Isolation and expression profiles analysis of AP2 / ERF-3 group transcription factor from Camellia sinensis.

In higher plant, ERF subfamily transcription factor involved in growth and development, signal transduction,and regulated the expression of related genes in order to improve the resistance to the abiotic stresses, such as high temperature, low temperature, drought and salt damage. Here, the molecular characterization, tissue expression and abiotic stresses response of the AP2/ ERF-B3 group transcription factor in different tea varieties were investigated. The results will contribute to understanding the roles of AP2/ ERF-B3 transcription factor in tea plant(Camellia sinensis). The CsERF-B3 genes,which encode to the AP2/ ERF-B3 transcription factor,were cloned by RT-PCR method using cDNA as template, from two tea plant cultivars' Anjibaicha' and 'Yingshuang', respectively. Then, cDNA and deduced amino acid sequence, phylogenetic tree, physical and chemical characterization, hydrophilicity/ hydrophobicity, molecular modeling and disordered residues were analyzed by related software. The expression profiles of the CsERF-B3 gene in the tissues of tea plants(roots, stems, leaves and flowers)were detected. The leaves, which were respectively treated with 2 h under 4 kinds of abiotic stresses(4 °C low temperature, 38 °C high temperature,200 g·L-1 PEG and 200 mmol·L-1 NaCl), were also detected by the quantitative real-time PCR analysis. Then,the multiple comparisons and plotting were finished by using Excel program. The results of sequence alignments and phylogenetic analysis showed that lengths of CsERF-B3 genes from the two tea plant cultivars were 639 bp, encoding 212 amino acids, respectively. The transcription factor of CsERF-B3 between 110-145 amino acid sites contained the AP2 DNA binding domain where both contained a conservative WLG and YRG element. The CsERF-B3 of tea plants was a typical AP2/ ERF family transcription factors in plants. Homologous phylogenetic tree showed that this ERF transcription factor was the closest relatives to AtERF1(AT4G17500.1)and AtERF2(AT5G47220.1)in Arabidopsis, they all belong to group B3,one group of the ERF subfamily transcription factors. The CsERF-B3 was hydrophilic protein and chemical properties were similar among related species. The CsERF-B3 and AtERF1 had similar three-dimension structure and disordered residues feature. The homologies of ABERF and YSERF were 92.1% and 93.7% compared with the DNA binding domain of crystal structure PDB ID:1gcc,respectively. The highest expression levels of the CsERF-B3 genes were found in the root of tea plant. The CsERF-B3 gene could respond quickly to high temperature(38 °C), low temperature (4 °C) and high-salinity(200 mmol·L-1 NaCl) treatments, respectively. The expression of CsERF-B3 gene was induced by abiotic stresses in tea plant, indicating that the transcription factor of AP2/ ERF-B3 plays an important role in the regulation of abiotic stress in tea plant. [ABSTRACT FROM AUTHOR]