An efficient somatic embryogenesis based plant regeneration from the hypocotyl of <i>Catharanthus roseus</i>

Abstract

An efficient and rapid somatic embryogenesis based plant regeneration from hypocotyls of three Catharanthus roseus cultivars, Pacifica cherry red (PCR), Heatwave mix color (HWMC), and Mediterranean Rose Red (MRR) was standardized. Hypocotyl-derived primary calluses (HPC) were formed on callus induction medium (MSCP1) after 10 days of culture. Embryogenic calluses (EC) with somatic embryos were induced from HPC on proliferation medium (MSCP2) within 2 weeks of culture. Later, EC were selected and maintained on plantlet formation medium (MSCP3) with periodic subculturing at an interval of 2 weeks. Somatic embryos were germinated well into plantlets on MSCP3 within 6 weeks of culture. As sources of nitrogen, casein hydrolysate (CH; acid free) and L-proline were necessary as standard addenda in the plant regeneration protocol of C. roseus. The promotive effects of CH and L-proline not only decreased the culturing time but also increased the number of somatic embryos and their derived plantlets. The percentage of EC and regenerated plant initiated from hypocotyls were higher than those previously reported.

Key words: Catharanthus roseus, multi-cultivar, hypocotyls, embryogenic callus, plant regeneration.