Isolation of a FLORICAULA/LEAFY putative orthologue from Chenopodium rubrum and its expression during photoperiodic flower induction

The short day plant (SDP) Chenopodium rubrum L. (ecotype 374) has been a model plant for physiological studies on photoperiodic flower initiation for many years. Using reverse transcription-polymerase chain reaction (RT-PCR) we identified a C. rubrum putative orthologue of the FLORICAULA/LEAFY genes from Antirrhinum majus and Arabidopsis thaliana, referred to as CrFL. Kinetics of the expression of CrFL in the apical part of C. rubrum during flower induction was followed using semi-quantitative RT-PCR. Expression of CrFL in vegetative apices was relatively high and started to decrease after 6 h of darkness (critical photoperiod). It reached its minimum between the 9th and the 12th hour of the 12-h inductive dark span, stayed at low levels for the next 6 h and increased again after the flower induction was completed. Our results indicate that expression of CrFL is regulated by photoperiod and that it is important both in the vegetative state and during flower development.