Central Research and Development Department, Experimental Station, E. I. du Pont de Nemours & Company, Wilmington, Delaware 19898.
Plant Physiol. 1978 Jun;61(6):929-32. doi: 10.1104/pp.61.6.929.
Preincubation of illuminated tobacco (Nicotiana tabacum L.) leaf disks in glycidate (2,3-epoxypropionate) or glyoxylate inhibited photorespiration by about 40% as determined by the ratio of (14)CO(2) evolved into CO(2)-free air in light and in darkness. However, under identical preincubation conditions used for the light/dark (14)C assays, the compounds failed to reduce photorespiration or stimulate net photosynthesis in tobacco leaf disks based on other CO(2) exchange parameters, including the CO(2) compensation concentration in 21% O(2), the inhibitory effect of 21% O(2) on net photosynthesis in 360 microliters per liter of CO(2) and the rate of net photosynthetic (14)CO(2) uptake in air.The effects of both glycidate and glyoxylate on the (14)C assay are inconsistent with other measures of photorespiratory CO(2) exchange in tobacco leaf disks, and thus these data question the validity of the light to dark ratio of (14)CO(2) efflux as an assay for relative rates of photorespiration (Zelitch 1968, Plant Physiol 43: 1829-1837). The results of this study specifically indicate that neither glycidate nor glyoxylate reduces photorespiration or stimulates net photosynthesis by tobacco leaf disks under physiological conditions of pO(2) and pCO(2), contrary to previous reports.
在光照下预孵育硝酸银处理的烟草（Nicotiana tabacum L.）叶圆片时，用光和黑暗条件下（14）CO2 释放到 CO2 自由空气中的比例，确定 2,3-环氧丙酸（glycidate）或乙醛酸（glyoxylate）抑制了约 40%的光呼吸。然而，在用于光/暗（14）C 测定的相同预孵育条件下，这些化合物未能减少烟草叶圆片中的光呼吸或刺激净光合作用，基于其他 CO2 交换参数，包括 21%O2 中的 CO2 补偿浓度、21%O2 对 360 微升/升 CO2 中净光合作用的抑制作用以及空气中净光合（14）CO2 摄取的速率。glycidate 和 glyoxylate 对（14）C 测定的影响与烟草叶圆片中其他测定光呼吸 CO2 交换的方法不一致，因此这些数据质疑光到暗的（14）CO2 流出比作为测定相对光呼吸速率的有效性（Zelitch 1968，Plant Physiol 43: 1829-1837）。本研究的结果特别表明，glycidate 和 glyoxylate 都不能在 pO2 和 pCO2 的生理条件下减少烟草叶圆片中的光呼吸或刺激净光合作用，这与以前的报告相反。
