Polyphasic Identification and Diversity of Aspergillus Species Associated With Maize in India

Abstract

A total of 40 Aspergillus isolates were collected from diverse agroclimatic zones across 14 states in India. All isolates were identified as Aspergillus flavus based on morphological characterisation. The morphological examination revealed significant variability in colony characteristics, including colony colour and growth pattern, as well as limited sclerotium production. The identity of 39 isolates of A. flavus was confirmed using ITS sequencing with 96.88%–100% similarity to GenBank reference sequences, whereas the remaining one isolate (AF-35) was identified as the closely related species A. nomiae. The aflatoxigenic potential of all 40 isolates was assessed using the ammonia vapour and the fluorescence test under UV light. Eight isolates (20%) were identified as potentially aflatoxigenic based on observable colour changes upon ammonia exposure. Thirteen isolates (32.5%) showed fluorescence under UV light, indicating aflatoxin production. The identity of 13 aflatoxigenic isolates along with four atoxigenic isolates was further confirmed using β-tubulin and calmodulin gene sequences. Sixteen isolates were identified as A. flavus, while isolate AF-35 showed conflicting results, aligning both with A. nomiae (calmodulin) and A. flavus (β-tubulin). The finding highlights the diversity within the Aspergillus spp. population in India, with a substantial proportion of aflatoxigenic isolates.