2.7 Observations of leaf stomata, chloroplasts, and autophagosome
The fully expanded leaves were immediately cut into small pieces and fixed in a 4% glutaraldehyde solution, then kept at 4°C for 24 h. After three washing with 0.2 M phosphate buffered solution, the samples underwent dehydration with different ethanol concentrations (70%, 80%, and 90%). The samples were then coated with gold using isoamyl acetate and imaged using a JSM-6360LV scanning electron microscope (SEM, JEOL Ltd., Tokyo, Japan) for observation and photography. The width/length ratio was calculated using the ImageJ software. The chloroplast and autophagosome were observed using a JEOL-1230 transmission electron microscope (TEM, Hitachi, Japan).