Characterization of antifungal metabolite phenazine from rice rhizosphere fluorescent pseudomonads (FPs) and their effect on sheath blight of rice

Nithya Karmegham; Shanmugaiah Vellasamy; Balasubramanian Natesan; Mahaveer P Sharma; Dunia A Al Farraj; Mohamed S Elshikh

doi:10.1016/j.sjbs.2020.10.007

Characterization of antifungal metabolite phenazine from rice rhizosphere fluorescent pseudomonads (FPs) and their effect on sheath blight of rice

Saudi J Biol Sci. 2020 Dec;27(12):3313-3326. doi: 10.1016/j.sjbs.2020.10.007. Epub 2020 Oct 15.

Authors

Nithya Karmegham¹, Shanmugaiah Vellasamy¹, Balasubramanian Natesan², Mahaveer P Sharma³, Dunia A Al Farraj⁴, Mohamed S Elshikh⁴

Affiliations

¹ Department of Microbial Technology, School of Biological Sciences, Madurai Kamaraj University, Madurai 625 021, Tamil Nadu, India.
² Department of Immunology, School of Biological Sciences, Madurai Kamaraj University, Madurai 625 021, Tamil Nadu, India.
³ Microbiology Section, ICAR-Indian Institute of Soybean Research (ICAR-IISR Indore), Khandwa Road, Indore 452 001, India.
⁴ Department of Botany and Microbiology, College of Science, King Saud University, Riyadh 11451, Saudi Arabia.

Abstract

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.

Keywords: Detached leaf assay; Fluorescent pseudomonads; Phenazine-1-carboxamide; Rhizoctonia solani; Sheath blight of rice; Thin layer chromatography.