GROWTH AND PHOTOSYNTHESIS OF PHOTOAUTOTROPHIC CALLUS DERIVED FROM PROTOPLASTS OF SOLANUM-TUBEROSUM L

We describe a photoautotrophic culture procedure of potato (cvs Kenneb ec, Haig, DTO-33) callus derived from mesophyll protoplasts. The proto plast culture was initiated at very low concentration of glucose (down to 0.25 g l-1). Callus was subcultured under CO2 enriched air and glu cose was suppressed by the successive dilutions with glucose free medi a. Regeneration was successfully obtained under photoautotrophic condi tions. The characterization of oxygen exchange and of some enzymes and metabolites of carbon assimilation indicated that chlorophyllous call us, grown on carbohydrate free medium, developed the photosynthetic pa thway typical of C3 plants. By comparing the fresh weight of callus cu ltivated in the light or in non-photosynthetic conditions (in darkness or in the light +3-(3,4-Dichlorophenyl)-1,1-dimethylurea) we conclude d that growth depended to about 70 to 88 % on photosynthesis.