Cloning and expression characteristics of ethylene receptor gene TtETR1 in response to salt stress in Tritipyrum

【Objective】Ethylene receptor gene TtETR1 was cloned from salt-tolerant Tritipyrum，and its expression characteristics were investigated in order to lay foundation for TtETR1 gene function analysis and wheat salt-tolerant breeding.【Method】Tritipyrum（2n=8x=56）was selected as material. According to the previous transcriptome data，special TtETR1 gene was screened from salt-tolerant Tritipyrum under salt stress. The cDNA sequence was obtained by homologous cloningand analyzed by bioinformatics softwares. Real-time quantitative fluorescence PCR（qRT-PCR）was used to detect its expression characteristics under salt stress.【Result】The full-length open reading frame（ORF）of TtETR1 gene was 2310 bp，encoding 769 amino acid residues. The upstream 2000 bp promoter contained functional elements such as methyl jasmonate and abscisic acid signal response，drought and anaerobic induction and meristem expression. The molecular weight of TtETR1 protein was 85.76 kD and the isoelectric point（pI）was 6.22. TtETR1 was a secretory protein with transmembrane structure. It was located in the cell plasma membrane，and contained ethylene receptor ETR，GAF（cGMP phosphodiesterase-adenylylcyclase-FhlA），HisKA（histidine kinase A），and HATPase domains. The secondary structure mainly consisted of α-helix and random coil. It contained domains like REC_ETR-like，HATPase_ETR2_ERS2-EIN4- like，cGMP phosphodiesterase-adenylate cyclase-FHLA（GAF）and histidine kinase（HisKA），and site for phosphorylation modification and regulation of ethylene signal transduction dominated by serine and supplemented by threonine. The relative expression level of TtETR1 gene in roots under salt stress was the highest，which were 1.6 times and 2.8 times of that in stems and leaves respectively，and significantly higher than that in non-salt stress treatment（control）（P<0.05）. However，after restoration treatment，the relative expression level of TtETR1 gene decreased rapidly to the control level， which was consistent with the results of transcriptome data analysis.【Conclusion】TtETR1 gene is highly expressed in roots induced by salt stress，thus improving plant salt tolerance.