Green light for the cell cycle

Abstract

In recent years, considerable progress has been made in unraveling the control mechanisms operating on the plant cell cycle and most of the key regulators have now been identified, including cyclin-dependent kinases (CDKs), cyclins, CDK-inhibitory proteins, the WEE kinase and proteins of the retinoblastoma-related protein (RBR)/E2F/DP pathway. The review discusses recent developments in our understanding of the plant cell cycle machinery and highlights the role of the cell cycle in plant development.

Figure 1

Schematic view of the various developmental and environmental signals that impinge on the plant cell cycle. For details, see text.

Figure 2

Examples of phenotypes caused by ectopic overexpression of cell cycle genes. (A, C, E, G, I, K) Wild-type plants and structures. (B, D) Plants constitutively overexpressing KRP2, a CDK inhibitor. Note the serrated leaves (B) composed of fewer, but much larger cells (D) (De Veylder et al, 2001; ©2001, American Society of Plant Biologists, reprinted with permission). (F, H) Overexpression of E2Fa leading to the formation of larger cotyledons (F, arrow), consisting of a larger number of cells with a smaller average size (H) (De Veylder et al, 2002). (J) Trichome-specific overexpression of CYCD3;1 causing the formation of multicellular hairs, whereas the wild-type hairs are unicellular (I) (Schnittger et al, 2002; © 2002, National Academy of Sciences, USA, reprinted with permission). (L) Constitutive overexpression of a dominant-negative CDKB1;1 interfering with the development of stomata. Whereas the wild-type stomata are built of two guard cells (K), the transgenic stomata often consist of only one kidney-shaped cell (L) (Boudolf et al, 2004a; © 2004, American Society of Plant Biologists, reprinted with permission).