Abstract
The δ13C values of several seagrasses were considerably less negative than those of terrestrial C3 plants and tended toward those of terrestrial C4 plants. However, for Thalassia hemprichii (Ehrenb.) Aschers and Halophila spinulosa (R. Br.) Aschers, phosphoglycerate and other C3 cycle intermediates predominated among the early labeled products of photosynthesis in 14C-labeled seawater (more than 90% at the earliest times) and the labeling pattern at longer times was brought about by the operation of the C3 pathway. Malate and aspartate together accounted for only a minor fraction of the total fixed label at all times and the kinetic data of this labeling were not at all consistent with these compounds being early intermediates in seagrass photosynthesis. Pulse-chase 14C-labeling studies further substantiated these conclusions. Significant labeling of photorespiratory intermediates was observed in all experiments. The kinetics of total fixation of label during some steady-state and pulse-chase experiments suggested that there may be an intermediate pool of inorganic carbon of variable size closely associated with the leaves, either externally or internally. Such a pool may be one cause for the C4-like carbon isotope ratios of seagrasses.
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- Benedict C. R., Scott J. R. Photosynthetic carbon metabolism of a marine grass. Plant Physiol. 1976 Jun;57(6):876–880. doi: 10.1104/pp.57.6.876. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Degroote D., Kennedy R. A. Photosynthesis In Elodea canadensis Michx: Four-Carbon Acid Synthesis. Plant Physiol. 1977 Jun;59(6):1133–1135. doi: 10.1104/pp.59.6.1133. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Schürmann P. Separation of phosphate esters and algal extracts by thin-layer electrophoresis and chromatography. J Chromatogr. 1969 Feb 25;39(4):507–509. [PubMed] [Google Scholar]
- Smith B. N., Epstein S. Two categories of c/c ratios for higher plants. Plant Physiol. 1971 Mar;47(3):380–384. doi: 10.1104/pp.47.3.380. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Van T. K., Haller W. T., Bowes G. Comparison of the photosynthetic characteristics of three submersed aquatic plants. Plant Physiol. 1976 Dec;58(6):761–768. doi: 10.1104/pp.58.6.761. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Whelan T., Sackett W. M., Benedict C. R. Carbon isotope discrimination in a plant possessing the C4 dicarboxylic acid pathway. Biochem Biophys Res Commun. 1970 Dec 9;41(5):1205–1210. doi: 10.1016/0006-291x(70)90214-7. [DOI] [PubMed] [Google Scholar]
- Wintermans J. F., de Mots A. Spectrophotometric characteristics of chlorophylls a and b and their pheophytins in ethanol. Biochim Biophys Acta. 1965 Nov 29;109(2):448–453. doi: 10.1016/0926-6585(65)90170-6. [DOI] [PubMed] [Google Scholar]