Bacillus amyloliquefaciens PKM16 acts as an antagonist of white mold and an inducer of defense enzymes in tomato plants

ABSTRACT. This study aimed to investigate the potential of rhizobacteria isolated from tomato plants to control Sclerotinia sclerotiorum and induce the activity of pathogenesis-related enzymes in Micro-Tom tomato plants. Three rhizobacterial isolates were evaluated to determine the most efficient antagonist agent, which was later identified by gene sequencing as Bacillus amyloliquefaciens PKM16. The antagonistic effects of B. amyloliquefaciens against S. sclerotiorum were assessed in vivo and in vitro using live and autoclaved cultures at concentrations of 0% (control), 20%, 30%, and 40% (v/v). The residual effects of four treatments (20% live culture, 20% autoclaved culture, a Bacillus subtilis-based commercial product, and autoclaved distilled water) on tomato plants inoculated with S. sclerotiorum were determined. The same treatments were also used to assess the myceliogenic germination of sclerotia and induction of plant defense enzymes (peroxidase, catalase, polyphenol oxidase, phenylalanine ammonia-lyase, and β-1,3-glucanase) in tomato plants. The live culture had a residual effect for 4 days and inhibited sclerotial germination by approximately 30%. Furthermore, live and autoclaved bacterial growth cultures stimulated enzyme activity. Therefore, B. amyloliquefaciens PKM16 was antagonistic to S. sclerotiorum, effectively inhibiting mycelial growth and activating defense mechanisms in Micro-Tom tomato plants.

摘要。本研究旨在探究从番茄植株中分离得到的根际细菌（rhizobacteria）防治核盘菌（Sclerotinia sclerotiorum），并诱导Micro-Tom番茄（Micro-Tom tomato）植株产生病程相关酶（pathogenesis-related enzymes）活性的潜力。本研究对3株根际细菌分离物进行了筛选，以确定最优拮抗菌株，后续通过基因测序将其鉴定为解淀粉芽孢杆菌（Bacillus amyloliquefaciens）PKM16。采用浓度分别为0%（对照组）、20%、30%、40%（体积比）的活菌培养液与高压灭菌培养液，分别在体内与体外条件下评估了解淀粉芽孢杆菌对核盘菌的拮抗效果。本研究还测定了4种处理方式——20%活菌培养液、20%高压灭菌培养液、基于枯草芽孢杆菌（Bacillus subtilis）的商用菌剂以及灭菌蒸馏水——对接种核盘菌的番茄植株的持效防治效果。同时，利用上述4种处理方式，探究其对菌核菌丝萌发的影响，以及诱导番茄植株产生防御酶活性的效果，所检测的防御酶包括过氧化物酶（peroxidase）、过氧化氢酶（catalase）、多酚氧化酶（polyphenol oxidase）、苯丙氨酸解氨酶（phenylalanine ammonia-lyase）以及β-1,3-葡聚糖酶（β-1,3-glucanase）。结果显示，活菌培养液的持效防治时长可达4天，且可抑制约30%的菌核萌发。此外，活菌与高压灭菌的细菌培养液均可显著提升防御酶活性。综上，解淀粉芽孢杆菌PKM16对核盘菌具有显著拮抗作用，可有效抑制菌丝生长，并激活Micro-Tom番茄植株的防御机制。