Figure 6.

SUMO conjugation also triggers NB formation in Arabidopsis, which depends genetically on SIZ1 for recruitment to COP1 NBs. A, Nuclear localization pattern of the SCE1∙SCE1 BiFC pair in Arabidopsis cells (wild type [WT], siz1-2, or cop1-4) transformed using particle bombardment. The BiFC constructs and the Arabidopsis genotypes used are indicated at the top. To detect the transformed cells, tissue was cobombarded with mCherry. The micrographs show from top to bottom the YFP, RFP, and the merged signal; nuclei are outlined with a white line. Four-week-old Arabidopsis rosettes were bombarded. Two days postbombardment, plant material was transferred to a dark box, and the fluorescence signals were examined after a further day. B, Nuclear localization pattern of GFP-COP1 and RFP-SCE1 in Arabidopsis cells (wild type, siz1-2, or sumo1;amiR-SUMO2) transformed using particle bombardment. To detect the transformed cells, tissue was either cobombarded with mCherry or RFP-SCE1. Micrographs with nuclei with GFP-COP1 containing NBs are shown. Scale bars, 10 μm. C, Normalized intensity profiles depict the fluorescence signal intensities of GFP-COP1 and RFP-SCE1 co-expressed in wild type and the siz1-2 mutant, along arrows 1 and 2 in the right two panels of (B).