Identification of a plastidial phenylalanine exporter that influences flux distribution through the phenylalanine biosynthetic network

Widhalm, Joshua R.; Gutensohn, Michael; Yoo, Heejin; Adebesin, Funmilayo; Qian, Yichun; Guo, Longyun; Jaini, Rohit; Lynch, Joseph H.; McCoy, Rachel M.; Shreve, Jacob; Thimmapuram, Jyothi; Rhodes, David; Morgan, John A.; Dudareva, Natalia

doi:10.1038/ncomms9142

Cited by 82 publications

(74 citation statements)

References 63 publications

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“…Interestingly, a similar trend of expression was also detected for a proton-dependent oligopeptide transporter (POT), which contains a PTR2 domain that characterizes both nitrate and peptide transporters (Widhalm et al, 2015). …”

Section: Resultsmentioning

confidence: 66%

Whole Plant Temperature Manipulation Affects Flavonoid Metabolism and the Transcriptome of Grapevine Berries

et al. 2017

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Among environmental factors, temperature is the one that poses serious threats to viticulture in the present and future scenarios of global climate change. In this work, we evaluated the effects on berry ripening of two thermal regimes, imposed from veraison to harvest. Potted vines were grown in two air-conditioned greenhouses with High Temperature (HT) and Low Temperature (LT) regimes characterized by 26 and 21°C as average and 42 and 35°C as maximum air daily temperature, respectively. We conducted analyses of the main berry compositional parameters, berry skin flavonoids and berry skin transcriptome on HT and LT berries sampled during ripening. The two thermal conditions strongly differentiated the berries. HT regime increased sugar accumulation at the beginning of ripening, but not at harvest, when HT treatment contributed to a slight total acidity reduction and pH increase. Conversely, growing temperatures greatly impacted on anthocyanin and flavonol concentrations, which resulted as strongly reduced, while no effects were found on skin tannins accumulation. Berry transcriptome was analyzed with several approaches in order to identify genes with different expression profile in berries ripened under HT or LT conditions. The analysis of whole transcriptome showed that the main differences emerging from this approach appeared to be more due to a shift in the ripening process, rather than to a strong rearrangement at transcriptional level, revealing that the LT temperature regime could delay berry ripening, at least in the early stages. Moreover, the results of the in-depth screening of genes differentially expressed in HT and LT did not highlight differences in the expression of transcripts involved in the biosynthesis of flavonoids (with the exception of PAL and STS) despite the enzymatic activities of PALs and UFGT being significantly higher in LT than HT. This suggests only a partial correlation between molecular and biochemical data in our conditions and the putative existence of post-transcriptional and post-translational mechanisms playing significant roles in the regulation of flavonoid metabolic pathways and in particular of anthocyanins.

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Section: Resultsmentioning

confidence: 66%

Whole Plant Temperature Manipulation Affects Flavonoid Metabolism and the Transcriptome of Grapevine Berries

et al. 2017

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“…For each aromatic amino acid, labeling percentage dynamics were numerically integrated with the following balance equations (Widhalm et al ., ) by ode15 solver in Matlab R2013a (The MathWorks, Natick, MA, USA):

\frac{d f_{{Phe}_{normalinteractive, t}}}{d t} = \frac{false(f_{{normalGlucose}_{t}} - f_{{normalPhe}_{interactive, t}} false) * v_{1}}{C_{{normalPhe}_{interactive, t}}}

\frac{d f_{{Tyr}_{t}}}{d t} = \frac{false(f_{{normalGlucose}_{t}} - f_{{normalTyr}_{t}} false) * v_{2}}{C_{{normalTyr}_{t}}}

\frac{d f_{{Trp}_{t}}}{d t} = \frac{false(f_{{normalGlucose}_{t}} - f_{{normalTrp}_{t}} false) * v_{3}}{C_{{normalTrp}_{t}}}

…”

