Analysis of the O 2 dependency in leaf‐level photosynthesis of two Reynoutria japonica populations growing at different altitudes

• Published in: Plant, cell and environment Vol. 25; no. 1; pp. 65 - 74
• Main Authors: Sakata, T., Yokoi, Y.
• Format: Journal Article
• Language: English
• Published: 01.01.2002
• ISSN: 0140-7791; 1365-3040
• DOI: 10.1046/j.0016-8025.2001.00809.x

Abstract To examine the effects of decreased CO 2 and O 2 partial pressure on leaf‐level photosynthesis in alpine plants at high altitude, we compared the maximal carboxylation efficiency, CE , of Reynoutria japonica Houtt. var. japonica growing in a highland with one growing in a lowland. CE under the native atmospheric conditions (native CE ) of the highland population was significantly lower than that of the lowland one. The O 2 dependency of CE was significantly less in the highland population than in the lowland. Using theoretical analysis, we explained that O 2 dependency of leaf‐level photosynthesis became less as internal conductance ( g i ) decreased. We also showed that g i and the content of active Rubisco ( E ) could be estimated from the O 2 dependency of leaf‐level photosynthesis. By applying the analysis, a severe limitation of CO 2 diffusion in the leaf was estimated in the highland population, whereas almost the same values of E were estimated in both populations. A reasonable explanation for the difference in the native CE is the smaller O 2 dependency and photosynthetic capacity caused by a smaller g i in the highland population in addition to the differences in the partial pressures of CO 2 and O 2 .