Synthetic Seed Development and Conversion to Plantlet in Catharanthus roseus (L.) G. Don.

An encapsulation protocol to obtain synthetic seeds was established in Catharanthus roseus (L.) G. Don. Hypocotyl derived embryogenic callus containing somatic embryos viz., torpedo, early cotyledonary and cotyledonary were encapsulated in sodium alginate and calcium chloride solution. Sodium alginate acts as an artificial endosperm, providing nourishment to the growing embryos, at the same time it protects embryos from damages and facilitates embryos germination later. Different levels of sodium alginate and calcium chloride were used in which perfect bead formation was observed in condition encapsulated with 2.5% sodium alginate and 100 mM calcium chloride solution. Calcium chloride exposure for 15 min improved bead quality by forming uniform and firm beads. Addition of 3% sucrose to sodium alginate solution was also very effective for synthetic seed germination. The encapsulated embryos germinated and produced seedlings at a high rate (84.332.1) in 1.34 M a-Naphthalene acetic acid +1.10 M 6-Benzylaminopurine amended MS medium. Synthetic seeds were kept at 0, 4 and 25C as to examine the best storage temperature; preservation at 4C was found to be the optimum temperature for embryo storage and germination purposes. The encapsulated embryos were preserved up to 10 weeks or more without losing germination abilities. The germination frequency was high (81.0%) after 30 days of storage which however reduced with extended storage time. Plantlets obtained from synseeds were morphologically similar to that of mother plant.