title: Mycorrhiza-induced resistance and priming of plant defenses.
abstract: Symbioses between plants and beneficial soil microorganisms like arbuscular-mycorrhizal fungi (AMF) are known to promote plant growth and help plants to cope with biotic and abiotic stresses. Profound physiological changes take place in the host plant upon root colonization by AMF affecting the interactions with a wide range of organisms below- and above-ground. Protective effects of the symbiosis against pathogens, pests, and parasitic plants have been described for many plant species, including agriculturally important crop varieties. Besides mechanisms such as improved plant nutrition and competition, experimental evidence supports a major role of plant defenses in the observed protection. During mycorrhiza establishment, modulation of plant defense responses occurs thus achieving a functional symbiosis. As a consequence of this modulation, a mild, but effective activation of the plant immune responses seems to occur, not only locally but also systemically. This activation leads to a primed state of the plant that allows a more efficient activation of defense mechanisms in response to attack by potential enemies. Here, we give an overview of the impact on interactions between mycorrhizal plants and pathogens, herbivores, and parasitic plants, and we summarize the current knowledge of the underlying mechanisms. We focus on the priming of jasmonate-regulated plant defense mechanisms that play a central role in the induction of resistance by arbuscular mycorrhizas.
authors.affiliation: Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín (EEZ), CSIC, Prof. Albareda 1, 18008, Granada, Spain.
authors.forename: Sabine C
authors.initials: SC
authors.lastname: Jung
authors.forename: Ainhoa
authors.initials: A
authors.lastname: Martinez-Medina
authors.forename: Juan A
authors.initials: JA
authors.lastname: Lopez-Raez
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Pozo
mesh_terms: D000818:Animals; D003517:Cyclopentanes / Q000276:immunology; D060434:Herbivory; D054884:Host-Pathogen Interactions; D007313:Insecta / Q000502:physiology*; D038821:Mycorrhizae / Q000502:physiology*; D054883:Oxylipins / Q000276:immunology; D010935:Plant Diseases / Q000276:immunology / Q000382:microbiology / Q000469:parasitology; D057865:Plant Immunity; D018521:Plant Physiological Phenomena; D018517:Plant Roots / Q000276:immunology / Q000382:microbiology / Q000469:parasitology / Q000502:physiology; D010944:Plants / Q000276:immunology / Q000382:microbiology* / Q000469:parasitology*; D013559:Symbiosis
chemical_list: D003517:Cyclopentanes; D054883:Oxylipins; C011006:jasmonic acid