Meta-QTLs linked to nitrogen use efficiency are randomly distributed in Indian rice germplasm

Nitrogen (N) recognized as a critical element for plant growth plays a fundamental role in rice cultivation. The N use efficiency (NUE) hovers around 30-35% in rice, suggesting a significant loss of N from the rice fields. Improving the NUE therefore would require genetic interventions and breeding. The cultivar improvement for N uptake and utilization is required to elevate NUE to further heights. Several quantitative trait loci (QTLs) for NUE under varying conditions and genetic backgrounds have been reported in rice. Consolidation of this distributed and unorganized information is necessary to identify critical genomic regions to be used for crop improvement. Therefore, a Meta-analysis from an assembly of 506 QTLs reported from 18 different studies was performed to identify the most significant genomic regions associated with NUE in rice. A total of 12 meta-QTLs (mQTLs) related to the traits such as NUE and grain yield per plant under N deficit conditions have been identified over four rice chromosomes namely 1, 3, 4, and 8. Evaluation of these mQTLs in a set of Indian rice germplasm revealed a significant association of the meta loci with N use parameters and showed wide distribution in the germplasm. Identification of mQTLs on different chromosomes together with their respective markers will help recruit them in marker-assisted selection (MAS) to develop N use efficient genotypes.