Expression of terpenoid indole alkaloid biosynthetic pathway genes corresponds to accumulation of related alkaloids in Catharanthus roseus (L.) G. Don.

Madagascar periwinkle, Catharanthus roseus (L.) G. Don, a medicinally important plant, produces anticancer dimeric alkaloids, vinblastine and vincristine, in the leaves and accumulates antihypertensive alkaloids, ajmalicine and serpentine, in the roots. This plant grows wild in distant tropical and sub-tropical geographical locations with different agro-climates and shows wide variations in morphological and alkaloid yield-related traits. In order to understand the correlation between the expression of terpenoid indole alkaloid (TIA) pathway genes and accumulation of related alkaloids, six different genetic resources of C. roseus, including the medicinal cultivars Nirmal, Prabal, Dhawal, the mutants gsr-3 and gsr-6, and one horticultural variety, Pacifica blush, were studied. The expression profiles of one early and two late TIA biosynthetic pathway genes, namely, strictosidine synthase, desacetoxyvindoline 4-hydroxylase and deacetyl vindoline 4-O-acetyl transferase were analyzed in these plants. A positive correlation between transcript abundance and accumulation of related alkaloids was observed in the different genetic resources. The potential of these TIA biosynthetic pathway genes for use in screening of high-yielding C. roseus germplasm has been discussed.