Partitioning of new carbon as ¹¹C in Nicotiana tabacum reveals insight into methyl jasmonate induced changes in metabolism

J Chem Ecol. 2010 Oct;36(10):1058-67. doi: 10.1007/s10886-010-9835-x. Epub 2010 Sep 15.

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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Acetates / pharmacology
  • Carbon Isotopes / metabolism*
  • Cyclopentanes / pharmacology*
  • Ecosystem
  • Oxylipins / pharmacology
  • Phenols / metabolism
  • Phenylalanine / metabolism
  • Plant Growth Regulators / pharmacology*
  • Plant Leaves / drug effects
  • Plant Leaves / metabolism
  • Shikimic Acid / metabolism
  • Time Factors
  • Tobacco / drug effects*
  • Tobacco / metabolism
  • Tryptophan / metabolism
  • Tyrosine / metabolism

Substances

  • Acetates
  • Carbon Isotopes
  • Cyclopentanes
  • Oxylipins
  • Phenols
  • Plant Growth Regulators
  • Shikimic Acid
  • Tyrosine
  • Phenylalanine
  • Tryptophan
  • methyl jasmonate