IN-VITRO REGENERATION PATTERNS OF PLATYCERIUM-BIFURCATUM LEAF CELL-SUSPENSION CULTURE

A simple suspension culture system of Platycerium bifurcatum was devel oped where sporophytes could be regenerated directly from leaf cells o r indirectly through an aposporous gametophyte stage under the same cu lture conditions. Single cells and aggregates of up to 100 cells devel oped aposporous gametophytes which later gave rise to sporophytes. Suc h gametophytes started apogamy when they were mostly less than 0.7 mm in length, bearing only rhizoids. In most cases, only one sporophyte w as regenerated from one gametophyte. Aggregates of 500-1000 or more ce lls, on the other hand, regenerated sporophytes directly. Intercellula r interaction was considered to be the physiological cause, and the se paration of leaf cells to a certain degree drove the cells to embark o n different regeneration paths. It is suggested that the possible exis tence of a threshold size of cell aggregates separates the two regener ation patterns.