Carbon flow scheme for an in vitro plant

In a tissue culture system plants have two main carbon sources (Fig. 1). Sucrose, absorbed from the medium, can be used as carbon source for the production of biomass or will sustain respiration. When sugars are catabolized for energy requirements all carbon will in the end be released as CO2.
Besides sucrose incorporation, depending on the degree of mixotrophy of a culture, net CO2-fixation can provide a considerable contribution to growth.In roses 15 to 25% of the biomass increase could be attributed to CO2-fixation (Fig 2).

Fig. 1. Schematic representation of the different carbon flows in a tissue cultured plant



 AB

Fig 2. Evolution of the sucrose uptake (A) and the total dry matter increase (B) of stage 2 cultures of micropropagated Rosa multiflora. The repartitioning over the different fractions is presented.



Fig.3. Experimental set-up to flush CO2 from the headspace of a culture vessel