Crucial regulatory role of NDH on C4 photosynthesis.

Cyclic electron transport (CET) pathways are mainly mediated by chloroplast NDH complex, and by proton gradient regulatory proteins PGR5 and PGRL1. In C3 plants, CET via NDH is usually upregulated under environmental stresses such as high temperature, high light and drought, when linear electron transport (LET) is suppressed. Compared with C3 plants, NDH content is significantly enhanced in many C4 species, especially in the BS cells of NADP-ME type C4 plants, but corresponding mutants and comparative analysis are lacking to experimentally dissect its importance for C4 pathway. In this work, we generated NDF6 and NDHU subunit deficient mutants in maize and rice for comparative study.