The essential Mcm7 protein PROLIFERA is localized to the nucleus of dividing cells during the G₁ phase and is required maternally for early Arabidopsis development

Patricia S. Springer, David R. Holding, Andrew Groover, Cristina Yordan and Robert A. Martienssen

Department of Botany and Plant Sciences, University of California, Riverside, CA 92521-0124, USA

QuickTime Video

Optical sections of a growing root tip from a transgenic Arabidopsis seedling were taken at four-minute intervals. The seedling is expressing a PROLIFERA::GFP gene fusion driven by the PROLIFERA promoter. The sequence begins with a lower magnification overview of the root tip containing dividing cells. Nuclei of cells expressing the nuclear-localised transgene are seen as green circles. Next, a portion of the root is brought into higher magnification, and an arrow highlights a cell of interest. The cell rapidly loses GFP signal between frames, corresponding to a four-minute time interval. This rapid loss of fluorescence signal from the nucleus likely represents the onset of mitosis. The two daughter cells (highlighted by red arrows) begin to show GFP accumulation in the nuclei about 30 minutes later, corresponding to the onset of G1. Z-sections were taken before and after timelapse capture to confirm the observed cells did not move out of section.