AMYLOPLASTS AS A POSSIBLE INDICATOR OF MORPHOGENIC POTENTIAL IN SUNFLOWER PROTOPLASTS

Sunflower plants (inbred line 47 302 bcd) can be regenerated from hypo cotyl protoplasts. During the regeneration process, we have observed t wo kinds of calli differing by their cell types. Morphogenic calli, fr om which of shoots was possible, were characterized by the presence of starch granules, and clusters of small meristematic-like cells. Non-m orphogenic calli did not contain either meristematic-like cells or sta rch, but a varying proportion of the typical callus cells at more or l ess advanced stages of degeneration. We have analyzed samples from eac h step of protoplast culture for the presence of starch, i.e. the init ial protoplast population, micro- and macro-colonies and calli. On eac h step, only a small percentage of the structures contained starch. Th ese results are discussed in view of a possible origin of. these morph ogenic calli from particular cell types existing in the donor tissue, i.e. stomatal guard cells and endodermis cells. (C) 1997 Elsevier Scie nce Ireland Ltd.