Metabolomics reveals herbivore-induced metabolites of resistance and susceptibility in maize leaves and roots.
Plants respond to herbivory by reprogramming their metabolism. Most research in this context has focused on locally induced compounds that function as toxins or feeding deterrents. We developed an ultra-high-pressure liquid chromatography time-of-flight mass spectrometry (UHPLC-TOF-MS)-based metabolomics approach to evaluate local and systemic herbivore-induced changes in maize leaves, sap, roots and root exudates without any prior assumptions about their function. Thirty-two differentially regulated compounds were identified from Spodoptera littoralis-infested maize seedlings and isolated for structure assignment by microflow nuclear magnetic resonance (CapNMR). Nine compounds were quantified by a high throughput direct nano-infusion tandem mass spectrometry/mass spectrometry (MS/MS) method. Leaf infestation led to a marked local increase of 1,3-benzoxazin-4-ones, phospholipids, N-hydroxycinnamoyltyramines, azealic acid and tryptophan. Only few changes were found in the root metabolome, but 1,3-benzoxazin-4-ones increased in the vascular sap and root exudates. The role of N-hydroxycinnamoyltyramines in plant-herbivore interactions is unknown, and we therefore tested the effect of the dominating p-coumaroyltyramine on S. littoralis. Unexpectedly, p-coumaroyltyramine was metabolized by the larvae and increased larval growth, possibly by providing additional nitrogen to the insect. Taken together, this study illustrates that herbivore attack leads to the induction of metabolites that can have contrasting effects on herbivore resistance in the leaves and roots.
School of Pharmaceutical Sciences, EPGL, University of Geneva and University of Lausanne, Geneva Switzerland.
Guillaume
G
Marti
Matthias
M
Erb
Julien
J
Boccard
Gaétan
G
Glauser
Gwladys R
GR
Doyen
Neil
N
Villard
Christelle A M
CA
Robert
Ted C J
TC
Turlings
Serge
S
Rudaz
Jean-Luc
JL
Wolfender
D000818:Animals; D002851:Chromatography, High Pressure Liquid; D003373:Coumaric Acids / Q000378:metabolism; D060434:Herbivory; D007477:Ions / Q000378:metabolism; D013058:Mass Spectrometry; D055442:Metabolome; D055432:Metabolomics; D018515:Plant Leaves / Q000378:metabolism*; D018517:Plant Roots / Q000378:metabolism*; D018411:Spodoptera; D003313:Zea mays / Q000378:metabolism*
D003373:Coumaric Acids; D007477:Ions; C001411:N-(4-hydroxy-beta-phenethyl)-4-hydroxycinnamide