Figure 4.—

Confocal microscopy analysis of 9-dap embryos and endosperms from bsl1/+ plants pollinated with wild-type pollen. (A, D, and F) Wild type. (B, C, E, and G) bsl1. (A) Wild-type coleoptile stage embryo with prominent shoot apical meristem and (B and C) sibling mutant embryos lagging at the transition stage. (D and E) BETL endosperm morphology. (D) Wild-type endosperm with BETL consisting of approximately three layers of slightly elongated cells (autofluorescent) located above the pedicel (intense autofluorescent signal). (E) Typical bsl1 endosperm possessing an irregular BETL containing fewer cell layers. Arrow points to region of basal endosperm devoid of BETL. (F and G) Starchy endosperm morphology. Cells in the central endosperm are large and regularly spaced in wild-type endosperms (F), but appear smaller and of variable size in bsl1 endosperms (G). betl, basal endosperm transfer layer; cse, central starchy endosperm; ep, embryo proper; esr, embryo surrounding region; p, pericarp; su, suspensor. Bar, 100 μm.