Morphological, physiological and biochemical variability among the isolates of Sclerotium rolfsii Sacc

The present study was carried to assess the morphological, physiological and genetic variability among the isolates of Sclerotium rolfsii from crossandra, groundnut and tomato. Potato Dextrose Agar and Richards medium were found to be good for the growth of all the isolates among solid and liquid media, respectively. Crossandra isolate produced maximum growth (84.2 mm) and mycelial dry weight (387.6 mg) in solid and liquid media respectively, followed by tomato isolate (76.0 mg and 336.9mg) and groundnut isolate. Sucrose, Maltose and Mannitol among carbon sources and nitrate and ammonical forms of nitrogen among nitrogen sources were equally preferred by the three isolates for growth and sclerotial production. Nitrite form proved detrimental to all the isolates. Tomato isolate produced more number of sclerotia (excellent) but small sized (0.9–1.1mm) sclerotia, whereas crossandra isolate produced very few (poor) but bigger (1.2–1.4 mm) sclerotia. Groundnut isolate appeared intermediary (fair to good, 1.1–1.2mm) to these isolates. Electrophoretical analysis reflected variations in total proteins and esterase isozyme pattern indicating the genetic variability among the isolates under the study. The importance of the S. rolfsii and the possibility of studying genetic variability using nucleic acid based techniques will be discussed.