Effect of cytokinin on the induction and macromolecules metabolic kinetics of somatic embryogenesis in Phalaenopsis sp.

Two ex-plants from test tube seedling of Phalaenopsis sp.were cultured on the media containing 6-BA and 2,4-D.From the stem ex-plant,embryogenic callus(EC)with large amounts of starch granules in cell could be induced with the presence of 6-BA.On the other hand,the callus induced with 2,4-D or with both 2,4-D and 6-BA were unable to differentiate.EC could also be induced efficiently from the leaf ex-plant cultured on the medium containing 6-BA.Histological observation and metabolic analysis conducted during somatic embryogenesis showed that,in leaf ex-plant,the DNA content increased slowly initially and sharply on the 25th day of induction.The RNA content increased when induction began,and reached a peak on the 11-18th day.The soluble protein content started to change later than RNA and peaked on the 25th day.