Construction Of Maize Starc SynthaseI (zsS1) Promoter And Transient Expression Of Gus In Maize Endosperm

This study is on maize starch synthase zsS1,which is a seed specific promoter,and does important effect on maize endosperm,zsS1 is a key enzyme in maize starch synthesis.It is on the purpose of understanding the genic regulatory mechanism of zsS1 and its specific expression in endosperm that this experiment analyses the cloned sequence 1637bp,constructs pCAMBIA1301 expressing vector with 5' deletion segment:pI1.6k,pI0.8k,pI0.5k,pI0.25k,pI0.18k,which are transient expressed in 15DAP endosperm after particle bombardment.Then using quantitative fluorometric GUS assay,we study 5' deletion segment of zsS1.The main results of study were summarized as follows:1) Transient expressing vector with 5' end different length deletions of zsS1 promoter are successfully constructed which are pI1.6k,pI0.8k,pI0.5k,pI0.25k, pI0.18k.2) The result of transient expression in maize endosperm shows that there are some depressor elements negative regulating promoter activity,especially sequence between-470bp and-186bp,there must be some key depressor elements;as for sequence between-184bp and-137bp there are some enhancer elements positive regulating promoter activity.3) The 5'end different length deletions of zsS1 are all expressed in maize endosperm,which means they all have promoter activity,but their promoter abilities are not the same.The result shows that the new construction,pI0.25k,in which GUS activity is the strongest.That suggests there are some important positive regulatory elements in this sequence.4)Doing analysis of DNA sequence,it shows that maize starch synthase zsS1 promoter is not a typical promoter,because it does not contain TATA-box.However,it dose contain "Inr(initiator)"elements and other important cis-acting elements,such as CAAT-box,G-box,AACA-motif.