Fig. 6. Cell-to-cell movement of fluorescent tracers in ise1 mutant embryos of Arabidopsis. (A) Immature siliques of both wild-type and +/ise1 heterozygous plants contain seeds developing synchronously during early embryo development, up to the heart stage. (B) A later stage silique of +/ise1 heterozygous plants contains dark green seeds (arrowhead) and light green seeds (arrow) in a ratio of 3:1. Seeds are 0.5 mm in length. (C,D) Embryos from the same silique; dark green seeds contain mid-torpedo wild-type embryos (C) and light green seeds contain ise1/ise1 mutant embryos (D), both showing red chlorophyll autofluorescence. (E) A keule embryo at torpedo stage loaded with HPTS. (F) A ise1/ise1 embryo allow the movement of 10 kDa F-dextran. The hypocotyl and the radicle show uniform and complete loading, and the cotyledons show partial loading at their bases. (G) Detail of the hypocotyl in F. 10 kDa F-dextran localizes in the cytoplasm as well as nuclei (arrowhead), but not in the cell wall in apoplastic regions (arrow). (H) A ise1/ise1 embryo fully loaded with HTPS, showing that the ise1 embryo constitutes a single symplast with open plasmodesmata. Scale bars, 50 µm.
