Isolation and Molecular Characterization of Collar Rot Causing Pathogen Aspergillus niger on Groundnut in Rajasthan, India

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Groundnut, a major pulse crop also grown as an oil seed over 90 countries worldwide, is important to the Indian economy. The states of Andhra Pradesh, Gujarat, Rajasthan and Tamil Nadu are the main producers of groundnut. In 2021, disease incidence with symptoms similar to collar rot was reported from Jaipur district of Rajasthan. The fungal strain was isolated from the collar region of susceptible groundnut variety TAG-24. White colonies with mycelia were observed in 3-4 days which eventually turned dark brown in color. Pathogenicity tests were performed on healthy groundnut and collar rot symptoms developed within 7-8 days of inoculation. Sequencing of PCR products amplified with the18S rRNA (NS1F-NS8R) and ITS (NS1F-ITS4R) primers indicated 99.4% and 100% identity respectively with a reference strain of Aspergillus niger CBS 554.65 (ATCC 16888) in the NCBI-Genebank database. Based on the morphological and molecular characteristics, the fungal pathogen was identified as Aspergillus niger and submitted to Gene Bank with the accession nos. ON954789 and OQ653131. The the culture is submitted to NCMR-NCCS (accession number MCC 9892).