title: Stress enhances the synthesis of secondary plant products: the impact of stress-related over-reduction on the accumulation of natural products.
abstract: Spice and medicinal plants grown under water deficiency conditions reveal much higher concentrations of relevant natural products compared with identical plants of the same species cultivated with an ample water supply. For the first time, experimental data related to this well-known phenomenon have been collected and a putative mechanistic concept considering general plant physiological and biochemical aspects is presented. Water shortage induces drought stress-related metabolic responses and, due to stomatal closure, the uptake of CO2 decreases significantly. As a result, the consumption of reduction equivalents (NADPH + H(+)) for CO2 fixation via the Calvin cycle declines considerably, generating a large oxidative stress and an oversupply of reduction equivalents. As a consequence, metabolic processes are shifted towards biosynthetic activities that consume reduction equivalents. Accordingly, the synthesis of reduced compounds, such as isoprenoids, phenols or alkaloids, is enhanced.
authors.affiliation: Institute for Plant Biology, Technische Universität Braunschweig, Mendelssohnstraße 4, D-38106 Braunschweig, Germany. d.selmar@tu-bs.de
authors.forename: Dirk
authors.initials: D
authors.lastname: Selmar
authors.forename: Maik
authors.initials: M
authors.lastname: Kleinwächter
mesh_terms: D001688:Biological Products / Q000378:metabolism*; D055864:Droughts; D004734:Energy Metabolism; D010944:Plants / Q000378:metabolism*; D064210:Secondary Metabolism; D013312:Stress, Physiological
chemical_list: D001688:Biological Products
keywords: Drought stress; Over-reduction; Secondary plant products; Surplus of energy