EFFECT OF LEAD AND COLCHICINE ON MORPHOGENESIS IN PROTONEMATA OF THE MOSS FUNARIA-HYGROMETRICA

organization. Protonemata of Funaria hygrometrica grown in artificial media containing different lead concentrations grow more slowly than controls and show a disturbance of polar growth, changed arrangement of chloroplasts, alterations of nucleus and septa position. Morphological effects are dose-dependent. At the lowest lead concentration (10(-6) hr), only a delay in development was observed, but no cellular alterations. At 10(-5) M Pb nuclear migration, cellular shape, size and position of plastids, were altered and a variety of aberrant forms were present. At 10(-4) M, besides these alterations, a drastic reduction of the protonemal system, high vacuolation and the growth of protonemal filaments from leaves were evident. The highest concentration, (10(-3) M), caused death. Patterns of protonemal development and cellular arrangement in lead-treated samples showed similarities as well as differences, if compared to alterations induced by colchicine. Indirect immunofluorescence demonstrated a correlation between lead concentration and alteration of cytoskeletal organization (alterations similar to those induced by colchicine). Hypotheses are raised to account for effects of lead on microtubule structure, arrangement and cytoplasm organization. (C) 1995 Annals of Botany Company