title: May photoinhibition be a consequence, rather than a cause, of limited plant productivity?
abstract: Photoinhibition in leaves in response to high and/or excess light, consisting of a decrease in photosynthesis and/or photosynthetic efficiency, is frequently equated to photodamage and often invoked as being responsible for decreased plant growth and productivity. However, a review of the literature reveals that photoinhibited leaves characterized for foliar carbohydrate levels were invariably found to possess high levels of sugars and starch. We propose that photoinhibition should be placed in the context of whole-plant source-sink regulation of photosynthesis. Photoinhibition may represent downregulation of the photosynthetic apparatus in response to excess light when (1) more sugar is produced in leaves than can be utilized by the rest of the plant and/or (2) more light energy is harvested than can be utilized by the chloroplast for the fixation of carbon dioxide into sugars.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, 80309-0334, USA, william.adams@colorado.edu.
authors.forename: William W
authors.initials: WW
authors.lastname: Adams
authors.forename: Onno
authors.initials: O
authors.lastname: Muller
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Cohu
authors.forename: Barbara
authors.initials: B
authors.lastname: Demmig-Adams
mesh_terms: D050260:Carbohydrate Metabolism; D010100:Oxygen / Q000378:metabolism; D055668:Photochemical Processes; D045332:Photosystem II Protein Complex / Q000378:metabolism; D063245:Plant Development; D018515:Plant Leaves / Q000378:metabolism
chemical_list: D045332:Photosystem II Protein Complex; D010100:Oxygen