Analysis of gene expression of Rhizoctonia solani, (AG-4) to understand its virulence and biology

The basidiomycete Rhizoctonia solani (Tele: Thanatephorus cucumeris) is comprised of important plant pathogens, saprophytes and mycorrhizae and exists in several hyphal anastomosis groups (AGs) with distinct host specializations. AG-4 isolates cause diseases in a broad range of hosts, including ornamentals and turfgrasses. Knowledge of the molecular mechanism of Rhizoctonia pathogenicity and virulence is only rudimentary at present. It is important to develop a greater understanding of the interactions involved in pathogenicity, particularly to differentiate the genes involved in establishment of infection from those involved in maintaining an infection, as different approaches would be taken to preventing infection compared to controlling infection. A thorough knowledge in this area is also necessary to assist breeders in identifying genes that can be targeted in order to generate resistant varieties and to determine whether such resistance is likely to be strain-specific or broadly effective. In an effort to extend our knowledge of the molecular mechanism of virulence of this pathogen, we have develop two normalized EST libraries specific to a virulent isolate and a 3-O-methylglucose induced virulence-repressed isolate of R. solani, AG-4, isolate Rs23. Thus far, about 2000 EST clones has been sequenced and an overall analysis of the cDNA sequences will be carried out Subsequently, more sequencing will be conducted and analyzed for differential gene expression to target pathogenicity associated genes of R. solani. Knowledge gained from gene expression of the AG-4 isolate will be utilized for conducting comparative genomic and proteomic studies of other AGs that infect ornamentals.