Virulence Diversity in Rhizoctonia Solani Causing Sheath Blight in RicePathogenicitya

Abstract

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.

In Vitro Evaluation of Trichoderma asperellum Isolate UGM-LHAF against Rhizoctonia solani Causing Sheath Blight Disease of Rice

“…isolate UGM-RBAF had perpendicular hyphae with a septum, a white colony that change to brownish-white when old, light brown to dark brown sclerotium with a round shape (diameter of 1.33-1.58 mm, the weight of 0.17 g/ Petri dish, and amount of 19.5/petri), and a growth rate of 40 mm/day (Figure 1d-f). The characteristics of R. solani isolate UGM-RBAF were similar to R. solani characterized by R. Singh et al (2015). Budiarti et al (2020) reported that 41 R. solani isolates isolated × 100 (C -T) C I = from Indonesia had cultural and morphological characteristics, i.e.…”

Morphological and Molecular Characterization of Rhizoctonia solani causing Sheath Blight in Rice

“…The isolate RS4 was found to be highly virulent with 78% disease incidence, while RS1 showed only 9.21% disease incidence. Many workers have reported morphological as well as pathological variations in fungal isolates associated with sheath diseases of rice (Guleria et al, 2007;Singh et al, 2015;Ramos-Molina and Chavarro-Mesa, 2016;Singh et al, 2018). Macro-sized sclerotia forming isolate RS4 was observed to be more virulent than isolate RS3 which formed micro-sized sclerotia; and nonsclerotia forming isolate RS1 was the least virulent.…”

“…Such findings emphasize the use of molecular markers for studying fungal pathogens of rice sheath disease. Several studies on rice sheath blight have used molecular markers such as RAPD (Guleria et al, 2007;Susheela, 2012;Lal et al, 2014;Singh et al, 2015), RFLP (Linde et al, 2005), AFLP (Taheri et al, 2007) and ISSR (Guleria et al, 2007;Yugander et al, 2015;Goswami et al, 2017) along with morphological markers. Recently, rDNA-ITS sequencing has been used for identifying variations (Ramos-Molina and Chavarro-Mesa, 2016;Bintang et al, 2017;Singh et al, 2018).…”