十字花科植物嫁接mRNA长距离运输基因IAA14的鉴定及比较

Identification and Comparative Analysis of the Brassicaceae IAA14 Genes of mRNA Long-distance Trafficking in Grafting

Aux/IAA家族基因是一类典型的生长素诱导表达基因,是植物生长素信号转导通路的重要调控基因。IAA14基因是Aux/IAA基因家族的成员,IAA14基因mRNA被认为在嫁接中发生了长距离运输。本研究从十字花科11个物种中鉴定了14个IAA14基因,每种植物中至少有1个IAA14基因。比较分析了IAA7、IAA14和IAA17的蛋白特性,显示IAA14蛋白特性不同于Aux/IAA家族的其他蛋白,氨基酸序列比对显示所有的IAA14蛋白均包含4个保守结构域。在基因组织结构分析中,发现所有的IAA14基因分享了保守的基因结构:均由5个外显子和4个内含子构成,且内含子定位在保守位置。分析了IAA14基因起始密码子上游1 500 bp序列中的生长素响应相关元件。基于现有的白菜RNA-seq数据,发现白菜IAA14基因在花器官中有大量表达,在胚胎发育中特异表达在心形胚和早期子叶胚中。通过本研究,我们对十字花科11个物种的IAA14基因的基因定位、蛋白特性、基因组织结构、进化关系、启动子基序以及基因表达情况有了基本了解,对于未来进一步深入研究IAA14基因奠定基础。

Aux/IAA family members are typical auxin-inducible genes, the important regulator of auxin signaling pathway in plants. IAA14 gene is a member of Aux/IAA gene family. In previous studies, the IAA14 mRNA was considered to be involved in long-distance transport in grafting. This study have identified 14 IAA14 genes from 11 Brassicaceae species. Each species have at least one IAA14 gene. Comparative analysis of protein characteristics of IAA14, IAA7 and IAA17 indicated that IAA14 protein characteristics was different from that of other Aux/IAA family members. The alignment of amino acid sequences showed all IAA14 proteins contained four conserved domains. In intron-exon structure analysis, these IAA14 genes shared conserved gene structure, composed of 5exons and 4 introns in conserved position. The sequences of the upstream 1 500 bp of initiation codon of IAA14 genes were analyzed to identify auxin-responsive promoter element. Based on published data of RNA-seq of Brassica rapa, Br IAA14 gene was expressed in floral organs. During embryogenesis, Br IAA14 was expressed in heart embryo and early cotyledon embryo. The study analyzed gene location, protein characteristics, gene structure,evolutionary relationships, promoter motifs and the expression of 14 IAA14 genes from 11 Brassicaceae species,and provided basic understanding for the future study about IAA14 gene.