INCOMPOSITA: a MADS-box gene controlling prophyll development and floral meristem identity in Antirrhinum.
INCOMPOSITA (INCO) is a MADS-box transcription factor and member of the functionally diverse StMADS11 clade of the MADS-box family. The most conspicuous feature of inco mutant flowers are prophylls initiated prior to first whorl sepals at lateral positions of the flower primordium. The developing prophylls physically interfere with subsequent floral organ development that results in aberrant floral architecture. INCO, which is controlled by SQUAMOSA, prevents prophyll formation in the wild type, a role that is novel among MADS-box proteins, and we discuss evolutionary implications of this function. Overexpression of INCO or SVP, a structurally related Arabidopsis MADS-box gene involved in the negative control of Arabidopsis flowering time, conditions delayed flowering in transgenic plants, suggesting that SVP and INCO have functions in common. Enhanced flowering of squamosa mutants in the inco mutant background corroborates this potential role of INCO as a floral repressor in Antirrhinum. One further, hitherto hidden, role of INCO is the positive control of Antirrhinum floral meristem identity. This is revealed by genetic interactions between inco and mutants of FLORICAULA, a gene that controls the inflorescence to floral transition, together with SQUAMOSA. The complex regulatory and combinatorial relations between INCO, FLORICAULA and SQUAMOSA are summarised in a model that integrates observations from molecular studies as well as analyses of expression patterns and genetic interactions.
Masiero
Simona
S
Abteilung für Molekulare Pflanzengenetik, Max-Planck-Institut für Züchtungsforschung, 50829 Köln, Germany.
Li
Ming-Ai
MA
Will
Isa
I
Hartmann
Ulrike
U
Saedler
Heinz
H
Huijser
Peter
P
Schwarz-Sommer
Zsuzsanna
Z
Sommer
Hans
H
D000483:Alleles; D000595:Amino Acid Sequence; D032161:Antirrhinum / Q000378:metabolism* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000378:metabolism; D015152:Blotting, Northern; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D035264:Flowers; D005786:Gene Expression Regulation; D018506:Gene Expression Regulation, Plant; D018745:Genome, Plant; D018398:Homeodomain Proteins / Q000378:metabolism; D017403:In Situ Hybridization; D026161:MADS Domain Proteins / Q000235:genetics* / Q000502:physiology*; D008855:Microscopy, Electron, Scanning; D008954:Models, Biological; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D010802:Phylogeny; D010940:Plant Proteins / Q000378:metabolism; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000378:metabolism; D020798:Two-Hybrid System Techniques
D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D026161:MADS Domain Proteins; D010940:Plant Proteins; D012333:RNA, Messenger; C407549:SVP protein, Arabidopsis; D014157:Transcription Factors; C074081:SQUA protein, Antirrhinum majus; D004247:DNA