Ectopic expression of the petunia MADS box gene UNSHAVEN accelerates flowering and confers leaf-like characteristics to floral organs in a dominant-negative manner.
Several genes belonging to the MADS box transcription factor family have been shown to be involved in the transition from vegetative to reproductive growth. The Petunia hybrida MADS box gene UNSHAVEN (UNS) shares sequence similarity with the Arabidopsis thaliana flowering gene SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1, is expressed in vegetative tissues, and is downregulated upon floral initiation and the formation of floral meristems. To understand the role of UNS in the flowering process, knockout mutants were identified and UNS was expressed ectopically in petunia and Arabidopsis. No phenotype was observed in petunia plants in which UNS was disrupted by transposon insertion, indicating that its function is redundant. Constitutive expression of UNS leads to an acceleration of flowering and to the unshaven floral phenotype, which is characterized by ectopic trichome formation on floral organs and conversion of petals into organs with leaf-like features. The same floral phenotype, accompanied by a delay in flowering, was obtained when a truncated version of UNS, lacking the MADS box domain, was introduced. We demonstrated that the truncated protein is not translocated to the nucleus. Using the overexpression approach with both the full-length and the nonfunctional truncated UNS protein, we could distinguish between phenotypic alterations because of a dominant-negative action of the protein and because of its native function in promoting floral transition.
Ferrario
Silvia
S
Business Unit Bioscience, Plant Research International, 6700 AA, Wageningen, The Netherlands.
Busscher
Jacqueline
J
Franken
John
J
Gerats
Tom
T
Vandenbussche
Michiel
M
Angenent
Gerco C
GC
Immink
Richard G H
RG
D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D003001:Cloning, Molecular; D035264:Flowers / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D017353:Gene Deletion; D015870:Gene Expression; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D005799:Genes, Dominant / Q000235:genetics*; D017343:Genes, Plant / Q000235:genetics; D005816:Genetic Complementation Test; D026161:MADS Domain Proteins / Q000235:genetics / Q000378:metabolism*; D032306:Petunia / Q000235:genetics* / Q000254:growth & development* / Q000378:metabolism; D010641:Phenotype; D010802:Phylogeny; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011485:Protein Binding; D011523:Protoplasts / Q000378:metabolism; D013997:Time Factors; D020798:Two-Hybrid System Techniques
D026161:MADS Domain Proteins; D010940:Plant Proteins