Alison D. Gilday

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Hydrophilic interaction chromatography/electrospray mass spectrometry analysis of carbohydrate‐related metabolites from Arabidopsis thaliana leaf tissue

Rapid Communications in Mass Spectrometry (2008)

Carla António Tony R. Larson Alison D. Gilday Ian A. Graham Ed Bergström

Abstract This work describes the development and application of an on‐line liquid chromatography/mass spectrometry (LC/MS) method using hydrophilic interaction chromatography (HILIC) coupled to negative ion mode electrospray ionisation ion trap mass spectrometry (ESI‐MS) for the analysis of highly polar carbohydrate‐related metabolites commonly found in plants, ranging from reducing and non‐reducing sugars and sugar alcohols to sugar phosphates. Using this method, separation and detection of a mixture of eight authentic standard compounds containing glucose (Glc), sucrose (Suc), raffinose, verbascose, mannitol, maltitol, glucose‐6‐phosphate (Glc6P) and trehalose‐6‐phosphate (Tre6P) were achieved in less than 15 min. The method is rapid, robust, selective, and sensitive, with limits of detection (LODs) ranging from 0.2 µM obtained for neutral sugars, to 1.0 µM obtained for sugar alcohols, and 2.0 µM obtained for negatively charged sugar phosphates. We have studied the negative ion collision‐induced dissociation (CID) fragmentation behaviour of the non‐reducing raffinose family oligosaccharides (RFOs) raffinose, stachyose, and verbascose. Mainly B i and C i glycosidic and A i cross‐ring structurally informative cleavages are observed. We have applied this HILIC/ESI‐MS method for the analysis of Arabidopsis thaliana wild‐type Columbia‐0 (Col‐0) and its starchless phosphoglucomutase mutant ( pgm1 ) leaf extracts. The method was used to quantify Glc, Suc, raffinose, and Glc6P in A . thaliana extracts. Data obtained using this HILIC/ESI‐MS method were compared with those obtained using a comparable porous graphitic carbon‐based LC/ESI‐MS method. Copyright © 2008 John Wiley & Sons, Ltd.

Stachyose

10.1002/rcm.3519

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Citations (104)

A role for the root cap in root branching revealed by the non-auxin probe naxillin

Nature Chemical Biology (2012)

Bert De Rybel Dominique Audenaert Wei Xuan Paul Overvoorde Lucia C. Strader

Root (linguistics)

Plant Roots

Branching (polymer chemistry)

10.1038/nchembio.1044

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Citations (128)

Oil accumulation in leaves directed by modification of fatty acid breakdown and lipid synthesis pathways

Plant Biotechnology Journal (2009)

Stephen P. Slocombe Jo Cornah Helen Pinfield‐Wells Kelly Soady Qianyi Zhang

Plant oils in the form of triacylglycerol (TAG) are used for food, industrial feedstock and biofuel manufacture. Although TAG is typically harvested from the fruit or seeds of oil crop species, plants can also accumulate small amounts of TAG in the leaves and other vegetative tissues. Here we show that leaf TAG levels can be increased significantly (10-20 fold) by blocking fatty acid breakdown, particularly during extended dark treatments or leaf senescence in the model plant Arabidopsis. Generation of a double mutant in fatty acid breakdown and diacylglycerol acyltransferase 1 (DGAT1) resulted in a severe vegetative growth phenotype suggesting that partitioning of fatty acids to TAG in leaves is carried out predominantly by this acyltransferase. LEC2, a seed development transcription factor involved in storage product accumulation, was ectopically expressed during senescence in the fatty acid breakdown mutant COMATOSE (cts2). This resulted in accumulation of seed oil type species of TAG in senescing tissue. Our data suggests that recycled membrane fatty acids can be re-directed to TAG by expressing the seed-programme in senescing tissue or by a block in fatty acid breakdown. This work raises the possibility of producing significant amounts of oil in vegetative tissues of biomass crops such as Miscanthus.

