Millets for next generation climate-smart agriculture

Abstract

Panicoids (subfamily: panicoideae) are a group of C4 grasses, which include agronomically important crops such as sorghum and maize, bioenergy feedstocks including sugarcane and miscanthus, nutri-cereals such as millets, and biofuel crops including switchgrass, napier grass and guinea grass. Among these, millets are known for their climate-resilient features including adaptation to a wide range of ecological conditions, less irrigational requirements, better growth and productivity in low nutrient input conditions, less reliance on synthetic fertilizers, and minimum vulnerability to environmental stresses (Kole et al., 2015). Also, millets are nutritionally superior to other major cereals as they are rich in dietary fibers, resistant starches, vitamins, essential amino acids, storage proteins and other bioactive compounds (Amadou et al., 2013). These attributes have made millets a crop of choice for cultivation in arid and semi-arid regions of the world; however, the less attempt has been made to study the climate-resilient features of millets compared to other major cereals. Among millets, foxtail millet (Setaria italica) and its wild progenitor, green foxtail (S. viridis) are extensively studied since they are considered as models for studying the traits related to C4 photosynthesis, stress biology, and bioenergy characteristics (Muthamilarasan and Prasad, 2015). The availability of genome sequence information of these two species (Bennetzen et al., 2012; Zhang et al., 2012) has unlocked the wealth of information pertaining to stress tolerance and biofuel characteristics. It has also expedited the development of large-scale genomic resources for crop improvement. On the other hand, studies on other millets are still in their infancy. The challenge to feed the ever-growing population with a healthy balanced diet and the threats faced by agricultural crops due to changing climate highlight the immediate requirement to exploit the beneficial attributes of millets. This could be utilized for the improvement of millets per se as well as other related grass species. The extensive gene-level synteny shared between the grass genomes would facilitate the transfer and introgression of useful genes, alleles and quantitative trait loci (QTL) of agronomic importance identified in millets to other major cereals. In the above context, this article advocates for initiating extensive research on millets to dissect their agronomic, nutritional as well as stress tolerance traits and develop strategies to transfer the useful traits to cultivated major cereals such as rice, wheat, maize, and sorghum.