Cell-cycle control and plant development.

The cell cycle is driven by the activity of cyclin-dependent kinase (CDK)-cyclin complexes. Therefore, internal and external signals converge on the regulation of CDK-cyclin activity to modulate cell proliferation in specific developmental processes and under various environmental conditions. CDK-cyclin activity is fine-tuned by multiple mechanisms, for example, transcriptional control, protein degradation, phosphorylation, and binding to CDK inhibitor. These molecular mechanisms underlie the regulation of the entry into or the exit from the cell cycle, the rate of cell cycle, or the transition from the mitotic cell cycle to the endocycle. The multiple mechanisms regulating CDK-cyclin activity coordinately enable the elaborate control of cell cycle by various upstream signals. Here, we review the molecular mechanisms that regulate the cell cycle and the endocycle in plants. We also introduce the recent progress in elucidating the regulatory mechanisms underlying plant development and the stress response in terms of cell-cycle control.