Acyltransferases

10.1111/j.1467-7652.2009.00435.x

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Citations (188)

Cold and Light Control Seed Germination through the bHLH Transcription Factor SPATULA

Current Biology (2005)

Steven Penfield Eve‐Marie Josse Rubini Kannangara Alison D. Gilday Karen Halliday

Transcription

10.1016/j.cub.2005.11.010

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Citations (376)

AtTPS1-mediated trehalose 6-phosphate synthesis is essential for embryogenic and vegetative growth and responsiveness to ABA in germinating seeds and stomatal guard cells

The Plant Journal (2010)

Leonardo D. Gómez Alison D. Gilday Regina Feil John E. Lunn Ian A. Graham

Trehalose and associated metabolites are part of the sugar signalling system in plants and have profound effects on development. Disruption of the TREHALOSE 6-PHOSPHATE SYNTHASE (TPS1) gene in Arabidopsis results in delayed embryo growth, altered cell wall morphology and carbon metabolism and abortion at the torpedo stage. Here we investigate the role of the TPS1 gene in post-embryonic development using two approaches. In the first we use the seed-specific ABI3 promoter to drive the TPS1 cDNA during embryo development, resulting in rescue of the embryo-lethal tps1 phenotype. Lack of expression from the ABI3::TPS1 transgene in post-germinative tps1 seedlings results in severe growth arrest, accumulation of soluble sugars and starch and leads to an increase in expression of genes related to ABA signalling. In the second approach we use TILLING (targeted induced local lesions in genomes) to generate three weaker, non-embryo-lethal, alleles (tps1-11, tps1-12 and tps1-13) and use these to demonstrate that the TPS1 protein plays a key role in modulating trehalose 6-phosphate (T6P) levels in vegetative tissues of Arabidopsis. All three weaker alleles give a consistent phenotype of slow growth and delayed flowering. Germination of tps1-11, tps1-12 and tps1-13 is hypersensitive to ABA with the degree of hypersensitivity correlating with the decrease in T6P levels in the different alleles. Stomatal pore aperture is regulated by ABA, and this was found to be affected in tps1-12. Our results show that the TPS1 gene product plays an essential role in regulating the growth of vegetative as well as embryogenic tissue in a mechanism involving ABA and sugar metabolism.

10.1111/j.1365-313x.2010.04312.x

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Citations (187)

A DELLA in Disguise: SPATULA Restrains the Growth of the DevelopingArabidopsisSeedling

The Plant Cell (2011)

Eve‐Marie Josse Yinbo Gan Jordi Bou‐Torrent Kelly L. Stewart Alison D. Gilday

The period following seedling emergence is a particularly vulnerable stage in the plant life cycle. In Arabidopsis thaliana, the phytochrome-interacting factor (PIF) subgroup of basic-helix-loop-helix transcription factors has a pivotal role in regulating growth during this early phase, integrating environmental and hormonal signals. We previously showed that SPATULA (SPT), a PIF homolog, regulates seed dormancy. In this article, we establish that unlike PIFs, which mainly promote hypocotyl elongation, SPT is a potent regulator of cotyledon expansion. Here, SPT acts in an analogous manner to the gibberellin-dependent DELLAs, REPRESSOR OF GA1-3 and GIBBERELLIC ACID INSENSITIVE, which restrain cotyledon expansion alongside SPT. However, although DELLAs are not required for SPT action, we demonstrate that SPT is subject to negative regulation by DELLAs. Cross-regulation of SPT by DELLAs ensures that SPT protein levels are limited when DELLAs are abundant but rise following DELLA depletion. This regulation provides a means to prevent excessive growth suppression that would result from the dual activity of SPT and DELLAs, yet maintain growth restraint under DELLA-depleted conditions. We present evidence that SPT and DELLAs regulate common gene targets and illustrate that the balance of SPT and DELLA action depends on light quality signals in the natural environment.

Phytochrome

Cotyledon

10.1105/tpc.110.082594

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Citations (84)

The Arabidopsis thaliana multifunctional protein gene (MFP2) of peroxisomal β‐oxidation is essential for seedling establishment

The Plant Journal (2006)

Elizabeth L. Rylott Peter J. Eastmond Alison D. Gilday Stephen P. Slocombe Tony R. Larson

