On the Cover: Primary reactions of photosynthesis are mediated by three multi-subunit pigment-protein complexes including PSII, cytochrome b₆f (Cyt b₆f) complex, and PSI, the biogenesis of which requires various nuclear-encoded auxiliary proteins. In this issue, Wang et al. (pp. 1710–1728) study the physiological function of three m-type thioredoxins (TRX m1, TRX m2, and TRX m4) in the biogenesis of photosynthetic complexes in Arabidopsis thaliana. Their data demonstrate that three TRX m proteins play a redundant role in the regulation of PSII biogenesis via modulating the redox status of PSII core subunits, suggesting a mechanism to assist the assembly of PSII core subunits into PSII complex. The cover shows the phenotypic comparison between triple TRX m-silenced plant (left) and the control plant (right). Cover image credits: Peng Wang and Hong-Bin Wang.