Effects of elevated CO2 on the vasculature and phenolic secondary metabolism of Plantago maritima

• Published in: Phytochemistry (Oxford) Vol. 65; no. 15; pp. 2197 - 2204
• Main Authors: Davey, M.P, Bryant, D.N, Cummins, I, Ashenden, T.W, Gates, P, Baxter, R, Edwards, R
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier 01.08.2004
• Subjects: abiotic stress; Animal, plant and microbial ecology; Applied ecology; atmospheric circulation; Biological and medical sciences; Biomass; carbon dioxide; Carbon Dioxide - metabolism; Carbon Dioxide - physiology; chemical structure; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on plants and fungi; flavonoids; Fundamental and applied biological sciences. Psychology; glycosides; lignification; Lignin - metabolism; phenolic compounds; Phenols - metabolism; phenylpropanoids; Plant growth. Development of the storage organs; Plant Leaves - genetics; Plant Leaves - growth & development; Plant Leaves - metabolism; Plant physiology and development; plant response; Plant Roots - genetics; Plant Roots - growth & development; Plant Roots - metabolism; Plant Shoots - genetics; Plant Shoots - growth & development; Plant Shoots - metabolism; plant stress; plant veins; Plantaginaceae; Plantago - genetics; Plantago - growth & development; Plantago - metabolism; Plantago maritima; Plants, Genetically Modified; secondary metabolites; Vegetative apparatus, growth and morphogenesis. Senescence; Growth; Carbon dioxide; Caffeic acid; Phenylethanoid glycosides; Plantaginaceae; Medium enrichment; Flavonoids; Lignification; Dicotyledones; Angiospermae; Plantago; Phenols; Spermatophyta; Phenylpropanoids; Elevated atmospheric CO2; Plantago maritima; Secondary metabolism
• ISSN: 0031-9422; 1873-3700
• DOI: 10.1016/j.phytochem.2004.06.016

We have examined the effect of elevated CO2 on the vasculature and phenolic secondary metabolism on clones of the maritime plant Plantago maritima (L.). Plants were exposed to either ambient (360 mol CO2 mol-1) or elevated (600 mol CO2 mol-1) atmospheric CO2 within a Solardome facility and harvested after 12 months' growth. Histochemical analysis of the leaves identified increases in the diameter of the minor leaf vein and associated lignified vessels in plants exposed to elevated CO2. In the roots the number of lignified root vessels and stele width were also increased, but overall the lignified vessel-wall thickness was reduced in plants exposed to elevated CO2, compared to those grown under ambient CO2. To investigate whether or not these subtle changes in lignification were associated with perturbations in phenolic metabolism, aromatic natural products were analysed by HPLC-MS after treatment with cellulase to hydrolyse the respective glycosidic conjugates. The phenylpropanoids p-coumaric acid, caffeic acid, ferulic acid and the flavone luteolin were identified, together with the caffeoyl phenylethanoid glycosides, verbascoside and plantamajoside which were resistant to enzymatic digestion. Exposure to enhanced CO2 resulted in subtle changes in the levels of individual metabolites. In the foliage a one-year exposure to enhanced CO2 resulted in an increased accumulation of caffeic acid, whilst in the roots p-coumaric acid and verbascoside were enhanced. Our results suggest that significant changes in the vasculature of P. maritima on exposure to increased CO2 are associated with only minor changes in the leaves of specific lignin-related metabolites.