Differences in the activation state of ribulose-1,5-bispliosphate carboxylase/oxygenase in barley, pea, and wheat at two altitudes.

Activation state of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) is an important parameter determining the rate of net photosynthesis (P-N) in situ for which no information is available with reference to altitude. We analyzed activation state along with P-N in three plant species and their cultivars grown at low (LA, 1300 in) and high (HA, 4 200 m) altitudes. No significant change in P-N and the initial activity of RuBPCO was obtained with reference to altitude. However, activation state of RuBPCO was reduced significantly in the HA plants as compared to the LA ones. Hence low partial pressure of CO2 prevailing at HA might be responsible for the lower activation state of RuBPCO