Exeter University Archives - Weeding the Gems

GARNet Research Roundup: July 16th

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Published on: July 16, 2018

This week’s GARNet research roundup begins with a set of papers looking at aspects of the plant defence response with a focus on the cell wall. Firstly work from Mike Deeks’ lab in Exeter assesses the role of FORMIN4 during pre-invasion cell wall apposition. Secondly Sara Pose and Paul Knox (Leeds) are involved with a study looking at how altered cell wall lignin composition alters the defense response. Finally Joe McKenna and Cyril Zipfel are co-authors on a Norwegian-led study that looks at the influence of plant cell wall integrity maintenance in immune signalling.

Relatedly is a study from the Devoto lab at RHUL looks at the role of the defence hormone methyl jasmonate in Arabidopsis cell culture.

Next are two papers that research different aspects of the plant ER. Verena Kriechbaumer (Oxford Brookes) looks at plant ER-localised Lunapark proteins whilst a study from the University of Warwick provides a preliminary structural analysis of the RTNLB13 reticulon protein.

The seventh and eight papers are involved with the plant response to different growth conditions. Research from University of Nottingham looks at the response of the cortical cell layer of the root meristem to low phosphate conditions whilst work from University of Southampton investigates the relationship between nitrate and copper signaling.

The next paper is from Emily Flashman’s lab at the University of Oxford and looks at the role of plant cysteine oxidases as oxygen sensors whilst the tenth paper features John Doonan (Aberystwyth University) as a co-author and investigates how a histone acetyltransferase affects trichome development.

Finally is a paper from Pierre Baudal and Kirsten Bomblies (John Innes Centre) that uses Arabidopsis arenosa as a model to investigate the emergence of novel flowering time alleles in populations that have colonised along railway corridors.

Sassmann S, Rodrigues C, Milne SW, Nenninger A, Allwood E, Littlejohn GR, Talbot NJ, Soeller C, Davies B, Hussey PJ, Deeks MJ (2018) An Immune-Responsive Cytoskeletal-Plasma Membrane Feedback Loop in Plants. Curr Biol. doi: 10.1016/j.cub.2018.05.014

https://www.sciencedirect.com/science/article/pii/S096098221830616X?via%3Dihub

Open Access

Stefan Sassmann is the lead author of this paper from Mike Deeks’s lab in Exeter. They investigate the role of the membrane-integrated FORMIN4 protein in the process of cell wall apposition, which occurs as part of the plant immune response and is dependent on actin dynamics. FORMIN4 is stably localised apart from the active traffic of the endomembrane system and removing its function compromises the defense response, presumably by altering actin distribution at sites of cell wall apposition. This work demonstrates that FORMIN4 acts as a key component of the pre-invasion defense response.

Gallego-Giraldo L, Posé S, Pattathil S, Peralta AG, Hahn MG, Ayre BG, Sunuwar J, Hernandez J, Patel M, Shah J, Rao X, Knox JP, Dixon RA (2018) Elicitors and defense gene induction in plants with altered lignin compositions. New Phytol. doi: 10.1111/nph.15258

Open Access

Sara Pose and Paul Knox (University of Leeds) are co-authors on this US-led study that investigates how lignin composition can influence the defence response. Plants with the same lignin content but changed lignin compositions show altered expression in genes involved with different arms of the defense response. This indicates that cell wall lignin composition plays a significant role in the plants ability to response to different sources of pathogen attack.

Engelsdorf T, Gigli-Bisceglia N, Veerabagu M, McKenna JF, Vaahtera L, Augstein F, Van der Does D, Zipfel C, Hamann T (2018) The plant cell wall integrity maintenance and immune signaling systems cooperate to control stress responses in Arabidopsis thaliana. Sci Signal. doi: 10.1126/scisignal.aao3070

Joe McKenna (Imperial College, now Oxford Brookes University) and Cyril Zipfel (The Sainsbury Laboratory, Norwich) are co-authors on this Norwegian-led study that looks at the plant cell wall integrity maintenance mechanism and how it responses to the challenges of growth, development and environmental stresses. They identified a set of receptor-like kinases that are key for the responses elicted by cell wall damage (CWD). Conversely they showed that the components of the pattern-triggered immunity (PTI) signaling pathway repress responses to CWD. This study provides insights into how cell wall responses interact with downstream gene expression changes following pathogen challenge.

Bömer M, O’Brien JA, Pérez-Salamó I, Krasauskas J, Finch P, Briones A, Daudi A, Souda P, Tsui TL, Whitelegge JP, Paul Bolwell G, Devoto A (2018) COI1-dependent jasmonate signalling affects growth, metabolite production and cell wall protein composition in Arabidopsis. Ann Bot. doi: 10.1093/aob/mcy109

Open Access

Moritz Bömer works with Alessandra Devoto at Royal Holloway University of London and leads this research that looks at the effect of MeJA treatment on growth and gene expression in Arabidopsis cell culture. They demonstrate that both MeJA treatment or COI1 overexpression causes changes in the abundance of proteins involved in cell wall loosening as well as altered levels of primary metabolites alanine, serine and succinic acid. This work demonstrates a close link between hormone signaling, the defence response and the metabolic profile of Arabidopsis cells.

Dr Devoto and her academic colleagues at RHUL are profiled in the latest GARNish newsletter available for download from the GARNet website.

