Presenter: Nikki D. Charlton
Advisor(s): Marc A. Cubeta
Author(s): Nikki D. Charlton, Ignazio Carbone, Stellos M. Tavantzis, and Marc A. Cubeta
Graduate Program: Plant Pathology, Plant Pathology, Biological Sciences, Plant Pathology

Title: The Influence of the M2 dsRNA Virus on the Ecology and Parasitic Activity of the Soil Fungus Rhizoctonia solani

Abstract: Double-stranded ribonucleic acid (dsRNA) viruses have been detected in more than 100 species of fungi. In the soil fungus Rhizoctonia solani, dsRNA viruses are common and have been studied for more than 30 years because they are thought to be involved in reducing the disease causing ability of the fungus (a phenomenon referred to as hypovirulence). Recently Tavantzis and colleagues have provided compelling experimental evidence that a specific dsRNA virus (called M2) is associated with hypovirulence by altering a metabolic pathway used by the fungus to produce phenylacetic acid (PAA), a toxin that damages and kills plant cells. Currently, no information is available on the genetic diversity of the M2 dsRNA virus in naturally occurring field populations of R. solani AG-3 and how this diversity influences the disease causing activity of the fungus from an ecological perspective. Preliminary experimental evidence from my research suggests that the M2 dsRNA is present in high frequency in field populations of R. solani AG-3 and that there are at least two genetically divergent lineages of the dsRNA with unique evolutionary histories of mutation and recombination based on sequence analysis. Information generated from phylogenetic analyses is currently being used to design and conduct virus transmission experiments to determine whether the M2 dsRNA can be transmitted to genetically different individuals of R. solani AG-3 and how acquisition of this dsRNA influences the phenotype of the fungus.