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Genetics

Quantitative Genetic Analysis of Pathogenicity and Virulence of Moesziomyces penicillariae. Jeffrey P. Wilson, USDA-ARS Forage and Turf Research Unit and Department of Statistical and Computer Services, University of Georgia, Coastal Plain Experiment Station, Tifton 31793-0748; Khorsand Bondari, USDA-ARS Forage and Turf Research Unit and Department of Statistical and Computer Services, University of Georgia, Coastal Plain Experiment Station, Tifton 31793-0748. Phytopathology 80:1173-1177. Accepted for publication 25 June 1990. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1990. DOI: 10.1094/Phyto-80-1173.

Forty-five isolates were selected to determine the genetic basis of pathogenicity and virulence of Moesziomyces penicillariae, the smut pathogen of pearl millet. Solopathogenicity of mycelial isolates, sporidial isolates, and sporidial isolates with a low frequency of reversion to the mycelial type were evaluated. The mycelial and revertant isolates expressed the highest levels of solopathogenic ability, as determined by greater numbers of sori formed per panicle (*=42.3% and 28.0% infected florets, respectively). Sporidial isolates expressed the lowest levels of solopathogenic ability (*=1.2% infected florets). Twenty-two sporidial isolates were used alone and in all combinations to inoculate 3 inflorescences each of Tift 23DA in the greenhouse and Tift 85DB in the field. In the partial diallel inoculations, specific combining ability effects were significant, indicating the presence of nonadditive genes conferring compatibility types. General combining ability effects were also significant, suggesting that the isolates differed in additive genes conferring virulence. Six mating or compatibility groups were identified among the isolates. Differences in general combining ability effects existed among isolates within mating groups.