Kriechbaumer V, Breeze E, Pain C, Tolmie F, Frigerio L, Hawes C (2018) Arabidopsis Lunapark proteins are involved in ER cisternae formation. New Phytol. doi: 10.1111/nph.15228

https://nph.onlinelibrary.wiley.com/doi/abs/10.1111/nph.15228

Open Access

Verena Kriechbaumer from Oxford Brookes University leads this research that investigates the in planta function of novel ER network-shaping proteins called Lunaparks (LNP). They show that these proteins localise to the entire ER network in Arabidopsis. They use confocal microscopy to show that altering the level of LNP gene expression changes ER morphology, possibly by regulating the formation of ER cisternae.

Chow M, Sklepari M, Frigerio L, Dixon AM (2018) Bacterial expression, purification and biophysical characterization of the smallest plant reticulon isoform, RTNLB13 Protein Expr Purif. doi: 10.1016/j.pep.2018.06.015

Open Access

Michael Chow worked with Lorenzo Frigerio and Ann Dixon at the University of Warwick to provide a preliminary structure and topology analysis of the plant RTNLB13 reticulon protein. This ER-associated integral membrane protein was expressed in bacteria and then a variety of analysis techniques were used to suggest that RTNLB13 has a high level of self-association and protein-membrane interactions.

Janes G, von Wangenheim D, Cowling S, Kerr I, Band L, French AP, Bishopp A (2018) Cellular Patterning of Arabidopsis Roots Under Low Phosphate Conditions Front Plant Sci. doi: 10.3389/fpls.2018.00735

https://www.frontiersin.org/articles/10.3389/fpls.2018.00735/full

Open Access

George Janes works with Anthony Bishopp at the University of Nottingham and leads this study that looks at root meristem development under low phosphate conditions. They show that in phosphate-limiting conditions the cortex layer of the root meristem contains almost double the number of cells, which results in a greater number of root hair-forming epidermal cells. As this change can occur within 24hrs the rapidity of the response represents a significant adaptation to a changing root environment.

Hippler FWR, Mattos-Jr D, Boaretto RM, Williams LE (2018) Copper excess reduces nitrate uptake by Arabidopsis roots with specific effects on gene expression J Plant Physiol. doi: 10.1016/j.jplph.2018.06.005

https://www.sciencedirect.com/science/article/pii/S0176161718302888

Open Access

Franz Hippler (University of Southampton) leads this UK-Brazil collaboration showing that growth of Arabidopsis plants in excess copper conditions causes a downregulation in nitrate uptake. This is due to both direct and indirect changes on the gene expression of nitrate transporters as well as a reduction in transcript level of the plasma membrane proton pump, AHA2. This effect was altered when copper levels were reduced demonstrating that copper toxicity acts at the level of nitrate transport and homeostasis.

White MD, Kamps JJAG, East S, Taylor Kearney LJ, Flashman E (2018) The Plant Cysteine Oxidases from Arabidopsis thaliana are kinetically tailored to act as oxygen sensors J Biol Chem.

doi: 10.1074/jbc.RA118.003496

Open Access

Mark White is the lead author on this work from the lab of Emily Flashman at the University of Oxford in which they look at the role of plant cysteine oxidases (PCOs) as oxygen sensors. They assessed the kinetics of each of AtPCO1 to AtPCO5 proteins and show that the most catalytically competent isoform is AtPCO4, in terms of both responding to O2, and oxidizing hypoxic responsive proteins. This work validates an O2-sensing role for the PCOs and provides evidence for functional differences between members of this enzyme family.

Kotak J, Saisana M, Gegas V, Pechlivani N, Kaldis A, Papoutsoglou P, Makris A, Burns J, Kendig AL, Sheikh M, Kuschner CE, Whitney G, Caiola H, Doonan JH, Vlachonasios KE, McCain ER, Hark AT (2018) The histone acetyltransferase GCN5 and the transcriptional coactivator ADA2b affect leaf development and trichome morphogenesis in Arabidopsis. Planta. doi: 10.1007/s00425-018-2923-9 Open Access

John Doonan (Aberystwyth University) is a co-author on this manuscript led by Jenna Kotak and Amy Herd in the USA. They investigate plants that have mutations in the histone acetyltransferase GCN5 and associated transcriptional coactivator ADA2b. These genes have been previously demonstrated as being involved in endoreduplication and trichome branching. They show that these mutants have alterations in the number and patterning of trichome-branches and that ADA2b and GCN5 are required to couple nuclear content with cell growth and morphogenesis.

Baduel P, Hunter B, Yeola S, Bomblies K. Genetic basis and evolution of rapid cycling in railway populations of tetraploid Arabidopsis arenosa (2018) PLoS Genet.

doi: 10.1371/journal.pgen.1007510 Open Access

Pierre Baduel and Kirsten Bomblies (John Innes Centre) lead this work that was conducted prior to Kirsten’s move to Norwich. In this study they follow the colonization of populations of Arabidopsis arenosa along mountain railway corridors. They demonstrate that selective pressure has occurred on novel alleles of flowering time genes and discuss the implications for ruderal communities linked to railways as allele conduits linked to local adaptations.

