Molecular Breeding in Rice for Abiotic Stress Resilience

More than half of the world’s population consumes rice as a staple food, with India and China alone contributing 50% of consumption and production. Rice is grown in all ecosystems and is affected by various abiotic stresses such as acidity, salinity, drought, and low and high temperature, which in turn affect its yield. Therefore, sustainable rice cultivation practices need to be developed and implemented to meet the global demand of the growing population. Over the years, efforts in breeding for abiotic stress-resilient rice have led to the development of varieties that can be grown under adverse climatic conditions with minimum yield penalty. Most of these efforts have focused on the identification of quantitative trait loci (QTLs) and fine mapping followed by deployment in field conditions. Hundreds of QTLs for various traits correlated with stress tolerance have been identified to date. With the development of a high-quality sequenced reference genome, the availability of potential molecular markers increased exponentially, ultimately resulting in robust, affordable allele-specific marker datasets that can be used for molecular breeding. However, the markers linked or associated with abiotic stress tolerance, working across diverse genetic backgrounds, and deployed successfully in the field remain only a handful. In this chapter, we discuss how breeding in rice was accelerated with the availability of a sequenced genome, with an emphasis on progress made in achieving abiotic stress tolerance. Further, we also discuss the impediments and bottlenecks still faced by breeders in successfully implementing the molecular information available for meaningful genetic gains.