Population structure of Sclerotinia homoeocarpa from turfgrass
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Date
2010-04-29
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Abstract
The purpose of this research was to determine population structure of Sclerotinia homoeocarpa, the causal organism of dollar spot, from turfgrass worldwide. Sclerotinia
homoeocarpa is prevalent throughout the entire world and more money is spent controlling
dollar spot than any other turf disease. The lack of disease cycle knowledge coupled with
increased levels of fungicide resistance make understanding the genetic diversity of this
fungus vital to ensure acceptable levels of control in the future. One hundred and nine
isolates of S. homoeocarpa were obtained from the United States, Dominican Republic,
Chile, Italy, United Kingdom and Japan. Isolates were analyzed using nuclear DNA from the
ITS, β-tubulin, Calmodulin and TEF1-α loci. The nuclear DNA data suggests strong
subdivision of S. homoeocarpa isolates based on host species, with isolates from warm
season hosts and isolates from cool season hosts being genetically distinct. Vegetative
compatibility tests for the 109 isolates were also utilized to determine the ability of
individuals within the population to form heterokaryons with other individuals. Isolates in
the study were compared to previously determine vegetative compatibility groups (VCGs) as
well as tested with one another. The VCG work resulted in 9 previously unidentified VCGs.
Isolates from warm season host species and isolates from cool season host species belonged
to separate VCGs, supporting the subdivision seen in the nuclear DNA data. This work has
shed new light on the population structure of Sclerotinia homoeocarpa and could potentially
lead to alterations in control recommendations of dollar spot.
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Keywords
VCG, sclerotinia homoeocarpa, population structure
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Degree
MS
Discipline
Plant Pathology