擎天凤梨SAMs基因的分离及开花期的表达分析

为了获得擎天凤梨SAMs基因,明确其在乙烯生物合成中的作用,本试验在前期构建全长c DNA文库、批量EST测序的基础上,对目标单克隆进行Primer Walking测序获得了2个SAMs基因,分别命名为SAMs1和SAMs2。SAMs1基因(Gen Bank:KF787113)序列全长1 375bp,开放阅读框1 086 bp,编码一条361个氨基酸的序列;SAMs2基因(Gen Bank:KF787114)序列全长1 235bp,开放阅读框945 bp,编码一条314个氨基酸的序列。应用生物信息学方法对2个基因编码蛋白的氨基酸组成、理化性质、保守结构域、二级结构、三级晶体结构等方面进行了预测和分析。分子系统进化分析表明,SAMs1与禾本科植物的SAMs基因聚为一类,与SAMs2关系较远。对2个基因在开花期的表达变化以及乙烯释放量变化分析表明,SAMs1基因表达与内源乙烯的释放水平变化趋势一致,即在完全呈色的红色苞片中含量最高,其次是绿色苞片,最后为绿色叶片。推测SAMs1在乙烯的生物合成中起重要作用,SAMs2参与了除乙烯生物合成外的其它SAM生物代谢过程。本试验结果对研究擎天凤梨的乙烯生物合成、苞片呈色机理以及催花应用具有重要意义。

Isolation of Guzmania SAMs Genes and Expression in Flowering Period

In order to obtain guzmania SAMs(S-adenosylmethionine synthetase) genes sequence and know their function in ethylene biosynthesis pathway,based on full-length cDNA library constructed and batch EST sequencing in the early stage,we performed Primer Walking Sequencing to obtain two SAMs genes,named SAMsl and SAMs2,respectively.SAMsl (GenBank:KF787113) cDNA is 1 375bp in length,and has a 1 086 bp open reading frame that encode 361AA amino acid residuals.SAMs2(GenBank:KF787114) is 1 235bp and has a 945 bp open reading frame that encode 314AA amino acid residuals.Their amino acid composition,physical and chemical properties,conserved domains,secondary structure,and tertiary crystal structure and had been predicted and analyzed,by bioinformatics methods.Molecular phylogenetic analysis showed that SAMsl were clustered with SAMs gene of grass family into one group,while far from SAMs2.That analysis of gene expression of the two genes and ethylene release production among different tissues in flowering stage showed SAMsl’s gene expression change trend consistent with ethylene release trend.Namely,those of red bracts were the highest,followed by green bracts,finally green leaves.Therefore,we considered that SAMsl may play an important role in ethylene biosynthesis pathway.SAMs2 may be involved in other S-adenosylmethionine biological metabolic processes in addition to ethylene biosynthesis.The study had an important sense in ethylene biosynthesis,bract coloration mechanism and flower induction in Guzmania.