Mechanistic analysis of OsmiR408-mediated OsUCL8 silencing with respect to increasing grain yield. A, Total copper content in wild-type (WT), OXmiR408, and OXUCL8 leaves. B, Chloroplastic copper content in wild-type, OXmiR408, and OXUCL8 leaves. C, PC content in the leaves and panicles of wild-type, OXmiR408, and OXUCL8 plants as determined by western blot. OsHSP90 was used as a control. D, Photosynthetic light-response curves of wild-type, OXmiR408, and OXUCL8 flag leaves. E, Electron transport rate (ETR) in wild-type, OXmiR408, and OXUCL8 flag leaves. F, PSII quantum yield (ϕPSII) in wild-type, OXmiR408, and OXUCL8 flag leaves. G and H, Sugar content in the flag leaves (G) and panicles (H) of wild-type, OXmiR408, and OXUCL8 plants. Values in A, B, and D to H are expressed as means ± sd (for A, B, G, and H, n = 3 replicates; for D–F, n = 25 plants). Significant differences were identified at the 1% (**) probability level using Student’s t test. FW, Fresh weight.