Fig. 3.

Nuclear import of MYBS2 is promoted by sugar provision. (A) Roots of 5-d-old transgenic rice seedlings overexpressing CaMV35S:GFP and CaMV35S:MYBS2-GFP and CaMV35S:MYBS2(54-264)-GFP were incubated in +S or −S medium for 24 h under darkness, and the GFP signal in root tips was examined by confocal microscopy. The red-colored cell walls were stained with propidium iodide that is a membrane-impermeable dye for staining the extracellular space and its constituents (including cell walls and secreted polysaccharides). (Scale bar, 20 μm.) (B and C) Barley aleurones were transfected with Ubi:MYBS2-GFP and incubated in +S or −S medium for 24 h. Thirty optical sections, each of 0.9 to 1.1 μm thickness, were prepared for each cell (SI Appendix, Fig. S4), but only 5 regularly spaced sections (sections 4, 10, 16, 22, and 28; from top to bottom of cell) are shown here. “N” and “C” indicate higher GFP signals in the nucleus and cytoplasm, respectively, whereas “n” and “c” represent lower respective signals. Percentage indicates the number of cells with GFP distribution in the nucleus or cytoplasm divided by the total number of cells examined. n > 200. (B) After transfection, barley aleurones were incubated in +S or −S medium for 24 h. (C) After transfection, barley aleurones were incubated in +S medium for 24 h, and transferred (indicated by the arrow) to −S medium for a further 24 h.