A CDC2 cDNA, PcCDC2, whose deduced amino acid sequence contains the conserved motifs characteristic of the PSTAIRE class of cyclin-dependent kinase has been isolated from Pinus contorta. The gymnosperm CDC2s are very similar and group together in a phylogenetic comparison, but the presence of a large gene family in Picea is not present in Pinus. During auxin-induced adventitious root development, the steady-state transcript levels of PcCDC2 show a linear increase the first 12 d after treatment. In untreated hypocotyl cuttings, the level of PcCDC2 expression is equal to the level of expression in roots and shoots harbouring meristems of high proliferation activity. The expression of PcCDC2 during adventitious root development does not coincide with histone H2A expression, a S-phase correlated marker. Therefore, the expression of PcCDC2 in hypocotyls suggests a state of competence in which the appropriate cells are capable of responding to auxin for adventitious root development.