071 Partial Sequence of Ethylene Receptor Genes in Carnations with Different Ethylene Sensitivity

Abstract

The plant hormone ethylene plays an important role in the senescence process of carnation flowers. Recently, various genes that concern ethylene responses have been cloned from many sources of plants. Our main aim is to compare the sequences of ethylene receptor genes among carnations with different ethylene sensitivities. Four carnations, `White Sim' (ethylene sensitive control), `Chinera' (lower ethylene sensitivity), 64-13 and 64-54 were used. The carnations temporarily named as 64-13 and 64-54 are our breeding lines with less ethylene sensitivity, thus better flower retention. Total RNA was extracted using SDS-phenol method. Putative ethylene receptor genes were cloned by RT-PCR using degenerate primers that correspond to the highly conserved regions of ETR1 and ERS genes. Two kinds of DNA fragments, ≈1 kb in the length encoding putative ethylene receptor genes were cloned from all samples. An ERS-type gene was cloned that is identical to the gene, known as DC-ERS2 (Accession No. AF034770). Another was ETR1-type gene, which has not been reported in carnations yet. That was 91% identical to the ETR1 gene from melon or apple at the translated amino acid level. The deduced amino acid sequences of ERS-type genes among four samples were almost the same. However there were five mutations in `Chinera', one mutation in 64-13 and two mutations in 64-54, compared to `White Sim' at the translated amino acid level. As they located rather conserved regions of the gene, it is expected to affect the less ethylene sensitivity of the carnations.