Elevated Expression of PGR5 and NDH-H in bundle sheath chloroplasts in C4 flaveria species

Abstract

Cyclic electron transport around PSI has been proposed to supply the additional ATP required for C4 photosynthesis. To investigate the nature of cyclic electron pathways involved in C4 photosynthesis, we analyzed tissue-specific expression of PGR5 (PROTON GRADIENT REGULATION 5), which is involved in the antimycin A-sensitive pathway, and NDH-H, a subunit of the plastidial NAD(P)H dehydrogenase complex, in four Flaveria species comprising NADP-malic enzyme (ME)-type C4, C3C4 intermediate and C3 species. PGR5 was highly expressed in the C4 species and enriched in bundle sheath chloroplasts together with NDH-H, suggesting that electron transport of both PGR5-dependent and NDH-dependent cyclic pathways is promoted to drive C4 photosynthesis. © 2010 The Author.