Analysis of tandem repeat units of the promoter of capsanthin/capsorubin synthase (Ccs) gene in pepper fruit.

Capsanthin/capsorubin synthase (Ccs) gene is a key gene that regulates the synthesis of capsanthin and the development of red coloration in pepper fruits. There are three tandem repeat units in the promoter region of Ccs, but the potential effects of the number of repetitive units on the transcriptional regulation of Ccs has been unclear. In the present study, expression vectors carrying different numbers of repeat units of the Ccs promoter were constructed, and the transient expression of the β-glucuronidase (GUS) gene was used to detect differences in expression levels associated with the promoter fragments. These repeat fragments and the plant expression vector PBI121 containing the 35s CaMV promoter were ligated to form recombinant vectors that were transfected into Agrobacterium tumefaciens GV3101. A fluorescence spectrophotometer was used to analyze the expression associated with the various repeat units. It was concluded that the constructs containing at least one repeat were associated with GUS expression, though they did not differ from one another. This repeating unit likely plays a role in transcription and regulation of Ccs expression.