Arabidopsis Research Roundup: October 23rd

by Geraint

Categories: Cambridge University, CPIB, Exeter University, Global, Nottingham University, Oxford Brookes University, SLCU, Uncategorized, University of Sheffield

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Published on: October 23, 2017

Different aspects of plant cell wall biology dominant the first few papers of this weeks Arabidopsis Research Roundup. Firstly Andrew Fleming (University of Sheffield) and colleagues identify that a specific type of cell wall stiffening is important in control of stomatal opening. Secondly are two papers from the lab of Paul Dupree (University of Cambridge) that investigate the role that xylan modifications play in the formation of the cell wall. Finally in this broad area John Runions (Oxford Brookes) and colleagues show that attachment to the cell wall is critical for correct function of the dynamic actin filament network. Elsewhere Jerry Roberts (CPIB) leads a study that looks at proteins that control floral development. Next the group of Alexander Jones at SLCU has developed an exciting new tool that allows for in vivo visualization of the plant hormone GA. Finally the lab of Phil Wigge (also at SLCU) further expands their work that dissects the signaling pathways that controlling the response to temperature.

Carter R, Woolfenden H, Baillie A, Amsbury S, Carroll S, Healicon E, Sovatzoglou S, Braybrook S, Gray JE, Hobbs J, Morris RJ, Fleming AJ (2017) Stomatal Opening Involves Polar, Not Radial, Stiffening Of Guard Cells. Curr Biol. doi: 10.1016/j.cub.2017.08.006 Open Access

This broad UK collaboration is led by Andrew Fleming at the University of Sheffield and looks into the factors that control stiffening of cell walls in stomatal guard cells. They use Atomic Force Microscopy to show that stiffening of the polar regions of guard cell walls pins down these ends of cells during stomatal opening. This study provides exciting new insights into the importance of cell wall dynamics on stomatal opening and likely has significant agronomic importance.

Grantham NJ, Wurman-Rodrich J, Terrett OM, Lyczakowski JJ, Stott K, Iuga D, Simmons TJ, Durand-Tardif M, Brown SP, Dupree R, Busse-Wicher M, Dupree P (2017) An even pattern of xylan substitution is critical for interaction with cellulose in plant cell walls. Nat Plants doi: 10.1038/s41477-017-0030-8

Lyczakowski JJ,,, Wicher KB,, Terrett OM, Faria-Blanc N, Yu X, Brown D,, Krogh KBRM, Dupree P,,, Busse-Wicher M (2017) Removal of glucuronic acid from xylan is a strategy to improve the conversion of plant biomass to sugars for bioenergy. Biotechnol Biofuels. doi: 10.1186/s13068-017-0902-1

Open Access

Paul Dupree (University of Cambridge) is involved in two papers that investigate the chemical decorations that adorn components of the plant cell wall. In the first paper they demonstrate that the incorrect addition of acetyl esters onto xylan prevents the formation of the secondary cell wall due to a reduced interaction between xylan and cellulose microfibrils. They undertake a genetic study to show that the ESKIMO1/XOAT1/TBL29, a xylan-specific O-acetyltransferase is responsive for correct attachment of acetyl esters to xylan.

In the second paper they show that a reduction in the attachment of the acetyl ester glucuronic acid to xylan allows increased isolation of ethanol following saccharification. This has enormous potential significance in ongoing attempts to generate lignocellulose biomass that is more amenable to conversion into potential biofuels.

Tolmie F, Poulet A, McKenna J, Sassmann S, Graumann K, Deeks M, Runions J (2017) The cell wall of Arabidopsis thaliana influences actin network dynamics. J Exp Bot. doi: 10.1093/jxb/erx269.
This collaboration between Oxford Brookes and Exeter Universities looks in details at the Arabidopsis actin filament network using a set of novel imaging tools. In addition they show that the network is distributed when the link to the cell wall is disrupted. As might be expected this also effects the function of the network as evidenced by changes in Golgi body motility.

González-Carranza ZH, Zhang X, Peters JL, Boltz V, Szecsi J, Bendahmane M, Roberts JA (2017) HAWAIIAN SKIRT controls size and floral organ number by modulating CUC1 and CUC2 expression. PLoS One.

doi: 10.1371/journal.pone.0185106 Open Access

Jerry Roberts (CPIB, Nottingham) leads a collaboration with Dutch and French colleagues to investigate the role of the F-box gene HAWAIIAN SKIRT in control of flower development. This protein acts by interacting with the CUC-SHAPED COTYLEDON 1 (CUC1) and CUC2 transcription factors to restrict petal size by altering cell proliferation and mitotic growth.

Rizza A, Walia A, Lanquar V, Frommer WB, Jones AM (2017) In vivo gibberellin gradients visualized in rapidly elongating tissues. Nat Plants. doi: 10.1038/s41477-017-0021-9

Free with the link: rdcu.be/wnOh

Alexander Jones (SLCU) collaborates with Wolf Frommers’ lab in Stanford to develop a novel tool to analyse the plant hormone gibberellin in planta. This optogenetic biosensor protein allowed them to show that GA levels correlate with cell length in hypocotyl and root tissues. GA levels are dependent on PIF signalling in a relationship that controls rapid tissue elongation in reponse to favourable environmental conditions. We’re pleased to announce that Alexander will be speaking at next September’s GARNet2018: A Plant Science Showcase at the University of York.

