GENETIC DIVERSITY AND ALKALOID PRODUCTION IN CATHARANTHUS-ROSEUS, C-TRICHOPHYLLUS AND THEIR HYBRIDS

Inter and intraspecific variation was analyzed in two Catharanthus spe cies with regard to isozyme polymorphism and indole alkaloid content i n roots and leaves. No significant differences in alkaloid production were observed in three groups of C. roseus plants individualized for t heir flower color. Conversely, comparisons between C. trichophyllus an d C. roseus, showed large differences of alkaloid profiles in both roo ts and leaves. Specific isozyme markers on four presumed loci were fou nd allowing us to establish that natural hybridizations could occur be tween the two species when grown together. Experimental hybridizations confirmed that introgressions were feasible but suggested that a repr oductive barrier was acting and involved interspecific incompatibility . The identification and assay of the main alkaloid compounds in natur al interspecific hybrids displayed such a high hybrid vigor that inter specific hybridization may present a new and successful way of improvi ng alkaloid production in Catharanthus species.