Executive Summary : | India aims to double rice production by the middle of the 21st century, with nitrogen (N) being the most important and cost-intensive input in wheat crop production. However, N use efficiency (NUE) in cereals is low (30-40%) due to soil factors, injudicious application, and genotypic responses. To improve NUE, enhancing the expression of positive regulators or knocking down negative regulators of NUE could be feasible. The development of RNA-guided genome editing (CRISPR-Cas9) technology has revolutionized plant genome editing, allowing for high NUE rice development. This technology will enhance genetic improvement for high NUE and improve agriculture sustainability. Previous attempts to improve NUE and yield without improving grain protein content have been unsuccessful. During grain filling, N present in proteins and other macromolecules is remobilized to grain, contributing 50-90% of seed N in cereal crops. Negative feedback regulation of NRE and N status is an important avenue to improve grain protein content and NUE. Rice plants with higher expression of amino acid permease 1 (AAP1) showed higher tiller number and yield. There is potential for improving NUE by altering organic N metabolite transport. Targeting OsAAP3 and OsAAP5 by CRISPR gene-editing in indica rice in an elite genotype background can lead to improvements in NUE and yield. The present proposal aims to develop mutants of amino acid permease genes AAP3 and AAP5 in rice using the CRISPR/Cas system, understanding their role in nitrogen remobilization and identifying CRISPR-Cas mutants with improved yield and nitrogen use efficiency in rice. |