Fig. 1

Electron micrographs of paper mulberry leaf cells from control and treated plants. a Cells from control plant (0 h); b 3 h at 4 °C, showing early stage, chloroplasts with starch grains were noted; c 6 h at 4 °C, starch grains were present in many; d 12 h at 4 °C, showing invagination of the plasma membrane (arrow) accompanied with amounts of membrane vesicles (arrowhead), note the deformation of chloroplast; e 24 h at 4 °C, chloroplast envelope membrane swell (arrow); f 48 h at 4 °C, invagination of the plasma membrane and protrusion of vesicles into the vacuoles were noted (arrowhead), swelling continued until plastids were round (arrow). Abbreviations in the figures: V: vacuole, Chl: chloroplast, S: starch grain. Bar = 2 μm