THE INFLUENCE OF SUCROSE AND AN ELEVATED CO2 CONCENTRATION ON PHOTOSYNTHESIS OF PHOTOAUTOTROPHIC PEANUT (ARACHIS-HYPOGAEA L) CELL-CULTURES

Using photoautotrophic cells of Arachis hypogaea (L.) growing at ambie nt CO2, it was shown that exogenous sucrose supplied to the liquid med ium reduced (CO2)-C-14 fixation (supplied as NaH (CO3)-C-14) . This wa s mostly due to a reduced labelling in P-esters, and to a lesser exten t, in the serine/glycine moiety. However, radioactivity in the neutral sugar fraction was increased upon supplement of exogenous sucrose. Th e reduced labelling of P-esters and serine/glycine agrees with a lower concentration and specific activity of Rubisco in the sucrose supplie d treatments as compared to the control. Following a transfer into a s ugar free nutrient medium the concentration and activity of Rubisco is increased. The concentration of PEPCase was not influenced by sucrose application, although its specific activity was increased. At elevate d CO2 concentration (2.34% v/v) the Rubisco concentration and specific activity was at the same level as in the control (0.03% V/V CO2). How ever, the concentration and the specific activity of PEPCase was incre ased and dry weight increase was about 8-9-fold higher than at ambient CO2.