芹菜热激转录因子基因AgHSFB2的克隆及不同温度处理下的表达响应

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

[目的]热激转录因子HSF(heat shock transcription factor)在植物遭遇高温胁迫时起关键的调节作用,研究芹菜热激转录因子基因及相关蛋白的结构、功能对探究芹菜耐热机制、培育耐热新品种有重要作用。[方法]以‘六合黄心芹’‘津南实芹’和美国西芹‘文图拉’为试验材料,分离并克隆出Ag HSFB2基因,分析相关序列并采用实时定量荧光PCR技术检测该基因在不同温度(4、38和42℃)下的表达响应情况。[结果]研究发现该基因含有1个918 bp的开放阅读框,编码305个氨基酸。推测其蛋白质相对分子质量为34 048,理论等电点p I值为5.09。芹菜Ag HSFB2与拟南芥中HSF蛋白进行比对构建进化树,发现Ag HSFB2与拟南芥HSFB2a和HSFB2b进化距离最近,该基因属于HSFB2亚族。芹菜Ag HSFB2与茄科的番茄、马铃薯相应蛋白的亲缘关系较近。Ag HSFB2蛋白的高级结构主要由3个α螺旋和4个β折叠组成。Ag HSFB2基因主要在芹菜的叶中表达,具有组织、品种特异性,同时对4、38和42℃等多种温度信号有明显响应。该基因对温度胁迫的响应时间和强度有品种的差异:4和38℃处理下‘文图拉’均在2 h有明显上调表达;42℃处理下‘津南实芹’和‘文图拉’均在1 h有明显上调表达。[结论]高温胁迫下Ag HSFB2基因可诱导下游热激蛋白大量表达,帮助植物抵御高温胁迫所带来的伤害。

[ Objectives ] AgHSFB2 of celery （Apium graveolens L. ）belongs to I-ISF 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 cuhivars, ‘Liuhehuangxinqin＇‘ Jinnanshiqin＇ and ‘ Ventura＇, respectively. Sequence analysis and quantitative real-time PCR were used to detect the expression profiles under different temperature treatments（4,38 and 42 ℃）. [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. Phylo- genetic analysis among differnt plants illuminated that the I-ISFB2 of celery was close to Solanum tuberosum and Solanum lycopersicum from Solanaceae. Structure analysis implied that AgHSFB2 was composed of 3 ct helixes and 4 13 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 ℃ ）, the expression profiles of AgHSFB2 had similar response trend,hut the response time and intensity of AgHSFB2 had significant differences. AgHSFB2 of＇ Ventura＇ was greatly upregulated after 2 h in 4 ℃ and 38 ℃ treatments. AgHSFB2 in＇ Jinnanshiqin＇ and＇ Ventura＇ both were upregulated obviously after 1 h in 42℃.