Cortijo S, Charoensawan V, Brestovitsky A, Buning R, Ravarani C, Rhodes D, van Noort J, Jaeger KE, Wigge PA (2017) Transcriptional regulation of the ambient temperature response by H2A.Z-nucleosomes and HSF1 transcription factors in Arabidopsis. Molecular Plant doi: 10.1016/j.molp.2017.08.014

Open Access

Phil Wigge (SLCU) leads this work that investigates how the temperature responsive histone variant H2A.Z interacts with heat shock transcription factors (HSFs). They find that the activity of HSFs is able to evict H2A.Z histones yet at non-inducible temperatures these heat responsive genes show an over-representation of H2A.Z-nucleosomes. They demonstrate that this relationship allows plants to be primed to rapidly response to temperature change whilst preventing leaky transcription in times of low temperature.

Arabidopsis Research Roundup: August 8th

by Geraint

Categories: Arabidopsis, Audio, Durham University, Exeter University, Global, John Innes Centre, Open Access, Oxford Brookes University, Rothamsted Research, sheffield university, Uncategorized

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Published on: August 8, 2016

This weeks Arabidopsis Roundup contains a wide breadth of UK research. Firstly the lab of Jurriaan Ton undertakes a global analysis into the role of methylation in the immune response. Jurriaan kindly provides a short audio description of this work. Secondly Dame Caroline Dean’s lab further add to our understanding of the vernalisation response in Arabidopsis. Thirdly is work from Rothamstead that evaluates the fatty acid composition of the seed aleurone while fourthly is a study from Durham and Oxford Brookes that introduces a novel regulator of autophagy. Finally is a study that adds clarity to the phenotypic effects resulting from ascorbic acid deficiency.

López Sánchez A, H M Stassen J, Furci L, Smith LM, Ton J (2016) The role of DNA (de)methylation in immune responsiveness of Arabidopsis Plant Journal http://dx.doi.org/10.1111/tpj.13252 Open Access

Jurriaan Ton is the corresponding for study from the University of Sheffield that looks into the role of reversible methylation on the Arabidopsis immune response. Methylation is a well known regulator of gene expression and in this research the authors attempt to interrogate its effect on the immune response. Hypo-methylated mutants are more resistant, whilst hyper-methylated mutants are more suspectible to the biotrophic pathogen Hyaloperonospora arabidopsidis (Hpa). Downstream gene expression changes in these methylation mutants focus at the level of cell-wall modification and salicylic acid (SA)-responses. Oppositely the hypo-methylated mutant nrpe1 is more suspective to the necrotrophic pathogen Plectosphaerella cucumerina whilst the hyper-methylated ros1 mutant is resistant to this organism. The Ton-lab has been involved in the discovery of the exciting phenomon of transgenerational acquired resistance, and both nrpe1 and ros1 fail to develop this response against Hpa. Global gene expression shows that either NRPE1 or ROS1 influence about 50% of the gene expression changes that occur following Hpa infection. Finally since less than 15% of genes with altered gene expression reside close to NRPE1 or ROS1, the authors are able to propose that much of this regulation is due to methylation effects that act in trans- throughout the genome.

Jurriaan kindly provides a comprehensive description of this work:

Qüesta JI, Song J, Geraldo N, An H, Dean C (2016) Arabidopsis transcriptional repressor VAL1 triggers Polycomb silencing at FLC during vernalization Science. 353(6298):485-8 http://dx.doi.org/10.1126/science.aaf7354

From http://science.sciencemag.org/content/353/6298/485

Dame Caroline Dean (John Innes Centre) is the lead author of this manuscript that builds upon the portfolio of work from her lab aimed at characterising the vernalization response. This work again uses the FLOWERING LOCUS C (FLC) gene as a model to study the factors that allow gene-silencing mediated by Polycomb silencing complexes. The authors find that a single intragenic point mutation prevents nucleation of the homeodomain-Polycomb repressive complex 2 (PHD-PRC2) to this region, a process that involves the transcriptional repressor VAL1. In the wildtype FLC locus the localisation of VAL1 promotes transcriptional silencing through histone deacylation through interaction with the conserved apoptosis- and splicing-associated protein (ASAP) complex. This study adds an additional layer of molecular complexity to the process of regulating the FLC locus and provides insight into the important role for primary sequence-specific targeting during gene silencing.

Bryant F, Munoz-Azcarate O, Kelly AA, Beaudoin F, Kurup S, Eastmond PJ (2016) Acyl carrier protein DESATURASE 2 and 3 are responsible for making omega-7 fatty acids in the aleurone Plant Physiology http://dx.doi.org/10.1104/pp.16.00836 Open Access

Peter Eastmond (Rothamstead) leads this work that investigates the components that determine seed fatty acid content. Specifically Omega-7 monounsaturated fatty acids (ω-7s) are enriched in the aleurone of Arabidopsis seeds so this study used a Multiparent Advanced Generation Inter-Cross population to identify a QTL linked to ω-7 content that includes the ACYL-ACYL CARRIER PROTEIN DESATURASE1 (AAD1) and AAD3 genes. AAD family members possess both stearoyl- and palmitoyl-ACP Δ9 desaturase activity and aad3 mutants show a significant reduction in ω-7 content, which is common with mutants in other AAD family members. In addition the authors show that the FATTY ACID ELONGASE1 protein is required for accumulation of long-chain ω-7s in the aleurone. Overall this research provides new insight into the pathway that produces ω-7s in the aleurone, indicating that these genes might represent a target for future strategies to alter seed fatty acid content.

