THE GREENHOUSE-EFFECT - ACCLIMATION OF TOMATO PLANTS GROWING IN HIGH CO2, RELATIVE CHANGES IN CALVIN CYCLE ENZYMES

Tomato plants (cv. Findon Cross) were grown in a normal concentration of CO2 (approximately 340vpm) or in elevated CO2 (1000vpm) with a 12h photoperiod of 400 μmol quanta m-2s-1, PAR. The activities of three Calvin cycle enzymes, RuBPco (E.C. 4.1.1.39), 3 phosphoglyceric acid phosphokinase (E.C. 2.7.2.3) and NADP-dependent glyceraldehyde 3-phosphate dehydrogenase (E.C. 1.2.1.13) were determined in extracts from the unshaded 5th leaf during leaf development. RuBPco activity was reduced in the high-CO2 grown leaves at 60% expansion compared with leaves grown in 340 vpm CO2, but there were no apparent differences in the other two Calvin cycle enzymes at this stage of expansion. With subsequent leaf development in high CO2 there was an accelerated decline in all three enzyme activities. The loss of RuBPco activity was studied further by raising antibodies to RuBPco and the large subunit of RuBPco (LSU) was detected in electroblotted crude extracts from normal and high-CO2 grown plants. This specific immunoassay estimated a 75% reduction of LSU in the high-CO2 grown leaf at full expansion. © 1990, Gustav Fischer Verlag, Stuttgart. All rights reserved.