Compact callus cluster suspension cultures of Catharanthus roseus with enhanced indole alkaloid biosynthesis

Compact callus clusters showing a certain level of cellular or tissue diffe rentiation were established from Catharanthus roseus stem and leaf explants in a modified MS liquid induction medium supplemented with 5.37 muM alpha -naphthaleneacetic acid and 4.65 muM kinetin. In the induction medium most leaf explants developed into friable half-closed hollow callus clusters, wh ereas in the same medium containing 2,4-dichlorophenoxyacetic acid instead of alpha -naphthaleneacetic acid, most leaf explants were induced to form d ispersed cell suspension cultures. Characteristics of these different types of suspension cultures were compared, and the results showed that the comp act callus clusters could synthesize indole alkaloids 1.9- and 2.4-fold hig her than the half-closed hollow callus clusters and dispersed cell cultures , respectively. The degree of compaction expressed by the ratio of fresh we ight to dry weight of these suspension cultures was correlated to indole al kaloid production. Our studies also postulated that the level of cellular/t issue differentiation might be responsible for these different alkaloid syn thesis capabilities. Sucrose regime affected some properties (the size, deg ree of compaction, differentiation level) of the compact callus cluster cul tures and therefore influenced alkaloid production.