Analysis of the Arabidopsis shoot meristem transcriptome during floral transition identifies distinct regulatory patterns and a leucine-rich repeat protein that promotes flowering.
Flowering of Arabidopsis thaliana is induced by exposure to long days (LDs). During this process, the shoot apical meristem is converted to an inflorescence meristem that forms flowers, and this transition is maintained even if plants are returned to short days (SDs). We show that exposure to five LDs is sufficient to commit the meristem of SD-grown plants to flower as if they were exposed to continuous LDs. The MADS box proteins SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1) and FRUITFULL (FUL) play essential roles in this commitment process and in the induction of flowering downstream of the transmissible FLOWERING LOCUS T (FT) signal. We exploited laser microdissection and Solexa sequencing to identify 202 genes whose transcripts increase in the meristem during floral commitment. Expression of six of these transcripts was tested in different mutants, allowing them to be assigned to FT-dependent or FT-independent pathways. Most, but not all, of those dependent on FT and its paralog TWIN SISTER OF FT (TSF) also relied on SOC1 and FUL. However, this dependency on FT and TSF or SOC1 and FUL was often bypassed in the presence of the short vegetative phase mutation. FLOR1, which encodes a leucine-rich repeat protein, was induced in the early inflorescence meristem, and flor1 mutations delayed flowering. Our data contribute to the definition of LD-dependent pathways downstream and in parallel to FT.
Max Planck Institute for Plant Breeding Research, D-50829 Cologne, Germany.
Stefano
S
Torti
Fabio
F
Fornara
Coral
C
Vincent
Fernando
F
Andrés
Karl
K
Nordström
Ulrike
U
Göbel
Daniela
D
Knoll
Heiko
H
Schoof
George
G
Coupland
D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D035264:Flowers / Q000254:growth & development*; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D061346:Laser Capture Microdissection; D000090263:Leucine-Rich Repeat Proteins; D026161:MADS Domain Proteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D018519:Meristem / Q000235:genetics* / Q000254:growth & development; D049488:Phosphatidylethanolamine Binding Protein / Q000235:genetics / Q000378:metabolism; D017440:Photoperiod; D018520:Plant Shoots / Q000235:genetics / Q000254:growth & development; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D059467:Transcriptome
C419046:AGL20 protein, Arabidopsis; C097414:AGL8 protein, Arabidopsis; D029681:Arabidopsis Proteins; D002352:Carrier Proteins; C418905:FT protein, Arabidopsis; C441478:Flor1 protein, Arabidopsis; D000090263:Leucine-Rich Repeat Proteins; D026161:MADS Domain Proteins; D008565:Membrane Proteins; D049488:Phosphatidylethanolamine Binding Protein; D011506:Proteins; C500577:TSF protein, Arabidopsis