MORPHOGENETIC PLASTICITY OF CALLUS REINITIATED FROM CELL-SUSPENSION CULTURES OF THE FERN PLATYCERIUM-CORONARIUM

Cell suspension cultures were initiated from gametophyte-derived callu s of the fern Platycerium coronarium. Two distinct types of callus mas ses, distinguished by their colouration, were obtained when the cells from suspension culture were plated on semisolid Murashige and Skoog ( MS) medium containing 10 mu M kinetin. The two types of callus masses had distinct morphogenetic capacities despite their common origin. Mor phogenesis into either gametophytes or sporophytes occurred when these callus masses were cultured on phytohormone-free MS medium depending on the type of callus used. The dark-green gametophytic callus showed a faster rate of growth and morphogenesis as compared to the pale-gree n sporophytic callus. Total chlorophyll content and autofluorescence a nd size of chloroplasts of the sporophytic callus and cell suspension cultures were lower than that of the gametophytic callus. Observations from confocal laser scanning microscopy were in agreement with the ph ysiological parameters measured. The availability of cell cultures of the same ploidy level, but with two distinct pathways of development w ill be useful for comparative studies of developmental plasticity.