The QF/QS Binary Expression System for Regulation of Targeted Transgene Expression in Plants

Binary expression is a powerful strategy for the precise manipulation of the transgene expression in a restricted manner. Derived from the qa gene cluster in the fungus Neurospora crassa, the QF/QS repressible binary expression system has shown promising results regulating transgene expression in Drosophila and mammalian cells. We aimed to perform a preliminary investigation of the regulatory effects of the QF/QS binary expression system on targeted transgene expression in plants. Using agroinfiltration of tobacco leaves, we found that overexpression of the QF by the CaMV 35S promoter can specifically activate expression of the reporter gene pporRFP from the hard coral Porites porites. The reporter was driven by different synthetic promoters containing a 5× QUAS binding site that is activated only by the QF. We also found that QF can activate the reporter gene expression driven by each synthetic promoter to be two times the expression rendered by the full-length 35S promoter alone. Repression of QF activity can be achieved by its repressor QS driven by the 35S promoter. Thus, the QF/QS binary expression system is demonstrated to be effective for regulation of targeted transgene expression in plants.