Multiplication of Annatto (Bixa orellana L.) using cotyledons and leaf explants

Abstract

Annatto (Bixa orellana L.) is an important natural dye yielding plant. To improve theregeneration capacity of annatto, the effects of explants size, plant growth regulators, lightregime and leaf position were evaluated using cotyledons and leaf explants derived fromseedlings. Explants having entire lamina with petiole showed maximum response. Thecotyledonary explants produced highest regeneration frequency (78.1%) and maximumnumber of shoots (12.4) on Murashige and Skoog medium supplemented with 20 μM benzyladenine (BA). Leaf explants on MS medium containing 20 μM BA gave 67% regenerationfrequency and 11.3 new shoots per explant. A photoperiod of 16/8 h (light/dark) was foundto be superior to continuous dark or light. Position of leaf on the seedling had significantrole in organogenic response and is found decreasing from the base to shoot apex. Theregenerated shoots were rooted on MS medium supplemented with 10 μM IBA. The rootedplantlets were transferred initially in the growth chamber and then moved to a green house.The present protocol can be utilized for the mass multiplication and also for effective genetictransformation aimed at the improvement of annatto.