Genetically modified crops are superior in their nitrogen use efficiency-A meta-analysis of three major cereals

Mengjiao Li,Yajun Gao,Jili Xu,Zhiyuan Gao,Hui Tian,Khalil Kariman

doi:10.1038/s41598-020-65684-9

Mengjiao Li, Yajun Gao + Show 4 more

Open Access

https://doi.org/10.1038/s41598-020-65684-9

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Abstract

It is currently uncertain to what extent genetic transformations of strategic crops (targeting diverse traits) have improved their N use efficiency (NUE), and what the key factors affecting their NUE are. Based on data collected from 130 publications, the effect sizes of genetic transformations and the key factors influencing NUE for three major cereal crops (rice, maize, and wheat), were investigated using a meta-analysis approach. Genetic transformations increased yield, shoot biomass, N uptake efficiency (NUpE), and partial factor productivity of N (PFPN) in the crops, but decreased shoot NUE (SNUE) and grain NUE (GNUE). Transporter genes improved yield and NUE parameters more efficiently, than did the other gene types. The effect sizes for some NUE parameters varied according to crop species and experimental conditions but did not differ between the overexpression and ectopic expression methods. Most effect sizes did not correlate with gene overexpression levels. These results indicate a promising potential of genetic transformations approaches for improving certain NUE parameters.

Highlights

It is currently uncertain to what extent genetic transformations of strategic crops have improved their N use efficiency (NUE), and what the key factors affecting their NUE are
Shoot biomass, and N concentration/ content data, and calculated (1) shoot N utilization efficiency (SNUE, total shoot biomass produced per unit of N in shoot); (2) grain N utilization efficiency (GNUE, total grain yield produced per unit of N in shoot); and (3) partial factor productivity of N (PFPN, grain yield per unit of N applied in soil), where it was possible
The highest effect sizes of yield for rice, maize, and wheat occurred under stress conditions after ectopic expression of an ADP ribosylation factor 1 gene (SaARF1), a Bacillus thuringiensis (Bt) gene, and an alanine aminotransferase (AlaAT) gene, respectively (Supplementary Table 1)

Summary

Introduction

It is currently uncertain to what extent genetic transformations of strategic crops (targeting diverse traits) have improved their N use efficiency (NUE), and what the key factors affecting their NUE are. Based on data collected from 130 publications, the effect sizes of genetic transformations and the key factors influencing NUE for three major cereal crops (rice, maize, and wheat), were investigated using a meta-analysis approach. Improved NUpE can lead to less excess N in agricultural soils and reduced environmental risks, while improved NUtE contributes to higher crop yields or biomass with less N input Both the NUpE and NUtE factors should be considered in NUE studies. Overexpression of some other key enzymes such as nitrate reductase and nitrite reductase did not improve the NUE of crops[30,31], suggesting that genes involved in N assimilation pathways might play different roles in modifying the NUE of plants. Based on 130 publications, the present study aimed to investigate: (1) whether the three major GM cereals have improved NUE; (2) which NUE parameters can be improved by genetic transformations; and (3) how target gene types, gene expression level, and environmental conditions influence the effects of genetic transformations on the NUE of a given crop

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