Phenotypic diversity, Virulence and genetic characterization of Colletotrichum gloeosporioides, the incitant of leaf blight of small cardamom in South India

Abstract: Small cardamom (Elettaria cardamomum Maton) is one of the most important spice crops in India, cultivated for its economic, culinary and medicinal values. Leaf blight incited by Colletotrichum gloeosporioides is a serious threat to the cultivation of cardamom in India. In the present study, an attempt was made to isolate and characterize the pathogen both morphologically and on molecular basis. Significant variations were observed in twenty isolates for conidial dimensions, the length of conidia ranged from 7.8-21.5 ?m. The width of the conidia ranged from 3.3 to 7.8 ?m. Isolate CD14 recorded the highest width of conidium (7.8 ?m) and the lowest width was observed in CD8 isolate (3.3 ?m). Variation was also observed in size and lobes, length and width of appressoria produced by the pathogen. Differential reaction of isolates to three varieties revealed that CD5, CD8 and CD7 are highly virulent based on lesion area. Molecular characterization with RAPD, SSR and ISSR primers showed that RAPD and SSR markers are not linked to any characters of pathogen but ISSR primers showed linkage to the virulence of the pathogen.