Characteristics of chalcone isomerase promoter in crabapple leaves (M.cv. ‘royalty’) and transient expression assay modified in onion epidermal cell

Abstract

Anthocyanins are secondary metabolites found in higher plants that contribute to the colors of plants and chalcone isomerase (CHI) is one of the key enzymes in anthocyanin biosynthetic pathway. What characteristic is CHI promoter known as the regulation sequence of CHI gene, has been rarely investigated. We isolated A 329 bp 5’-upstream sequence of McCHI promoter sequence from Malus crabapple cultivar ‘royalty’. According to PLACE database, we found all kinds of cis-elements which contained light, hormone, stress, Ca²⁺ and MYB responsive factor in McCHI promoter. Transient expression assay showed that the McCHI promoter fragments had the promoter activity and can drive GUS expression. So it is presumed that McCHI promoter had a promising application prospect in the genetic transformation to modify the color of plant and anthocyanins production. We also compared the effect of GUS gene expression in different bombardment distances and in different onion epidermis culture patterns. The results show that 6 cm was the best bombardment distance and sorbitol was better to conduct plasmolysis than mannitol and that 4 to 5 layers onion epidermis was suitable for transient expression assay. As is in the foregoing, the GUS gene expression is sufficient and is the best state to analyze promoter activity.

Key words: Chalcone isomerase, promoter, cis-element, transient expression assay, Malus crabapple.