洋葱开花相关基因AcLFY的克隆与表达分析

Cloning and Expression Analysis of Flowering Related Gene AcLFY from Allium cepa

以洋葱(Allium cepa L.)品系‘1007’为试材,采用同源基因克隆及RACE-PCR的方法,获得植物开花调控关键基因LEAFY的同源基因的cDNA序列,命名为AcLFY,GenBank登录号为JX275962。序列分析表明,该基因包含1个1119bp的开放阅读框,编码372个氨基酸,该氨基酸序列含有5′-N端脯氨酸富集区,亮氨酸拉链结构和中央酸性区,具有LEAFY(FLO)家族的典型结构特征。同源分析表明,该氨基酸序列与水仙的同源性接近70%,与其他高等植物LEAFY类蛋白的同源性均在50%以上。进化树分析表明AcLFY与单子叶植物的亲缘关系高于双子叶植物。荧光定量结果显示,AcLFY在洋葱抽薹开花的整个过程中都有表达,在抽薹初期的花序分生组织中表达量最高,在花器官中只有微量表达,花器官形成后,主要在叶片中表达。

The LEAFY gene plays a key role in the regulation network of plant flower development, and its homologous gene named AcLFY （GenBank accession No.： JX275962） was isolated from onion （Allium cepa L. ＇ 1007＇ ） using homology gene cloning and RACE-PCR. Sequence analysis showed that the AcLFY gene has a 1 119 bp open reading frame （ORF） encoding 372 amino acids. The amino acid sequence contains a 5＇-N praline-rich region, a leucine zipper and a central acidic region, which are typical structure features of LEAFY （FLO） family. Homology analysis showed that the deduced AcLFY protein is highly homologous to other LEAFY proteins from different species, especially to the one from Narcissus tazetta with approximately 70% identity. Phylogenetic tree analysis indicated that AcLFY is more related to LEAFY in monocotyledons than those in dicotyledonous plants. The real-time PCR results showed that^the AcLFY was detected during the whole period of bolting and flowering in onion, and it had a high transcription level in inflorescence meristem at the beginning of the bolting but nearly no transcription in floral organ. After the development of floral organ, the AcLFY gene mainly expressed in leaves.