*4.7. Isolation of Thylakoid Proteins and Western Blotting*

Thylakoid membrane proteins were isolated as described by Fristedt et al. [71]. Isolated thylakoid membrane protein was separated by SDS-PAGE (5% acrylamide stacking gel + 15% separation gel + 6 M urea) [72]. Western blotting analysis was performed according to Chen et al. [73]. The primary antibodies (all raised in rabbits) including anti-Arabidopsis D1, D2, CP43, LHCb1, LHCb2, LHCb3, LHCb4, LHCb5, LHCb6, LHCa1, LHCa2, LHCa3, and LHCa4, and horseradish-peroxidase-conjugated secondary antibody were purchased from *Agrisera* (Umea, Sweden). The Western blotting signal was detected by a chemiluminescent detection system (ECL, GE Healthcare, Buckinghamshire, UK). The quantification of immunoblots was done with Quantity One software (Bio-Rad, Hercules, CA, United States).

#### *4.8. Observation of Transmission Electron Microscopy*

Transmission electron microscopy (TEM) analysis of leaves was carried out following a previous method [74]. Leaf tissue was fixed with 3% glutaraldehyde in 0.1 M sodium cacodylate buffer (pH 6.9) at 4 ◦C overnight, after being washed with phosphate buffer three times. Samples were post-fixed with 2.5% osmium tetroxide, then dehydrated in a gradient solution of alcohol–acetone mixture and embedded in Epon Ultrathin cross sections were cut with an ultramicrotome (Ultracut F-701704, Reichert-Jung, Reichert, Austria), which was then stained with uranyl acetate and observed using a transmission electron microscope (TEM H-9500, Itachi, Tokyo, Japan) operating at 75 kV.
