*Correspondence: rajeev.varshney@murdoch.edu.au

Wheat (Triticum aestivum L.) is one of the most important crops in the world, but the grain quality and quantity is heavily reliant on applied nitrogen. Wheat utilizes only about a third of the applied nitrogen, making it one of the most nitrogen-inefficient crops.

Australian wheat industry has been suffering from low nitrogen use efficiency (NUE) and nitrogen dilution effect, leading to lower grain protein content (GPC). Since GPC is the prime decider of market price in national and international markets, optimizing NUE is paramount for enhancing the productivity and profitability of the farmers while also alleviating the negative impacts of fertilizers on the environment.

A previous study assessed the genetic basis of 22 traits contributing to enhanced NUE using 6 doubled haploid (DH) populations. Based on phenotypic screening across four locations in Australia, the study identified 14 quantitative trait locus (QTL) groups on 10 different chromosomes. Through reanalysis of the QTLs using the combined consensus map of the six DH populations, six major effect QTL clusters have been identified for 3 key traits namely GPC, grain yield (GY) and NUE, accounting for 4.36 – 22.89% of the phenotypic variance.

Out of the 6 clusters, one cluster on chromosome 2B has been identified to be associated with all the three traits across two locations while accounting for 14.09 – 22.89% of the phenotypic variance. Our study aims to introgress this QTL cluster into 2-3 leading Australian varieties/lines to develop lines with higher NUE and GPC without any compromise on yield.

The parent of the DH contributing to the superior alleles of the QTL cluster and specific DH lines will be used to perform strategic crosses with target Australian genotypes for marker-assisted backcrossing (MABC) in controlled conditions followed by rapid generation advancement.

The resultant lines will be screened on the basis of background recovery of the genomes of the target Australian genotypes to obtain a subset of high NUE introgression lines, which can be advanced for multi-location trials across different Australian wheat production environments.

This study will not only provide markers associated with NUE-related traits but also the superior NUE lines for global wheat improvement.