Cell-cycle control as a target for calcium, hormonal and developmental signals: the role of phosphorylation in the retinoblastoma-centred pathway

During the life cycle of plants, both embryogenic and post-embryogenic growth are essentially based on cell division and cell expansion that are under the control of inherited developmental programmes modified by hormonal and environmental stimuli. Considering either stimulation or inhibition of plant growth, the key role of plant hormones in the modification of cell division activities or in the initiation of differentiation is well supported by experimental data. At the same time there is only limited insight into the molecular events that provide linkage between the regulation of cell-cycle progression and hormonal and developmental control. Studies indicate that there are several alternative ways by which hormonal signalling networks can influence cell division parameters and establish functional links between regulatory pathways of cell-cycle progression and genes and protein complexes involved in organ development.