Thylakoid membrane proteins weredenatured and separated using 15% polyacrylamide gradient gelcontaining 6 M urea. Separated proteins were electro-blotted topolyvinylidene difluoride membranes (Millipore, Billerica, MA,USA), and probed with a D1 protein antibody. The secondary anti-body was peroxidase-conjugated goat anti-rabbit IgG purchasedfrom Tiangen Biotech. The D1 protein antibody was used at a dilu-tion of 1:500, and the secondary antibody was used at 1:5000.