<i>Arabidopsis</i> LHT1 Is a High-Affinity Transporter for Cellular Amino Acid Uptake in Both Root Epidermis and Leaf Mesophyll

Hirner, Axel A.; Ladwig, Friederike; Stransky, Harald; Okumoto, Sakiko; Keinath, Melanie; Harms, Agnes; Frommer, Wolf B.; Koch, Wolfgang

doi:10.1105/tpc.106.041012

Cited by 325 publications

(404 citation statements)

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“…utes to the root import of several amino acids (19,20), might also be involved in m-tyrosine uptake from the medium. Inhibition of the shikimate pathway enzyme 3-deoxy-Darabino-heptulosonic acid 7-phosphate synthase by m-tyrosine in E. coli (21) suggested that similar effects could produce toxicity in plants.…”

Section: Resultsmentioning

confidence: 99%

“…Aqueous solution of commercial m-tyrosine (10,20,40,80, and 160 M concentrations) or 1 ml of an aqueous solution of dried Intrigue root exudates extract adjusted to contain m-tyrosine at identical concentrations, as determined by HPLC, were spotted onto filter paper. Root growth of L. sativa and D. sanguinalis (10 seedlings per Petri dish) were measured after 5 days (L. sativa) or 7 days (D. sanguinalis) and compared with the lengths of root and shoot of control plants grown on plates treated only with 1 ml water.…”

Section: Comparison Of the Phytotoxic Activities Of M-tyrosine And Rootmentioning

confidence: 99%

See 1 more Smart Citation

Grass roots chemistry: meta -Tyrosine, an herbicidal nonprotein amino acid

Bertin

Weston²,

Huang

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

178

192

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Fine fescue grasses displace neighboring plants by depositing large quantities of an aqueous phytotoxic root exudate in the soil rhizosphere. Via activity-guided fractionation, we have isolated and identified the nonprotein amino acid m-tyrosine as the major active component. m-Tyrosine is significantly more phytotoxic than its structural isomers o-and p-tyrosine. We show that mtyrosine exposure results in growth inhibition for a wide range of plant species and propose that the release of this nonprotein amino acid interferes with root development of competing plants. Acid hydrolysis of total root protein from Arabidopsis thaliana showed incorporation of m-tyrosine, suggesting this as a possible mechanism of phytotoxicity. m-Tyrosine inhibition of A. thaliana root growth is counteracted by exogenous addition of protein amino acids, with phenylalanine having the most significant effect. The discovery of m-tyrosine, as well as a further understanding of its mode(s) of action, could lead to the development of biorational approaches to weed control.allelopathy ͉ festuca ͉ rhizosphere ͉ root ecology ͉ Arabidopsis R oot exudation of small molecules plays a major role in plant ecosystems and is often associated with the development of competitive advantage through allelopathy (1, 2). Juglone, a highly phytotoxic naphthoquinone produced by black walnut (Juglans nigra L.), and sorgoleone, a substituted quinone from sorghum (Sorghum spp.), are two classic examples of potently active allelochemicals deposited via the plant's living root system ( Fig. 1) (3). Elucidation of the structures and mode of action of previously unknown root-derived phytotoxins could lead to new biorational approaches to weed control.Because of their stress tolerance and disease resistance, fescue (Festuca spp.) grasses are commonly used in landscape, roadside, and pasture settings, as well as for conservation purposes (4, 5). The unusual ability of many fine leaf fescue species to outcompete other plants is well known, and previous investigations suggested that fescue root exudates have phytotoxic properties (4). Here, we report the isolation, identification, and biological activity of m-tyrosine, a potent, structurally unusual broadspectrum phytotoxin exuded by the roots of some fine leaf fescue grasses. Results and DiscussionIn an initial field evaluation of 80 fine fescue cultivars, 8 cultivars with strong weed suppressive potential were identified and their allelopathic potential in laboratory settings was confirmed (4). Based on both field and laboratory results, we selected ''Intrigue,'' a common Chewing's fescue cultivar (Festuca rubra L. ssp. commutata), for further studies.To identify the allelopathic compound(s) contained in Intrigue root exudates, we developed an activity-guided separation scheme based on the inhibition of lettuce (Lactuca sativa L.) radicle elongation in a filter paper-based assay. By using this assay, we compared the phytotoxicity of root surface washes (hexanes, dichloromethane, methanol, and water) prepared from 2-w...

