Assessment of morpho-genetic variability of Mycogone perniciosa affecting Agaricus bisporus in the North–West Himalayas

Wet bubble disease ( Mycogone perniciosa ) is one of the major issues in Agaricus bisporus production leading to huge losses to mushroom growers in India. Extensive surveys across mushroom farms all over Himachal Pradesh revealed that incidence of wet bubble disease ranged from 3.99 to 13.12 per cent and intensity ranged from 25.51 to 38.59% district wise. 18 isolates M. perniciosa were collected with the aim to understand their morphological and genetic variability. The isolates of the pathogen exhibited varying symptoms like appearance of cauliflower like fruiting bodies, scattered sclerodermoid mass with amber-coloured droplets, thickened stipe and interior stipe browning. The isolates were categorized into three virulence groups’ viz., HV (highly virulent), MV (moderately virulent) and LV (low virulent) on the basis of pathogenicity assays and visible morphological characters. RAPD, ISSR and a combined analysis of both clustered the eighteen isolates into two distinct groups with a high level of polymorphism with Jaccard’s similarity coefficient of 28–89%, 8–88% and 12–85%, respectively. The findings of this research indicated a high degree of genetic variability within M. perniciosa populations, reflecting their adaptability and potential for pathogenicity under diverse environmental conditions.