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 (78) Citing Articles via Google Scholar Google Scholar Articles by Zelitch, I. Articles by Day, P. R. Search for Related Content PubMed PubMed Citation Articles by Zelitch, I. Articles by Day, P. R. Agricola Articles by Zelitch, I. Articles by Day, P. R.

Articles

Variation in Photorespiration. The Effect of Genetic Differences in Photorespiration on Net Photosynthesis in Tobacco

Department of Biochemistry, The Connecticut Agricultural Experiment Station, New Haven, Connecticut 06504, Department of Genetics, The Connecticut Agricultural Experiment Station, New Haven, Connecticut 06504

The hypothesis that net photosynthesis is diminished in many plant species because of a high rate of CO₂ evolution in the light has been tested further. High rates of CO₂ output in CO₂-free air in comparison with dark respiration were found in Chlamydomonas reinhardi, wheat leaves, tomato leaves, and to a lesser extent in Chlorella pyrenoidosa by means of the ¹⁴C-photorespiration assay. In tobacco leaves high photorespiration was characteristic of a standard variety, Havana Seed, and a possibly still higher rate was found in a yellow heterozygous mutant, JWB Mutant. However, the dark homozygous sibling of the latter, JWB Wild, had a low photorespiration for the tobacco species. The relative rates of photorespiration were in the same sequence when measured by the ¹⁴CO₂ released in normal air from leaf disks supplied with glycolate-1-¹⁴C in the light.

As would be predicted by the hypothesis, the maximal net rate of photosynthesis at 300 ppm of CO₂ in the air in JWB Wild leaves was greater (24%) than in Havana Seed, while JWB Mutant had less CO₂ uptake than the standard variety (21%). At 550 ppm of CO₂ the differences in net photosynthesis were not as great between the 2 siblings as at 200 ppm. The relative leaf expansion rates of seedlings of the 3 tobacco varieties in a greenhouse had the same relationship as their rates of CO₂ assimilation.

Thus within the tobacco species, as in a comparison between tobacco and maize, low photorespiratory CO₂ evolution was correlated with higher photosynthetic efficiency. Therefore it seems that increased CO₂ uptake should be achieved by genetic interference with the process of photorespiration.

This article has been cited by other articles:

				J. A. Bassham Increasing Crop Production Through More Controlled Photosynthesis Science, August 12, 1977; 197(4304): 630 - 638. [PDF]

				I. Zelitch Improving the Efficiency of Photosynthesis Science, May 9, 1975; 188(4188): 626 - 633. [PDF]