Genome Wide Association Study of Water Use Efficiency and Drought Resistance Traits in Rice

Rice (Oryza sativa L.) is an important cereal crop that uses 30% of the global fresh water resources during its life cycle. Water deficit causes loss of rice crop productivity, with drought a major challenge limiting rice production. Drought affects various physiological processes (photosynthesis, water use efficiency, stomatal conductance), crucial processes for plant growth and production of assimilates that reduce rice grain yield. However, the abundant diversity of rice has naturally evolved genetic variation for water use efficiency and drought resistance, from which favorable loci can be identified for improvement of rice productivity traits for superior biomass, economic yield, WUE and drought tolerance (Impa et al., 2005). The USDA rice mini-core collection has been screened for multiple productivity and yield traits, and is being used for genome wide association study (GWAS) to identify the genetic resources and favorable loci for improving WUE and other drought resistance related traits in rice. A global level genetic analysis of WUE and drought resistance related traits within the natural genetic variation available will help uncover diverse sources and characterize genetic loci for plant genomics and breeding, and provide an understanding of mechanisms useful for improving WUE and drought resistance of rice cultivars. The improved productivity of the rice crop under drought and other abiotic stresses remains as one the most important current and future challenges in plant genomics & breeding for stabilizing crop production with the challenges of climate change.