Pseudomonas fluorescens Induced Enzymological Changes in Banana Roots (Cv. Rasthali) against Fusarium Wilt Disease

Abstract

Pseudomonas fluorescens isolated from banana rhizosphere reduced the vascular discolouration associated with Fusarium wilt disease and induced the accumulation of resistance associated enzymes in roots. The banana roots inoculated with talc based formulation of P. fluorescens at 10 g / plant had minimum vascular discolouration index when compared to pathogen Fusarium oxysporum f.sp. cubense alone inoculated roots. The resistance associated enzymes viz., peroxidase and polyphenol oxidase activity increased two folds on 8 days in roots treated with P. fluorescens and challenged with F. oxysporum f.sp. cubense. Whereas phenylalanine ammonia lyase activity increased two folds on 6 days, later shows decreasing trend in the roots. In F. oxysporum f.sp. cubense alone inoculated plants, peroxidase, polyphenol oxidase and phenylalanine ammonia lyase activities increased upto 4 days after inoculation. The induction was compared with other fungal biocontrol agent's viz., Trichoderma viride and Trichoderma harzianum. Same trend of enzymes induction were noticed in T. viride and T. harzianum inoculated roots. Further more, in Native Poly Acrlyamide Gel Electrophoresis analysis, two isoforms of peroxidase and five isoforms of polyphenol oxidase were observed in roots treated with P. fluorescens and challenged with F. oxysporum f.sp. cubense.