Author:
Elfstrand Malin,Chen Jun,Cleary Michelle,Halecker Sandra,Ihrmark Katarina,Karlsson Magnus,Davydenko Kateryna,Stenlid Jan,Stadler Marc,Durling Mikael Brandström
Abstract
Abstract
Background
The dieback epidemic decimating common ash (Fraxinus excelsior) in Europe is caused by the invasive fungus Hymenoscyphus fraxineus. In this study we analyzed the genomes of H. fraxineus and H. albidus, its native but, now essentially displaced, non-pathogenic sister species, and compared them with several other members of Helotiales. The focus of the analyses was to identify signals in the genome that may explain the rapid establishment of H. fraxineus and displacement of H. albidus.
Results
The genomes of H. fraxineus and H. albidus showed a high level of synteny and identity. The assembly of H. fraxineus is 13 Mb longer than that of H. albidus’, most of this difference can be attributed to higher dispersed repeat content (i.e. transposable elements [TEs]) in H. fraxineus. In general, TE families in H. fraxineus showed more signals of repeat-induced point mutations (RIP) than in H. albidus, especially in Long-terminal repeat (LTR)/Copia and LTR/Gypsy elements.
Comparing gene family expansions and 1:1 orthologs, relatively few genes show signs of positive selection between species. However, several of those did appeared to be associated with secondary metabolite genes families, including gene families containing two of the genes in the H. fraxineus-specific, hymenosetin biosynthetic gene cluster (BGC).
Conclusion
The genomes of H. fraxineus and H. albidus show a high degree of synteny, and are rich in both TEs and BGCs, but the genomic signatures also indicated that H. albidus may be less well equipped to adapt and maintain its ecological niche in a rapidly changing environment.
Funder
The Royal Swedish Academy of Agriculture and Forestry
CF Lundström Foundation
SLU Foundation for Forest Science Research
European Cost Action
the Swedish Research Council FORMAS
Swedish University of Agricultural Sciences
Publisher
Springer Science and Business Media LLC
Cited by
6 articles.
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