தாவர நோயியல் & நுண்ணுயிரியல் இதழ்

சுருக்கம்

Virulence Diversity in Rhizoctonia Solani Causing Sheath Blight in RicePathogenicitya

Ramji Singh, Shiw Murti, Mehilal, Ajay Tomer and Durga Prasad

Knowledge of variations in Rhizoctonia Solani causing rice sheath blight disease in different geographic regionsis still scarce and may be a useful tool for examining the nature and spread of population, disease epidemiology and host-pathogen interaction within rice patho-system. Molecular markers provide a basis for identifying patterns, dispersal and colonization in spatial and temporal distribution of pathogenic population and in development of species concepts by providing information about the limits of genetically isolated group in relation to patterns of morphological variation and behavior of any pathogen. Twenty-five isolates of Rhizoctonia Solani causing sheath blight in rice were collected from Kerala, New Delhi, Punjab, Uttarakhand and Uttar Pradesh of India and subjected for determination of virulence diversity. There was great diversity in the population of R. Solani which deferred greatly according to color and texture of colony, number and size of sclerotia, time taken for sclerotia formation and also the place and manner of sclerotia formation in the colony. At molecular level, also there was great diversity in the R. Solani population. A total of 80 PCR bands were detected among 25 isolates of R. Solani. The number of alleles per locus, varied from 1to7. Highest [1] PCR products were obtained with primers-OPW-13 and OPA-04 whereas lowest PCR products [2] were obtained with primer UBC-310 and OPB-08. There was only one monomorphic band, which was present in related primer UBC-373.The similarity coefficients among the R. Solani population ranged between 0.53 to 0.94. One isolate of R. Solani from Uttar Pradesh (RS-16) and another isolate from Punjab (RS-1) were most distantly related. The R. Solani isolates (RS-11&RS-12) and (RS-20& RS-21) all belonging to Uttar Pradesh were genetically most closely to each other.