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Abstract：
Biological control is a great hope for reducing the overutilization of pesticides in agricultural soils. It often involves microorganisms or molecules produced by microorganisms that will be able to interact with either a plant or pathogens of this plant to reduce the growth of the pathogen and limit its negative impact on the host plant. When new biocontrol products are developed, strains were mostly selected based on their ability to inhibit a pathogen of interest under in vitro conditions via antagonistic effects. Strains with no in vitro effect are often discarded and not tested in planta. But is the in vitro selection of bacterial agents according to their antagonism activities towards a plant pathogen the best way to get effective biocontrol products? To answer this question, we used wheat and the fungal pathogen Fusarium graminearum as a study pathosystem model. A library of 205 soil bacteria was screened in 2 types of in vitro growth inhibition tests against F. graminearum, and in an in planta experiment. We find strains which do not have inhibition phenotypes in vitro but good efficacy in planta. Interestingly, some strains belong to species (Microbacterium, Arthrobacter, Variovorax) that are not known in the literature for their ability to protect plants against fungal pathogens. Thus, developing a biocontrol product against F. graminearum must be preferentially based on the direct screening of strains for their protective activity on wheat plants against fungal diseases, rather than on their in vitro antagonistic effects on fungal growth.
摘要：
生物防治是减少农业土壤中农药过度利用的巨大希望。它通常涉及能够与植物或该植物的病原体相互作用以减少病原体的生长并限制其对宿主植物的负面影响的微生物或由微生物产生的分子。当开发新的生物防治产品时，菌株主要是基于它们在体外条件下通过拮抗作用抑制目的病原体的能力来选择的。没有体外作用的菌株通常被丢弃并且不在植物中测试。但是，根据细菌对植物病原体的拮抗活性在体外选择细菌是获得有效生物防治产品的最佳途径吗？我们使用小麦和真菌病原体镰刀菌作为研究病理系统模型。在2种类型的体外生长抑制试验中筛选了205个土壤细菌文库，在植物内的实验中。我们发现菌株在体外没有抑制表型，但在植物中具有良好的功效。有趣的是,一些菌株属于物种(微细菌，节杆菌,Variovorax）在文献中未知其保护植物免受真菌病原体侵害的能力。因此，开发针对F.graminearum的生物防治产品必须优先基于直接筛选菌株对小麦植物对真菌疾病的保护活性，而不是它们对真菌生长的体外拮抗作用。
