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[Objectives] AgHSFB2 of celery (Apium graveolens L.) belongs to HSF gene family, which plays key roles in protecting plants from heat stress. Studying the related genes and proteins of the HSF family is important to exploring the heat resistant mechanism of celery. [ Methods ] AgHSFB2 gene was isolated from three celery cultivars, 4 Liuhehuangxinqin' 'Jinnanshiqin' and 'Ventura', respectively. Sequence analysis and quantitative real-time PCR were used to detect the expression profdes under different temperature treatments(4,38 and 42 °C ). [Results]Sequence analysis indicated that the ORF length of AgHSFB2 was 918 bp,encoding 305 amino acids. The predicted molecular weight of AgHSFB2 was 34 048 and pi value was 5.09. Phylogenetic analysis between AgHSFB2 of celery and HSF family factors in Arabidopsis showed that AgHSFB2 was close to HSFB2a and HSFB2b in the HSFB2 subgroup. Phylogenetic analysis among differnt plants illuminated that the HSFB2 of celery was close to Solarium tuberosum and Solarium lycopersicum from Solanaceae. Structure analysis implied that AgHSFB2 was composed of 3 a helixes and 4 p sheets. Quantitative real-time PCR analysis demonstrated that AgHSFB2 was tissue-specific and cultivars-specific. AgHSFB2 was mainly expressed in leaves of the three celery cultivars. Under different temperature treatments (4,38 and 42 °C ) , the expression profiles of AgHSFB2 had similar response trend, but the response time and intensity of AgHSFB2 had significant differences. AgHSFB2 of 'Ventura' was greatly upregulated after 2 h in 4 °C and 38 °C treatments. AgHSFB2 in 'Jinnanshiqin' and 'Ventura' both were upregulated obviously after 1 h in 42 °C treatment. [ Conclusions] The excessive expression of heat shock proteins can be induced by the overexpression of AgHSFB2 gene, helping the plants resist damages from the high temperature stress. [ABSTRACT FROM AUTHOR]

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]