产品的限制以及监管限制，必须鉴定广泛的菌株，因为有些菌株肯定不适合商业生物防治；一开始就大量购买是最好的策略。活性菌株将通过HPLC、GC/MS、MALDI-TOF和/或NMR分析以生产抗菌化合物。这些化合物的抗cmm活性将通过圆盘扩散试验（琼脂板上）进行评估，并确定每种化合物的最小抑制浓度。我们还将研究生物防治菌及其抗cmm化合物组合的抗cmm活性。此外，我们还将研究生物防治菌株/抗Cmm化合物、Cmm与寄主番茄植株的三方关系。将进行温室研究，以研究生物防治细菌及其抗生素在一系列组合中的应用地点（种子、根、叶及其各种组合），以控制Cmm。我们还将确定这些细菌/抗cmm化合物是否能够诱导番茄植株抗病，从而增加寄主植物对病原体的防御活性。最后，生物防治菌株/抗Cmm化合物对Cmm的防治研究将在类似于商业温室的条件下进行。

Clavibacter michiganensis subsp. michiganensis (Cmm) is the causal agent of bacterial wilt and canker of tomato (Lycopersicon esculentum), causing substantial economic losses worldwide. During the last decade research work on Cmm of tomato has largely focused on epidemiology, however, there has been little research on biological control. There is growing interest in organic production of tomatoes and biocontrol is compatible with this approach. The goal of this proposal is to screen plant rhizospheres for bacteria antagonistic to Cmm, and to investigate their ability to protect tomato plants against Cmm. We propose to isolate root epiphytic and endophytic bacteria from rhizosphere soil and plant root samples. These isolates will then be screened for activity against Cmm. A first small effort in this regard discovered four strains that show anti-Cmm activity, however, a wide range of strains must be identified as some are certain to be found unsuitable for commercial biocontrol, due to an application and product constraints, and to regulatory restrictions; a large number at the outset is the best strategy. The active strains will be analyzed for production of anti-bacterial compounds using HPLC, GC/MS and MALDI-TOF and/or NMR spectroscopy. The anti-Cmm activity of these compounds will be assessed via the disk diffusion assay (on agar plates), and the minimum inhibitory concentration of each will be determined. We will also study the anti-Cmm activity of combinations of biocontrol bacteria and their anti-Cmm compounds. In addition, we will study the tripartite association of the biocontrol strains/anti-Cmm compounds, Cmm and the host tomato plant. Greenhouse studies will be conducted to study application sites (seed, root, foliar and various combinations of these) for biocontrol bacteria and their antibiotics in a range of combinations, for the control of Cmm. We will also determine if these bacteria/anti-Cmm compounds are able to induce disease resistance in tomato plants, thus adding to host plant defense activity against the pathogen. Finally, studies on the control of Cmm by biocontrol strains/anti-Cmm compounds will be conducted under conditions similar to commercial greenhouses.