Study on the pathogenesis diversity of Rhizoctonia solani AG-1 IA populations, the casual agent of rice sheath blight disease in the North of Iran.
2014
Padasht Dehkaei, Fereidoun | Dodabinejad, Ebrahim | Poorfarhang, Hassan
Rhizoctonia solani AG-1 IA (teleomorph: Thanatephorus cucumeris [Frank] Donk) is the most important pathogen of improved verities of rice in north of Iran. In this study 351 isolates of this pathogen were isolated from infected sheath samples of different rice cultivars in paddy fields of northern Iran as populations of Rasht (R), Tonekabon (T), Amol (A), Guilan (Gu) and Golestan (Go). Pathogenesis behavior and weight and number of sclerotia of all isolates were characterized using detached leaf inoculation technique on rice cultivars Hashemi, Khazar, Nada and Tetep in vitro condition. Also, in each isolate mycelia growth was measured on PSA medium. Results showed the positive and negative significant correlations between leaf length affected (%) and number of sclerotia on host leaves (P=0.0047) and colony diameter of the pathogen isolates on PSA medium (P=0.0328), respectively. Relationships of colony diameter of pathogen with its sclerotial number and weight on host plant leaves were negative (P0.0001). According to the results of pathogenicity test, all populations of pathogen were significantly differ from each other, and the populations of R, T, A, Gu, and Go divided into 4, 3, 3, 2 and 2 pathogenic groups by cluster analysis method. According to these finding two most pathogenic isolates from all or 3 tested cultivars, from 10 ranked isolates of each population can be candidate for evaluation of rice cultivars / lines resistance to sheath blight disease pathogen in the north of Iran. Keywords: Pathogenesis behavior, Rice sheath blight disease, Sclerotia
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