Morphological and toxigenic variability in the Aspergillus flavus isolates from peanut (Arachis hypogaea L.)...

Morphological and toxigenic variability in 187 Aspergillus flavus isolates, collected from a major Indian peanut production system, from 10 districts of Gujarat was studied. On the basis of colony characteristics, the isolates were grouped as group A (83%), B (11%) and G (6%). Of all the isolates, 21%, 47% and 32% were found to be fast-growing, moderately-fast and slow-growing respectively, and nosclerotia and sclerotia production was recorded in 32.1% and 67% isolates respectively. Large, medium and small number of sclerotia production was observed in 55, 38 and 34 isolates respectively. Toxigenic potential based on ammonia vapour test was not found reliable, while ELISA test identified 68.5%, 18.7% and 12.8% isolates as atoxigenic, moderately-toxigenic and highly-toxigenic, respectively. On clustering, the isolates were grouped into 15 distinct clusters, 'A' group of isolates was grouped distinctly in different clusters, while 'B' and 'G' groups of isolates were clustered together. No association was observed between morphological-diversity and toxigenic potential of the isolates. From the present investigation, most virulent isolates were pooled to form a consortium for sick-plot screening of germplasm, against Aspergillus flavus. In future, atoxigenic isolates may be evaluated for their potential to be used as bio-control agent against toxigenicisolates.