Growth Rate, Aggressiveness, Chlorate Phenotypes and Genetic Variability of Macrophomina phaseolina Isolates from Apricot Plants

Abstract

Surveys were conducted in apricot orchards and gardens in Hatay province of Turkey in 2014 summer season. Apricot plants showing yellowing, wilting and root rot symptoms were collected. Infected plant tissues were surface sterilized and transferred to PDA medium which contains tetracycline. After 5-days incubation period, fungal colonies were identified based on their microscopic and macroscopic characteristics. Totally, 30 isolates were identified as Macrophomina phaseolina. All the isolates were subcultured by single microsclerotia or hyphal tip techniques and kept in +6°C room conditions. Discs of 10mm from each isolate were transferred to PDA medium and kept in 15, 20, 25, 30, 35 and 40°C temperature conditions and optimum growing temperatures were determined as 25 and 30°C. For phenotypical characterizations, all isolates were grown on minimal medium containing 120mM potassium chlorate and 21 of 30 were observed to be dense, 6 were feathery and 3 were restricted, respectively. According to results, there was no correlation between location and phenotype. For the pathogenicity tests, isolates were inoculated onto apricot, peanut, soybean, maize and melon plants and disease severity was measured by using 0-4 scale after 21-days incubation period. The observed disease severity was very high on apricot with the value of 3.87 and moderate on the other plants. There was no difference in disease severity on peanut, soybean, maize and melon seedlings statistically. For molecular characterizations, 14 RAPD primers were used and based on the analysis, 14 of 51 bands were found to be polymorphic. According to phylogenetic analysis, the isolates were grouped into 2 main clusters with many of sub-clusters. No correlation was observed between clusters and locations, temperature responses, chlorate phenotypes or pathogenicity.