The SOC1 MADS-box gene integrates vernalization and gibberellin signals for flowering in Arabidopsis.
The floral transition in Arabidopsis is regulated by at least four flowering pathways: the long-day, autonomous, vernalization, and gibberellin (GA)-dependent pathways. Previously, we reported that the MADS-box transcription factor SUPPRESSOR OF OVEREXPRESSION OF CO 1 (SOC1) integrates the long-day and vernalization/autonomous pathways. Here, we present evidences that SOC1 also integrates signaling from the GA-dependent pathway, a major flowering pathway under non-inductive short days. Under short days, the flowering time of GA-biosynthetic and -signaling mutants was well correlated with the level of SOC1 expression; overexpression of SOC1 rescued the non-flowering phenotype of ga1-3, and the soc1 null mutant showed reduced sensitivity to GA for flowering. In addition, we show that vernalization-induced repression of FLOWERING LOCUS C (FLC), an upstream negative regulator of SOC1, is not sufficient to activate SOC1; positive factors are also required. Under short days, the GA pathway provides a positive factor for SOC1 activation. In contrast to SOC1, the GA pathway does not regulate expression of other flowering integrators FLC and FT. Our results explain why the GA pathway has a strong effect on flowering under short days and how vernalization and GA interact at the molecular level.
Moon
Jihyun
J
School of Biological Sciences, Seoul National University, Seoul 151-742, Korea.
Suh
Sung-Suk
SS
Lee
Horim
H
Choi
Kyu-Ri
KR
Hong
Choo Bong
CB
Paek
Nam-Chon
NC
Kim
Sang-Gu
SG
Lee
Ilha
I
D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D035264:Flowers / Q000235:genetics* / Q000254:growth & development; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005875:Gibberellins / Q000494:pharmacology*; D026161:MADS Domain Proteins / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D017440:Photoperiod; D015398:Signal Transduction / Q000235:genetics* / Q000502:physiology
C419046:AGL20 protein, Arabidopsis; D029681:Arabidopsis Proteins; C418902:At5g10140 protein, Arabidopsis; C418905:FT protein, Arabidopsis; D005875:Gibberellins; D026161:MADS Domain Proteins