Decision-MakingPlant Cell Cycle

Cell cycle control plays a fundamental role in plants by supporting their largely postembryonic growth and development. Basic cell cycle mechanisms are shared with other eukaryotes, but a number of plant specific cell cycle features are thought to contribute to the remarkable robustness of the plant cell cycle, while at the same time allowing for the necessary plasticity of a sessile organism. Here, we review the different components of the plant cell cycle and how they are regulated by internal and external signals, so that a diversity of cell cycle variants can occur in a well-coordinated process during a plant’s lifetime. One of such variants is the endocycle, originating polyploidy by abolishing the M-phase of the regular cell cycle. Asymmetric cell division is another variant, which we exemplify by the specification of the male germ line in flowering plants. Misguided control of the cell cycle machinery generates chronic proliferation that may result in tumorigenesis. However, tumors in plants are substantially less frequent and destructive than in mammals. We discuss possible reasons for such a discrepancy in an attempt to clarify the mysterious ability of plants to restrain tumor growth.