XVI International Botanical Congess

In normal plant development, cell cycle activity is confined to meristems, mutations in meristem identity genes lead to aberrant organogensis. However, the existence of a meristem is not necessary for cell cycle activity as is shown by division of cultured cells. The link between meristem identity genes and cell cycle genes is thus not absolute. However, there is a tight linkage between the three 'levels' of gene expression that drive the cycle itself. The three levels are first, the overall control of the cycle as seen, e.g., in the activity of the CDKs, second, the complex network of mechanisms (including checkpoints) that link overall control to the phases of the cycle and third, the enzymes and other proteins that mediate the specific events of the cycle. This talk deals with this third level, focussing on the genes encoding proteins involved in the initiation of DNA replication.