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TOC1 in Nicotiana attenuata regulates efficient allocation of nitrogen to defense metabolites under herbivory stress
Author(s) -
Valim Henrique,
Dalton Heidi,
Joo Youngsung,
McGale Erica,
Halitschke Rayko,
Gaquerel Emmanuel,
Baldwin Ian T.,
Schuman Meredith C.
Publication year - 2020
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.16784
Subject(s) - manduca sexta , biology , circadian clock , nicotiana tabacum , herbivore , nicotine , sphingidae , plant defense against herbivory , botany , nicotiana , jasmonic acid , solanaceae , circadian rhythm , biochemistry , salicylic acid , larva , neuroscience , gene
Summary The circadian clock contextualizes plant responses to environmental signals. Plants use temporal information to respond to herbivory, but many of the functional roles of circadian clock components in these responses, and their contribution to fitness, remain unknown. We investigate the role of the central clock regulator TIMING OF CAB EXPRESSION 1 (TOC1) in Nicotiana attenuata 's defense responses to the specialist herbivore Manduca sexta under both field and glasshouse conditions. We utilize 15 N pulse‐labeling to quantify nitrogen incorporation into pools of three defense compounds: caffeoylputrescine (CP), dicaffeoyl spermidine (DCS) and nicotine. Nitrogen incorporation was decreased in CP and DCS and increased in nicotine pools in irTOC1 plants compared to empty vector (EV) under control conditions, but these differences were abolished after simulated herbivory. Differences between EV and irTOC1 plants in nicotine, but not phenolamide production, were abolished by treatment with the ethylene agonist 1‐methylcyclopropene. Using micrografting, TOC1 's effect on nicotine was isolated to the root and did not affect the fitness of heterografts under field conditions. These results suggest that the circadian clock contributes to plant fitness by balancing production of metabolically expensive nitrogen‐rich defense compounds and mediating the allocation of resources between vegetative biomass and reproduction.