Phenotypic, genetic and expression profiling of a vindoline-rich genotype of Catharanthus roseus

Abstract

Catharanthus roseus is known for its scarce and expensive anticancer bisindole alkaloids, vincristine and vinblastine, which are derived from the coupling of monomeric terpenoid indole alkaloids, catharanthine and vindoline. Vindoline represents the bottleneck in bisindole semi-synthesis as unlike catharanthine, its biosynthesis is restricted to the plant leaves, which are the only commercially-viable source for it. For reducing the exorbitant cost of bisindoles, identification of C. roseus genotypes accumulating higher-than-usual amount of vindoline is urgently required. Here, one such vindoline-rich genotype (CIMAP866) was identified and characterized. It was comparatively analyzed with elite varieties, Dhawal and Nirmal, for morphology, genetic profile, leaf vindoline content (% dry weight), elemental composition, and expression pattern of alkaloid biosynthetic genes. Its vindoline content (~0.20%) was significantly higher than that of Dhawal (~0.09%) and Nirmal (~0.04%). CIMAP866 possesses dwarf character, spreading/bushy growth, wider canopy, shorter petiole and internodes, more laticifers, higher chlorophyll content, altered content of certain elements and distinct genetic profile, as compared to the other genotypes. Significantly higher dat expression in CIMAP866 was a key determinant for its vindoline-rich nature. Vindoline content was a direct function of dat expression and laticifer number. This study has provided a lead towards developing an industrially-useful C. roseus variety.