Cloning And Expression Analysis Of The Gene Of A Key Factor CTR1 In Melon Ethylene Signal Transduction Pathway

The gaseous hormone ethylene has very important effects during plant growth and development, such as seed germination, leaf senescence and fruit ripening, etc. Its physiological role was achieved by the ethylene signal transduction pathway, ultimately. In this experiment, the cDNA encoding Constitutive Triple Respond 1(CTR1) which is related the ethylene signal transduction was amplified from ripening fruit of melon. The expression characterization of this gene during melon fruit development and ripening was analyzed. The results are showed below:1 The cDNA of CTR1 was amplified by reverse transcription polymerase chain reaction (RT-PCR) from ripening fruit of melon. The length cDNA of CmCTRl is 2613 bp which codes for a polypeptide of 870 amino acids. The cDNA includes a whole open reading frame. The relative molecular weight of Cm-CTR1 was 96.09KD and its isoelectric point was 5.71. This sequence has been submitted to GenBank, whose accession number is HQ848663. This structure has all the eleven conserved motifs of Ser/Thr protein kinase domains, including ATP-binding signature(located in 562-569) and Ser/Thr protein kinase active site consensus sequence(located in 716-723), and the deduced amino acids sequences are consistent with those of the Arabidopsis thaliana, Lycopersicon esculentum, Rosa hybrid preciously. By using NCBI's BLASTP, we analysised the conserved domains of the Cm-CTR1 amino acid sequence and obtained six whole conserved domains. They are Pkinase-Tyr domain, S-Tkc domain, TyrKc domain, Pkinase domain, STYKc domain and SPS1 domain respectively. The CmCTR1 was 54.04-66.74% identical in amino acid sequence to At-CTR1, Pp-CTR1 and Le-CTR1, etc.2 Quantitative real-time PCR analysis showed that the expression of CmCTR1 was increased obviously from the 15th day to the 20th day after pollination and the transcription level in the 20th day was 2.5 times as much as that of 15th day. Then, the transcription of CmCTR1 was tended to be stable. The transcription level of CmCTR1 decreased from the 40th day to the 45th day.