Mature first leaves of Phaseolus vulgaris L. were exposed to low partial pressures of CO2 (7, 6 and 0 Pa CO2) for 24 h. After exposure of leaves to 6 Pa CO2 for 24 h, there was a reduction in the carbon exchange rate (CER) at all partial pressures of CO2 at which measurements were made. After exposure to 7 Pa CO2, the CER decreased only at high partial pressures of CO2. The rates of electron transport from water to methyl viologen, through the whole chain, decreased in parallel with the decrease in CER measured at 90 Pa CO2. One site of inhibition in leaves exposed for 24 h to 6 Pa CO2 appeared to be the intersystem electron-transport chain since there were no significant changes in the activities of PSI and PSII, as determined from the level of P-700 and measurement of fluorescence, respectively. Another inhibitory phenomenon appeared to be a negative change in the activation state of Rubisco, while the level of Rubisco was unaffected by the exposure to 6 Pa CO2. These decreases in photosynthetic activity caused by depletion of CO2 explains at least in part, the inhibition of photosynthesis that is caused by rain treatment [Ishibashi and Terashima (1995) Plant Cell Environ. 18: 431].
|ジャーナル||Plant and Cell Physiology|
|出版ステータス||Published - 1997 5月|
ASJC Scopus subject areas