小麦谷氨酰胺合成酶同工酶转录特点及其启动子序列分析

Transcription characteristics of wheat glutamine synthetase isoforms and the sequence analysis of their promoters

谷氨酰胺合成酶是小麦氮同化关键酶,分为胞液型和质体型(TaGS2)两类,其中胞液型TaGS又分为TaGS1、TaGSr和TaGSe。为了研究异源六倍体小麦A、B、D染色体组TaGS同工酶表达差异及调控机制,本项目利用三代测序技术测定了TaGS同工酶基因转录水平,依据中国春基因组序列克隆了豫麦49的12个TaGS同工酶启动子,并对其序列进行了分析。结果表明,TaGS1主要由6B染色体基因转录,TaGSe和TaGSr主要由4D染色体基因转录,TaGS2主要由2D染色体基因转录,不同TaGS同工酶转录起始位点距起始密码子ATG的距离不同。启动子元件分析显示,6B染色体上的TaGS1启动子有较多W-box、AC-I、ABRE、as-1和茉莉酸甲酯等响应元件,4D染色体上的TaGSe启动子有较多胁迫响应转录因子(MYB、MBS、LTR等)结合元件和植物生长素响应元件,4D染色体上的TaGSr启动子有较多WRE3等转录因子结合元件,2D染色体上的TaGS2启动子有较多A-box、WRE3、ARE及AT富集区。不同TaGS同工酶启动子顺式元件种类、数目及排列顺序均不同,为进一步研究GS同工酶调控机制奠定了基础。

As a key enzyme for nitrogen assimilation in wheat,glutamine synthetase is grouped into two classes:cytosolic GS and chloroplastic GS(TaGS2),and cytosolic GS includes TaGS1,TaGSr,and TaGSe.In order to study the expression characteristics and regulatory mechanisms of GS isozymes in chromosome A,B,and D of heterohexaploid wheat,transcripts of TaGS isoforms were analyzed based on the third-generation sequencing technology transcriptome analysis,and 12 promoters of TaGS isozymes of Yumai 49 were cloned based on Chinese Spring genome,and the sequence of the promoters were analyzed.The results showed that TaGS1 was mainly transcribed on chromosome 6B,TaGSe and TaGSr on chromosome 4D,and TaGS2 on chromosome 2D.Furthermore,the distance from initiation codon ATG to initiation site of transcript for each promoter of TaGS was distinct.Promoter element analysis showed that the promoter of TaGS1 in 6B had more W-box,AC-I,ABRE,as-1,and methyl jasmonic response elements,the promoter of TaGSe in 4D had more stress response elements(MYB,MBS,LTR,etc.)and auxin response element,the promoter of TaGSr in 4D had more WRE3 and transcript factor response elements,the promoter of TaGS2 in 2D had more A-box,WRE3,ARE,and an AT enrichment region.In summary,the number,type and order of cis-elements of different promoters of TaGS isozymes were distinct,which provided the foundation for further study on the regulation mechanism of TaGS isozymes.