Regulation of amino acid metabolic enzymes and transporters in plants

Pratelli, Réjane; Pilot, Guillaume

doi:10.1093/jxb/eru320

Cited by 318 publications

(208 citation statements)

References 233 publications

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“…These catabolic enzymes are coregulated at steady state mRNA level under diel and extended darkness conditions as well as during seed development, consistent with the mutant results (Peng et al, 2015;Uygun et al, 2016). While less is known about the importance of genetic regulation of BCAA biosynthetic enzymes, the activities of committed enzymes of the BCAA network are sensitive to in vitro regulation by amino acid products (Less and Galili, 2008;Pratelli and Pilot, 2014). Such allosteric mechanisms could play an important role in BCAA homeostasis; however, relatively little is known about their in vivo importance.…”

Section: Introductionsupporting

confidence: 71%

A Regulatory Hierarchy of the Arabidopsis Branched-Chain Amino Acid Metabolic Network

Xing

2017

Plant Cell

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The branched-chain amino acids (BCAAs) Ile, Val, and Leu are essential nutrients that humans and other animals obtain from plants. However, total and relative amounts of plant BCAAs rarely match animal nutritional needs, and improvement requires a better understanding of the mechanistic basis for BCAA homeostasis. We present an in vivo regulatory model of BCAA homeostasis derived from analysis of feedback-resistant Arabidopsis thaliana mutants for the three allosteric committed enzymes in the biosynthetic network: threonine deaminase (also named L-O-methylthreonine resistant 1 [OMR1]), acetohydroxyacid synthase small subunit 2 (AHASS2), and isopropylmalate synthase 1 (IPMS1). In this model, OMR1 exerts primary control on Ile accumulation and functions independently of AHAS and IPMS. AHAS and IPMS regulate Val and Leu homeostasis, where AHAS affects total Val+Leu and IPMS controls partitioning between these amino acids. In addition, analysis of feedback-resistant and loss-of-function single and double mutants revealed that each AHAS and IPMS isoenzyme contributes to homeostasis rather than being functionally redundant. The characterized feedback resistance mutations caused increased free BCAA levels in both seedlings and seeds. These results add to our understanding of the basis of in vivo BCAA homeostasis and inform approaches to improve the amount and balance of these essential nutrients in crops.

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Section: Introductionsupporting

confidence: 71%

A Regulatory Hierarchy of the Arabidopsis Branched-Chain Amino Acid Metabolic Network

Xing

2017

Plant Cell

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“…The export of re-mobilized N terminates at the growing leaves (Yoneyama and Sano, 1978). The AAs exported in the phloem (Fukumorita and Chino, 1982) include: (i) actively metabolized AAs and amides, such as glutamine, glutamic acid, asparagine, aspartic acid, and alanine, which are derived from inorganic N assimilation and also produced after active interconversion in the source organs, and (ii) more importantly, coordinately regulated AAs such as lysine, arginine, histidine, valine, tyrosine, phenylalanine, and leucine (Noctor et al, 2002), which are synthesized in the chloroplast under the tight control of feedback-regulation (Pratelli and Pilot, 2014) and are also supplied after protein degradation.…”

Section: Current Knowledge On the Uptake Assimilation And Transportmentioning

confidence: 99%

Whole-Plant Dynamic System of Nitrogen Use for Vegetative Growth and Grain Filling in Rice Plants (Oryza sativa L.) as Revealed through the Production of 350 Grains from a Germinated Seed Over 150 Days: A Review and Synthesis

Yoneyama

Tanno²,

Tatsumi³

et al. 2016

Front. Plant Sci.

