Fig. 5. Abaxial NUB expression promotes connective growth. (A-D) SEM images of the abaxial side (A-C) and adaxial side (D) of anthers from plants transformed with a FIL::NUB transgene. (A,B) The JD148-B transgenic line develops moderate defects in anther morphology. Anthers from this line develop enlarged connectives (A) that can also be elongated (B). (C,D) The JD148-A transgenic line develops strong defects in anther morphology. Anthers from this line develop enlarged and elongated connectives, as well as extended sheets of abaxial tissue that extend apically beyond the normal limits of the anther (white arrowhead). (E) Plastic-thin section through a stage 10 anther from a FIL::NUB transgenic line that develops strong defects in anther development. Ectopic tissue proliferation can be seen in the connective region (black arrowhead). No pollen development occurs in the ectopic tissue, indicating that this tissue does not have microsporangia identity. (F) FIL expression detected by in situ hybridization using an anti-sense probe. FIL expression can be seen in this stage 7 flower throughout the abaxial side. ad, adaxial; ab, abaxial; co, connective; fi, filament; lo, locules; ms, microsporangia. Scale bars: 50 µm.