Metabolite Transporters in the Control of Plant Primary Metabolism

Tegeder, Mechthild; Weber, Andreas

doi:10.1002/9780470988640.ch4

Cited by 23 publications

(14 citation statements)

References 213 publications

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“…, 1999). Molecular studies on amino acid transport have mostly concentrated on Arabidopsis and the AAPs, eight members being the best‐investigated transporters (for review see Liu and Bush, 2006; Tegeder and Weber, 2006; Wipf et al. , 2002).…”

Section: Discussionmentioning

confidence: 99%

AAP1 transports uncharged amino acids into roots of Arabidopsis

et al. 2007

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SummaryAmino acids are available to plants in some soils in significant amounts, and plants frequently make use of these nitrogen sources. The goal of this study was to identify transporters involved in the uptake of amino acids into root cells. Based on the fact that high concentrations of amino acids inhibit plant growth, we hypothesized that mutants tolerating toxic levels of amino acids might be deficient in the uptake of amino acids from the environment. To test this hypothesis, we employed a forward genetic screen for Arabidopsis thaliana mutants tolerating toxic concentrations of amino acids in the media. We identified an Arabidopsis mutant that is deficient in the amino acid permease 1 (AAP1, At1g58360) and resistant to 10 mM phenylalanine and a range of other amino acids. The transporter was localized to the plasma membrane of root epidermal cells, root hairs, and throughout the root tip of Arabidopsis. Feeding experiments with [ 14 C]-labeled neutral, acidic and basic amino acids showed significantly reduced uptake of amino acids in the mutant, underscoring that increased tolerance of aap1 to high levels of amino acids is coupled with reduced uptake by the root. The growth and uptake studies identified glutamate, histidine and neutral amino acids, including phenylalanine, as physiological substrates for AAP1, whereas aspartate, lysine and arginine are not. We also demonstrate that AAP1 imports amino acids into root cells when these are supplied at ecologically relevant concentrations. Together, our data indicate an important role of AAP1 for efficient use of nitrogen sources present in the rhizosphere.

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Section: Discussionmentioning

confidence: 99%

AAP1 transports uncharged amino acids into roots of Arabidopsis

et al. 2007

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“…While much of the initial research on molecular aspects of organic N transport was performed using Arabidopsis thaliana , some transporter homologs have been identified and analyzed in other model or crop plants, including tomato, potato, broad and castor bean, pea, barley, and rice [3–6]. Many of the Arabidopsis N transporters were isolated using heterologous complementation of yeast ( Saccharomyces cerevisiae ) mutants deficient in the uptake of the respective metabolites.…”

Section: Transporters For Organic Nitrogen Compounds In Plantsmentioning

confidence: 99%

“…Nevertheless, the analyses showed that most of the transporters of the same clade (subfamily) share similar substrate selectivity and affinity (see below). The gene families that have been functionally characterized are briefly described here, but for a detailed description of individual gene families and the phylogenetic relationship of the transporters, for analysis of characteristic motifs, as well as other information such as an overview of transporter expression and regulation of expression, we refer to recent reviews [3–5,8–11].…”

Section: Transporters For Organic Nitrogen Compounds In Plantsmentioning

confidence: 99%

Transporters for uptake and allocation of organic nitrogen compounds in plants

2007

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Nitrogen is an essential macronutrient for plant growth. Following uptake from the soil or assimilation within the plant, organic nitrogen compounds are transported between organelles, from cell to cell and over long distances in support of plant metabolism and development. These translocation processes require the function of integral membrane transporters. The review summarizes our current understanding of the molecular mechanisms of organic nitrogen transport processes, with a focus on amino acid, ureide and peptide transporters.

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“…While a large number of amino acid transporters has been identified in plants, mainly by genome analyses and sequence comparison, still very little is known about their physiological function (Lalonde et al. , 2003; Liu and Bush, 2006; Tegeder and Weber, 2006; Rentsch et al. , 2007).…”

Section: Introductionmentioning

confidence: 99%

“…For the sequence of transfer of amino acids from roots to leaves, to sink organs and uptake into embryo cells, plasma membrane-located transport proteins are essential. While a large number of amino acid transporters has been identified in plants, mainly by genome analyses and sequence comparison, still very little is known about their physiological function (Lalonde et al, 2003;Liu and Bush, 2006;Tegeder and Weber, 2006;Rentsch et al, 2007). Experiments that employ amino acid transporter mutants to find phenotypic changes compared with wild-type have been unsuccessful (Okumoto et al, 2004) or mainly addressed transporter function in amino acid uptake from the soil (Hirner et al, 2006;Lee et al, 2007;Svennerstam et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

AAP1 regulates import of amino acids into developing Arabidopsis embryos

et al. 2009

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SUMMARYThe embryo of Arabidopsis seeds is symplasmically isolated from the surrounding seed coat and endosperm, and uptake of nutrients from the seed apoplast is required for embryo growth and storage reserve accumulation. With the aim of understanding the importance of nitrogen (N) uptake into developing embryos, we analysed two mutants of AAP1 (At1g58360), an amino acid transporter that was localized to Arabidopsis embryos. In mature and desiccated aap1 seeds the total N and carbon content was reduced while the total free amino acid levels were strongly increased. Separately analysed embryos and seed coats/endosperm of mature seeds showed that the elevated amounts in amino acids were caused by an accumulation in the seed coat/ endosperm, demonstrating that a decrease in uptake of amino acids by the aap1 embryo affects the N pool in the seed coat/endosperm. Also, the number of protein bodies was increased in the aap1 endosperm, suggesting that the accumulation of free amino acids triggered protein synthesis. Analysis of seed storage compounds revealed that the total fatty acid content was unchanged in aap1 seeds, but storage protein levels were decreased. Expression analysis of genes of seed N transport, metabolism and storage was in agreement with the biochemical data. In addition, seed weight, as well as total silique and seed number, was reduced in the mutants. Together, these results demonstrate that seed protein synthesis and seed weight is dependent on N availability and that AAP1-mediated uptake of amino acids by the embryo is important for storage protein synthesis and seed yield.

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Metabolite Transporters in the Control of Plant Primary Metabolism

Cited by 23 publications

References 213 publications

AAP1 transports uncharged amino acids into roots of Arabidopsis

AAP1 transports uncharged amino acids into roots of Arabidopsis

Transporters for uptake and allocation of organic nitrogen compounds in plants

AAP1 regulates import of amino acids into developing Arabidopsis embryos

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