Wang P, Richardson C, Hawes C, Hussey PJ.(2016) Arabidopsis NAP1 Regulates the Formation of Autophagosomes Current Biology http://dx.doi.org/10.1016/j.cub.2016.06.008

From http://www.sciencedirect.com/science/article/pii/S0960982216306200

This is collaborative effort between the labs of Patrick Hussey (Durham) and Chris Hawes (Oxford Brookes) investigates the role of the NAP1 protein, which is a member of the SCAR/WAVE complex, on the formation of autophagosomes. These organelles are induced by certain stress conditions and fewer are produced in nap1 mutants after starvation stress. This also corresponds to wildtype NAP1 localisation. Concomitantly nap1 mutants, as well as mutants of other members of SCAR/WAVE complex, are more suspectible to nitrogen starvation and is less tolerant to salt stress. The best characterised role of the SCAR/WAVE complex is during ARP2/3-mediated actin nucleation yet this study demonstrates an addition function as a regulatory of autophagy.

Lim B, Smirnoff N, Cobbett CS, Golz JF (2016) Ascorbate-Deficient vtc2 Mutants in Arabidopsis Do Not Exhibit Decreased Growth Front Plant Sci. 7:1025

http://dx.doi.org/10.3389/fpls.2016.01025 Open Access

Nick Smirnoff (Exeter) is a co-author on the Australian-led research into Arabidopsis vtc mutants, which have a significant reduction in ascorbate-acid levels. Ascorbate is synthesized via the L-galactose pathway, the first enzyme of which is encoded by the paralogs VITAMIN C2 (VTC2) and VTC5. This study characterises the growth of a vtc2 T-DNA mutant that has a 30% reduction in ascorbate levels. Surprisingly this does not result in any signficant phenotypic and they suggest that a previously characterised growth reduction in other vtc2 mutant alleles is likely due to unknown genetic lesions.

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Arabidopsis Research Roundup: March 4th 2016

by Geraint

Categories: Arabidopsis, Audio, Bristol University, Cardiff University, Edinburgh University, Exeter University, funding, GARNet, Global, John Innes Centre, New Phytologist, Oxford University, Sainsbury Lab, Uncategorized, University of Oxford, University of York

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Published on: March 3, 2016

There are six articles in this weeks Arabidopsis Research Roundup that bridge a diverse range of topics. Firstly lead author Deirdre McLachlan provides an audio description of a study that investigates the role of triacylglycerol breakdown in stomatal signaling. Secondly is a study that assesses the role of a Rab GTPase in control of anisotropic cell growth. The third and fourth papers looks into the defence response, focused on either JA or nitric oxide signaling. Finally are two papers that look into the response of Arabidopsis seedlings to growth on either arsenic or cadmium.

McLachlan DH, Lan J, Geilfus CM, Dodd AN, Larson T, Baker A, Hõrak H, Kollist H, He Z, Graham I, Mickelbart MV, Hetherington AM (2016) The Breakdown of Stored Triacylglycerols Is Required during Light-Induced Stomatal Opening Current Biology http://dx.doi.org/10.1016/j.cub.2016.01.019 Open Access

The control of stomatal opening is a key environmental response to changes in CO2 levels and water availability. This study, led by Alistair Hetherington (Bristol), demonstrates that triacylglycerols (TAGs), contained in lipid droplets (LD), are critical for light-induced stomatal opening. Following illumination, the number of LDs are reduced through the β-oxidation pathway, a response that requires blue-light receptors. The authors postulate that a reduction in ATP-availability due to delayed fatty acid breakdown contributed to the stomatal phenotype. The lack of available ATP was confirmed following analysis of the activity of a plasma membrane H+-ATPase. Overall the authors suggest that the light-induced breakdown of TAG contributes to an evolutionarily conserved signaling pathway that controls stomatal opening therefore playing a key role in environmental adaptation.

The lead author of this study, Deidre McLachlan kindly provides a brief audio description of this paper.

During our discussion Deidre mentioned some related work that links blue-light signaling and starch degradation during stomatal opening that was included in a recent ARR.

Kirchhelle C, Chow CM, Foucart C, Neto H, Stierhof YD, Kalde M, Walton C, Fricker M, Smith RS, Jérusalem A, Irani N, Moore I (2016) The Specification of Geometric Edges by a Plant Rab GTPase Is an Essential Cell-Patterning Principle During Organogenesis in Arabidopsis. Developmental Cell 36(4):386-400 http://dx.doi.org/10.1016/j.devcel.2016.01.020 Open Access

Ian Moore (Oxford) is the corresponding author on this UK-German collaboration that investigates the role of a Rab GTPase in pattern formation during organogenesis. It is known that the endomembrane system controls the asymmetric distribution of cargoes to different ‘geometric edges’ of a plant cell, establishing biochemically distinct domains that are important for anisotropic growth. This study identifies a new type of membrane vesicle that accumulates specifically along geometric edges and that contains the RAB-A5c protein which, when inhibited, distorts the geometry of cells in subsequently formed lateral organs (in this case, lateral roots). Interestingly this effect is independent of changes to general endomembrane trafficking. The precise mechanism of RAB-A5c activity is unknown but loss of its activity reduces cell wall stiffness at domain-specific locations, therefore perturbing cell growth in those directions. Therefore this study provides interesting insight into fundamental mechanisms that control the growth of cells in a developing organ.

