Fig. 9

Transmission electron micrographs of microspores from wild-type (WT) and FLA14-overexpressing (OE) transgenic Arabidopsis plants. a-h Microspores from WT plants. i-t Microspores from OE plants. a, i Microspore mother cell stage. b, j Tetrad stage. c, d, k, l Uninucleate microspore stage. The degradation of the cytoplasm is evident in (k). e, f, m-p Bicellular stage. The degenerated microspore is shown in (m). Abnormal pollen wall patterning is visible in (o). g, h, q-t Mature pollen stage. The mature pollen grain in (q) is devoid of any content and nuclei. The pollen wall structure in (s, t) is aberrant. d, f, h, l, n, p, r, t Detailed structure of pollen walls in (c, e, g, k, m, o, q, s). Intine layers are absent in (l, n, r). The abnormal thickening of intine layers in (p, t) is obvious. Ba, baculum; Ex, exine; In, intine; Ne I, nexine I; Ne II, nexine II; Te, tectum; Tr, tryphine. Scale bars = 20 μm (a-c, e, g, i-k, m, o, q, s); 0.5 μm (d, f, h, l, n, p, r, t)