title: The dual effects of root-cap exudates on nematodes: from quiescence in plant-parasitic nematodes to frenzy in entomopathogenic nematodes.
abstract: To defend themselves against herbivores and pathogens, plants produce numerous secondary metabolites, either constitutively or de novo in response to attacks. An intriguing constitutive example is the exudate produced by certain root-cap cells that can induce a state of reversible quiescence in plant-parasitic nematodes, thereby providing protection against these antagonists. The effect of such root exudates on beneficial entomopathogenic nematodes (EPNs) remains unclear, but could potentially impair their use in pest management programmes. We therefore tested how the exudates secreted by green pea (Pisum sativum) root caps affect four commercial EPN species. The exudates induced reversible quiescence in all EPN species tested. Quiescence levels varied with the green pea cultivars tested. Notably, after storage in root exudate, EPN performance traits were maintained over time, whereas performances of EPNs stored in water rapidly declined. In sharp contrast to high concentrations, lower concentrations of the exudate resulted in a significant increase in EPN activity and infectiousness, but still reduced the activity of two plant-parasitic nematode species. Our study suggests a finely tuned dual bioactivity of the exudate from green pea root caps. Appropriately formulated, it can favour long-term storage of EPNs and boost their infectiousness, while it may also be used to protect plants from plant-parasitic nematodes.
authors.affiliation: Division of Plant Sciences, University of Missouri, 205 Curtis Hall, Columbia, MO 65211-7020, USA hiltpoldi@missouri.edu.
authors.forename: Ivan
authors.initials: I
authors.lastname: Hiltpold
authors.affiliation: FARCE laboratory, University of Neuchâtel, Emile-Argand 11, 2000 Neuchâtel, Switzerland.
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Jaffuel
authors.affiliation: FARCE laboratory, University of Neuchâtel, Emile-Argand 11, 2000 Neuchâtel, Switzerland.
authors.forename: Ted C J
authors.initials: TC
authors.lastname: Turlings
mesh_terms: D000818:Animals; D006790:Host-Parasite Interactions / Q000187:drug effects*; D009348:Nematoda / Q000187:drug effects / Q000502:physiology*; D018532:Pisum sativum / Q000737:chemistry; D053147:Plant Exudates / Q000494:pharmacology*; D018518:Plant Root Cap / Q000737:chemistry*; D013696:Temperature; D013997:Time Factors
chemical_list: D053147:Plant Exudates
keywords: Below-ground food web; Heterodera glycine; Heterorhabditis bacteriophora; Meloidogyne incognita; biological control; entomopathogenic nematode (EPN); plant defence; plant-parasitic nematode; root-cap exudate.