Flowering in time: genes controlling photoperiodic flowering in Arabidopsis

Successful sexual reproduction in plants relies upon the strict coordinatio n of flowering time with favourable seasons of the year. One of the most im portant seasonal cues for the model plant Arabidopsis thaliana (Arabidopsis ) is day length. Genes influencing flowering time in Arabidopsis have been isolated, some of which are involved in the perception and signalling of da y length. This review discusses recent progress that has been made in under standing how Arabidopsis integrates environmental and internal signals to e nsure a sharp transition to flowering and new insights on the role of the c ircadian clock in controlling the expression of genes that promote flowerin g in response to day length.