Abstract
Identification of genes and their alleles capable of improving plant growth under low nitrogen (N) conditions is key for developing sustainable agriculture. Here, we show that a genome-wide association study using Arabidopsis thaliana accessions suggested an association between different magnitudes of N deficiency responses and diversity in NRT1.1/NPF6.3 that encodes a dual-affinity nitrate transporter involved in nitrate uptake by roots. Various analyses using accessions exhibiting reduced N deficiency responses revealed that enhanced NRT1.1 expression in shoots rather than in roots is responsible for better growth of Arabidopsis seedlings under N deficient conditions. Furthermore, polymorphisms that increased NRT1.1 promoter activity were identified in the NRT1.1 promoter sequences of the accessions analyzed. Hence, our data indicated that polymorphism-dependent activation of the NRT1.1 promoter in shoots could serve as a tool in molecular breeding programs for improving plant growth in low N environments.
Highlights
Identification of genes and their alleles capable of improving plant growth under low nitrogen (N) conditions is key for developing sustainable agriculture
To evaluate differences in N deficiency responses among Arabidopsis accessions, the total chlorophyll content of all 52 accessions was quantified at the seedling stage (Supplementary Data 1) because yellowing of premature leaves, which is caused by the degradation of chlorophyll, is a typical N deficiency symptom
genome-wide association study (GWAS) of Arabidopsis accessions and further analyses of selected accessions presenting reduction in chlorophyll degradation under low N conditions revealed that polymorphism-dependent enhancement of NRT1.1 expression in shoots contributes to improved plant growth under low N conditions
Summary
Identification of genes and their alleles capable of improving plant growth under low nitrogen (N) conditions is key for developing sustainable agriculture. We show that a genomewide association study using Arabidopsis thaliana accessions suggested an association between different magnitudes of N deficiency responses and diversity in NRT1.1/NPF6.3 that encodes a dual-affinity nitrate transporter involved in nitrate uptake by roots. The results implied an association between N deficiency responses and NRT1.1 polymorphisms This association was further examined using two Arabidopsis accessions, Gr-5 and Ullapool-8, both of which displayed high NRT1.1 expression and reduced N deficiency responses. Several lines of evidence indicate that polymorphism-dependent activation of the NRT1.1 promoter in aerial plant parts confers better growth under N deficient conditions in Arabidopsis
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