Genes for NUE in rice: a way forward for molecular breeding and genome editing

Abstract

Nitrogen is one of the most critical nutrients in rice production and increased rice productivity is attributed mostly to the nitrogen fertilizer responsive rice varieties. With its relevance to environment, breeding for nitrogen use efficiency is now a research priority in rice. Based on the physiological, biochemical and genetic studies, several genes have been identified for nitrogen uptake, transport, remobilization and assimilation. Many of the genes and gene families associated with tissues like root, shoot, leaf and panicle have been characterized under differential nitrogen conditions. Functional validation of the identified genes in nitrogen use efficiency, yield and other agro-morphological traits demonstrated their potential for deployment in rice breeding programs. In the present review, the information on possible genes associated with nitrogen use efficiency has been presented. The epigenetic regulation of genes including the non-coding RNA and new breeding technologies like genome editing have also been discussed for identification and validation of genes for NUE. We propose a combinatorial approach of deploying the information available for genes reported to be associated with NUE of rice by haplotyping, allele mining, spatial and temporal expression analyses, gene networking and validation through genome editing towards development of high yielding rice varieties under optimum nitrogen.