Fig. 4.

ADT2 forms structures consistent with chloroplast division rings. (A) In addition to being expressed within chloroplasts and stromules, ADT2 was also found to accumulate in places consistent with chloroplast division rings. The top panel shows ADT2 forming rings at the equatorial plate of the chloroplast. On occasion, ADT2 was found in the constriction zone of chloroplasts (two middle panels). In these cases, the chloroplasts have a distinct dumb-bell shape and the degree of indentation depends on how far the division process has proceeded. In addition, ADT2 accumulated in a spindle-like shape that tapers at chloroplast poles (bottom panel). This fusiform ADT2 accumulation was only found at one pole of the chloroplast and is distinct from a stromule pattern shown in Fig. 2. (B) Schematic of chloroplast division stages: from top to bottom, positioning of chloroplast division rings; slightly constricted chloroplast just prior to division; two daughter chloroplast following division. Analogous to the fluorescent images, chloroplasts are shown in red and the position of ring proteins in blue (adapted from Miyagishima, 2011).