Microscopy and phenotypic characterization
Pollen viability was assessed using Alexander’s staining. For scanning
electron microscopic (SEM) analysis, mature pollen grains from freshly
dehisced anthers were mounted and coated with gold on stubs. The samples
were then immediately observed using FESEM (SU8010). TEM (transmission
electron microscopy) analysis was performed as described previously (Z.
B. Zhang et al., 2007). The procedure of semi-thin section and lipid
staining were performed as described previously (Lou et al., 2014; Z. B.
Zhang et al., 2007).