​Morphological and Molecular Diversity of Botrytis cinerea Infecting Chickpea in India

Abstract

Background: The Botrytis gray mold (BGM) caused by Botrytis cinerea Pers. ex Fr., has become a major threat for chickpea cultivation in India. In view of monetary significance of this disease and growing its spread into new regions through seed and soil (sclerotia) encouraged us to study variability of this pathogen from diverse regions. Methods: Botrytis cinerea infected chickpea samples were collected from Punjab and Uttarakhand states. Pathogen was isolated using chickpea dextrose agar media. Pathogenicity was proved by inoculation of spore suspension (3x105 spores’mL-1) of the fungus on susceptible cultivar. In vitro studies were conducted for observations of morphological and cultural variability of the fungus. The pathogenic fungus was also identified through molecular characterization using ITS primers. Result: The isolates were categorized into different groups based on growth rate of the pathogen on PDA media. Pathogenicity test proved that B. cinerea isolates from Punjab were showed less disease severity scale compared to Uttarakhand state isolates. The B. cinerea fungus prefers PDA for efficient growth and multiplication than Chickpea Dextrose Agar (CDA) media. There was no conspicuous difference in colour of the colony on PDA and CDA media. The colour of the mycelium were initially white or dirty white or greyish and sporulated culture shown to have as grey with profuse mass on the surface of the mycelium. The fungus B. fabae, a different species was also responsible for causing BGM disease which was confirmed through pathogenicity and ITS sequencing. Twenty-eight isolates were studied for diversity in cultural, morphological and molecular level. The diversity in colony colour, growth type and diameter of mycelial growth, sclerotia initiation, number and pattern of sclerotia formation were observed amongst the isolates. This study would help in designing breeding strategy for development of disease resistant cultivars.