IMBIV   05474
INSTITUTO MULTIDISCIPLINARIO DE BIOLOGIA VEGETAL
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Ectomycorrhizal associations with Salix humboldtiana in Southern South America: An ancient cross-continental exchange
Autor/es:
MUJIC, ALIJA; MATTHEW SMITH; EDUARDO NOUHRA; FRANCISCO KUHAR
Lugar:
San Juan
Reunión:
Congreso; 11th International Mycological Congress; 2018
Institución organizadora:
International Mycological Association
Resumen:
Ectomycorrhizal (ECM) forests in southern South America (SSA) are dominated by Nothofagaceae (southern beech) trees. Based upon the fossil record, Nothofagaceae trees and their ECM fungi have been present in SSA for 60 ? 100 million years with little evidence for co-occurring ECM hosts during this time. A second native ECM host tree, Salix humboldtiana (Humboldt?s willow), colonized SSA from the north between 3 ? 15 MYA. This event followed the formation of the Isthmus of Panama during the Great American Biotic Interchange. While Nothofagaceae species and S. humboldtiana overlap in latitudinal range, these trees represent different lineages, occupy different niches, and seldom inhabit the same forests. Both Salix and Nothofagaceae associate with a diverse assemblage of ECM fungi but the biogeographic origins of these communities is expected to be different (Salix from the Northern and Nothofagaceae from the Southern Hemisphere respectively). However, it is possible the two hosts have exchanged ECM fungi since the colonization of SSA by Salix. In this study we characterize ECM communities associated with S. humboldtiana in Argentina and compare these communities with Nothofagaceae to investigate the potential for ECM host jumping between these taxa. We sampled rhizosphere soil, ECM root tips, and ECM fungal sporocarps from stands of S. humboldtiana at 18 sites throughout its range in Argentina from Parque Nacional Calilegua (Northern Argentina) to the Chubut River (Central Patagonia). Since exotic Eurasian Salix spp. were present along the same watercourse throughout our sampling range, we also sampled rhizosphere soil and ECM root tips from exotic Salix at 5 sites to investigate the potential for shared ECM communities between exotic Salix and S. humboldtiana . Fungal communities from soil DNA and ECM root tips were identified using Illumina Miseq meta-barcoding of the ITS1 region. Operational taxonomic units (OTUs) were sorted by putative ecological niche (saprobic, pathogenic, mycorrhizal) using a combination of FUNGUILD and Blast searches of NCBI GenBank and our extensive in-house database.. Results of our comparative metagenomic analyses indicate that ECM fungal communities of S. humboldtiana consist of fungi primarily from northern hemisphere ECM lineages and lack representatives from endemic southern hemisphere ECM fungal lineages (eg. Descolea, Phaeohelotium, Austropaxillus). There are several species of exotic ECM Basidiomycota that were likely introduced into S. humboldtiana ECM communities from exotic European Salix. Some lineages of ECM host generalist fungi may also have moved between S. humboldtiana stands and Nothofagaceae forests. Exemplar from our dataset include species of ECM host generalists Hebeloma (Agaricales), which are likely to have moved into Nothofagaceae forests from S. humboldtiana stands, and Tomentella (Thelephorales) which may have undergone bidirectional host shifts between Nothofagaceae and S. humboldtiana.