Combinatorial efficacy of Trichoderma spp. and Pseudomonas fluorescens to enhance suppression of cell wall degrading enzymes produced by Fusarium wilt of Arachis hypogaea.L

P Rajeswari,R Kapoor

doi:10.3329/ijarit.v7i2.35320

Abstract

Fusarium oxysporum, the soil borne pathogen causes vascular wilt, on majority of crop plants. It has been demonstrated that two different species of Trichoderma and Pseudomonas fluorescens suppress disease by different mechanisms. Therefore, application of a mixture of these biocontrol agents, and thus of several suppressive mechanisms, may represent a viable control strategy. A necessity for biocontrol by combinations of biocontrol agents can be the compatibility of the co-inoculated micro-organisms. Hence, compatibility between Trichoderma spp. and Pseudomonas fluorescens that have the ability to suppress Fusarium oxysporum in vitro on the activity of pectinolytic enzymes of Fusarium oxysporum. The activity of pectinolytic enzymes, i.e. pectin methyl esterase, endo and exo polymethylgalacturonases and exo and endo pectin trans eliminases produced by Fusarium oxysporum (Control) was higher. Maximum inhibition of pectin methylesterase, exo and endo polymethylgalacturonase and exo and endopectin trans eliminase was shown by culture filtrate of Trichoderma viride + Pseudomonas fluorescens (Tv+Pf) (1+2%), followed by Trichoderma harzianum + Pseudomonas fluorescens, (Th +Pf) (1.5+2%) and Trichoderma viride + Trichoderma harzianum (Tv+Th) (1+1.5%). However, pathogenecity suppression of Fusarium oxysporum, a causative of Arachis hypogaea. L by the compatible combination of Trichodema viride + Pseudomonas fluorescens (1+2%) was significantly better as compared to the single bio-agent. This indicates that specific interactions between biocontrol agents influence suppression of pathogenicity factors directly by combinations of these compatible bio-agents.Int. J. Agril. Res. Innov. & Tech. 7 (2): 36-42, December, 2017

Highlights

Fusarium oxysporum is considered as an important fungus because of its ability to cause wilt disease on wide range of plants
The highest Pectin methyl esterase (PME) activity was recorded in enzyme source of control by specific activity unit (89.25 specific activity units (SAU))
Shukla and Dwivedi (2012) demonstrated that polygalacturonase, pectinmethylesterase, and Cellulose enzymes play an important role in inducing pathogenesis and the enzyme activity was increased in Fusarium sp. causing wilt in pigeon pea which determines higher pathogenicity in comparison to Fusarium oxysporum f.sp. ciceri causing wilt in chickpea

Summary

Introduction

Fusarium oxysporum is considered as an important fungus because of its ability to cause wilt disease on wide range of plants. Fusarium oxysporum causing wilt produces several enzymes that act upon the pectic and components of cell wall of host plant. These enzymes are involved in degradation of plant cell components and lignin. Polygalacturonases catalyze the hydrolysis of α- (1→4)-glycosidic bonds between adjacent non- esterified D-GalpA units in HG, which leads to substrate depolymerization and viscosity reduction. Fungal endo-PGs bind to 4 till 5 adjacent α-D-GalpA units from the main chain and hydrolyze between the last two residues at the reducing end (Prade et al, 1999). Transeliminases (Pectate lyase) catalyze the nonhydrolytic depolymerization of HG chains by α-

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