بررسي تنوع ژنتيكي جدايه هاي ايراني Rhizoctonia solani AGI-IA با استفاده از نشانگر مولكولي RAPD

STUDY 0.ʹ GENETIC DIVERSITY OF IRANIAN ISOLATES OF RHlZOCTONIA SOLANl AGI-IA USING RAPD MARKERS

Rhizoctonia sotani AGI-IA (telecmorph: Thanatephorus cucumeris), is the causal agent of sheath blight disease of riee in northern paddies of Iran. Due to the importance of this disease and the lack of knowledge on genetic diversity of its causative agent in Iran. 15 isolates were colleeted from Guilan (23 isolates) and Mazandaran (two isolates) provinces and examined for their morphological characteristics and genetic diversity. This study showed that all isolates were AGI-IA and further confirmed using AGI-IA specific primers for 10 selected isolates which amplified a single band of 265bp. No band was amplified in AG4 as negative control. The results of colony growth rate divided the isolates into high (68~·~ of isolates) and low (32% of isolates) growth rate categories. Genetic diversity was estimated among all isolates, using RAPD analysis. Seven out of 20 random primers showed reproducible polymorphic handing pattern. The size of amplified DNA bands ranged from 0.25 to 5Kb. Cluster analysis of the resulting data was performed using UPGMA method. Jaccardʹs coefficient in NTSYS·pc software. The resulting dendrogram categorized the isolates into two groups of high and low growth rate at 34% similarity level. At 80% similarity level. the isolates were categorized into 23 groups which indicate a high genetic diversity of rice sheath blight fungus revealed by RAPD primers. The result of molecular analysis showed that there was no correlation between geographical origins of isolates and the resulting genetic diversity patterns. This is the first study (In direct identification of R. solani AGl-fA by specific primers and evolution of genetic diversity of rice sheath blight fungus using RAPD marker in Iran .