Summary The multifunctional protein (MFP) of peroxisomal β ‐oxidation catalyses four separate reactions, two of which (2‐ trans enoyl‐CoA hydratase and l ‐3‐hydroxyacyl‐CoA dehydrogenase) are core activities required for the catabolism of all fatty acids. We have isolated and characterized five Arabidopsis thaliana mutants in the MFP2 gene that is expressed predominantly in germinating seeds. Seedlings of mfp2 require an exogenous supply of sucrose for seedling establishment to occur. Analysis of mfp2‐1 seedlings revealed that seed storage lipid was catabolized more slowly, long‐chain acyl‐CoA substrates accumulated and there was an increase in peroxisome size. Despite a reduction in the rate of β ‐oxidation, mfp2 seedlings are not resistant to the herbicide 2,4‐dichlorophenoxybutyric acid, which is catabolized to the auxin 2,4‐dichlorophenoxyacetic acid by β ‐oxidation. Acyl‐CoA feeding experiments show that the MFP2 2‐ trans enoyl‐CoA hydratase only exhibits activity against long chain (C18:0) substrates, whereas the MFP2 l ‐3‐hydroxyacyl‐CoA dehydrogenase is active on C6:0, C12:0 and C18:0 substrates. A mutation in the abnormal inflorescence meristem gene AIM1 , the only homologue of MFP2 , results in an abnormal inflorescence meristem phenotype in mature plants ( Richmond and Bleecker, Plant Cell 11, 1999 , 1911) demonstrating that the role of these genes is very different. The mfp2‐1 aim1 double mutant aborted during the early stages of embryo development showing that these two proteins share a common function that is essential for this key stage in the life cycle.

Catabolism

Glyoxysome

10.1111/j.1365-313x.2005.02650.x

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Citations (94)

Gene discovery and virus-induced gene silencing reveal branched pathways to major classes of bioactive diterpenoids in Euphorbia peplus

Proceedings of the National Academy of Sciences (2022)

Tomasz Czechowski Edith Forestier Sandesh H Swamidatta Alison D. Gilday Amy Cording

Significance Euphorbia peplus , a member of the Euphorbia genus, is rich in jatrophane and ingenane diterpenoids. Using a metabolomics-guided transcriptomic approach to gene candidate identification, we have discovered a short-chain dehydrogenase gene involved in the production of the lathyrane jolkinol E. We have developed a virus-induced gene-silencing method in E. peplus that has allowed us to demonstrate the direct relationship between casbene and polycyclic diterpenoids and that jolkinol C acts as a key branch point intermediate in the production of ingenanes and jatrophanes. This work contributes both knowledge and tools for engineering production of bioactive diterpenoids in heterologous host systems, thus enabling their further evaluation and development.

Euphorbia

Heterologous

Heterologous expression

10.1073/pnas.2203890119

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Citations (13)

MOTHER-OF-FT-AND-TFL1 represses seed germination under far-red light by modulating phytohormone responses in Arabidopsis thaliana

Proceedings of the National Academy of Sciences (2018)

Fabián E. Vaistij Thiago Barros‐Galvão Adama Cole Alison D. Gilday Zhesi He

Significance Seeds sense environmental conditions, such as light quality, to regulate their germination. Light enriched in the far-red wavelength, such as under-the-canopy light (shade), increases abscisic acid (ABA) and decreases gibberellin (GA) levels, the phytohormones repressing and promoting germination, respectively. We have discovered that MFT functions as a key repressor of germination under far-red light conditions by modulating ABA and GA responses.

10.1073/pnas.1806460115

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Citations (84)

Production of Bioactive Diterpenoids in the Euphorbiaceae Depends on Evolutionarily Conserved Gene Clusters

The Plant Cell (2014)

Andrew King Geoffrey D. Brown Alison D. Gilday Tony R. Larson Ian A. Graham

The Euphorbiaceae produce a diverse range of diterpenoids, many of which have pharmacological activities. These diterpenoids include ingenol mebutate, which is licensed for the treatment of a precancerous skin condition (actinic keratosis), and phorbol derivatives such as resiniferatoxin and prostratin, which are undergoing investigation for the treatment of severe pain and HIV, respectively. Despite the interest in these diterpenoids, their biosynthesis is poorly understood at present, with the only characterized step being the conversion of geranylgeranyl pyrophosphate into casbene. Here, we report a physical cluster of diterpenoid biosynthetic genes from castor (Ricinus communis), including casbene synthases and cytochrome P450s from the CYP726A subfamily. CYP726A14, CYP726A17, and CYP726A18 were able to catalyze 5-oxidation of casbene, a conserved oxidation step in the biosynthesis of this family of medicinally important diterpenoids. CYP726A16 catalyzed 7,8-epoxidation of 5-keto-casbene and CYP726A15 catalyzed 5-oxidation of neocembrene. Evidence of similar gene clustering was also found in two other Euphorbiaceae, including Euphorbia peplus, the source organism of ingenol mebutate. These results demonstrate conservation of gene clusters at the higher taxonomic level of the plant family and that this phenomenon could prove useful in further elucidating diterpenoid biosynthetic pathways.

Euphorbiaceae

Gene cluster

Subfamily

10.1105/tpc.114.129668

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Citations (97)