Light signals and flowering.
Physiological studies over a long period have shown that light acts to regulate flowering through the three main variables of quality, quantity, and duration. Intensive molecular genetic and genomic studies with the model plant Arabidopsis have given considerable insight into the mechanisms involved, particularly with regard to quality and photoperiod. For photoperiodism light, acting through phytochromes and cryptochromes, the main photomorphogenetic photoreceptors, acts to entrain and interact with a circadian rhythm of CONSTANS (CO) expression leading to transcription of the mobile floral integrator, FLOWERING LOCUS T (FT). The action of phytochromes and cryptochromes in photoperiodism is augmented by ZEITLUPE (ZTL) and FLAVIN-BINDING, KELCH REPEAT, F-BOX (FKF1) acting as accessory photoreceptors on entrainment and interaction, respectively. Light quality acts independently of the circadian system through Phytochromes B, D, and E to regulate FT. Light quantity effects, on the other hand, are still incompletely understood but are likely to be linked either directly or indirectly to patterns of assimilate partitioning and resource utilization within the plant.
Thomas
Brian
B
Warwick HRI, University of Warwick, Wellesbourne CV35 9EF, UK. brian.thomas@warwick.ac.uk
D017360:Arabidopsis / Q000254:growth & development* / Q000378:metabolism / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D002940:Circadian Rhythm; D056931:Cryptochromes; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D005420:Flavoproteins / Q000378:metabolism / Q000502:physiology; D035264:Flowers / Q000254:growth & development* / Q000378:metabolism / Q000502:physiology; D008027:Light; D008954:Models, Biological; D017440:Photoperiod; D010834:Phytochrome / Q000378:metabolism / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D029681:Arabidopsis Proteins; C092776:CONSTANS protein, Arabidopsis; C538962:CRY1 protein, Arabidopsis; D056931:Cryptochromes; D004268:DNA-Binding Proteins; C410504:FKF1 protein, Arabidopsis; C418905:FT protein, Arabidopsis; D005420:Flavoproteins; D014157:Transcription Factors; C410503:ZTL protein, Arabidopsis; D010834:Phytochrome