title: Molecular signals required for the establishment and maintenance of ectomycorrhizal symbioses.
abstract: Ectomycorrhizal (ECM) symbioses are among the most widespread associations between roots of woody plants and soil fungi in forest ecosystems. These associations contribute significantly to the sustainability and sustainagility of these ecosystems through nutrient cycling and carbon sequestration. Unfortunately, the molecular mechanisms controlling the mutual recognition between both partners are still poorly understood. Elegant work has demonstrated that effector proteins from ECM and arbuscular mycorrhizal (AM) fungi regulate host defenses by manipulating plant hormonal pathways. In parallel, genetic and evolutionary studies in legumes showed that a 'common symbiosis pathway' is required for the establishment of the ancient AM symbiosis and has been recruited for the rhizobia-legume association. Given that genes of this pathway are present in many angiosperm trees that develop ectomycorrhizas, we propose their potential involvement in some but not all ECM associations. The maintenance of a successful long-term relationship seems strongly regulated by resource allocation between symbiotic partners, suggesting that nutrients themselves may serve as signals. This review summarizes our current knowledge on the early and late signal exchanges between woody plants and ECM fungi, and we suggest future directions for decoding the molecular basis of the underground dance between trees and their favorite fungal partners.
authors.affiliation: Department of Agronomy, University of Wisconsin-Madison, Madison, WI, 53706, USA.
authors.forename: Kevin
authors.initials: K
authors.lastname: Garcia
authors.affiliation: Department of Agronomy, University of Wisconsin-Madison, Madison, WI, 53706, USA.
authors.forename: Pierre-Marc
authors.initials: PM
authors.lastname: Delaux
authors.affiliation: Department of Agronomy, University of Wisconsin-Madison, Madison, WI, 53706, USA.
authors.forename: Kevin R
authors.initials: KR
authors.lastname: Cope
authors.affiliation: Department of Agronomy, University of Wisconsin-Madison, Madison, WI, 53706, USA.
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Ané
mesh_terms: D002244:Carbon / Q000378:metabolism; D007887:Fabaceae / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D065928:Forests; D005658:Fungi / Q000235:genetics / Q000378:metabolism; D017343:Genes, Plant; D038821:Mycorrhizae / Q000235:genetics* / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D015398:Signal Transduction; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology; D013559:Symbiosis; D014197:Trees / Q000235:genetics* / Q000378:metabolism / Q000382:microbiology
chemical_list: D012987:Soil; D002244:Carbon; D009584:Nitrogen
keywords: arbuscular mycorrhiza; common symbiosis pathway; ectomycorrhiza; effectors; nitrogen (N); nutrient exchange; phosphorus (P); signaling