黄瓜全基因组热激转录因子(HSFs)的鉴定与表达分析

Genome-wide identification,sequence characteristic and expression analysis of heat shock factors(HSFs)in cucumber

热激转录因子（Heat shock factors,HSFs）普遍存在于整个生物界.尽管植物HSFs的DNA结合域具有较高的保守性,但其结构特征、生物功能具有多样化的特点.本文利用黄瓜（Cucumis sativus L.）全基因组测序结果,运用生物信息学方法鉴定了黄瓜HSFs,并对其数量、序列特征、染色体定位以及系统发育关系等进行分析.结果表明,黄瓜至少含有21个HSFs基因家族成员,编码184 ～ 560个氨基酸,分子量21.2～62.3 kDa,等电点（PI）4.70～9.10;序列比对发现这些成员都具有转录因子特有的DNA结合域（DNA binding domain,DBD）;染色体定位分析表明,除Csa026480之外,其余HSFs不均匀分布在黄瓜7条染色体上.从拟南芥（Arabidopsis thaliana）和黄瓜HSFs系统发育树可以看出,这些转录因子分为3个分支,其中1分支进一步可分为3类（A、B、C类）,系统发育分析揭示黄瓜HSFs蛋白存在9对直系同源蛋白,3对旁系同源蛋白,表明HSF转录因子基因家族的多样化发生在黄瓜和拟南芥分化之前.EST表达分析发现这些热激转录因子参与黄瓜的果实、雌花和两性花的发育与形成;通过qRT-PCR分析,发现这些基因在黄瓜苗期应对高温热激响应中表达水平存在显著的差异.研究结果为进一步分析黄瓜热激转录因子奠定了基础.

Heat shock factors （HSFs） are ubiquitous in eukaryotes with diversification in structural feature and biological function in plants.Based on the availability of whole cucumber genome sequences,we characterized the cucumber HSFs gene family which contains at least 21 members.Sequence alignments show that all HSFs possess a specific DNA binding domain （DBD）.These HSFs genes are unevenly distributed in the seven cucumber chromosomes except for Csa026480 （located on Scaffold repeat037858）.Phylogenetic analysis shows that HSFs in cucumber could be divided into three families,in which family I included three categories （A,B and C）.Phylogenetic tree also reveals nine pairs of orthologous genes and three pairs of paralogous genes,suggesting that HSFs gene family have existed before the separation of cucumber and Arabidopsis thaliana.EST analysis shows that cucumber HSFs may be involved in the development of fruit,female flower and hermaphrodite flower.qRT-PCR analysis demonstrated that these genes exhibit different expression levels in heat stress treatment.These results will provide a foundation for the functions of the HSF gene family.