Photoautotrophic cell suspension cultures of periwinkle (Catharanthus roseus (L.) G. Don): Transition from heterotrophic to photoautotrophic growth.

Chlorophyllous, heterotrophic periwinkle (Catharanthus roseus (L.) G. Don) cells were capable of sustained photoautotrophic growth in sugar-free B5 medium containing naphthaleneacetic acid and kinetin when provided with a CO2-enriched atmosphere. An increase in cell fresh weight, first observed approximately 2 weeks after transfer from heterotrophic to photoautotrophic conditions, coincided with the development of maximum chlorophyll content and photosynthetic activity. Electron micrographs revealed that chloroplasts of cells cultured photoautotrophically in continuous light contained large starch granules and exhibited a less extensive thylakoid system than did periwinkle mesophyll chloroplasts. Photoautotrophic cells did not accumulate vindoline or dimeric alkaloids.