title: Microbiome change by symbiotic invasion in lichens.
abstract: Lichens are obligate symbioses between fungi and green algae or cyanobacteria. Most lichens resynthesize their symbiotic thalli from propagules, but some develop within the structures of already existing lichen symbioses. Diploschistes muscorum starts as a parasite infecting the lichen Cladonia symphycarpa and gradually develops an independent Diploschistes lichen thallus. Here we studied how this process influences lichen-associated microbiomes and photobionts by sampling four transitional stages, at sites in Sweden and Germany, and characterizing their microbial communities using high-throughput 16S rRNA gene and photobiont-specific ITS rDNA sequencing, and fluorescence in situ hybridization. A gradual microbiome shift occurred during the transition, but fractions of Cladonia-associated bacteria were retained during the process of symbiotic reorganization. Consistent changes observed across sites included a notable decrease in the relative abundance of Alphaproteobacteria with a concomitant increase in Betaproteobacteria. Armatimonadia, Spartobacteria and Acidobacteria also decreased during the infection of Cladonia by Diploschistes. The lichens differed in photobiont specificity. Cladonia symphycarpa was associated with the same algal species at all sites, but Diploschistes muscorum had a flexible strategy with different photobiont combinations at each site. This symbiotic invasion system suggests that partners can be reorganized and selected for maintaining potential roles rather than depending on particular species.
authors: Department of Botany, Swedish Museum of Natural History, P.O. Box 50007, Stockholm, SE-104 05, Sweden.
authors: Mats
authors: M
authors: Wedin
authors: Institute of Plant Sciences, University of Graz, Holteigasse 6, Graz, A-8010, Austria.
authors: Stefanie
authors: S
authors: Maier
authors: Department of Botany, Swedish Museum of Natural History, P.O. Box 50007, Stockholm, SE-104 05, Sweden.
authors: Samantha
authors: S
authors: Fernandez-Brime
authors: Department of Bioinformatics and Genetics, Swedish Museum of Natural History, P.O. Box 50007, Stockholm, SE-104 05, Sweden.
authors: Bodil
authors: B
authors: Cronholm
authors: Department of Botany, Swedish Museum of Natural History, P.O. Box 50007, Stockholm, SE-104 05, Sweden.
authors: Martin
authors: M
authors: Westberg
authors: Institute of Plant Sciences, University of Graz, Holteigasse 6, Graz, A-8010, Austria.
authors: Martin
authors: M
authors: Grube
mesh_terms: D020561:Alphaproteobacteria / Q000235:genetics / Q000302:isolation & purification; D001203:Ascomycota / Q000502:physiology*; D001419:Bacteria / Q000235:genetics / Q000302:isolation & purification*; D020562:Betaproteobacteria / Q000235:genetics / Q000302:isolation & purification; D017404:In Situ Hybridization, Fluorescence; D008011:Lichens / Q000382:microbiology*; D064307:Microbiota; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D013559:Symbiosis
chemical_list: D012336:RNA, Ribosomal, 16S