CONSTANS activates SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 through FLOWERING LOCUS T to promote flowering in Arabidopsis.
CONSTANS (CO) regulates flowering time by positively regulating expression of two floral integrators, FLOWERING LOCUS T (FT) and SUPPRESSOR OF OVEREXPRESSION OF CO 1 (SOC1), in Arabidopsis (Arabidopsis thaliana). FT and SOC1 have been proposed to act in parallel pathways downstream of CO based on genetic analysis using weak ft alleles, since ft soc1 double mutants showed an additive effect in suppressing the early flowering of CO overexpressor plants. However, this genetic analysis was inconsistent with the sequential induction pattern of FT and SOC1 found in inducible CO overexpressor plants. Hence, to identify genetic interactions of CO, FT, and SOC1, we carried out genetic and expression analyses with a newly isolated T-DNA allele of FT, ft-10. We found that ft-10 almost completely suppressed the early flowering phenotype of CO overexpressor plants, whereas soc1-2 partially suppressed the phenotype, suggesting that FT is the major output of CO. Expression of SOC1 was altered in gain- or loss-of-function mutants of FT, whereas expression of FT remained unchanged in gain- or loss-of-function mutants of SOC1, suggesting that FT positively regulates SOC1 to promote flowering. In addition, inactivation of FT caused down-regulation of SOC1 even in plants overexpressing CO, indicating that FT is required for SOC1 induction by CO. Taken together, these data suggest that CO activates SOC1 through FT to promote flowering in Arabidopsis.
Yoo
Seung Kwan
SK
Plant Signaling Network Research Center, School of Life Sciences and Biotechnology, Korea University, Seoul.
Chung
Kyung Sook
KS
Kim
Joonki
J
Lee
Jeong Hwan
JH
Hong
Sung Myun
SM
Yoo
Seong Jeon
SJ
Yoo
So Yeon
SY
Lee
Jong Seob
JS
Ahn
Ji Hoon
JH
D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D035264:Flowers / Q000254:growth & development; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D026161:MADS Domain Proteins / Q000235:genetics*; D008954:Models, Biological; D010641:Phenotype; D017440:Photoperiod; D030821:Plants, Genetically Modified; D014157:Transcription Factors / Q000235:genetics*
C419046:AGL20 protein, Arabidopsis; D029681:Arabidopsis Proteins; C092776:CONSTANS protein, Arabidopsis; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; C418905:FT protein, Arabidopsis; D026161:MADS Domain Proteins; C036483:T-DNA; D014157:Transcription Factors