title: Damage-induced root nitrogen metabolism inNicotiana sylvestris: Testing C/N predictions for alkaloid production.
abstract: "Nitrogen surplus" models for nicotine production induced by leaf damage predict that the observed increase in root nicotine synthesis after leaf damage results from "overflow" metabolism; reduced nitrogen existing in excess of growth requirements is shunted into nicotine biosynthesis. To test the nitrogen surplus model for induced nicotine production, we measured the concentrations of the majorN-containing metabolites exported from the roots and the nitrate reductase activity (NRA) of roots and shoots in damaged and undamagedNicotiana sylvestris plants. Leaf damage: (1) had no significant effect on root or shoot NRA, (2) increased nicotine export and decreased amino-acid and amide export from the roots of NO3-fertilized plants, and (3) had no significant effect on the export of anyN-containing metabolite from the roots of NH4-fertilized plants. These results are not consistent with the nitrogen surplus model and indicate that leaf damage has a direct influence on root alkaloid metabolism.
authors.affiliation: Department of Biological Sciences, SUNY University at Buffalo, 14260-1300, Buffalo, New York.
authors.forename: I T
authors.initials: IT
authors.lastname: Baldwin
authors.forename: R C
authors.initials: RC
authors.lastname: Oesch
authors.forename: P M
authors.initials: PM
authors.lastname: Merhige
authors.forename: K
authors.initials: K
authors.lastname: Hayes