Ht7800 transmission

The surface and cross-sectional morphologies of sesame seeds were observed by a Quanta Feg 250 scanning electron microscope (SEM) (Thermal Fisher Scientific Inc., USA). Sesame seed was glued to the conductive tape, sprayed with a gold film, and observed under the acceleration voltage of 20.0 kV.
The subcellular structures of sesame seeds were observed by the HT7800 transmission electron microscope (TEM) (Hitachi Co. Ltd., Japan). The sample preparation for TEM was referred to Xu et al. (2019) (link). Sesame seeds were fixated with 2.5 % glutaraldehyde, buffered at pH 7.0 by 0.2 M phosphate buffer, and stored at −4 °C for 8 h. The solution was removed and the sample tissue was rinsed with the phosphate buffer (0.1 M, pH 7.0). The sample was then fixated with 1 % osmic acid solution for 2 h. The osmic acid solution was then removed and the samples were rinsed with the phosphate buffer (0.1 M, pH 7.0). The sample was dehydrated sequentially with increasing concentrations of ethanol solutions (from 30 %, 50 %, 70 %, 80 %, 90 %, 95 % to 100 %). The dehydrated sample tissue was then embedded in Spurr’s resin at 70 °C overnight before being cut to 80 nm sections by the LEICA EM UC7 ultramicrotome (Leica Co. Ltd., Germany). Then, the ultrathin sections were stained with 1 % lead citrate solution and 5 % aqueous uranyl acetate before being examined by the TEM.