Cloning and expressional response analysis of AgHSFB2 under different temperature treatments in celery.

[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]