Figure 4

Reactivation of transgene expression from the post-transcriptionally silenced E82 locus after exposure to GFP-COP1 C73. Epifluorescence micrographs of whole-mounted seedlings are shown. Note that GFP-COP1 protein accumulates in the form of a single inclusion body per cell. Left column (panels A, D, G, and J): Control: Progeny of a GFP-COP1 E82 hemizygous plant. GFP-COP1 was active only in the root. Central column (panels B, E, H, and K): Progeny of a GFP-COP1 C73 × E82 di-hybrid plant. GFP-COP1 was often active in the root, cotyledon, and first and second sets of leaves. Arrows highlight the reactivated GFP-COP1 in the cotyledon, leaf epidermis, as well as in trichomes of the second set of leaves. Right column (panels C, F, I, and L): Control: Progeny of a GFP-COP1 C73 hemizygous plant. GFP-COP1 was active in the root and in guard cells (note paired dots) of the cotyledon.