IDENTIFICATION AND GENETIC VARIATION OFFUSARIUM SPECIES&

The genus Fusarium is a species rich genus. Different media are required to study the morphological characters and classify different species, a time consuming technique. In this study pectic zymograms were used to identify species and form species of Fusarium isolates. Fusarium isolates (318) were obtained from different areas and hosts in Isfahan Province, Iran. Isolates were identified to species based on morphological characters. A pectic enzyme solution was prepared for each isolate using liquid media containing citrus pectin as the sole carbon source. Electrophoresis was performed using acrylamide gel containing 0.2% citrus pectin as the enzyme substrate. The gels were incubated in 0.1M malic acid before staining overnight in 0.02% ruthenium red, to visualize enzyme electrophoretic patterns. Several zymogram phenotypes were obtained for polygalacturonase and pectin esterase. In total, 12 zymogram patterns were determined for the 318 isolates tested. The results showed that there is considerable intraspecific variation in Fusarium species. There were 3, 5 and 2 zymogram electrophoretic patterns for Fusarium oxysporum, F. solani and F. culmorum respectively. However, there was only one zymogram pattern for F. subglutinans and also one for F. equiseti. Although the intraspecific variation based on pectic zymograms was not correlated to the form species of Fusarium, species of Fusarium could be distinguished using this technique as there was no common zymogram pattern among species.