菲油果LEAFY基因的表达模式及启动子克隆

Expression Pattern of FsLFY Gene and its Promoter Cloning in Feijoa Sellowiana

LEAFY(简称LFY)是植物花分生组织特征基因,在植物由营养生长向生殖生长转变过程中起着重要作用,是启动开花的枢纽。菲油果是一种新兴的果树资源,为研究菲油果LFY基因(FsLFY)的表达调控规律,本研究通过实时荧光定量PCR技术研究了FsLFY基因的时空表达模式,并通过染色体步移技术克隆了该基因的启动子序列。荧光定量PCR结果表明,FsLFY基因在菲油果花蕾不同发育阶段以及其他组织器官中均有表达。在花蕾中,小蕾期最高,中蕾期最低;组织器官中,营养枝茎段最高,花瓣最低。FsLFY基因启动子序列长度为2436 bp(GenBank登录号:KF766536),运用PLACE、PlantCARE等在线软件对其序列进行顺式作用元件分析,结果显示该序列不仅含有CAAT-box、TATA-box等核心启动子元件,而且还具有响应水分、光、赤霉素(GA)以及其他功能未知的顺式调控元件,表明FsLFY基因的表达受多种外界环境条件的调控。本研究为阐明菲油果的开花机理,以及通过分子育种手段使菲油果早花早果奠定了理论基础。

LEAFY（ LFY） is a tagged gene of floral meristem and plays an important role in the transformation process from vegetative growth to reproductive growth in flowering plants. Feijoa sellowiana,a promising fruit tree species,has been introduced to China for fruits production and ornamental usage in recent years. FsLFY（ F. sellowiana LFY） gene expression in different tissues and at different development stage of floral buds was studied by realtime fluorescent quantitative PCR（ qPCR） technology,and the promoter sequences were isolated by the genome walking technology. The qPCR analysis showed that the FsLFY gene was expressed at all developmental stages of floral buds and all different tissue and organs. In developmental buds,the expression level of the FsLFY was the highest in small bud stage and the lowest in middle bud stage. In tissues and organs,the expression level was the highest in stems from vegetative branches and the lowest in petals. The newly cloned FsLFY promoter sequence was2436 bp in length and had been deposited in GenBank with accession no. KF766536. Promoter analysis with online softwares PLACE and PlantCARE showed that the FsLFY promoter contained not only CAAT-box,TATA-box,and other core promoter elements,but also the unknown cis-regulatory elements response to water,light,and gibberellin（ GA）,implying that the expression of the FsLFY gene was regulated by various external environmental factors. This study would provide a theoretical basis for fully understanding the flowering mechanism of the F. sellowiana tree and accelerating flowering and fruit setting via molecular breeding strategy.