Morpho-pathological, Genetic Variations and Population Structure of Sclerotinia sclerotiorum

Study was conducted to determine the variation in the population of Sclerotinia sclerotiorum in crop production fields of North-West Plain Zone (NWPZ) of India. Diseased samples were collected from eight different crops belong to different plant families. Morphological variation on PDA, pathogenicity variation on different host and molecular variation through RAPD analyses were used to determine variation among the isolates. Pathogenic reactions were evaluated on 17 selected hosts through the fungal disc method of inoculation. Brassica oleracea var capitata and Cicer arietinum were susceptible to all isolates. None of the 9 isolates caused infection on garlic plant. Eight RAPD Decamer primers were used to analyze polymorphism among S. sclerotiorum isolates. The specific marker bands obtained with primers OPA-05, OPF-09 (200 Kb), OPF-17, OPF-19 and OPG-19 were linked and were used as marker band to identify S. sclerotiorum isolate from particular host. Statistical analysis was carryout to determine the genetic uniformity in Sclerotinia isolates using NTSYS-PC software. RAPD results revealed genetic similarity coefficients between isolates which ranged from 0.52 to 0.85. Sclerotinia isolates were grouped into three clusters and cluster I contained maximum number of isolates (6). Clusters II and III contained only one isolate. In cluster I, Mullugo lotoides and Solanum melongena isolates showed high similarity (0.85). The presence of S. sclerotiorum disease on non-economical plants and its ability to cause infection on economically important plants is alarming.