Introducon
Rice (Oryza sativa L.), the principal cereal crop, requires
more nitrogen (N) than any other crop of the world. As
a plant nutrient element, availability of N is naturally
limited in the soil due to its high mobility and volatility.
Therefore, intervention through fertilization is essential in
agriculture to maintain the soil N status. Although under-
use of N can jeopardize crop production, excess use can
end up in environmental degradation. Owing to several
factors, exogenous and endogenous, plants are unable to
utilize applied N efficiently. The exogenous factors include
soil denitrification and rapid N loss through leaching,
volatilization, and run-off. The average level of N use
efficiency among the field crops is about 33% (Abrol et al.
1999), with crop utilization ranging between 30 - 40 % of the
applied N (Raun and Johnson 1999). A sizeable portion of
the unutilized N is lost into the environment and becomes
unavailable to the plants (Abrol 1 et al. 2007). A sustainable
solution for this impasse is to develop nitrogen-efficient
varieties that can give optimum or high yield at reduced N
input. The plant use of applied N in agriculture is measured in
terms of the parameter, overall N use efficiency (NUE) which
is the ratio of grain yield to the applied N (Pathak et al. 2008).
Abstract
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.
Keywords: Crop production, marker-assisted selection, meta-QTLs, nitrogen use efficiency, rice
Meta-QTLs linked to nitrogen use efficiency are randomly
distributed in Indian rice germplasm
Rahul Kumar, K. K. Vinod*, S. Gopala Krishnan, Dinesh Kumar
1
, Shweta Mehrotra
1
, Lekshmy Sathee
2
, Ranjith K. Ellur,
A. K. Singh, P. K. Bhowmick, Haritha Bollinedi, M. Nagarajan
3
and P. K. Mandal
4
Division of Genetics,
1
Division of Agronomy,
2
Division of Plant
Physiology,
3
Rice Breeding and Genetics Research Centre, ICAR-
Indian Agricultural Research Institute, New Delhi 110012, India;
4
ICAR-National Institute of Plant Biotechnology, New Delhi
110012, India
Corresponding Author: K. K. Vinod, Division of Genetics, ICAR-
Indian Agricultural Research Institute, New Delhi 110012, India,
E-Mail: kkvinodh@gmail.com
How to cite this article: Kumar R., Vinod K. K., Krishnan S. G.,
Kumar D., Mehrotra S., Sathee L., Ellur R. K., Singh A. K., Bhowmick
P. K., Bollinedi H., Nagarajan M., Mandal P. K. 2022. Meta-QTLs
linked to nitrogen use efficiency are randomly distributed in
Indian rice germplasm. Indian J. Genet. Plant Breed., 82(1): 7-15.
Source of support: Nil
Conflict of interest: None.
Received: Nov. 2021 Revised: Jan. 2022 Accepted: Feb. 2022
NUE has two components, N uptake efficiency (NUpE) and N
utilization efficiency (NUtE), the product of which gives NUE.
Improving NUE is possible through breeding because
the trait is genetically regulated, but the progress is slow
due to the low heritability of the trait and its complex
regulatory nature (Gallais and Hirel 2004). Quantitative
© ISGPB 2022. This article is Published by the Indian Society of Genetics & Plant Breeding, NASC Complex, IARI P.O., Pusa Campus, New Delhi 110 012;
www.isgpb.org
RESEARCH ARTICLE
Indian J. Genet. Plant Breed., (2022) 82(1): 7-15
www.isgpg.org
ISSN: 0975-6906
doi: 10.31742/IJGPB.82.1.2