Section: Methodsmentioning

confidence: 99%

Multifaceted plant responses to circumvent Phe hyperaccumulation by downregulation of flux through the shikimate pathway and by vacuolar Phe sequestration

et al. 2017

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Detrimental effects of hyperaccumulation of the aromatic amino acid phenylalanine (Phe) in animals, known as phenylketonuria, are mitigated by excretion of Phe derivatives; however, how plants endure Phe accumulating conditions in the absence of an excretion system is currently unknown. To achieve Phe hyperaccumulation in a plant system, we simultaneously decreased in petunia flowers expression of all three Phe ammonia lyase (PAL) isoforms that catalyze the non-oxidative deamination of Phe to trans-cinnamic acid, the committed step for the major pathway of Phe metabolism. A total decrease in PAL activity by 81-94% led to an 18-fold expansion of the internal Phe pool. Phe accumulation had multifaceted intercompartmental effects on aromatic amino acid metabolism. It resulted in a decrease in the overall flux through the shikimate pathway, and a redirection of carbon flux toward the shikimate-derived aromatic amino acids tyrosine and tryptophan. Accumulation of Phe did not lead to an increase in flux toward phenylacetaldehyde, for which Phe is a direct precursor. Metabolic flux analysis revealed this to be due to the presence of a distinct metabolically inactive pool of Phe, likely localized in the vacuole. We have identified a vacuolar cationic amino acid transporter (PhCAT2) that contributes to sequestering excess of Phe in the vacuole. In vitro assays confirmed PhCAT2 can transport Phe, and decreased PhCAT2 expression in PAL-RNAi transgenic plants resulted in 1.6-fold increase in phenylacetaldehyde emission. These results demonstrate mechanisms by which plants maintain intercompartmental aromatic amino acid homeostasis, and provide critical insight for future phenylpropanoid metabolic engineering strategies.

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“…Chloroplasts (and the cytosol) are the sites of de novo biosynthesis of a large number of proteinogenic amino acids, and membrane proteins are essential to facilitate their movement across the plastid envelope and towards the phloem (Weber & Tegeder, 2006). To date, only two chloroplast amino acid transporters have been characterized, the Arabidopsis glutamate/malate exchanger dicarboxylate transporter (DiT2) (Renne et al, 2003) and the Petunia hybrida Cationic Amino Acid Transporter (PhpCAT) which functions in export of aromatic amino acids (Widhalm et al, 2015).…”

Section: Nitrogen Assimilation and Amino Acid Synthesismentioning

confidence: 99%

Source and sink mechanisms of nitrogen transport and use

2017

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Contents Summary35I.Introduction35II.Nitrogen acquisition and assimilation36III.Root‐to‐shoot transport of nitrogen38IV.Nitrogen storage pools in vegetative tissues39V.Nitrogen transport from source leaf to sink40VI.Nitrogen import into sinks42VII.Relationship between source and sink nitrogen transport processes and metabolism43VIII.Regulation of nitrogen transport43IX.Strategies for crop improvement44X.Conclusions46Acknowledgements47References47 Summary Nitrogen is an essential nutrient for plant growth. World‐wide, large quantities of nitrogenous fertilizer are applied to ensure maximum crop productivity. However, nitrogen fertilizer application is expensive and negatively affects the environment, and subsequently human health. A strategy to address this problem is the development of crops that are efficient in acquiring and using nitrogen and that can achieve high seed yields with reduced nitrogen input. This review integrates the current knowledge regarding inorganic and organic nitrogen management at the whole‐plant level, spanning from nitrogen uptake to remobilization and utilization in source and sink organs. Plant partitioning and transient storage of inorganic and organic nitrogen forms are evaluated, as is how they affect nitrogen availability, metabolism and mobilization. Essential functions of nitrogen transporters in source and sink organs and their importance in regulating nitrogen movement in support of metabolism, and vegetative and reproductive growth are assessed. Finally, we discuss recent advances in plant engineering, demonstrating that nitrogen transporters are effective targets to improve crop productivity and nitrogen use efficiency. While inorganic and organic nitrogen transporters were examined separately in these studies, they provide valuable clues about how to successfully combine approaches for future crop engineering.

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Identification of a plastidial phenylalanine exporter that influences flux distribution through the phenylalanine biosynthetic network

Cited by 82 publications

References 63 publications

Whole Plant Temperature Manipulation Affects Flavonoid Metabolism and the Transcriptome of Grapevine Berries

Whole Plant Temperature Manipulation Affects Flavonoid Metabolism and the Transcriptome of Grapevine Berries

Multifaceted plant responses to circumvent Phe hyperaccumulation by downregulation of flux through the shikimate pathway and by vacuolar Phe sequestration

Source and sink mechanisms of nitrogen transport and use

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