The plot thickens: haploid and triploid-like thalli, hybridization, and biased mating type ratios in Letharia

Ament-Velásquez, Sandra Lorena,Ph.D.1988-Uppsala universitet,Systematisk biologi (author)

The plot thickens : haploid and triploid-like thalli, hybridization, and biased mating type ratios in Letharia

The study of the reproductive biology of lichen fungal symbionts has been traditionally challenging due to their complex lifestyles. Against the common belief of haploidy, a recent genomic study found a triploid-like signal in Letharia. Here, we infer the genome organization and reproduction in Letharia by analyzing genomic data from a pure culture and from thalli, and performing a PCR survey of the MAT locus in natural populations. We found that the read count variation in the four Letharia specimens, including the pure culture derived from a single sexual spore of L. lupina, is consistent with haploidy. By contrast, the L. lupina read counts from a thallus’ metagenome are triploid-like. Characterization of the mating-type locus revealed a conserved heterothallic configuration across the genus, along with auxiliary genes that we identified. We found that the mating-type distributions are balanced in North America for L. vulpina and L. lupina, suggesting widespread sexual reproduction, but highly skewed in Europe for L. vulpina, consistent with predominant asexuality. Taken together, we propose that Letharia fungi are heterothallic and typically haploid, and provide evidence that triploid-like individuals are hybrids between L. lupina and an unknown Letharia lineage, reconciling classic systematic and genetic studies with recent genomic observations.

Tuovinen, VeeraSwedish University of Agricultural Sciences,Sveriges lantbruksuniversitet,Uppsala universitet,Systematisk biologi,Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden,Institutionen för ekologi,Uppsala University(Swepub:slu)49341 (author)
Bergström, LinneaUppsala universitet,Systematisk biologi (author)
Spribille, TobyBiological Sciences CW 405, University of Alberta, Edmonton, AB, Canada (author)
Vanderpool, DanDepartment of Biology, Indiana University, Bloomington, IN, United States (author)
Nascimbene, JuriDepartment of Biological, Geological and Environmental Sciences, University of Bologna, Bologna, Italy (author)
Yamamoto, YoshikazuDepartment of Bioproduction Science, Faculty of Bioresource Sciences, Akita Prefectural University, Akita, Japan (author)
Thor, GöranSwedish University of Agricultural Sciences,Sveriges lantbruksuniversitet,Institutionen för ekologi,Department of Ecology,Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden(Swepub:slu)48792 (author)
Johannesson, HannaUppsala universitet,Systematisk biologi(Swepub:uu)hajoh452 (author)
Uppsala universitetSystematisk biologi (creator_code:org_t)
Sveriges lantbruksuniversitet

By the author/editor: Ament-Velásquez, ...; Tuovinen, Veera; Bergström, Linne ...; Spribille, Toby; Vanderpool, Dan; Nascimbene, Juri; show more...; Yamamoto, Yoshik ...; Thor, Göran; Johannesson, Han ...; show less...

About the subject

NATURAL SCIENCES: NATURAL SCIENCES; and Biological Scien ...; and Biochemistry and ...

By the university: Uppsala University; Swedish University of Agricultural Sciences

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