Abstract: Ethylene receptor is the initial composition of ethylene perception and signal transduction. In order to investigate the function of melon ethylene receptor gene Cm-ETR1 during fruit ripening in melon, a pair of gene specific primers was designed based on the cDNA nucleotide sequence of Cm-ETR1 gene from melon（accession number：AF054806）in GenBank. The full-length cDNA of Cm-ETR1 was cloned by RT-PCR from ripening fruit of melon（Cucumis melo L. cv. Hetao）, and was submitted to GenBank（accession number：EF495185）. Sequence analysis showed that the cloned cDNA was 2 256 bp long, contained an 2 223 bp ORF that encoded a polypeptide of 740 amino acids, and the cDNA sequence was consistent with that of reported melon variety cantalupenis ETR1 cDNA. Cm-ETR1 protein phylogenetic tree analysis show that the ethylene receptor protein is highly conserved in all species, and Cm-ETR1 is highest similarity with cucumber ethylene receptor protein by 99% consistency, and lowest similarity of longan ethylene receptor protein by 86% consistency. Quantitative PCR analysis indicated that the expression level of Cm-ETR1 gene was increased, which coincided with the raise of the melon fruit ethylene production and fruit ripening process, and peaked at ethylene climacteric stage. The amount of endogenous ethylene had a positive correlation with the expression of Cm-ETR1 gene. It reveals that Cm-ETR1 gene may play an important role in fruit ripening.

Key words: Melon, Ethylene receptor, Cm-ETR1, Fruit ripening, Gene expression