Male meiotic cytokinesis defects in myb33 myb65 Arabidopsis plants. Aniline blue staining of tetrads in wild-type Col-0 (A) and single myb33 (B) and myb65 (C) mutant plants. D, Combined aniline blue/DAPI staining of tetrad-stage male meiocytes in wild-type Col-0 plant. E, DAPI staining of haploid unicellular stage microspore in wild-type Col-0 plants. F to I, Aniline blue staining of defective tetrad stage male meiocytes in double myb33 myb65 mutant plants. J to N, Combined aniline blue/DAPI staining of defective tetrad-stage male meiocytes in double myb33 myb65 mutant plants. O, DAPI staining of an enlarged unicellular stage microspore isolated from myb33 myb65 mutant plant. RMA (P) and MI and MII spindles (Q and R) in wild-type Col-0 plants. Defective RMA (S–U) and normal MI and MII spindles (V and W) in the double myb33 myb65 mutant. Green: α-tubulin, cyan: DAPI. Scale bars = 10 µm.