Genetic isolation between two recently diverged populations of a symbiotic fungus.
Fungi are an omnipresent and highly diverse group of organisms, making up a significant part of eukaryotic diversity. Little is currently known about the drivers of fungal population differentiation and subsequent divergence of species, particularly in symbiotic, mycorrhizal fungi. Here, we investigate the population structure and environmental adaptation in Suillus brevipes (Peck) Kuntze, a wind-dispersed soil fungus that is symbiotic with pine trees. We assembled and annotated the reference genome for Su. brevipes and resequenced the whole genomes of 28 individuals from coastal and montane sites in California. We detected two clearly delineated coast and mountain populations with very low divergence. Genomic divergence was restricted to few regions, including a region of extreme divergence containing a gene encoding for a membrane Na(+) /H(+) exchanger known for enhancing salt tolerance in plants and yeast. Our results are consistent with a very recent split between the montane and coastal Su. brevipes populations, with few small genomic regions under positive selection and a pattern of dispersal and/or establishment limitation. Furthermore, we identify a putatively adaptive gene that motivates further functional analyses to link genotypes and phenotypes and shed light on the genetic basis of adaptive traits.
Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
Sara
S
Branco
Laboratoire d'Ecologie, Systematique et Evolution, Bâtiment 360, 91405 Orsay, France.|CNRS, Bâtiment 360, 91405 Orsay, France.
Pierre
P
Gladieux
Department of Integrative Biology, University of California, Berkeley, CA 94720, USA.
Christopher E
CE
Ellison
Department of Energy, Joint Genome Institute, 2800 Mitchell Dr., Walnut Creek, CA 94598, USA.
Alan
A
Kuo
Department of Energy, Joint Genome Institute, 2800 Mitchell Dr., Walnut Creek, CA 94598, USA.
Kurt
K
LaButti
Department of Energy, Joint Genome Institute, 2800 Mitchell Dr., Walnut Creek, CA 94598, USA.
Anna
A
Lipzen
Department of Energy, Joint Genome Institute, 2800 Mitchell Dr., Walnut Creek, CA 94598, USA.
Igor V
IV
Grigoriev
Department of Biology, Duke University, Durham, NC 27708, USA.
Hui-Ling
HL
Liao
Department of Biology, Duke University, Durham, NC 27708, USA.
Rytas
R
Vilgalys
Department of Biology, Stanford University, Stanford, CA 94305, USA.
Kabir G
KG
Peay
Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
John W
JW
Taylor
Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
Thomas D
TD
Bruns
D001487:Basidiomycota / Q000235:genetics*; D002140:California; D004271:DNA, Fungal / Q000235:genetics; D017753:Ecosystem; D049810:Genetic Speciation; D005828:Genetics, Population; D016681:Genome, Fungal; D016013:Likelihood Functions; D038821:Mycorrhizae / Q000235:genetics; D028223:Pinus / Q000382:microbiology; D060047:Reproductive Isolation; D012641:Selection, Genetic; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology; D013559:Symbiosis
D004271:DNA, Fungal
Suillus brevipes; adaptation; mycorrhizal fungi; population genomics