The distribution of mating-type bias in natural populations of the anther-smut Ustilago violacea on Silene alba in Virginia

• Published in: Mycologia Vol. 90; no. 3; pp. 372 - 381
• Main Authors: Oudemans, P.V. (University of Kansas, Lawrence, KS.), Alexander, H.M, Antonovics, J, Altizer, S, Thrall, P.H, Rose, L
• Format: Journal Article
• Language: English
• Published: Taylor & Francis 01-05-1998; New York Botanical Garden
• Subjects: AGENT PATHOGENE; COMPATIBILITY; Diploidy; disease epidemiology; DISTRIBUCION ESPACIAL; DISTRIBUCION GEOGRAFICA; DISTRIBUTION GEOGRAPHIQUE; DISTRIBUTION SPATIALE; Ecological genetics; ENFERMEDADES FUNGOSAS; ESPORAS; ESPORAS FUNGICAS; FUNGAL DISEASES; FUNGAL SPORES; Fungi; Genetics/Molecular Biology; GEOGRAPHICAL DISTRIBUTION; GERMINACION; GERMINATION; haplolethal deficiency; HOSTS; HOTE; HUESPEDES; Infections; intrapromycelial conjugation; MALADIE FONGIQUE; mating system; Medical genetics; Microbotryum violaceum; ORGANISMOS PATOGENOS; PATHOGENS; Plants; REPRODUCCION SEXUAL; REPRODUCTION SEXUEE; Roadside; Sampling bias; SEXUAL REPRODUCTION; Silene alba; Silene latifolia; SILENE PRATENSIS; solopathogenicity; SPATIAL DISTRIBUTION; SPORE; SPORE FONGIQUE; SPORES; teliospore germination; Teliospores; Ustilaginales; Ustilago; USTILAGO VIOLACEA; Ustilago violaceae; VIRGINIA; VIRGINIE
• ISSN: 0027-5514; 1557-2536
• DOI: 10.1080/00275514.1998.12026921

Complete individual-wide mating-type bias (retrieval of sporidia of only one mating type from germinated teliospores of one fungal individual) was observed to be a common and widespread feature of the anther-smut fungus, Ustilago violacea, collected from natural populations of its host, Silene alba. The bias was usually to mating type A1, but the frequency of bias and its spatial distribution varied from region to region. Populations with high frequencies of bias still showed high rates of disease transmission. Crosses between A1 mating type sporidial lines from completely biased individuals and A2 mating types from unbiased individuals showed no bias in the progeny. During teliospore germination, biased individuals often showed conjugation among adjacent cells of the promycelium, suggesting that both mating types are present in the germinating teliospore but one mating type is unable to grow as free-living sporidia. The complete bias was most readily interpreted as evidence of "haploid lethals" linked to mating type that cause poor survival or growth of the sporidial stage. The results show that such "haploid lethals" may be a common occurrence in natural populations, and that fungal mating systems may vary considerably over short distances.