title: Plant-fungal ecology. Niche engineering demonstrates a latent capacity for fungal-algal mutualism.
abstract: Mutualistic symbioses shape the evolution of species and ecosystems and catalyze the emergence of biological complexity, yet how such symbioses first form is unclear. We show that an obligate mutualism between the yeast Saccharomyces cerevisiae and the alga Chlamydomonas reinhardtii--two model eukaryotes with very different life histories--can arise spontaneously in an environment requiring reciprocal carbon and nitrogen exchange. This capacity for mutualism is phylogenetically broad, extending to other Chlamydomonas and fungal species. Furthermore, we witnessed the spontaneous association of Chlamydomonas algal cells physically interacting with filamentous fungi. These observations demonstrate that under specific conditions, environmental change induces free-living species to become obligate mutualists and establishes a set of experimentally tractable, phylogenetically related, synthetic systems for studying the evolution of symbiosis.
authors.affiliation: Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA. Faculty of Arts and Sciences Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA. erik@fyhom.com amurray@mcb.harvard.edu.
authors.forename: Erik F Y
authors.initials: EF
authors.lastname: Hom
authors.affiliation: Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA. Faculty of Arts and Sciences Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA. erik@fyhom.com amurray@mcb.harvard.edu.
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Murray
mesh_terms: D001233:Aspergillus nidulans / Q000235:genetics / Q000502:physiology; D016825:Chlamydomonas reinhardtii / Q000145:classification / Q000378:metabolism / Q000382:microbiology*; D018920:Coculture Techniques; D005818:Genetic Engineering; D005947:Glucose / Q000378:metabolism; D053858:Metabolic Networks and Pathways / Q000235:genetics / Q000502:physiology; D009492:Neurospora crassa / Q000235:genetics / Q000502:physiology; D009573:Nitrites / Q000378:metabolism; D010802:Phylogeny; D012441:Saccharomyces cerevisiae / Q000145:classification / Q000378:metabolism / Q000502:physiology*; D013559:Symbiosis / Q000235:genetics / Q000502:physiology*
chemical_list: D009573:Nitrites; C041349:potassium nitrite; D005947:Glucose