Cultural, morphological and bio-chemical variability of different isolates of Colletotrichum truncatum causing anthracnose of greengram

Abstract

A laboratory experiment was conducted to study the variability among the eight isolates of Colletotrichum truncatum of greengram collected from different locations on the basis of cultural, morphological and biochemical characteristics by using nine different culture media viz., Potato Dextrose Agar (PDA), Potato Carrot Agar (PCA), Oat Meal Agar (OMA), Corn Meal Agar (CMA), Carrot Agar (CA), Sabouraud’s Agar (SA), Czapek’s Dox Agar (CDA), Richard’s Agar (RA) and V8 Juice Agar. Colony colour varied in different media from white or white with light brown centres which later changed to black or dark to light brown with increase in the age of the fungal cultures. Mostly, the colonies had fluffy or cottony mycelial growth with slight variations and regular to irregular white margin. PDA, PCA, CA and RA produced maximum mycelial growth (90 mm) at 10 DAI (days after inoculation). Minimum growth was observed on SA (69.56 mm) and V8 juice agar media (55.42 mm) and their difference was statistically significant. Morphological variability among the isolates was studied by comparing their conidial length, breadth and length and breadth of setae and their differences were statistically significant. Biochemical variability among the isolates was based on α- and β-esterase and peroxidise profiling. Positive activity was observed for both α- and β-esterase. α-Esterase enzyme showed the highest enzyme activity in terms of maximum numbers of banding loci among the three isozymes tested. The findings of the present study clearly revealed that cultural, morphological and biochemical variability did exist among the different isolates of C. truncatum.