Research Background And Significance Of Food And Fuel Supply

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Research Background and Significance Overview Food and fuel supply need to increase in order to adequately satisfy current and future populations (Tilman et al., 2011). It has been proposed that improvements to photosynthesis are likely to be a part of the way in which this demand can be met but first a more thorough understanding of the different carbon fixing mechanisms needs to be obtained (Sinclair et al., 2004). There are different methods by which plants fix carbon. Most plants fix carbon using either the C3 or C4 pathways. C4 photosynthesis involves the operation of a carbon concentrating mechanism (CCM) across mesophyll and bundle sheath cells by adding an initial carboxylation reaction in the mesophyll and decarboxylation reaction in the bundle sheath. This increases photosynthetic efficiency by concentrating CO2 around the final carboxylase ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) in order to increase the average carboxylation rate of RuBisCO (Vc) and supress the energetically wasteful photorespiration pathway (Jordan and Ogren, 1983). The majority of agriculturally important C4 species, such as maize and sorghum, fix carbon using the NADP-ME pathway subtype (Vicentini et al., 2008). The first carboxylation step in C4 species is the fixation of HCO3- to phosphoenolpyruvate (PEP). This step is catalysed by C4 PEP carboxylase (PEPC) but little information exists as to how C4 PEPC activity affects the ability of NADP-ME plants to concentrate carbon
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