Genetics of Drought Stress Tolerance in Crop Plants

Ensuring stable crop yields in an era where climate change threatens traditional agricultural practices through altered rainfall patterns and increased urban consumption has become a vital concern in global food security. Projected freshwater availability for irrigation indicates that between 20 and 60 Mha of irrigated cropland may have to be reverted to rainfed management [57]. Formerly irrigated crops would become entirely dependent on rainfall and vulnerable to yield loss due to drought. Biotechnology and mining of germplasm of numerous crop species has resulted in discovery of traits that control water use efficiency (WUE) and improve drought tolerance, but only a few of these traits have been implemented in the field [116]. “We need a Blue Revolution in agriculture that focuses on increasing productivity per unit of water—more crop per drop,” Secretary-General Kofi Annan called for a “Blue Revolution” in agriculture [153]. The Green Revolution drastically increased agricultural productivity by remediating nutrient-poor soils with fertilizer, developing irrigation methods and systems, instigating integrated control strategies for weeds and pests, and selected crops that responded to these changes with high yields. The Blue Revolution proposes to address decreasing water availability and climate change. This requires not just drought-tolerance traits, but a high level of control of WUE while still maintaining high yields required by both industrial agriculture and smallholders. An integrated research approach has emerged as a valuable strategy to tackle these necessities. One component of this approach is the mining and introduction of traits from landraces and wild relatives in order to improve drought