title: Lauric acid in crown daisy root exudate potently regulates root-knot nematode chemotaxis and disrupts Mi-flp-18 expression to block infection.
abstract: Tomato (Solanum lycopersicum) crops can be severely damaged due to parasitism by the root-knot nematode (RKN) Meloidogyne incognita, but are protected when intercropped with crown daisy (Chrysanthemum coronarium L.). Root exudate may be the determining factor for this protection. An experiment using pots linked by a tube and Petri dish experiments were undertaken to confirm that tomato-crown daisy intercropping root exudate decreased the number of nematodes and alleviated nematode damage, and to determine crown daisy root exudate-regulated nematode chemotaxis. Following a gas chromatography-mass spectrometry assay, it was found that the intercropping protection was derived from the potent bioactivity of a specific root exudate component of crown daisy, namely lauric acid. The Mi-flp-18 gene, encoding an FMRFamide-like peptide neuromodulator, regulated nematode chemotaxis and infection by RNA interference. Moreover, it was shown that lauric acid acts as both a lethal trap and a repellent for M. incognita by specifically regulating Mi-flp-18 expression in a concentration-dependent manner. Low concentrations of lauric acid (0.5-2.0mM) attract M. incognita and consequently cause death, while high concentrations (4.0mM) repel M. incognita. This study elucidates how lauric acid in crown daisy root exudate regulates nematode chemotaxis and disrupts Mi-flp-18 expression to alleviate nematode damage, and presents a general methodology for studying signalling systems affected by plant root exudates in the rhizosphere. This could lead to the development of economical and feasible strategies for controlling plant-parasitic nematodes, and provide an alternative to the use of pesticides in farming systems.
authors.affiliation: Key Laboratory of Plant-Soil Interactions, Ministry of Education, Center for Resources, Environment and Food Security, China Agricultural University, Beijing 100193, China.
authors.forename: Linlin
authors.initials: L
authors.lastname: Dong
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Li
authors.forename: Li
authors.initials: L
authors.lastname: Huang
authors.forename: Ying
authors.initials: Y
authors.lastname: Gao
authors.forename: Lina
authors.initials: L
authors.lastname: Zhong
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Zheng
authors.forename: Yuanmei
authors.initials: Y
authors.lastname: Zuo
mesh_terms: D000818:Animals; D002633:Chemotaxis / Q000187:drug effects; D031202:Chrysanthemum / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D005786:Gene Expression Regulation; D006790:Host-Parasite Interactions; D007850:Lauric Acids / Q000494:pharmacology*; D018551:Solanum lycopersicum / Q000469:parasitology*; D009479:Neuropeptides / Q000235:genetics / Q000378:metabolism*; D010935:Plant Diseases / Q000469:parasitology / Q000517:prevention & control*; D053147:Plant Exudates / Q000737:chemistry / Q000302:isolation & purification; D018517:Plant Roots / Q000737:chemistry / Q000469:parasitology; D034622:RNA Interference; D058441:Rhizosphere; D015398:Signal Transduction / Q000187:drug effects; D014431:Tylenchoidea / Q000187:drug effects / Q000502:physiology*
chemical_list: D007850:Lauric Acids; D009479:Neuropeptides; D053147:Plant Exudates; C030358:lauric acid
keywords: Chemotaxis; Meloidogyne incognita; Mi-flp-18; crown daisy; lauric acid; root exudate.