CO₂ enrichment and carbon partitioning to phenolics: do plant responses accord better with the protein competition or the growth-differentiation balance models?

Abstract

Rising levels of atmospheric CO₂ can alter plant growth and partitioning to secondary metabolites. The protein competition model (PCM) and the extended growth/differentiation balance model (GDB_e) are similar but alternative models that address ontogenetic and environmental effects on whole-plant carbon partitioning to the phenylpropanoid biosynthetic pathway, making many divergent predictions. To test the validity of the models, we compare plant responses to one key prediction: if CO₂ enrichment simultaneously stimulates both photosynthesis and growth, then PCM predicts that partitioning to phenolic compounds will decline, whereas GDB_e generally predicts the opposite. Elevated CO₂ (at 548 ppm) increased the biomass growth (ca 23%) as well as the net photosynthesis (ca 13%) of 1-year-old potted paper birch, Betula papyrifera Marsh., in a free air carbon dioxide enrichment study (FACE) in northern Wisconsin. Concomitantly, elevated CO₂ increased carbon partitioning to all measured classes of phenolics (Folin-Denis phenolics, HPLC low molecular weight phenolics (i.e. cinnamic acid derivatives, flavonol glycosides, and flavon-3-ols), condensed tannins, and acid-detergent lignin) in leaves.

Citation

Mattson, W.J.; Julkunen-Tiitto, R.; Herms, D.A. 2005. CO₂ enrichment and carbon partitioning to phenolics: do plant responses accord better with the protein competition or the growth-differentiation balance models?. Oikos. 111: 337-347.