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. 1982 Feb;69(2):469–473. doi: 10.1104/pp.69.2.469

Influence of Varying CO2 and Orthophosphate Concentrations on Rates of Photosynthesis, and Synthesis of Glycolate and Dihydroxyacetone Phosphate by Wheat Chloroplasts 1

Hideaki Usuda 1,2, Gerald E Edwards 1,2
PMCID: PMC426232  PMID: 16662231

Abstract

Intact chloroplasts of wheat (Triticum aestivum) were isolated from mesophyll protoplasts. With decreasing concentrations of bicarbonate from 10 to 0.3 millimolar (pH 8.0), the optimal concentration of orthophosphate (Pi) for photosynthetic O2 evolution decreased from a value of 0.1 to 0.2 millimolar to 0 to 0.025 millimolar. The extremely low Pi optimum for photosynthesis at the low bicarbonate levels of 0.3 millimolar was increased by lowering the O2 concentration from 253 (21% gas phase) to 72 micromolar (6% gas phase). The relative amount of glycolate and dihydroxyacetone phosphate (DHAP) synthesized under high and low levels of bicarbonate and varying levels of Pi was determined. At low levels of bicarbonate, glycolate was the main product, whereas at high bicarbonate levels, DHAP was the main product. Most of the DHAP and glycolate was found in the extrachloroplastic fraction.

The rate of photosynthesis at low levels of bicarbonate (0.3 millimolar) was as high as 75 to 95% of that at high levels of bicarbonate (10 millimolar) at the respective optimal levels of Pi. At low bicarbonate levels, and without Pi, there was little lag in photosynthetic O2 evolution upon illumination in comparison to that of high bicarbonate levels and optimal levels of Pi. It is proposed that conditions which favor glycolate synthesis allow photosynthesis to continue without a depletion of internal Pi, whereas consumption of Pi may occur in the chloroplast during the net synthesis of organic phosphates under high levels of bicarbonate and without addition of Pi. At low bicarbonate levels, the extreme susceptibility of photosynthesis to inhibition by Pi may be due to excessive export of carbon from the chloroplast in the form of both glycolate and triose phosphate.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Edwards G. E., Robinson S. P., Tyler N. J., Walker D. A. A requirement for chelation in obtaining functional chloroplasts of sunflower and wheat. Arch Biochem Biophys. 1978 Oct;190(2):421–433. doi: 10.1016/0003-9861(78)90295-3. [DOI] [PubMed] [Google Scholar]
  2. Edwards G. E., Robinson S. P., Tyler N. J., Walker D. A. Photosynthesis by isolated protoplasts, protoplast extracts, and chloroplasts of wheat: influence of orthophosphate, pyrophosphate, and adenylates. Plant Physiol. 1978 Aug;62(2):313–319. doi: 10.1104/pp.62.2.313. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Ellyard P. W., Gibbs M. Inhibition of photosynthesis by oxygen in isolated spinach chloroplasts. Plant Physiol. 1969 Aug;44(8):1115–1121. doi: 10.1104/pp.44.8.1115. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Flügge U. I., Freisl M., Heldt H. W. Balance between Metabolite Accumulation and Transport in Relation to Photosynthesis by Isolated Spinach Chloroplasts. Plant Physiol. 1980 Apr;65(4):574–577. doi: 10.1104/pp.65.4.574. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Huber S. C. Orthophosphate control of glucose-6-phosphate dehydrogenase light modulation in relation to the induction phase of chloroplast photosynthesis. Plant Physiol. 1979 Nov;64(5):846–851. doi: 10.1104/pp.64.5.846. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Jones M. G., Outlaw W. H., Lowry O. H. Enzymic assay of 10 to 10 moles of sucrose in plant tissues. Plant Physiol. 1977 Sep;60(3):379–383. doi: 10.1104/pp.60.3.379. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Krause G. H., Thorne S. W., Lorimer G. H. Glycolate synthesis by intact chloroplasts. Studies with inhibitors of photophosphorylation. Arch Biochem Biophys. 1977 Oct;183(2):471–479. doi: 10.1016/0003-9861(77)90382-4. [DOI] [PubMed] [Google Scholar]
  8. Latzko E., Gibbs M. Enzyme activities of the carbon reduction cycle in some photosynthetic organisms. Plant Physiol. 1969 Feb;44(2):295–300. doi: 10.1104/pp.44.2.295. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Lilley R. M., Chon C. J., Mosbach A., Heldt H. W. The distribution of metabolites between spinach chloroplasts and medium during photosynthesis in vitro. Biochim Biophys Acta. 1977 May 11;460(2):259–272. doi: 10.1016/0005-2728(77)90212-2. [DOI] [PubMed] [Google Scholar]
  10. Lorimer G. H. Determination of glycolic acid by the Eegriwe (Calkins) methods. Anal Biochem. 1977 Dec;83(2):785–787. doi: 10.1016/0003-2697(77)90087-2. [DOI] [PubMed] [Google Scholar]
  11. Robinson J. M., Gibbs M. Photosynthetic intermediates, the warburg effect, and glycolate synthesis in isolated spinach chloroplasts. Plant Physiol. 1974 Jun;53(6):790–797. doi: 10.1104/pp.53.6.790. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Usuda H., Edwards G. E. Localization of glycerate kinase and some enzymes for sucrose synthesis in c(3) and c(4) plants. Plant Physiol. 1980 May;65(5):1017–1022. doi: 10.1104/pp.65.5.1017. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. 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]

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