Phylogenetic analyses and in-seedling expression of ammonium and nitrate transporters in wheat

Prabin Bajgain,Blake Russell,Mohsen Mohammadi

doi:10.1038/s41598-018-25430-8

Prabin Bajgain, Blake Russell + Show 1 more

Open Access

https://doi.org/10.1038/s41598-018-25430-8

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Abstract

Plants deploy several ammonium transporter (AMT) and nitrate transporter (NRT) genes to acquire NH4+ and NO3− from the soil into the roots and then transport them to other plant organs. Coding sequences of wheat genes obtained from ENSEMBL were aligned to known AMT and NRT sequences of Arabidopsis, barley, maize, rice, and wheat to retrieve homologous genes. Bayesian phylogenetic relationships among these genes showed distinct classification of sequences with significant homology to NRT1, NRT2, and NRT3 (NAR2). Inter-species gene duplication analysis showed that eight AMT and 77 NRT genes were orthologous to the AMT and NRT genes of aforementioned plant species. Expression patterns of these genes were studied via whole transcriptome sequencing of 21-day old seedlings of five spring wheat lines. Eight AMT and 52 NRT genes were differentially expressed between root and shoot; and 131 genes did not express neither in root nor in shoot of 21-day old seedlings. Homeologous genes in the A, B, and D genomes, characterized by high sequence homology, revealed that their counterparts exhibited different expression patterns. This complement and evolutionary relationship of wheat AMT and NRT genes is expected to help in development of wheat germplasm with increased efficiency in nitrogen uptake and usage.

Highlights

Nitrogen (N) is a major element in plant physiology and metabolic processes
One of the main goals of this study was to retrieve ammonium and nitrate transporter gene sequences in wheat, and assess their phylogenetic relationships. We observed that such relationships among the wAMT and wNRT genes mostly resulted in grouping of similar genes and gene families
The number of ammonium transporter (AMT) and NRT genes detected in this study is higher when compared to wheat[12,19] as well as in other plant species such as Arabidopsis, rice, and poplar[11,13,21,22]

Summary

Introduction

Nitrogen (N) is a major element in plant physiology and metabolic processes. It is used in synthesis of amino acids, proteins[1], and secondary metabolites[2] as well as in signaling of several cellular and morphological processes that regulate plant growth and development[3]. Plants have evolved to develop different affinity transport systems to cope with and operate under variable (high and low) external nitrogen availability[6,7]. These two uptake systems are referred to as low affinity transport system (LATS) and high affinity transport system (HATS)[8]. Only 16 nitrate transporter (NPF) genes are postulated in hexaploid wheat and are localized in all chromosomes except 4A12. Understanding how and when nitrate and ammonium transporter genes express in plants from their earliest growth stages is one way to further characterize genotypes with superior NUE. As wheat is one of the most important staple crops in the world, identifying accessions with higher NUE could increase wheat production at lesser cost to meet the demands of a growing global population

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