Nitrogen use efficiency is regulated by interacting proteins relevant to development in wheat

Abstract

Summary Wheat ( Triticum aestivum ) has low nitrogen use efficiency ( NUE ). The genetic mechanisms controlling NUE are unknown. Positional cloning of a major quantitative trait locus for N‐related agronomic traits showed that the vernalization gene Ta VRN ‐A1 was tightly linked with Ta NUE 1 , the gene shown to influence NUE in wheat. Because of an Ala 180 /Val 180 substitution, Ta VRN ‐A1a and Ta VRN ‐A1b proteins interact differentially with Ta ANR 1, a protein encoded by a wheat orthologue of Arabidopsis nitrate regulated 1 ( ANR 1 ). The transcripts of both Ta VRN ‐ A1 and Ta ANR 1 were down‐regulated by nitrogen. Ta ANR 1 was functionally characterized in Ta ANR 1:: RNA i transgenic wheat, and in a natural mutant with a 23‐bp deletion including 10‐bp at the 5′ end of intron 5 and 13‐bp of exon 6 in gDNA sequence in its gDNA sequence, which produced transcript that lacked the full 84‐bp exon 6. Both Ta ANR 1 and Ta HOX 1 bound to the Ala 180 /Val 180 position of Ta VRN ‐A1. Genetically incorporating favourable alleles from Ta VRN ‐A1 , Ta ANR 1 and Ta HOX 1 increased grain yield from 9.84% to 11.58% in the field. Molecular markers for allelic variation of the genes that regulate nitrogen can be used in breeding programmes aimed at improving NUE and yield in novel wheat cultivars.