Wockenfuss Anna, Chan Kevin, Cooper Jessica G, Chaya Timothy, Mauriello Megan A, Yannarell Sarah M, Maresca Julia A, Donofrio Nicole M
Microbiology Graduate Program, University of Delaware, Newark, DE, United States.
Department of Plant and Soil Sciences, University of Delaware, Newark, DE, United States.
Front Fungal Biol. 2024 Feb 23;5:1332755. doi: 10.3389/ffunb.2024.1332755. eCollection 2024.
Biological control uses naturally occurring antagonists such as bacteria or fungi for environmentally friendly control of plant pathogens. spp. have been used for biocontrol of numerous plant and insect pests and are well-known to synthesize a variety of bioactive secondary metabolites. We hypothesized that bacteria isolated from agricultural soil would be effective antagonists of soilborne fungal pathogens. Here, we show that the Delaware soil isolate strain S4 has activity against soilborne and foliar plant pathogenic fungi, including two with a large host range, and one oomycete. Further, this strain shows putative protease and cellulase activity, consistent with our prior finding that the genome of this organism is highly enriched in antifungal and antimicrobial biosynthetic gene clusters. We demonstrate that this bacterium causes changes to the fungal and oomycete hyphae at the inhibition zone, with some of the hyphae forming bubble-like structures and irregular branching. We tested strain S4 against spores, which typically form germ tubes and penetration structures called appressoria, on the surface of the leaf. Our results suggest that after 12 hours of incubation with the bacterium, fungal spores form germ tubes, but instead of producing appressoria, they appear to form rounded, bubble-like structures. Future work will investigate whether a single antifungal molecule induces all these effects, or if they are the result of a combination of bacterially produced antimicrobials.
生物防治利用细菌或真菌等天然存在的拮抗物对植物病原体进行环境友好型控制。某些菌株已被用于多种植物和害虫的生物防治，并且众所周知它们能合成多种生物活性次生代谢产物。我们推测从农业土壤中分离出的细菌可能是土壤传播真菌病原体的有效拮抗物。在此，我们表明特拉华土壤分离株S4对土壤传播和叶部植物致病真菌具有活性，包括两种寄主范围广的真菌以及一种卵菌。此外，该菌株显示出假定的蛋白酶和纤维素酶活性，这与我们之前的发现一致，即该生物体的基因组在抗真菌和抗菌生物合成基因簇方面高度富集。我们证明这种细菌在抑制区域会导致真菌和卵菌的菌丝发生变化，一些菌丝会形成泡状结构和不规则分支。我们在叶片表面测试了菌株S4对孢子的作用，这些孢子通常会形成芽管和称为附着胞的穿透结构。我们的结果表明，与该细菌孵育12小时后，真菌孢子形成芽管，但它们没有产生附着胞，而是似乎形成了圆形的泡状结构。未来的工作将研究是单一抗真菌分子诱导了所有这些效应，还是它们是细菌产生的抗菌物质组合的结果。
