Tetracycline operator/repressor system to visualize fluorescence-tagged T-DNAs in interphase nuclei ofArabidopsis

The bacterial tetracycline operator/repressor (tetO/TetR) system and enhanced yellow fluorescent protein (EYFP) have been adapted for use inArabidopsis to visualize tagged T-DNAs in interphase nuclei of living cells. The 2-component system was assembled on a single T-DNA construct that contained a gene encoding a nuclear-targeted TetR-EYFP fusion protein under the control of the 35S promoter of the cauliflower mosaic virus together with multiple tandemly arranged copies of thetetO. In a number of independentArabidopsis lines transformed with this construct, bright fluorescent dots corresponding to tagged T-DNAs were observed in interphase nuclei of various cell types using standard fluorescence microscopy. In selfed progeny of a single locus line, hemizygous and homozygous plants were distinguished by having 1 or 2 fluorescent dots, respectively. Low background fluorescence of EYFP in many plant tissues facilitates the visualization of tagged T-DNAs. We compared features of thetetO/TetR-EYFP system to a second system we developed on the basis of the bacteriallac operator/repressor and enhanced green fluorescent protein.