Phylogenetic groups in Rhizoctonia solani AG 2-2 from sugar beet and related host range

Authors: Hanson, Linda; MINIER, DOUGLAS - Michigan State University; Martin, Frank

Submitted to: Journal of Sugar Beet Research
Publication Type: Abstract Only
Publication Acceptance Date: 1/30/2019
Publication Date: 2/28/2019
Citation: Hanson, L.E., Minier, D.H., Martin, F.N. 2019. Phylogenetic groups in Rhizoctonia solani AG 2-2 from sugar beet and related host range [abstract]. Journal of Sugar Beet Research. 56:69.

Interpretive Summary:

Technical Abstract: Rhizoctonia solani AG 2-2 is the causal agent of seedling damping-off and root and crown rot of sugar beet. Rhizoctonia root and crown rot is the most important soil-borne disease of sugar beet in the USA. Historically the isolates of this anastomosis group (AG) on sugar beet have been separated into two intraspecific groups (ISG), IIIB and IV. These vary in host range and virulence. However attempts to develop rapid screening methods for the ISG were problematic. A four gene phylogeny revealed these ISG are artificial, and instead identified 3 major phylogenetic groups that do not correspond to ISG IIIB and IV. These genetic types in Rhizoctonia solani AG 2-2 may help to explain some of the varying reports for host range for the ISG. To check for phenotypic differences in the 3 phylogenetic groups, isolates representing the groups were tested for virulence on dry bean and sugar beet at both seedling and adult plant growth stages. While there was variability in virulence within all three phylogenetic groups, significant differences between groups were identified. The phylogenetic group with the highest average virulence on dry bean was different than the one that had the highest average virulence on sugar beet. The identification of genetically supported groups provides the potential to develop rapid screening methods to allow for improved identification of the genetic types important in different geographic regions and on varying crops.