Thatcher LF, Cevik V, Grant M, Zhai B, Jones JD, Manners JM, Kazan K (2016) Characterization of a JAZ7 activation-tagged Arabidopsis mutant with increased susceptibility to the fungal pathogen Fusarium oxysporum J Exp Bot. http://dx.doi.org/10.1093/jxb/erw040 Open Access

Jonathan Jones (TSL) and Murray Grant (Exeter) are collaborators on this research that investigates the role of jasmonic acid signaling in plant resistance to the fungal pathogen Fusarium oxysporum. In this study they show that the JASMONATE ZIM-domain7 (JAZ7) gene is induced by Fusarium oxysporum and that the jaz7-1D mutant has increased suspectibility to infection. This genotype has constitutive JAZ7 expression and also demonstrates sensitivity to a bacterial pathogen. To cause alterations in gene expression, the JAZ7 protein interacts with a range of transcriptional activators and repressors. The authors postulate that in wildtype plants JAZ7 represses the JA-transcriptional network through its interaction with the co-repressor TOPLESS protein and that in the jaz7-1D plants this response network is hyper-activated leading to an inappropriately high response to pathogen attack.

Yun BW, Skelly MJ, Yin M, Yu M, Mun BG, Lee SU, Hussain A, Spoel SH, Loake GJ (2016) Nitric oxide and S-nitrosoglutathione function additively during plant immunity. New Phytol. http://dx.doi.org/10.1111/nph.13903

Gary Loake and GARNet Advisory board member Steven Spoel (Edinburgh) are the leaders of this UK-Korean collaboration that studies the role of Nitric Oxide (NO) in the plant defence response. NO often undergoes S-nitrosylation to produce S-nitrosothiol (SNO), which is important for its bioactivity. This reaction involves the S-nitrosoglutathione reductase 1 (GSNOR1) enzyme, which serves to turnover the NO donor, S-nitrosoglutathione (GSNO). In this study the authors investigate mutant plants that accumulate NO and some a reduction in the basal defence response due to a reduction in salicylic acid (SA) signaling. This response was not rescued by the overexpression of GSNOR1 even though this was able to reduce phenotypes resulting from SNO accumulation. Mutant plants that have increased NO accumulation but lower activity of GSNOR1, so therefore an increased ratio of NO:SNO, were more suspectible to growth of bacterial pathogens. The authors conclude that the relationship between NO and GSNO is critically for plant immunity and development.

Lindsay ER, Maathuis FJ (2016) Arabidopsis thaliana NIP7;1 is Involved in Tissue Arsenic Distribution and Tolerance in Response to Arsenate FEBS Lett. http://dx.doi.org/10.1002/1873-3468.12103

Francois Maathuis (York) is the corresponding author of this study that investigates the role of the Arabidopsis aquaglyceroporin NIP7;1 in the uptake of different chemical forms of arsenic. Mutant nip7;1 plants improved the tolerance of arsenic by reducing uptake of the chemical. This is the first demonstration for the role of a NIP transporter in the response to arsenic and highlights the possibility of focussing on these proteins as a target for breeding or genetically-modifying tolerance to this toxic metal.

Wang H, He L, Song J, Cui W, Zhang Y, Jia C, Francis D, Rogers HJ, Sun L, Tai P, Hui X, Yang Y, Liu W (2016) Cadmium-induced genomic instability in Arabidopsis: Molecular toxicological biomarkers for early diagnosis of cadmium stress Chemosphere 150:258-265 http://dx.doi.org/10.1016/j.chemosphere.2016.02.042

Hilary Rodgers (Cardiff) is the sole UK representative on this Chinese study that has developed screening parameters to evaluate the growth of plants on cadmium. The study uses microsatellite instability (MSI) analysis, random-amplified polymorphic DNA (RAPD), and methylation-sensitive arbitrarily primed PCR (MSAP-PCR) to define a range of genomic alterations that occurred after growth of Arabidopsis plants across a range of concentrations of cadmium. They conclude that analysis of genomic methylation polymorphisms were the most sensitive biomarkers to diagnosis early cadmium stress in these plants and provide important insights for future biomonitoring strategies.

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Arabidopsis Research Roundup: February 9th

by Geraint

Categories: Arabidopsis, CPIB, Essex University, Exeter University, Global, Rothamsted Research, University of Sheffield, Warwick University

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Published on: February 9, 2016

It has been a quiet couple of weeks for newly published UK Arabidopsis Research but what might be lacking in quantity is made up for in quality! Firstly the PRESTA consortium use gene regulatory network analysis to identify a key component in the response to drought stress. Secondly is a paper featuring researchers from Rothamstead that identifies a new molecular participant in the control of RNA surveillance. Thirdly is a paper that investigates the function of aquaporins during lateral root emergence and includes researchers from Warwick and Nottingham. Finally is a study from Sheffield that investigates necrotropic and biotropic strategies employed by an ascomycete pathogen. It is also nice to observe that each of these papers are open access.

