Fusarium oxysporum f.sp. cubense Tropical Race 4 (FOC TR4), is one of the newly emerged dreaded pathogens of banana with an established global presence. Fungicides have not been effective in controlling the disease. There are very few effective antagonistic microbes reported for the biological management of this pathogen.

In the present study, suppressive soil was selected for isolation of potential biocontrol plant growth-promoting bacteria. The bacterial strain CSR-D4 Bacillus licheniformis was identified with significant antagonistic attributes and plant growth-promoting properties. This strain exhibited a high inhibition percentage (77.59%) against the FOC TR4 pathogen in the dual plate assay. Further, the bioactive metabolite of the strain conferring biocontrol of FOC-TR4 was also identified through the Liquid Chromatography-Mass Spectrophotometry technique. Our analysis revealed the presence of many antifungal metabolites in the isolate CSR-D4, the majority of which were identified as iturin, fengycin, surfactin, and bacillomycin. These results indicated the involvement of metabolites in the antifungal activity of the strain CSR-D4 against FOC TR4. During sick-pots studies taken with susceptible Cavendish banana cultivar Grand Naine, application of B. licheniformis CSR-D4 showed a significant reduction in the disease incidence percentage (10%). B. licheniformis CSR-D4 treated plants also showed enhanced activity of defense-related enzymes such as β-1,3 glucanase, peroxidase, chitinase, polyphenol oxidase, and phenyl-alanine ammonium lyase compared to FOC TR4 alone treated plants that suggest the occurrence of induced host tolerance in Bacillus licheniformis CSR-D4 treated plants. Our results suggest the antagonistic potential of rhizobacterium Bacillus licheniformis CSR-D4 strain through secreted metabolites mediated the effective biocontrol of Fusarium oxysporum f.sp. cubense Tropical Race 4.

尖孢镰刀菌f.sp. 立方热带物种4（FOC TR4）是香蕉的一种新近出现的可怕病原体，已在全球范围内建立。杀菌剂尚未有效控制该疾病。报道很少有有效的拮抗微生物用于这种病原体的生物处理。

在本研究中，选择抑制性土壤来分离潜在的生防植物促进细菌生长。细菌菌株CSR-D4地衣芽孢杆菌具有明显的拮抗特性和促进植物生长的特性。在双板试验中，该菌株对FOC TR4病原体表现出较高的抑制率（77.59％）。此外，还通过液相色谱-质谱法鉴定了赋予FOC-TR4生物控制的菌株的生物活性代谢物。我们的分析显示，分离物CSR-D4中存在许多抗真菌代谢物，其中大多数被鉴定为伊图林，丰霉素，表面活性素和杆菌霉素。这些结果表明，代谢产物参与了菌株CSR-D4对FOC TR4的抗真菌活性。在对易受感染的卡文迪许香蕉栽培种Grand Naine进行的病灶研究期间，地衣芽孢杆菌的应用CSR-D4显着降低了疾病发病率（10％）。与仅用FOC TR4处理的植物相比，用地衣芽孢杆菌CSR-D4处理的植物还显示出与防御相关的酶（例如β-1,3葡聚糖酶，过氧化物酶，几丁质酶，多酚氧化酶和苯丙氨酸铵裂解酶）的活性增强，表明这种情况的发生地衣芽孢杆菌CSR-D4处理植物的诱导宿主耐受性 我们的结果表明，地衣芽孢杆菌CSR-D4菌株通过分泌的代谢产物介导了尖孢镰刀菌的有效生物防治而具有拮抗作用。立方热带种族4。