Setaria: A Food Crop and Translational Research Model for C4 Grasses

It is increasingly evident that new environmentally sustainable agricultural practices will be necessary to support an estimated human population of 9 billion by 2050. Considering the predicted climate change-associated events such as flooding, drought, increased temperatures, and increased soil salinity, it is critical to broaden our study and use of cereals and small grains. Millets offer significant potential toward meeting these goals. The genus Setaria comprises more than one hundred species distributed in a wide range of habitats in Asia, Africa, South America, and North America. Millets, including foxtail millet (Setaria italica), pearl millet (Pennisetum glaucum) and proso millet (Panicum milaceum), are consumed by millions of humans across the world, as well as used as forage and bird feed. Recently, foxtail millet and its wild-progenitor, green foxtail millet (S. viridis), have emerged as model plant systems for studying C 4 grass biology and other agronomic traits (Doust et al. Here, we comment on the significance of S. italica and S. viridis as model systems for agronomic and translational research related to improvement of nutritional quality, biotic and abiotic stress responses, photosynthetic efficiency and biomass potential of C 4 grasses. Foxtail millet is in the Paniceae tribe (sub-family Panicoideae of the Poaceae), which also contains pearl millet and proso millet. Foxtail millet was domesticated from green foxtail in northern China ca. 8000 years ago (Barton et al., 2009), and has been widely cultivated in arid and semi-arid regions of Asia, Africa and the Americas (Lata et al., 2013). It is one of the most resilient cereal crops, with good yields in dry and marginal land with minimal agricultural inputs. Foxtail millet also adapts well to adverse weather conditions such as low and unpredictable precipitation Because global climate change will have significant adverse effects on the production of other major cereals, foxtail-, pearl-and proso-millets are increasingly attractive alternatives for small grain production (Tadele, 2016). Green foxtail millet has also come into the spotlight in recent years as an attractive alternative to more established grass model systems such as rice and maize (Figure 1). S. viridis offers several research advantages, including short stature (10–30 cm), rapid life cycle (6–9 weeks), prolific seed production (∼13,000 seeds per plant), self-compatibility, small genome size (∼395 Mb), diploid genetics (2n = 18), ability to be grown in controlled environments under relatively low light levels, and amenability to transformation (Devos et al. Like maize, green and foxtail millets …