The influence of sucrose and an elevated CO2 concentration on photosynthesis of photoautotrophic peanut (Arachis hypogaea L.) cell cultures

Using photoautotrophic cells ofArachis hypogaea (L.) growing at ambient CO₂, it was shown that exogenous sucrose supplied to the liquid medium reduced¹⁴CO₂ fixation (supplied as NaH¹⁴CO₃). This was mostly due to a reduced labelling in P-esters, and to a lesser extent, in the serine/glycine moiety. However, radioactivity in the neutral sugar fraction was increased upon supplement of exogenous sucrose. The reduced labelling of P-esters and serine/glycine agrees with a lower concentration and specific activity of Rubisco in the sucrose supplied treatments as compared to the control. Following a transfer into a sugar 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 elevated 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). However, the concentration and the specific activity of PEPCase was increased and dry weight increase was about 8–9-fold higher than at ambient CO₂.