Cryptic genetic elements for regulation of gene expression in plants: The tcup gene expression system

Cryptic gene regulatory elements are a class of regulatory elements that possess the same activities as regulatory elements associated with genes but they are inactive at their native locations in the plant genome. Cryptic elements have been found widely among organisms and, at AAFC, a family of cryptic elements were found by random insertion of a promoterless marker gene into the tobacco genome - an approach also known as promoter tagging. tCUP is a cryptic, constitutive promoter and is a member of a repetitive family of elements (RENT) in the tobacco genome. tCUP comprises a short TATA-less core promoter region with a Inr (initiator) sequence, a region of upstream enhancer elements and a translational enhancer in the mRNA leader sequence. By modifying the sequence of the upstream enhancer elements, core promoter and translational enhancer element, tCUP can be enhanced and modified to suit a wide range of applications. tCUP has been shown to an effective promoter sequence in a wide range of dicot plants: alfalfa, tobacco, canola, cauliflower, tomato, pea, Arabidopsis, conifer species, and fruit tree species. Specific elements of the tCUP system have also been shown to be active in diverse species ranging from alfalfa, tomato, tobacco, corn and wheat to conifers and yeast. Through development of the tCUP Gene Expression System we have shown: cryptic elements can replace or compliment existing expression systems derived from genes to control gene expression in transgenic plants; they can be combined with elements from genes to create novel, composite gene regulatory systems in plants; they can be modified to alter the level and specificity of transgene expression in diverse crops; they are as diverse and efficient as elements associated with genes in regulating transcription and translation of cloned genes in transgenic crops.