Wheat Ammonium Transporter (AMT) Gene Family: Diversity and Possible Role in Host–Pathogen Interaction with Stem Rust

Abstract

Ammonium transporter (AMT) proteins have been reported in many plants, but no comprehensive analysis was performed in wheat. In this study, we identified 23 AMT members (hereafter TaAMTs) using a protein homology search in wheat genome. Tissue-specific expression analysis showed that TaAMT1;1a, TaAMT1;1b, and TaAMT1;3a were relatively more highly expressed in comparison with other TaAMTs. TaAMT1;1a, TaAMT1;1b, and TaAMT1;3a-GFP were localized in the plasma membrane in tobacco leaves, and TaAMT1;1a, TaAMT1;1b, and TaAMT1;3a successfully complemented a yeast 31019b strain in which ammonium uptake was deficient. In addition, the expression of TaAMT1;1b in an Arabidopsis AMT quadruple mutant (qko) successfully restored NH4+ uptake ability. Resupply of NH4+ rapidly increased cellular NH4+ contents and suppressed expression of TaAMT1;3a, but not of TaAMT;1;1a and TaAMT1;1b expressions. Expression of TaAMT1;1a, TaAMT1;1b, and TaAMT1;3a was not changed in leaves after NH4+ resupply. In contrast, nitrogen (N) deprivation induced TaAMT1;1a, TaAMT1;1b, and TaAMT1;3a gene expressions in the roots and leaves. Expression analysis in the leaves of the stem rust-susceptible wheat line “Little Club” and the rust-tolerant strain “Mini 2761” revealed that TaAMT1;1a, TaAMT1;1b, and TaAMT1;3a were specifically induced in the former but not in the latter. Rust-susceptible wheat plants grown under N-free conditions exhibited a lower disease index than plants grown with NH4+ as the sole N source in the medium after infection with Puccinia graminis f. sp. tritici, suggesting that NH4+ and its transport may facilitate the infection of wheat stem rust disease. Our findings may be important for understanding the potential function TaAMTs in wheat plants.

Difference in Nitrogen Starvation-Inducible Expression Patterns among Phylogenetically Diverse Ammonium Transporter Genes in the Red Seaweed <i>Pyropia yezoensis</i>

“…This hypothesis is supported by our gene expression analyses indicating differences in temporal and nitrogen stress-inducible expression patterns for the PyAMT1 genes (Figure 7 and Nitrogen deficiency results in leaf senescence in land plants [40] [41]. In leaf senescence, nitrogen is reused to support plant growth and reproduction by reallocating from aging leaves to younger tissues [8] [9] and degradation of chlorophylls and following discoloration of tissues occur in aging leaves [42] [43]. Thus, loss of nitrogen and degradation of photosynthetic pigments are responsible for leaf senescence [40] [44].…”

“…Our phylogenetic analysis demonstrated the diversity of the AMT1 subfamily, consisting of independent phylum-specific clades (Figure 3). Land plants have their own AMT1 subfamily, with five genes in Arabidopsis [4] [11] [12] [13], at least 10 genes in rice [9], and 23 genes in wheat [8]. Although AMT1s from land plants formed a single clade, it was separated from the algal AMT1 subfamily, in which the unicellular green algae C. reinhardtii and the red seaweed Po.…”

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

“…Our work expands on this idea, and attempts to capture a snapshot of the physiological level landscape of nitrate and ammonium transporter genes in wheat by making use of the publicly available wheat gene sequences 16 . Previously reported ammonium and nitrate transporter studies 12 , 17 – 19 have used fewer genes obtained from less and different plant species. Here, we present a comprehensive set of wheat AMT and NRT genes leveraging on the availability of abundant genomic information and tools.…”

Multiple quantitative trait loci contribute tolerance to bacterial canker incited byPseudomonas syringaepv.actinidiaein kiwifruit (Actinidia chinensis)

“…Other gene families that are differentially expressed encode proteins with putative functions associated with PTI, for example detoxification-like protein Acc00747.1 69 , a MADS-box like transcription factor Acc03527.1 70 , terpene synthases Acc13740.1, Acc13742.1, Acc22685.1, Acc22685.1 71 , MLP-like proteins Acc18987.1, Acc13742.1 72 Acc20584.1, Acc20586.1 thioredoxin-like protein 73 , cellulose synthase-like protein Acc27502.1 74 , WD40-repeat containing super-family protein Acc23960.1 75 , UV-B - induced protein DUF760 Acc25706.1, Acc14728 76 , protein of unknown function (DUF247) /Acc08767, ammonium transporter 2/ Acc08664.1 77 . A defense gene that is linked to carbohydrate metabolism that was upregulated in Psa-TMT but downregulated in Psa-FT encodes a putative beta-galactosidase Acc13005.1.…”

“…Specifically, Acc16485.1 ( Alpha-glucan phosphorylase ), Acc03527.1 ( AGAMOUS-like ) and Acc08664.1 ( Ammonium transporter ) genes were confirmed to be significantly induced in P1 in greenhouse and field tolerant genotypes. Acc03527.1 ( AGAMOUS-like ) is located very close to the QTL on LG3 in P1 for Psa_score_Field and an ammonium transporter gene has been recently shown to be involved in stem rust resistance in wheat 77 . Our study therefore provide new resource for candidate RNA-biomarkers for predicting tolerance in kiwifruit field breeding nurseries that can lead to improve the speed of selective breeding of multi-genic trait 78 .…”