Spatio-temporal analysis of mitotic activity with a labile cyclin-GUS fusion protein

Plant growth responds rapidly to developmental and environmental signals, b ut the underlying changes in cell division activity are poorly understood. A labile cyclin-GUS reporter was developed to facilitate the spatio-tempora l analysis of cell division patterns. The chimeric reporter protein is turn ed over every cell cycle and hence its histochemical activity accurately re ports individual mitotic cells. Using Arabidopsis plants transformed with c yclin-GUS, we visualized patterns of mitotic activity in wounded leaves whi ch suggest a role for cell division in structural reinforcement.