spacer gif spacer gif spacer gif spacer gif spacer gif
QUICK SEARCH:   [advanced]


spacer gif
     Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents    

Right arrow Help viewing high resolution images
Right arrow Return to article
(Downloading may take up to 30 seconds.
If the slide opens in your browser, select File -> Save As to save it.)
Click on image to view larger version.



Fig. 1. Pathways controlling flowering-time in Arabidopsis. The flowering-time pathways control the expression of the floral pathway integrators SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1), FT and LEAFY (LFY). These genes encode proteins that activate the floral meristem identity (FMI) genes APETALA1 (AP1), APETALA2 (AP2), FRUITFULL (FUL), CAULIFLOWER (CAL) and LFY, which convert the vegetative meristem to a floral fate. Recent expression data has indicated that FUL may also act as a floral integrator (Schmid et al., 2004). The photoperiod, gibberellin, light-quality and ambient-temperature pathways activate floral pathway integrators. The CONSTANS (CO) transcription factor functions in the photoperiod pathway; long-day photoperiods promote flowering by circadian clock (CLOCK) dependent and independent mechanisms, which control the activity of CO. Activation of flowering is antagonised by the floral repressors encoded by (shown in green) FLOWERING LOCUS C (FLC), FLOWERING LOCUS M (FLM), TERMINAL FLOWER1 (TFL1), TERMINAL FLOWER2 (TFL2), SHORT VEGETATIVE PHASE (SVP), TARGET OF EAT1 (TOE1), TARGET OF EAT2 (TOE2), SCHNARCHZAPFEN (SNZ), SCHLAFMUTZE (SMZ) and EMBRYONIC FLOWER1/2 (EMF1, EMF2). TFL1 may also be downstream of CO, as it is induced after CO activation (Simon et al., 1996). FLC expression is controlled by a number of different pathways. The genes shown in purple, FRIGIDA (FRI), FRIGIDA-LIKE1 (FRL1), FRIGIDA-LIKE2 (FRL2), PHOTOPERIOD INSENSITIVE EARLY FLOWERING1 (PIE1), AERIAL ROSETTE1 (ART1), EARLY UNDER SHORT DAYS4 (ESD4), VERNALIZATION INDEPENDENCE3 (VIP3) and VERNALIZATION INDEPENDENCE4 (VIP4), encode proteins that promote FLC expression and delay flowering. FLC expression is downregulated in response to prolonged cold by proteins encoded by the genes (shown in blue) VERNALIZATION INSENSITIVE3 (VIN3), VERNALIZATION1 (VRN1) and VERNALIZATION2 (VRN2), and also by proteins encoded by the genes of the autonomous pathway (red): FCA, FY, LUMINIDEPENDENS (LD), FLOWERING LOCUS D (FLD), FVE, FLOWERING LOCUS K (FLK) and FPA. The distinction between potential transcriptional and post-transcriptional functions of genes of the autonomous pathway is not made here, but is shown more clearly in Fig. 3.





Right arrow Return to article