Cultural, morphological and pathological variation in Indian isolates of Ascochyta rabid, the chickpea blight pathogen

Abstract

Cultural, morphological and pathogenic variation in Indian isolates of Ascochyta rabiei, the causal agent of blight of chickpea, was investigated. Fungal isolates representative of seven agroclimatic regions in north western plain zones (NWPZ) of India showed variation in colony colour as mouse gray with green hue, light mouse gray with slate gray centre and gray with dark brown centre, when grown on chickpea dextrose agar (CDA). Conidiomatal color of the isolates varied from brown to slate gray and black. The number of conidiomata and conidia formed on CDA ranged from 49.7 to 90.7 and 5.5 x 104 to 3 x 105 cm-2, respectively. The size of conidiomata and conidia of A. rabiei isolates varied from 274 x 232 μm to 156 x 116 μm, and from 14.0 x 6.2 μm to 10.7 x 4.6 μm, respectively. Fourteen A. rabiei isolates from the seven agroclimatic regions of NWPZ were evaluated for their virulence on 180 chickpea genotypes in controlled environment. Cluster analysis based on the disease rating on a 1-9 scale indicated higher similarity coefficient (> 0.65) between isolates from different agroecological regions, while few isolates from the same region had less similarity. The 14 isolates were grouped into eight pathotypes at >0.5 similarity coefficient. Sixteen genotypes were identified as probable differentials to distinguish A. rabiei isolates. © The Korean Society of Plant Pathology.