Extracellular enzymes activity determining the virulence of Rhizoctonia bataticola, causing root rot in soybean

Enzymes play crucial role in successful host-pathogen interactions and degradation of the cell wall. The cellulolytic, hemicellulolytic, pectolytic and proteolytic enzymes produced by plant pathogens are capable of degrading major polymeric components of the host cell wall. A number of pathogenic fungi have been reported to produce cellulases, but relatively a small quantum of plant pathogens are able to degrade insoluble cellulose even after it has been physically or chemically modified to make it more susceptible to enzyme action. Present study revealed Rhizoctonia bataticola as major cause of soybean root rot. Result of the R. bataticola, 20 isolates collected from various regions of Maharashtra, seven isolates were moderate virulent and thirteen isolates highly virulent. These isolates showed wide variability in per cent root rot infection of soybean ranged from 48.00 to 69.33%. Highest extracellular enzyme activity was found in respect of cellulase (Rb-33), pectinase (Rb-33), lipase (Rb-10), protease (Rb-32) and amylase (Rb-36). The per cent root rot infection was found to be highly significant and positively correlated with the enzyme viz., cellulase, pectinase and protease. The entire 20 test isolates exhibited production of extracellular enzymes under both plate culture and plant sample assay methods. Maximum enzyme activity profile from R. bataticola infected root tissues was found in respect of cellulolytic (Rb-1), polygalacturonase (Rb-32) and pectin methylesterase (Rb-32) enzyme. There was low enzyme activity even the isolates were more virulent and vice versa.