2002 Volume 19 Issue 5 Pages 369-376
Sixteen colored cell lines of Portulaca sp. ‘Jewel’ forming betalain were established, seven cultured on modified Murashige and Skoog (mMS) medium and nine on modified Girod and Zrÿd (mJ1). Each line was different in term of betalain content. Both betacyanin and betaxanthin widely varied in quality and quantity from line to line. A magenta-colored phenotype contained the maximum betacyanin and an orange-colored phenotype contained the maximum betaxanthin. Modified MS medium was optimal for betacyanin synthesis whereas modified J1 medium synthesized more betaxanthin. Betacyanin and betaxanthin both accumulated in a positive correlation to the cell growth in our culture system, and the highest contents were recorded during the logarithmic phase. The addition of natural auxin, indole-3-acetic acid (IAA), to both types of culture media instead of synthetic auxin, 2, 4-dichloro-phenoxyacetic acid (2, 4-D) inhibited the growth and reduced betalain synthesis. But a few subcultures after transfer to IAA-containing medium, two cell lines were established one producing betacyanin and one betaxanthin. Different cell phenotypes (either magenta or yellow colored cells) exhibit same responses in their requirement of light. Cellular betacyanin and betaxanthin drastically increased under continuous illumination, particularly with blue light irradiation along with the increasing number of growth cycles.
