PHOTOSYNTHETIC ELECTRON TRANSPORT IN THE BUNDLE SHEATH OF MAIZE

摘要: Initial investigations into the mechanism of C4 photosynthesis showed that in species such as maize, CO* fmed mesophyll cells is transported form malate to bundle sheath cells, where its decarboxylation catalyzed chloroplasts by NADP’-dependent malic enzyme [ 11. The presence agranal these [2] and functional deficiency photosystem II activity 1,3,4] led view NADPH formed during essential for reduction part glycerate-1,3-bisphosphate reductive pentose phosphate pathway. marked stimulation which causes isolated tissue consistent with this [3,5]. Although extent has since been questioned [6,7], recent work strands having rates equal those parent implied photosynthetic Oa evolution (and uptake) COz acceptor limited high ATP demand COa fucation largely met cyclic photophosphorylation mediated I rather than via noncyclic or pseudocyclic [5]. Cyclic requires activation electron flow from a suitable reductanr, establishes appropriate redox poise carriers. In thisletter, flash spectrophotometric studies are described indicate inadequate sheaths supplies necessary electrons.