Setaria viridis as a Model for C4 Photosynthesis

Abstract

Climate change compounded with dwindling arable lands, and population growth has presented a grand challenge for plant science to develop higher yielding varieties grown on fewer acres with fewer inputs. The most productive and photosynthetically efficient crops are C4 grasses that have evolved mechanisms to concentrate CO2 and reduce photorespiration in hot and dry environments. This improved biochemistry is most often achieved through compartmentalization of photosynthetic activities into two cell types, the bundle sheath (BS) and mesophyll (M) cells. BS and M cells are arranged in files of concentric rings around the vasculature, in a pattern known as Kranz anatomy. Ambitious efforts to engineer C4 traits into C3 crops have the potential to increase the yield of rice by up to 50 %, improve nitrogen use efficiency, and reduce water loss (Hibberd et al., Curr Opin Plant Biol 11: 228--31, 2008). To accelerate these engineering efforts, a better understanding is needed of the developmental and regulatory mechanisms underlying C4 photosynthesis. Here, we discuss the many advantages of using Setaria viridis as a model system for dissecting C4 photosynthesis (Brutnell et al., Plant Cell 22:2537--44, 2010; Annu Rev Plant Biol 66:465--85, 2015), particularly as a platform for gene discovery and to unravel the complex genetic basis underlying the anatomical and biochemical innovations of this trait.