ABSTRACT
The reducing equivalents required for anabolism as well as for detoxifying and regenerative systems in plant cells derive (directly or indirectly) from both ferredoxin (Fd) and NADPH. The chloroplast protein Fd is the final acceptor of the photosynthetic electron transfer through the thylakoid membrane and, in its reduced form, is linked to conversion of NADP+ to NADPH, thus generating the primary products that conserve part of the energy from sunlight as reducing power (Rochaix 2011). NADPH and ATP are the main products of the light phase of photosynthesis that then are used for carbon assimilation during the synthetic phase (Cortassa et al. 2012; Iglesias and Podestá 2005). Plants exhibit the following key characteristics: (1) cells are highly compartmentalized, with the occurrence of plastids, and (2) there are two different kinds of tissues, with characteristic metabolic scenarios: photosynthetic or heterotrophic. Consequently, specific routes take place in the different cells to partition photosynthetically generated reducing equivalents intracellularly and intercellularly; the whole picture is schematized in Figure 8.1.
