Sl-ERF2, a tomato ethylene response factor involved in ethylene response and seed germination.
Ethylene response factors (ERFs) are plant transcriptional regulators mediating ethylene-dependent gene expression via binding to the GCC motif found in the promoter region of ethylene-regulated genes. We report here on the structural and functional characterization of the tomato Sl-ERF2 gene that belongs to a distinct class of the large ERF gene family. Both spliced and unspliced versions of Sl-ERF2 transcripts were amplified from RNA samples and the search in the public tomato expressed sequence tag (EST) database confirmed the existence of the two transcript species in a number of cDNA libraries. The unspliced transcript contains two open reading frames yielding two hypothetical proteins, a small highly truncated version lacking the APETALA2 domain and a bigger protein lacking the N-terminal MCGGAAI(I)/(L) consensus peptide specific to ERF members from subfamily IV. Nevertheless, functional Sl-ERF2 protein may only derive from spliced transcripts since, depending on the tissue, the level of the spliced transcript is much higher than that of the unspliced transcript. Sl-ERF2 is expressed in all plant tissues tested, though its transcript accumulates preferentially in germinating seeds and ripening fruit. Overexpression of the Sl-ERF2 gene in transgenic tomato lines results in premature seed germination and enhanced hook formation of dark-grown seedlings, which is indicative of increased ethylene sensitivity. The expression of the mannanase2 gene is upregulated in Sl-ERF2-overexpressing seeds, suggesting that Sl-ERF2 stimulates seed germination through the induction of the mannanase2 gene. It is noteworthy that the exaggerated hook phenotype is abolished when ethylene perception is blocked, strongly suggesting that Sl-ERF2 requires other ethylene-dependent components to impact the hook formation process.
Pirrello
Julien
J
UMR990 INRA/INP-ENSA Toulouse Génomique et Biotechnologie des Fruits Avenue de l'Agrobiopole, BP 32607, 31326 Castanet-Tolosan cedex, France.
Jaimes-Miranda
Fabiola
F
Sanchez-Ballesta
Maria Teresa
MT
Tournier
Barthélémy
B
Khalil-Ahmad
Qaiser
Q
Regad
Farid
F
Latché
Alain
A
Pech
Jean Claude
JC
Bouzayen
Mondher
M
D017398:Alternative Splicing; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D005030:Ethylenes / Q000378:metabolism*; D005638:Fruit / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D018525:Germination; D018551:Solanum lycopersicum / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D008969:Molecular Sequence Data; D010641:Phenotype; D010940:Plant Proteins / Q000235:genetics / Q000502:physiology; D030821:Plants, Genetically Modified; D012639:Seeds / Q000235:genetics / Q000254:growth & development*; D014170:Transformation, Genetic
D004268:DNA-Binding Proteins; D005030:Ethylenes; D010940:Plant Proteins; C036216:ethylene