Comparison of the cytological structure of anthers from control plants and from MES-treated plants throughout pollen developmental stages.

<p>(A) Normal anthers of control plants at the pollen mother cell (PMC) stage containing microspore mother cells (MMCs) in the centre and four somatic wall layers: epidermis (E), endothecium (EN), middle layer (ML) and tapetum (T). (B) Type-I structure of anthers of MES-treated plants at the PMC stage containing MMCs with condensed bulk in the centre and partial degenerating tapetal cells. (C) Type-II structure of anthers of MES-treated plants at the PMC stage containing MMCs and intact tapetal cells both with condensed bulk in the centre. (D) Normal fertile anther of control plants at the tetrad stage showing tetrads (labelled Tds) and densely stained tapetal cells. (E) Type-I structure of MES-induced male sterile anther at the tetrad stage containing less densely stained tetrads and some loosely arranged tapetal cells. (F) Type-II structure of MES-induced male sterile anther at the tetrad stage containing less densely stained tetrads and tapetal cells. (G) Fertile anther of the control plants at the middle-microspore stage showing normal microspores and tapetum. (H) Type-I structure of MES-induced male sterile anther at the middle-microspore stage showing abnormal microspores (labelled Msp) and disappeared tapetum. (I) Type-II structure of MES-induced male sterile anther at the middle-microspore stage showing abnormal microspores and less stained tapetum. (J) Fertile anther from control plants at the vacuolated-microspore stage showing vacuolated microspores and degenerating tapetum. (K) Type-I sterile anther at the vacuolated-microspore stage showing unviable microspores and disappeared tapetum. (L) Type-II sterile anther at the vacuolated-microspore stage showing unviable microspores and less stained tapetum. (M) Fertile anther of control plants at the mature pollen stage showing mature pollen and degenerating tapetum. (N) Type-I structure of MES-induced male sterile anther at the mature-pollen stage showing unviable pollen and disappeared tapetum. (O) Type-II structure of MES-induced male sterile anther at the mature-pollen stage showing unviable pollen and less stained tapetum.