Genetic determinants of drought stress tolerance in Setaria

Abstract

Cultivated foxtail millet (Setaria italica) and its wild progenitor (S. viridis) have collectively been considered as tractable model species for studying C4 photosynthesis, stress biology, and biofuel traits. Being cultivated in arid and semiarid tropics of the world, these species are well adapted to harsh environments such as drought, heat, and salinity. This adaptation or acclimation potential of Setaria spp. has drawn research interest, and attempts have been made to dissect the molecular mechanisms of stress tolerance. Compared to other stresses, drought response has been studied extensively in S. italica and many drought-responsive genes encoding for transcription factors, signaling molecules, and enzymes have been identified and characterized. Several genome-wide studies have reported on identification of stress-responsive gene family members, and speculated on the potential for expansion and neofunctionalization of paralogs in these gene families. In this context, this chapter discusses the key genetic determinants identified for stress tolerance in S. italica and demonstrates their use in improving drought tolerance. In addition, strategies for identification of genes underlying stress tolerance are also described. Little effort has so far been made towards understanding the stress-tolerance characteristics of Setaria as compared to studies reported in other crops. Comprehensive functional studies along with the use of integrated -omics approaches are required to elucidate the genetics and genomics of stress tolerance in Setaria, as it is important to develop climate change resilient crops to meet the growing demand for food and feed.