This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Web of Science (144) Citing Articles via Google Scholar Google Scholar Articles by Stitt, M. Search for Related Content PubMed PubMed Citation Articles by Stitt, M. Agricola Articles by Stitt, M.

Articles

Limitation of Photosynthesis by Carbon Metabolism ¹

I. Evidence for Excess Electron Transport Capacity in Leaves Carrying Out Photosynthesis in Saturating Light and CO₂

Institut für Biochemie der Pflanze, Untere Karspüle 2, 3400 Göttingen, Federal Republic of Germany

It has been investigated how far electron transport or carbon metabolism limit the maximal rates of photosynthesis achieved by spinach leaves in saturating light and CO₂. Leaf discs were illuminated with high light until a steady state rate of O₂ evolution was attained, and then subjected to a 30 second interruption in low light, to generate an increased demand for the products of electron transport. Upon returning to high light there is a temporary enhancement of photosynthesis which lasts 15 to 30 seconds, and can be up to 50% above the steady state rate of O₂ evolution. This temporary enhancement is only found when saturating light intensities are used for the steady state illumination, is increased when low light rather than darkness is used during the interruption, and is maximal following a 30 to 60 seconds interruption in low light. Decreasing the temperature over the 10 to 30°C range led to the transient enhancement becoming larger. The temporary enhancement is associated with an increased ATP/ADP ratio, a decreased level of 3-phosphoglycerate, and increased levels of triose phosphate and ribulose 1,5-bisphosphate. Since electron transport can occur at higher rates than in steady state conditions, and generate a higher energy status, it is concluded that leaves have a surplus electron transport capacity in saturating light and CO₂. From the alterations of metabolites, it can be calculated that the enhanced O₂ evolution must be accompanied by an increased rate of ribulose 1,5-bisphosphate regeneration and carboxylation. It is suggested that the capacity for sucrose synthesis ultimately limits the maximal rates of photosynthesis, by restricting the rate at which inorganic phosphate can be recycled to support electron transport and carbon fixation in the chloroplast.

This article has been cited by other articles:

				B. Rasulov, K. Huve, M. Valbe, A. Laisk, and U. Niinemets Evidence That Light, Carbon Dioxide, and Oxygen Dependencies of Leaf Isoprene Emission Are Driven by Energy Status in Hybrid Aspen Plant Physiology, September 1, 2009; 151(1): 448 - 460. [Abstract] [Full Text] [PDF]

				T. Araya, K. Noguchi, and I. Terashima Effects of Carbohydrate Accumulation on Photosynthesis Differ between Sink and Source Leaves of Phaseolus vulgaris L. Plant Cell Physiol., May 1, 2006; 47(5): 644 - 652. [Abstract] [Full Text] [PDF]

				C. J. Baxter, C. H. Foyer, J. Turner, S. A. Rolfe, and W. P. Quick Elevated sucrose-phosphate synthase activity in transgenic tobacco sustains photosynthesis in older leaves and alters development J. Exp. Bot., August 1, 2003; 54(389): 1813 - 1820. [Abstract] [Full Text] [PDF]

				A. J. Pieters, M. J. Paul, and D. W. Lawlor Low sink demand limits photosynthesis under Pi deficiency J. Exp. Bot., May 1, 2001; 52(358): 1083 - 1091. [Abstract] [Full Text] [PDF]

				G. Noctor and C. H. Foyer Homeostasis of adenylate status during photosynthesis in a fluctuating environment J. Exp. Bot., February 1, 2000; 51(90001): 347 - 356. [Abstract] [Full Text]