Promoter of chrysanthemum actin confers high-level constitutive gene expression in Arabidopsis and chrysanthemum

-  CmActin promoter was isolated from Chrysanthemum morifolium Ramat. 'White Wing'.
-  CmActin promoter activity was similar to that of the 35S promoter in Arabidopsis.
-  CmActin promoter activity was stronger than that of the 35S promoter in chrysanthemum.
-  CmActin promoter is able to drive high-level constitutive gene expression in plants.

A promoter that confers high-level constitutive expression of transgenes in crop plants, designated the CmActin promoter, was isolated from chrysanthemum (Chrysanthemum morifolium Ramat. 'White Wing'). We characterized Arabidopsis and chrysanthemum transformants bearing a CmActin promoter-β-glucuronidase (GUS) reporter construct. Analysis of GUS expression demonstrated that the promoter directed reporter gene expression during all developmental stages and tissues of transgenic Arabidopsis except in seeds. Higher expression of GUS was observed in organs and tissues of transgenic chrysanthemum compared to those of 35S promoter-GUS transgenic plants. In addition, BrSRS expression driven by the CmActin promoter induced dwarf and compact plants with narrow upwardly curled leaves and short petioles. Transgene expression driven by the CmActin promoter was very similar to that of the 35S promoter in Arabidopsis and was significantly stronger than that of the 35S promoter in chrysanthemum, suggesting that the CmActin promoter can induce constitutive gene expression in various plants and that its function is presumably conserved in different species. The CmActin promoter may provide a practical choice for high-level constitutive expression of target genes and could be a useful tool in floriculture plant genetic engineering.