Level of messenger RNA encoding small subunit ribulose bisphosphate carboxylase is enhanced by cytokinins in tobacco cell suspension cultures.

Chloroplast differentiation is induced by cytokinins in suspension cell cultures of Nicotiana tabacum, line 19M which is independent of the hormone supply for growth. Poly(A)RNA from cells cultured in basal medium or in kinetin-supplemented medium were analyzed by Northern blot and dot blot hybridizations to a 'RUBISCO' small subunit-encoding cDNA probe. It was found that the small subunit-encoding mRNA of cytokinin-supplemented cells was synthesized much earlier during the culture and in amounts one order of magnitude larger than in hormone-starved cells.