Relation between the amount of rolC gene product and indole alkaloid accumulation in Catharanthus roseus transformed root cultures

Transformed root lines of Catharanthus roseus were established after the inoculation of aseptic stem segments with Agrobacterium rhizogenes strain A4, and cultured in a hormone-free B5/2 solid medium. In these root cultures, in addition to the changes in the ethylene accumulated, the amount of rolC gene product was determined using specific antibodies in order to investigate their relation to growth rate, morphology and the indole alkaloid production of the cultured roots. Our results showed the presence, in all transformed root lines considered, of vindoline and catharanthine, the two monomer precursors for the enzymatic synthesis of the antineoplastic drugs vinblastine and vincristine. In the culture conditions of our experiment, roots with thin morphology that reached the highest rolC gene product amount showed lower growth rate and higher alkaloid production when compared with those with thick morphology and lowest rolC gene product amount. The effect of the protein encoded by this gene on ethylene production is also discussed.