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DeMers, Mara [1], May, Georgiana [2].

Evidence for recent sexual recombination in clonal populations of endophytic Alternaria alternata.

Prairie is one of the most endangered biomes in North America, and endophytic fungi may improve prairie plant resilience to climate change. Numerous studies have characterized the diversity of fungi inhabiting a vast variety of plants, but we know much less about the causes of variation in species abundance and genetic variation that give rise to community diversity. We previously determined Alternaria to be the dominant taxon of foliar endophytic fungi in the prairie legumes Dalea purpurea and D. candida across 17 sites representing the broad temperature and precipitation gradient spanned by Minnesota prairies. Previous results showed that community composition varied along a precipitation and temperature gradient, among hosts, and in apparent response to the abundance of Alternaria, but left unanswered patterns of genetic variation among isolates assigned to Alternaria alternata. In this study, we used genotyping-by-sequencing to evaluate the population structure of sampled Alternaria endophytes. We found cryptic diversity among sequenced samples, as only a subset aligned well to A. alternata reference genomes. Analysis of sequences closely related to A. alternata revealed that populations were largely clonal. However, we also detected evidence of recombination events consistent with sexual reproduction, as well as the two mating types, MAT1-1 and MAT1-2, present in roughly equal frequencies in all but one sampled population. Furthermore, we amplified both mating type idiomorphs from several samples. Together, the results show a lack of strong genetic structure among sites or between the two host species, suggesting recent gene flow to or among the sampled host populations. Clonal lineages may have arisen from sexual recombinant lineages, and spread relatively recently to the sampled populations. A. alternata may also exhibit previously undescribed and extensive variation in life histories, including clonal asexual and both homothallic and heterothallic sexual reproduction.

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1 - University of Minnesota, Plant & Microbial Biology, 140 Gortner Laboratory, 1479 Gortner Avenue, Saint Paul, MN, 55108, USA
2 - University of Minnesota, Ecology, Evolution and Behavior, 140 Gortner Laboratory, 1479 Gortner Avenue, Saint Paul, MN, 55108, USA

Population Genetics
endophytic fungi
mating type

Presentation Type: Oral Paper
Session: MY5, Mycology: Systematics, Biodiversity, and Evolution
Location: /
Date: Wednesday, July 21st, 2021
Time: 3:15 PM(EDT)
Number: MY5002
Abstract ID:714
Candidate for Awards:MSA Best Oral Presentation Award by a Graduate Student

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