Bechtold U, Penfold CA, Jenkins DJ, Legaie R, Moore JD, Lawson T, Matthews JS, Vialet-Chabrand SR, Baxter L, Subramaniam S, Hickman R, Florance H, Sambles C, Salmon DL, Feil R, Bowden L, Hill C, Baker NR, Lunn JE, Finkenstadt B, Mead A, Buchanan-Wollaston V, Beynon JL, Rand DA, Wild DL, Denby KJ, Ott S, Smirnoff N, Mullineaux PM (2016) Time-series transcriptomics reveals that AGAMOUS-LIKE22 links primary metabolism to developmental processes in drought-stressed Arabidopsis Plant Cell http://dx.doi.org/10.1105/tpc.15.00910 Open Access

This Large Scale Biology article is the result of the PRESTA collaboration that is based at the Universities of Essex, Exeter and Warwick. The research plan of the PRESTA project is based upon the generation of large scale transcriptomic datasets and in this case they investigate changes in gene expression in plants subjected to drought stress. They identified over 1800 differentially expressed genes and the early changes coincided with a drop in carbon assimilation together with a late increase in foliar ABA content. Using Bayesian network modelling of differentially expressed transcription factors they identified the AGAMOUS-LIKE22 (AGL22) gene as a key component in this gene regulatory network. AGL22 had been previously found to play an important role in the change from vegetative to floral development but in this context it influences photosynthetic rates and lifetime water use.

Hématy K, Bellec Y, Podicheti R, Bouteiller N, Anne P, Morineau C, Haslam RP, Beaudoin F, Napier JA, Mockaitis K, Gagliardi D, Vaucheret H, Lange H, Faure JD (2016) The Zinc-Finger Protein SOP1 Is Required for a Subset of the Nuclear Exosome Functions in Arabidopsis PLoS Genetics 12(2):e1005817 http://dx.doi.org/10.1371/journal.pgen.1005817 Open Access

This Franco-US collaboration also includes a contribution from Johnathan Napier’s group at Rothamstead Research. They investigated the function of the essential Arabidopsis PASTICCINO2 (PAS2) gene by isolating three suppressors of pas2 mutants (termed sop mutants). PAS2 is involved in correct splicing so the sop mutants prevented degradation of mis-spliced pas2 mRNA species. The suppressor genes were either previously characterized as being involved with function of the exosome (SOP2/RRP4, SOP3/HEN2) or as a novel zinc-finger protein (SOP1) that colocalised with HEN2 in nucleoplasmic loci. The authors show additional evidence suggesting that the SOP proteins are involved in RNA quality control and introduce SOP1 as a novel component that is involved in nuclear RNA surveillance.

Reinhardt H, Hachez C, Bienert MD, Beebo A, Swarup K, Voss U, Bouhidel K, Frigerio L, Schjoerring JK, Bennett MJ, Chaumont F (2016) Tonoplast aquaporins facilitate lateral root emergence Plant Physiology. http://dx.doi.org/10.1104/pp.15.01635 Open Access

This Belgian-led study includes lead-UK representation from Warwick (Lorenzo Frigerio) and Nottingham (Malcolm Bennett) and investigates the role of tonoplast-localised aquaporin proteins during lateral root emergence. The AtTIP1;1, AtTIP1;2 and AtTIP2;1 are abundant aquaporin proteins and the triple tip mutant shows a reduction in lateral root (LR) number without having a shorter primary root. This effect is not due to a reduction of LR primordia but rather due to a defect in the elongation of emerging LR. The authors show that spatial and temporal variations of TIP isoform expression throughout the root correlates with the tip mutant phenotype. Surprisingly, native expression of TIP2:1, which is found only at the base of the LR, can restore wildtype LR emergence to the triple mutant, suggesting that aquaporin activity in this region is sufficient to set-off LR outgrowth.

Pétriacq P, Stassen JH, Ton J (2016) Spore density determines infection strategy by the plant-pathogenic fungus Plectosphaerella cucumerina Plant Physiology http://dx.doi.org/10.1104/pp.15.00551 Open Access

Jurriaan Ton (Sheffield) is the lead researcher on this study that investigates the molecular factors that allow pathogens to switch between necrotropy and biotrophy, which elicit different response pathways within the infected plant. They used untargeted metabolomics to investigate the growth of the ascomycete pathogen Plectosphaerella cucumerina on Arabidopsis leaves. Higher spore densities activate a JA-dependent necrotropic defence response whilst lower spore numbers causes hemi-biotrophic SA-dependent responses. This change is reflected in the susceptibility of different Arabidopsis mutants to differing spore densities and allow the authors to conclude that P. cucumerina is able to gain an advantage over the host immunity by switching between different modes of infection.

Arabidopsis Research Roundup: November 25th

by Geraint

Categories: Arabidopsis, bioinformatics, Exeter University, GARNet, Global, John Innes Centre, Oxford University, plant pathogens, Plant Physiology, Uncategorized, University of Oxford, University of Southampton, Warwick University

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Published on: November 25, 2015

This weeks Arabidopsis Research Roundup contains four papers each with a different focus. Firstly is a large-scale investigation that attempts to define the transcriptional changes that occur in response to bacterial infection. Second is a study that investigates a newly proposed role for the chloroplast chaperone Hsp93. Thirdly is another piece of work that also involves University of Oxford researchers and investigates the genetic networks that control leaf morphology. Finally is an updated plant-specific protocol for the commonly used technique of Chromatin Immunoprecipitation.