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Section: Resultsmentioning

confidence: 99%

Section: Comparison Of the Phytotoxic Activities Of M-tyrosine And Rootmentioning

confidence: 99%

Grass roots chemistry: meta -Tyrosine, an herbicidal nonprotein amino acid

Bertin

Weston²,

Huang

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

178

192

View full text Add to dashboard Cite

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“…Tissue-specific overexpression of this transporter in the Arabidopsis root tip led to increased proline content of the root apex (0-5 mm) and increased growth under control conditions (Ueda et al, 2008), although the effects of such targeted overexpression on growth under stress conditions were not tested. Whether or not this function in Arabidopsis is performed by one of the ProTs, other transporters known to have proline uptake activity in roots such as LHT1 or AAP5 (Hirner et al, 2006;Rentsch et al, 2007;Svennerstam et al, 2008), or other yet uncharacterized transporters will be an interesting question for further experiments. Long distance proline transport may be important in taking proline produced in photosynthetic tissue as a way to buffer cellular redox status and moving it to non-photosynthetic tissue such as roots, where it can contribute to osmotic adjustment or be catabolized to support growth ( Figure 5A; see sections IV.-A.…”

Section: B Intercellular Transportersmentioning

confidence: 99%

Proline Metabolism and Its Implications for Plant-Environment Interaction

Verslues

Sharma

2010

The Arabidopsis Book

472

347

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Proline has long been known to accumulate in plants experiencing water limitation and this has driven studies of proline as a beneficial solute allowing plants to increase cellular osmolarity during water limitation. Proline metabolism also has roles in redox buffering and energy transfer and is involved in plant pathogen interaction and programmed cell death. Some of these unique roles of proline depend on the properties of proline itself, whereas others depend on the "proline cycle" of coordinated proline synthesis in the chloroplast and cytoplasm with proline catabolism in the mitochondria. The regulatory mechanisms controlling proline metabolism, intercellular and intracellular transport and connections of proline to other metabolic pathways are all important to the in vivo functions of proline metabolism. Connections of proline metabolism to the oxidative pentose phosphate pathway and glutamate-glutamine metabolism are of particular interest. The N-acetyl glutamate pathway can also produce ornithine and, potentially, proline but its role and activity are unclear. Use of model systems such as Arabidopsis thaliana to better understand both these long studied and newly emerging functions of proline can help in the design of nextgeneration experiments testing whether proline metabolism is a promising metabolic engineering target for improving stress resistance of economically important plants.

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“…In Arabidopsis roots, the three amino acid transporters AAP1, AAP5 and LHT1 have been shown to play a role in amino acid uptake. They each have different specificity and affinity for amino acids (Hirner et al, 2006;Lee et al, 2007;Svennerstam et al, 2008). Amino acid transporters are less well characterised in other species but it is well documented that amino acid uptake occurs in a wide range of species including gymnosperms (Nasholm et al, 1998;Persson and Nasholm, 2002), dicots (Ge et al, 2009;Kielland, 1994;Nasholm et al, 1998Nasholm et al, , 2000Streeter et al, 2000) and monocots (Biernath et al, 2008;El-Naggar et al, 2009;Henry and Jefferies, 2003;Jamtgard et al, 2008Jamtgard et al, , 2010Kielland, 1994;Lipson et al, 1999;Nasholm et al, 1998Nasholm et al, , 2000Nasholm and Persson, 2001;Schimel and Chapin, 1996;Streeter et al, 2000;Thornton, 2001;Thornton and Robinson, 2005;Yamagata and Ae, 1999).…”

Section: E Gioseffi Et Al: Organic and Inorganic N Interactions Inmentioning

confidence: 99%

Interactions between uptake of amino acids and inorganic nitrogen in wheat plants

2012

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Abstract. Soil-borne amino acids may constitute a source of nitrogen (N) for plants in various terrestrial ecosystems but their importance for total N nutrition is unclear, particularly in nutrient-rich arable soils. One reason for this uncertainty is lack of information on how the absorption of amino acids by plant roots is affected by the simultaneous presence of inorganic N forms. The objective of the present study was to study absorption of glycine (Gly) and glutamine (Gln) by wheat roots and their interactions with nitrate (NO − 3 ) and ammonium (NH + 4 ) during uptake. The underlying hypothesis was that amino acids, when present in nutrient solution together with inorganic N, may lead to down-regulation of the inorganic N uptake, thereby resulting in similar total N uptake rates. Amino acids were enriched with double-labelled 15 N and 13 C, while NO − 3 and NH + 4 acquisition was determined by their rate of removal from the nutrient solution surrounding the roots. The uptake rates of NO − 3 and NH + 4 did not differ from each other and were generally about twice as high as the uptake rate of organic N when the different N forms were supplied separately in concentrations of 2 mM. Nevertheless, replacement of 50 % of the inorganic N with organic N was able to restore the N uptake to the same level as that in the presence of only inorganic N. Co-provision of NO − 3 did not affect glycine uptake, while the presence of glycine down-regulated NO − 3 uptake. The ratio between 13 C and 15 N were lower in shoots than in roots and also lower than the theoretical values, reflecting higher C losses via respiratory processes compared to N losses. It is concluded that organic N can constitute a significant N-source for wheat plants and that there is an interaction between the uptake of inorganic and organic N.

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Arabidopsis LHT1 Is a High-Affinity Transporter for Cellular Amino Acid Uptake in Both Root Epidermis and Leaf Mesophyll

Cited by 325 publications

References 70 publications

Grass roots chemistry: meta -Tyrosine, an herbicidal nonprotein amino acid

Grass roots chemistry: meta -Tyrosine, an herbicidal nonprotein amino acid

Proline Metabolism and Its Implications for Plant-Environment Interaction

Interactions between uptake of amino acids and inorganic nitrogen in wheat plants

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