Sl-ERF2, a Tomato Ethylene Response Factor Involved in Ethylene Response and Seed Germination

Abstract

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.

The Hevea brasiliensis AP2/ERF superfamily: from ethylene signalling to latex harvesting and physiological disease response

“…The second is an active transcript encoding the full-length protein. This type of regulation was also observed in the ERF-VII in tomato and Arabidopsis (Pirrello et al, 2006, Licausi et al, 2010b. Furthermore, post-transcriptional regulation of AP2/ERF genes by microRNAs was also demonstrated.…”

Transcriptional Regulation of the Ethylene Response Factor LeERF2 in the Expression of Ethylene Biosynthesis Genes Controls Ethylene Production in Tomato and Tobacco

“…This difference in a single amino acid is caused by the exchange of guanine (G) in LeERF2 to cytosine (C) in TERF2 in the cDNA sequence. In order to analyze the gene structure, PCR amplifications based on the known cDNA sequence using genomic DNA of the tomato as a template were performed, and the results indicated that there is an intron of 74 bp in the gene, which is consistent with the report of Pirrello et al (2006). Based on the similarities of TERF2 to LeERF2, it should be possible that TERF2 is an allele of LeERF2.…”

“…Overexpressing LeERF2 in tomato is known to elicit the typical triple response in the form of exaggerated apical hook formation in the absence of exogenous ethylene treatment, whereas treatment with a potent inhibitor of ethylene perception, 1-methylcyclopropene, prevented the formation of a complete hook (Pirrello et al, 2006), suggesting a role for LeERF2 in ethylene biosynthesis. To test this assumption, we generated overexpressing (TERF2-OEm) and antisense (TERF2-RI) LeERF2/TERF2 in tomato (cv Lichun).…”

“…Based on the similarities of TERF2 to LeERF2, it should be possible that TERF2 is an allele of LeERF2. Functional investigations showed that overexpressing LeERF2 in tomato elicited the typical triple response, with exaggerated apical hook formation in the absence of exogenous ethylene treatment, whereas treatment with 1-methylcyclopropene, a potent inhibitor of ethylene perception, prevented the formation of a complete hook (Pirrello et al, 2006), indicating that LeERF2 may have a role in ethylene biosynthesis. In this study, we found that TERF2, the allele of LeERF2, interacted with GCC box and DRE/ CRT and affected ethylene levels through transcriptional activation of expression of the genes for ethylene biosynthesis in tomato and tobacco.…”

SlARF4, an Auxin Response Factor Involved in the Control of Sugar Metabolism during Tomato Fruit Development

“…The relative transcript abundance was monitored on an ABI PRISM 7900HT sequencer using SYBR Green PCR Master Mix (Applied Biosystems). The relative expression for each gene of interest was calculated using the comparative threshold cycle values and the SlActin (forward 59-TGTCCCTATCTACGAGGGTTATGC-39, reverse 59-AGTTAAATCACGACCA-GCAAGAT-39) as an internal standard, as described previously (Pirrello et al, 2006).…”