Fig. 2

qui-1 shows impaired tapetum differentiation and microsporogenesis starting from late stage 5. Semithin sections of anther lobes at different developmental stages from Col-0 (a–f) and qui-1 (g–l) after stained with toluidine blue. a, g Stage 4 anthers. The anthers from Col-0 and qui-1 showed no visible differences. b, h Early stage 5 anthers. The anthers from Col-0 and qui-1 showed no visible differences. c, i Late stage 5 anthers. Failed enlargement of tapetal cells and excessive microsporocytes were observed in qui-1 anthers. d, j Early stage 6 anthers. Significant excessive microsporocytes were observed in mutant anther locules. e, k Late stage 6 anthers. f, l Stage 7 anthers. Microsporocytes in qui-1 anthers cannot form tetrads. Epidermis (E), outer secondary parietal cell layer (OSP), inner secondary parietal cell layer (ISP), sporogenous cell (Sp), middle layer (ML), tapetum layer (T), tapetum-like layer (TL), microsporocytes (Ms), and tetrads (Tds) are indicated by arrows. Scale bars represent 20 μm