Co-expression of an ethylene receptor gene, ERS1, and ethylene signaling regulator gene, CTR1, in Delphinium during abscission of florets.
We are trying to determine the mechanisms responsible for ethylene-induced floret abscission in cut flowers of Delphinium and recently identified an ethylene receptor gene, ERS1, and studied its response to ethylene treatment. In order to identify additional components of the ethylene response network in Delphinium, we performed 3' and 5' rapid amplification of cDNA ends (RACE) using the consensus sequence of the serine/threonine kinase domain of the ethylene signaling regulator gene (CTR1) involved in the constitutive triple response (CTR) to ethylene. The full-length cDNA (2754 nt) encoded a protein of 800 amino acids, which contained the expected serine/threonine kinase domain, the consensus ATP-binding site, and the serine/threonine kinase catalytic site. The protein had quite high (>50%) overall identity to CTR1 from Arabidopsis and tomato, and 70-75% identity in the catalytic site. The amount of mRNA encoding both CTR1 and ERS1 more than doubled within 6 h in cut florets incubated in the presence of exogenous ethylene. Similarly, the amount of ERS1 transcript doubled in florets within 6 d of harvesting, presumably in response to endogenous ethylene, while CTR1 mRNA increased to about 40% over the same period. However, in the presence of silver thiosulfate (STS), an ethylene inhibitor, the level of both transcripts remained essentially unchanged for the first 8 d before declining to very low levels. Florets on the control plants had almost completely abscised by 6 d, but the florets on STS-treated plants had not abscised by 20 d, by which time the flowers were almost dead. The data are consistent with the hypothesis that endogenous ethylene evokes the accumulation of both these transcripts (and their encoded proteins), thereby speeding up abscission and reducing the useful shelf life of the cut flowers.
Laboratory of Molecular Cell Biology, Department of Biological Resources, Faculty of Agriculture, Ehime University, Matsuyama 7908566, Japan.
Satoshi
S
Kuroda
Yukio
Y
Hirose
Masaya
M
Shiraishi
Eric
E
Davies
Shunnosuke
S
Abe
D000595:Amino Acid Sequence; D001483:Base Sequence; D016384:Consensus Sequence; D031882:Delphinium / Q000502:physiology*; D005030:Ethylenes / Q000378:metabolism*; D035264:Flowers / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D010937:Plant Growth Regulators / Q000502:physiology*; D010940:Plant Proteins / Q000235:genetics*; D011494:Protein Kinases / Q000235:genetics*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics*; D011956:Receptors, Cell Surface / Q000235:genetics*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D005030:Ethylenes; D010937:Plant Growth Regulators; D010940:Plant Proteins; D011956:Receptors, Cell Surface; C083750:ethylene receptors, plant; C036216:ethylene; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases