Diversity of Colletotrichum species associated with blight of chickpea and its relevance to disease severity

Chickpea plants showing typical symptoms of blight disease were collected from farmer's field from Kadapa, Kurnool, Ananthapur and Prakasam districts of Andhra Pradesh and pathogen was isolated from the infected plants. The isolates were identified as Colletotrichum capsici based on morphological and cultural characters. The virulence of all the isolates was determined in vitro by artificial inoculation on three week old chickpea plants. The measurement of disease severity of chickpea plants revealed difference in the virulence among isolates and were grouped as highly virulent, moderately virulent and less virulent. The molecular variability among isolates of C. capsici was analyzed by Random Amplified Polymorphic DNA (RAPD), using 20 random primes. Analysis of the genetic coefficient matrix derived from scores of RAPD profiles showed minimum and maximum per cent similarities among C. capsici which were within the range of 69.2 to 86.6%. The cluster analysis, using the Unweighed Pair Group Method with Arithmetic Average (UPGMA), clearly separated isolates into two major clusters, Cluster I included Cb 1 and Cb 7, whereas cluster II was divided into two sub clusters, IIA (Cb 3, Cb 4 and Cb 5) and IIB (Cb 2 and Cb 6). No relationship between clustering in the dendogram and virulence of C. capsici isolates were observed.