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 c ontrols and show a disturbance of polar growth, changed arrangement of chloroplasts, alterations of nucleus and septa position. Morphologica l effects are dose-dependent. At the lowest lead concentration (10(-6) hr), only a delay in development was observed, but no cellular altera tions. At 10(-5) M Pb nuclear migration, cellular shape, size and posi tion of plastids, were altered and a variety of aberrant forms were pr esent. At 10(-4) M, besides these alterations, a drastic reduction of the protonemal system, high vacuolation and the growth of protonemal f ilaments from leaves were evident. The highest concentration, (10(-3) M), caused death. Patterns of protonemal development and cellular arra ngement in lead-treated samples showed similarities as well as differe nces, if compared to alterations induced by colchicine. Indirect immun ofluorescence demonstrated a correlation between lead concentration an d alteration of cytoskeletal organization (alterations similar to thos e induced by colchicine). Hypotheses are raised to account for effects of lead on microtubule structure, arrangement and cytoplasm organizat ion. (C) 1995 Annals of Botany Company