Abstract:PEPC and relevant enzymes in different photosynthetic organs of wheat and soybean were studied. Almost all green organs examined have been found to contain PEPC. PEPC activity in pod hull and seed coat of soybean as well as in paleae of wheat is higher than that in leaves. 14CO2 can be fixed in different green organs either in light or in dark, however in dark, 14CO2 fixation in pnl hull and seed coat of soybean as well as in paleae of wheat is higher than in leaves. Similarly, N AD-malic enzyme and NAD-malate dehydrogenase are also higher in those organs than in leaves. It was shown that active β-carboxylation of PEPC took place in the fruit organs. The above results indicate that PEPC is important not only for CO2 fixation during photosynthesis but also for recapturing CO2 released from respiration.