| Summary: | Rice, as a major staple crop, is one of the most important targets for plant breeders in an attempt to secure enough food for a growing world population. Producing nutrient efficient crops has become essential not only to attempt securing enough food for the growing population, but also to eliminate environmental consequences of using fertilizers. Nitrogen (N), phosphorus (P) and potassium (K) are major macronutrients that are rate limiting for plant growth and crop productivity. The aims of this project were to explore the genetic diversity of rice to identify genotypes with high efficiency under N, P and K deficient conditions, to identify chromosomal loci linked to NPK use efficiency using Genome Wide Association Studies (GWAS), and to manipulate a proton pump using CRISPR/Cas9 system with the aim of improving mycorrhiza-dependent nutrient uptake. Biomass and elemental analyses revealed considerable variations among 294 rice genotypes, and a subset of genotypes was identified that were relatively tolerant to NPK nutrient limitation. GWAS study revealed novel and previously known QTLs and genes with potential importance to the use efficiency of N, P and K. Alongside with N and K transporters and regulatory proteins, unexpectedly several genes involved in Na transport were identified as candidates. The CRISPR/Cas9 system was successfully applied to manipulate several candidate genes identified from GWAS, in addition to the rice H+-ATPase (OsHA1). Overall, the findings from this study can be used as a basis to conduct similar studies in other crops, which can all contribute to improve crop production, sustainable agriculture and food security.
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