title: Partitioning of new carbon as ¹¹C in Nicotiana tabacum reveals insight into methyl jasmonate induced changes in metabolism.
abstract: We examined the timeline by which methyl jasmonate (MeJA) reprograms new carbon partitioning into key metabolite pools. The radioactive isotope ¹¹C (t(¹/₂) 20.4 min), administered to intact leaves of Nicotiana tabacum L. (cv Samsun) as ¹¹CO(2) gas enabled us to measure changes in new carbon partitioning into soluble sugar and amino acid pools of [¹¹C]photosynthate. A 500 μM MeJA treatment resulted in a decrease in the [¹¹C]soluble sugar pool and an increase in the [¹¹C]amino acid pool after 4 h. This pattern was more pronounced 15 h after treatment. We also examined the timeline for ¹¹C-partitioning into aromatic amino acid metabolites of the shikimate pathway. [¹¹C]Tyrosine, [C¹¹C]phenylalanine and [¹¹C]tryptophan were elevated 1.5-fold, 12-fold and 12-fold, respectively, relative to controls, 4 h after MeJA treatment, while endogeneous pools were unchanged. This suggests that only new carbon is utilized during early stages of defense induction. By 15 h, [C¹¹C]tyrosine and [¹¹C]phenylalanine returned to baseline while [¹¹C]tryptophan was elevated 30-fold, suggesting that MeJA exerts selective control over the shikimate pathway. Finally, we measured trans-cinnamic acid levels as a gauge of downstream phenolic metabolism. Levels were unchanged 4 h after MeJA treatment relative to controls, but were increased 2-fold by 15 h, indicating a lag in response of secondary metabolism.
authors.affiliation: Fachbereich Chemie, Johannes Gutenberg Universität, 55099, Mainz, Germany.
authors.forename: Nils
authors.initials: N
authors.lastname: Hanik
authors.forename: Sara
authors.initials: S
authors.lastname: Gómez
authors.forename: Marcel
authors.initials: M
authors.lastname: Best
authors.forename: Michael
authors.initials: M
authors.lastname: Schueller
authors.forename: Colin M
authors.initials: CM
authors.lastname: Orians
authors.forename: Richard A
authors.initials: RA
authors.lastname: Ferrieri
mesh_terms: D000085:Acetates / Q000494:pharmacology; D002247:Carbon Isotopes / Q000378:metabolism*; D003517:Cyclopentanes / Q000494:pharmacology*; D017753:Ecosystem; D054883:Oxylipins / Q000494:pharmacology; D010636:Phenols / Q000378:metabolism; D010649:Phenylalanine / Q000378:metabolism; D010937:Plant Growth Regulators / Q000494:pharmacology*; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D012765:Shikimic Acid / Q000378:metabolism; D013997:Time Factors; D014026:Nicotiana / Q000187:drug effects* / Q000378:metabolism; D014364:Tryptophan / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism
chemical_list: D000085:Acetates; D002247:Carbon Isotopes; D003517:Cyclopentanes; D054883:Oxylipins; D010636:Phenols; D010937:Plant Growth Regulators; D012765:Shikimic Acid; D014443:Tyrosine; D010649:Phenylalanine; D014364:Tryptophan; C072239:methyl jasmonate