title: Root symbionts: Powerful drivers of plant above- and belowground indirect defenses.
abstract: Soil microbial mutualists of plants, including mycorrhizal fungi, non-mycorrhizal fungi and plant growth promoting rhizobacteria, have been typically characterized for increasing nutrient acquisition and plant growth. More recently, soil microbes have also been shown to increase direct plant defense against above- and belowground herbivores. Plants, however, do not only rely on direct defenses when attacked, but they can also recruit pest antagonists such as predators and parasitoids, both above and belowground, mainly via the release of volatile organic compounds (i.e., indirect defenses). In this review, we illustrate the main features and effects of soil microbial mutualists of plants on plant indirect defenses and discuss possible applications within the framework of sustainable crop protection against root- and shoot-feeding arthropod pests. We indicate the main knowledge gaps and the future challenges to be addressed in the study and application of these multifaceted interactions.
authors.affiliation: Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland.
authors.forename: Sergio
authors.initials: S
authors.lastname: Rasmann
authors.affiliation: Department of Ecological Sciences, James Hutton Institute, Dundee, UK.
authors.forename: Alison
authors.initials: A
authors.lastname: Bennett
authors.affiliation: Netherlands Institute of Ecology, Wageningen, the Netherlands.
authors.forename: Arjen
authors.initials: A
authors.lastname: Biere
authors.affiliation: Department of Ecological Sciences, James Hutton Institute, Dundee, UK.
authors.forename: Alison
authors.initials: A
authors.lastname: Karley
authors.affiliation: Institute for Sustainable Plant Protection, National Research Council of Italy, Portici, Italy.
authors.forename: Emilio
authors.identifier: http://orcid.org/0000-0002-0583-4667
authors.initials: E
authors.lastname: Guerrieri
mesh_terms: D000818:Animals; D018556:Crops, Agricultural; D060434:Herbivory; D007313:Insecta; D010572:Pest Control, Biological; D018517:Plant Roots / Q000382:microbiology*; D012988:Soil Microbiology; D013559:Symbiosis
keywords: Trichoderma; arbuscular mycorrhizal fungi; crop protection; entomopathogenic nematodes; plant growth promoting rhizobacteria