铁皮石斛热激蛋白HSP70家族基因鉴定及温度胁迫下的表达分析

Genome-wide Identification and Expression Analysis Under Temperature Stress of HSP70 Gene Family in Dendrobium catenatum

为研究铁皮石斛(Dendrobium catenatum Lindl.)应对温度胁迫的响应机制,利用生物信息学方法对其热激蛋白HSP70家族基因进行鉴定。荧光定量PCR技术分析它们的组织表达特性,以及在高温(42℃)和低温(4℃)胁迫下的表达模式。从其基因组中鉴定出10个家族成员,其编码的氨基酸数在628~702之间,分子量在69.65~75.15 kD,理论等电点在5.12~6.18之间。进化树分析可将这10个蛋白分为4个亚族,且每个亚族蛋白的保守基元相似。基因结构分析表明,HSP70的内含子数量为1~7不等。HSP70在铁皮石斛中的表达具有组织特异性,在合蕊柱中最高。低温处理铁皮石斛组培苗后,DcHSP70-1和DcHSP70-7呈上调表达,推测其响应低温胁迫;高温胁迫下,DcHSP70-2、DcHSP70-3、DcHSP70-5和DcHSP70-7的表达量上调比较明显,推测它们在响应高温胁迫中起主要作用。

In order to study the resistant mechanism of Dendrobium catenatum response to temperature stress,the heat shock protein 70(HSP70)gene families were identified using bioinformatics methods. Meanwhile,the expression profiles of HSP70 genes in different tissues and under high(42 ℃)and low(4 ℃)temperatures were assayed by quantitative real time PCR(qRT-PCR)method. The results showed that 10 HSP70 genes were identified from D. catenatum,which encode 628 to 702 amino acids,the molecular weight was between 69.65 to 75.15 kD, and the theoretical isoelectric point ranged from5.12 to 6.18. The HSP70 proteins were divided into four subgroups by phylogenetic tree analysis,and the conserved motifs of each subgroup were similar. Structural analysis showed that the number of introns in HSP70 gene varied from one to seven. Spatial expression pattern analysis showed that HSP70 gene expression was tissue specific and the highest expression was found in gynostemium. The expression levels of DcHSP7-1 and DcHSP70-7 increased after low temperature treatment, which indicated that DcHSP70-1 and DcHSP70-7 responded to cold stress. While the relative expression of DcHSP70-2,DcHSP70-3,DcHSP70-5 and DcHSP70-7 was up-regulated obviously under high temperatuer,then we can speculate that these genes play key roles in response to heat stress.