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A single germinated rice (Oryza sativa L) seed can produce 350 grains with the sequential development of 15 leaves on the main stem and 7–10 leaves on four productive tillers (forming five panicles in total), using nitrogen (N) taken up from the environment over a 150-day growing season. Nitrogen travels from uptake sites to the grain through growing organ-directed cycling among sequentially developed organs. Over the past 40 years, the dynamic system for N allocation during vegetative growth and grain filling has been elucidated through studies on N and 15N transport as well as enzymes and transporters involved. In this review, we synthesize the information obtained in these studies along the following main points: (1) During vegetative growth before grain-filling, about half of the total N in the growing organs, including young leaves, tillers, root tips and differentiating panicles is supplied via phloem from mature source organs such as leaves and roots, after turnover and remobilization of proteins, whereas the other half is newly taken up and supplied via xylem, with an efficient xylem-to-phloem transfer at stem nodes. Thus, the growth of new organs depends equally on both N sources. (2) A large fraction (as much as 80%) of the grain N is derived largely from mature organs such as leaves and stems by degradation, including the autophagy pathway of chloroplast proteins (e.g., Rubisco). (3) Mobilized proteinogenic amino acids (AA), including arginine, lysine, proline and valine, are derived mainly from protein degradation, with AA transporters playing a role in transferring these AAs across cell membranes of source and sink organs, and enabling their efficient reutilization in the latter. On the other hand, AAs such as glutamine, glutamic acid, γ-amino butyric acid, aspartic acid, and alanine are produced by assimilation of newly taken up N by roots and and transported via xylem and phloem. The formation of 350 filled grains over 50 days during the reproductive stage is ascribed mainly to degradation and remobilization of the reserves, previously accumulated over 100 days in the sequentially developed vegetative organs.

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“…Pratelli and Pilot (2014) suggested that pathogen infection leads to changes in expression of genes involved in amino acid metabolism and transport. They also tabulated the effect of nematode infection on AtAAP gene family members, showing that these responded differentially (induced or repressed) by infection.…”

Section: Introductionmentioning

confidence: 99%

Infection byRhodococcus fasciansmaintains cotyledons as a sink tissue for the pathogen

Dhandapani

Song

Novák

et al. 2016

Ann Bot

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Background and Aims Pisum sativum L. (pea) seed is a source of carbohydrate and protein for the developing plant. By studying pea seeds inoculated by the cytokinin-producing bacterium, Rhodococcus fascians, we sought to determine the impact of both an epiphytic (avirulent) strain and a pathogenic strain on source-sink activity within the cotyledons during and following germination.Methods Bacterial spread was monitored microscopically, and real-time reverse transcription-quantitative PCR was used to determine the expression of cytokinin biosynthesis, degradation and response regulator gene family members, along with expression of family members of SWEET, SUT, CWINV and AAP genes -gene families identified initially in pea by transcriptomic analysis. The endogenous cytokinin content was also determined.Key Results The cotyledons infected by the virulent strain remained intact and turned green, while multiple shoots were formed and root growth was reduced. The epiphytic strain had no such marked impact. Isopentenyl adenine was elevated in the cotyledons infected by the virulent strain. Strong expression of RfIPT, RfLOG and RfCKX was detected in the cotyledons infected by the virulent strain throughout the experiment, with elevated expression also observed for PsSWEET, PsSUT and PsINV gene family members. The epiphytic strain had some impact on the expression of these genes, especially at the later stages of reserve mobilization from the cotyledons.Conclusions The pathogenic strain retained the cotyledons as a sink tissue for the pathogen rather than the cotyledon converting completely to a source tissue for the germinating plant. We suggest that the interaction of cytokinins, CWINVs and SWEETs may lead to the loss of apical dominance and the appearance of multiple shoots.

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Regulation of amino acid metabolic enzymes and transporters in plants

Cited by 318 publications

References 233 publications

A Regulatory Hierarchy of the Arabidopsis Branched-Chain Amino Acid Metabolic Network

A Regulatory Hierarchy of the Arabidopsis Branched-Chain Amino Acid Metabolic Network

Whole-Plant Dynamic System of Nitrogen Use for Vegetative Growth and Grain Filling in Rice Plants (Oryza sativa L.) as Revealed through the Production of 350 Grains from a Germinated Seed Over 150 Days: A Review and Synthesis

Infection byRhodococcus fasciansmaintains cotyledons as a sink tissue for the pathogen

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