We have shown, the outcome of antifungal activity of phenazine derivatives which is produced by fluorescent pseudomonads (FPs) for the control of sheath blight of rice. A total of 50 fluorescent pseudomonads (FPs) were isolated from rice rhizosphere. Off which, 36 FPs exhibited antagonistic activity against Rhizoctonia solani, Macrophomina phaseolina, Fusarium oxysporum, Alternaria alternata and Sclerotium rolfsii up to 70–80% compared to control by dual culture method. BOX-PCR analyses of antagonistic isolates indicated that two phylogenetic group, where group I consisted of 28 isolates and eight isolates belongs to group II. Among 36 FPs, a total of 10 FPs revealed that the presence of phenazine derivatives on thin layer chromatography (TLC), which is coincided with that of authentic phenazine with R_f value 0.57. Similar to TLC analysis, antibiotic encoding gene phenazine-1-carboxamide (PCN) was detected in 10 FPs by PCR analysis with respective primer. Among, PCN detected isolates of FPs, a significant biocontrol potential possessing isolate designated as VSMKU1 and it was showed prominent antifungal activity against R. solani and other tested fungal pathogens. Hence, the isolate VSMKU1 was selected for further studies. The selected isolate VSMKU1 was identified as Pseudomonas aeruginosa by 16S rDNA sequence analysis. The antifungal metabolite phenazine like compound produced by VSMKU1 was confirmed by UV, FT-IR and HPLC analysis. The phenazine compound from VSMKU1 significantly arrest the growth of R. solani compared to carbendazim by well diffusion method. The detached leaf assay showed remarkable inhibition of lesion height 80 to 85% by the treatments of culture (VSMKU1), cell free culure filtrate and phenazine like compound compared to control and other treatments was observed in detached leaves of rice. These results emphasized that VSMKU1 isolate can be used as an alternative potential biocontrol agent against sheath blight of rice, instead of using commercial fungicide such as validamycin and carbendazim which cause environmental pollution and health hazards.

我们已经展示了由荧光假单胞菌 (FPs) 产生的吩嗪衍生物的抗真菌活性结果，用于控制水稻纹枯病。从水稻根际共分离出50个荧光假单胞菌（FPs）。其中，36 种 FPs 对立枯丝核菌、Macrophomina phaseolina、尖孢镰刀菌、交替链格孢菌和核盘菌具有拮抗活性与双重培养方法的对照相比，高达 70-80%。拮抗分离株的BOX-PCR分析表明，有两个系统发育组，其中第一组由28个分离株组成，8个分离株属于第二组。在 36 个 FP 中，共有 10 个 FP 显示在薄层色谱 (TLC) 上存在吩嗪衍生物，这与 R _f值为 0.57 的正宗吩嗪一致。与 TLC 分析类似，通过使用各自引物的 PCR 分析，在 10 个 FP 中检测到抗生素编码基因吩嗪-1-甲酰胺 (PCN)。其中，PCN 检测到 FP 的分离株，具有显着的生物防治潜力，具有被命名为 VSMKU1 的分离株，并且对R. solani显示出显着的抗真菌活性和其他经过测试的真菌病原体。因此，选择分离株 VSMKU1 进行进一步研究。通过 16S rDNA 序列分析，选定的分离株 VSMKU1 被鉴定为铜绿假单胞菌。VSMKU1产生的抗真菌代谢物吩嗪样化合物经UV、FT-IR和HPLC分析证实。来自 VSMKU1 的吩嗪化合物显着阻止了立枯病菌的生长通过井扩散法与多菌灵相比。离叶试验表明，与对照相比，培养物（VSMKU1）、无细胞培养滤液和吩嗪类化合物处理对病斑高度的显着抑制80%至85%，在水稻离叶叶中观察到其他处理。这些结果强调了VSMKU1分离物可以作为替代潜在的水稻纹枯病生物防治剂，而不是使用会造成环境污染和健康危害的商业杀菌剂如有效霉素和多菌灵。