Changes in Microstructure and Elements of Protocorm Like Bodies from Dendrobium huoshanense During the Development and Plantlet Regeneration

In order to get better understanding of the growth and officinal components during the development of protocorm like bodies (PLBs) from Dendrobium huoshanense and plantlet regeneration，changes in microstructure and microarea elements were analyzed by means of SEM and EDS. Cells which have the ability to divide from the surface of explants formed embryogenic callus in tissue culture when conditions were suitable. Embryogenic cells grew into PLBs and secondary PLBs after constant division. PLBs showed bipolarity gradually and produced buds and roots to form complete plants. After 30 days, root hair or velamina were not found in roots. Stems were characterized by several features such as surface longitudinal depressions, round cross sections with wavy edges, scattered external ductile finite vascular bundle and mucinous cells contents. Quadrilateral stomata only distributed in the lower epidermis of isobilateral leaves and the guard cells were like kidneys. And more Na, S, K, Al, Si and Fe were in PLBs, then the contents of P, Cl, Mn and Ca increased in differentiated PLBs, and the contents of Na, S, K increased in the complete plants while other elements were less or not changed significantly.