Constitutive expression of EIL-like transcription factor partially restores ripening in the ethylene-insensitive Nr tomato mutant.
Climacteric fruit ripening is regulated by the phytohormone ethylene. ETHYLENE-INSENSITIVE3 (EIN3) is a transcription factor that functions downstream from the ethylene receptors in the Arabidopsis ethylene signal transduction pathway. Three homologues of the Arabidopsis EIN3 gene have been identified in tomato, Lycopersicon esculentum, EIN3-like or LeEIL, LeEIL1, LeEIL2, and LeEIL3. These transcription factors have been proposed to be functionally redundant positive regulators of multiple ethylene responses. In order to test the role of such factors in the ethylene signal transduction pathway during ripening, EIL1 fused to green fluorescent protein (GFP) has been over-expressed in the ethylene-insensitive non-ripening Nr mutant of tomato. Increased levels of LeEIL1 compensated for the normally reduced levels of LeEIL1 in the Nr mutant, and transgenic Nr plants that exhibited high-level constitutive expression of LeEIL1GFP phenotypically resembled wild-type plants, the fruit ripened and the leaves exhibited epinasty, unlike Nr plants. The EIL1GFP fusion protein was located in the cell nuclei of ripe tomato fruit. The mRNA profile of these plants showed that the expression of certain ethylene-dependent ripening genes was up-regulated, including polygalacturonase and TOMLOX B. However, not all ripening genes and ethylene responses, such as seedling triple response, were restored. These results demonstrate that expressing candidate genes in the Nr ethylene-insensitive background is a valuable general approach for testing the role of putative downstream components in the ethylene-signalling pathway.
Chen
Guoping
G
Genetic Engineering Research Centre, College of Bioengineering, Chongqing University, Chongqing 400030, PR China.
Alexander
Lucille
L
Grierson
Donald
D
D029681:Arabidopsis Proteins / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics / Q000302:isolation & purification; D004268:DNA-Binding Proteins; D005030:Ethylenes / Q000494:pharmacology*; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D017930:Genes, Reporter; D008164:Luminescent Proteins / Q000235:genetics; D018551:Solanum lycopersicum / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics; D010937:Plant Growth Regulators / Q000494:pharmacology*; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development; D010940:Plant Proteins / Q000235:genetics*; D030821:Plants, Genetically Modified; D018749:RNA, Plant / Q000235:genetics / Q000302:isolation & purification; D015183:Restriction Mapping; D014157:Transcription Factors / Q000235:genetics*
D029681:Arabidopsis Proteins; D001426:Bacterial Proteins; D018744:DNA, Plant; D004268:DNA-Binding Proteins; C106987:EIN3 protein, Arabidopsis; D005030:Ethylenes; D008164:Luminescent Proteins; D009687:Nuclear Proteins; D010937:Plant Growth Regulators; D010940:Plant Proteins; D018749:RNA, Plant; D014157:Transcription Factors; C054562:yellow fluorescent protein, Bacteria; C036216:ethylene