Evolutionary classification of ammonium, nitrate, and peptide transporters in land plants

Abstract

BackgroundNitrogen uptake, reallocation within the plant, and between subcellular compartments involves ammonium, nitrate and peptide transporters. Ammonium transporters are separated into two distinct families (AMT1 and AMT2), each comprised of five members on average in angiosperms. Nitrate transporters also form two discrete families (NRT1 and NRT2), with angiosperms having four NRT2s, on average. NRT1s share an evolutionary history with peptide transporters (PTRs). The NRT1/PTR family in land plants usually has more than 50 members and contains also members with distinct activities, such as glucosinolate and abscisic acid transport.ResultsPhylogenetic reconstructions of each family across 20 land plant species with available genome sequences were supplemented with subcellular localization and transmembrane topology predictions. This revealed that both AMT families diverged prior to the separation of bryophytes and vascular plants forming two distinct clans, designated as supergroups, each. Ten supergroups were identified for the NRT1/PTR family. It is apparent that nitrate and peptide transport within the NRT1/PTR family is polyphyletic, that is, nitrate and/or peptide transport likely evolved multiple times within land plants. The NRT2 family separated into two distinct clans early in vascular plant evolution. Subsequent duplications occurring prior to the eudicot/monocot separation led to the existence of two AMT1, six AMT2, 31 NRT1/PTR, and two NRT2 clans, designated as groups.ConclusionPhylogenetic separation of groups suggests functional divergence within the angiosperms for each family. Distinct groups within the NRT1/PTR family appear to separate peptide and nitrate transport activities as well as other activities contained within the family, for example nitrite transport. Conversely, distinct activities, such as abscisic acid and glucosinolate transport, appear to have recently evolved from nitrate transporters.

A Laser Dissection-RNAseq Analysis Highlights the Activation of Cytokinin Pathways by Nod Factors in the Medicago truncatula Root Epidermis

“…Those included the previously mentioned MtHA1 ATPase, while a paralogous gene, MtAHA5, also encoding a protein rapidly phosphorylated upon NF addition (Nguyen et al, 2015), was down-regulated. Three NITRATE TRANSPORTER1/ PEPTIDE TRANSPORTER (PTR) proteins are encoded by NF-induced genes and likely transport oligopeptides, similar to other PTR1-and PTR3-like proteins (Léran et al, 2014;von Wittgenstein et al, 2014). Interestingly, the M. truncatula Gene Atlas (MtGEA; http://mtgea.noble.org/v3/) indicates that the NF-induced PTR3-like gene (Mtr.31737.1.S1_s_at) is almost nodule specific.…”

Nitrate transporters: an overview in legumes

“…Such a phylogenetic study can be taken as an insightful clue to start an analysis of the protein family. For example, following a phylogenetic study on nitrate and peptide transporters, including several species of angiosperms, it has been proposed that each separate group of NPF protein sequences identified within the NPF family shares common function (von Wittgenstein et al 2014). However, although phylogenetically close, two genes may exhibit different patterns of expression.…”

Plant and microbe genomics and beyond: potential for developing a novel molecular plant nutrition approach

“…in high-affinity systems (Krapp et al 2014). In a recent review, von Wittgenstein et al (2014) highlighted that nitrogen uptake, reallocation within the plant, and between subcellular compartments involved ammonium, nitrate and peptide transporters. In angiosperms, each of the two families of NH 4…”