Fig 4. Pollen in fzt anthers has reduced viability.

Modified Alexander stain to assess pollen viability; viable pollen stains pink (black arrowheads), nonviable pollen stains blue (white arrowheads). Top box depicts whole anther, bottom box depicts close-up of pollen grains. (A) Almost all pollen from normal anthers is viable; pollen are round and plump in shape and stain pink. (B) fzt anthers (D-0.5) are heterogeneous. Class 1 anthers contain almost entirely viable pollen, similar to normal anthers. Class 2 anthers contain a mixture of viable and non-viable pollen grains. Nonviable pollen stains blue and is shrivelled. Class 3 anthers contain almost entirely nonviable pollen. C) fzt anthers (D+0.5) are all Class 2 or Class 3. Scale bars: top row = 500 μm; bottom row = 50 μm.