Lewis LA, Polanski K, de Torres-Zabala M, Jayaraman S, Bowden L, Moore J, Penfold CA, Jenkins DJ, Hill C, Baxter L, Kulasekaran S, Truman W, Littlejohn G, Prusinska J, Mead A, Steinbrenner J, Hickman R, Rand D, Wild DL, Ott S, Buchanan-Wollaston V, Smirnoff N, Beynon J, Denby K, Grant M (2015) Transcriptional Dynamics Driving MAMP-Triggered Immunity and Pathogen Effector-Mediated Immunosuppression in Arabidopsis Leaves Following Infection with Pseudomonas syringae pv tomato DC3000 Plant Cell. http://dx.doi.org/10.1105/tpc.15.00471 Open Access

This ‘Large Scale Biology’ publication is a collaboration between the Universities of Exeter and Warwick, led by Murray Grant and current GARNet Advisory board member Katherine Denby. This study investigates the transcriptional changes that occur over a long time course in response to infection by the pathogen Pseudomonas syringae pv tomato DC3000. The authors aim to differentiate between the changes associated with endogenous microbial-associated molecular pattern (MAMP)-triggered immunity (MTI) and those orchestrated by pathogen effectors. The responses to pathogenic and non-pathogenic P.syringae were compared and using novel computational analysis, it was shown that the majority of gene expression changes that contribute to disease or defense responses occurred within 6hour post-infection, well before pathogen multiplication. Broadly it was found that chloroplast-associated genes are suppressed by a MAMP-triggered response, presumably to restrict nutrient availability. Ultimately this manuscript identified specific promotor elements that are involved in either the MTI response or utilised by the infecting bacteria.

Corresponding author Professor Murray Grant kindly takes ten minutes to discuss the finding of this paper and the community resource that it represents. He also discusses another paper involving the Jasmonate response that resulted from this dataset and was recently highlighted in the Research Roundup. Interview end at 11m10s.

Flores-Pérez Ú1, Bédard J1, Tanabe N2, Lymperopoulos P2, Clarke AK3, Jarvis P (2015) Functional analysis of the Hsp93/ClpC chaperone at the chloroplast envelope Plant Physiology. http://dx.doi.org/10.1104/pp.15.01538 Open Access

Paul Jarvis (Oxford) is the corresponding author on this study in which his lab collaborates with Swedish researchers to investigate the role of the Hsp93/ClpC chaperone protein in protein import into the chloroplast. This recently postulated role for this protein has not yet been experimental tested so they generated a hsp93[P-] mutant that lacked a functional ClpP-binding motif (PBM), which confers the already determined role for Hsp93 in proteolysis that occurs in the chloroplast stroma. The hsp93[P-] mutant localises to the chloroplast envelope and associates with TIC transport machinery but was unable to complement the phenotypes of a hsp93 null mutant. This showed that the PBM domain was essential for its function. Expression of the Hsp93[P-] mutant in the hsp93 null background did not improve protein import so the authors concluded that these results do not confirm this newly postulated role for the protein and they suggest that its functional role occurs immediately after its substrate had been transported into the chloroplast.

Rast-Somssich MI, Broholm S, Jenkins H, Canales C, Vlad D, Kwantes M, Bilsborough G, Dello Ioio R, Ewing RM, Laufs P, Huijser P, Ohno C, Heisler MG, Hay A, Tsiantis M (2015) Alternate wiring of a KNOXI genetic network underlies differences in leaf development of A. thaliana and C. hirsuta Genes Dev. 29(22):2391-404 http://dx.doi.org/10.1101/gad.269050.115 Open Access

The study includes researchers from Oxford and Southampton Universities in collaboration with those from Italy, France and Germany in work that is led by Angela Hay and Miltos Tsiantis, who were both previously based in Oxford. This is familiar territory for this group as they compare leaf development between Arabidopsis, which has simple leaves, and the related , Cardamine hirsuta, which has dissected leaves. In this new work they transfer the SHOOTMERISTEMLESS (STM) and BREVIPEDICELLUS (BP) homeobox genes between the two species and investigate their ability to modify leaf form. In Cardamine, expression of BP is controlled by crosstalk between the microRNA164A (MIR164A)/ChCUP-SHAPED COTYLEDON (ChCUC) module and ChASYMMETRIC LEAVES1 (ChAS1) gene. However this regulatory network does not function in Arabidopsis and therefore leads to the establishment of differing regulatory networks that the authors propose are responsible for the alterations in organ geometry.

Posé D, Yant L (2016) DNA-Binding Factor Target Identification by Chromatin Immunoprecipitation (ChIP) in Plants Methods Mol Biol. 1363:25-35. http://dx.doi.org/10.1007/978-1-4939-3115-6_3

Levi Yant is a new member of faculty at the John Innes Centre and is the lead author on this paper that introduces an updated protocol for Chromatin Immunoprecipitation in Plants (ChIP). They have used this technique in his lab to identify target genes for a number of transcriptional regulators that are involved in Arabidopsis floral development.

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Arabidopsis Research Roundup: November 13th.

by Geraint

Categories: Arabidopsis, Cambridge University, Edinburgh University, Exeter University, Global, John Innes Centre, Open Access, plant hormone, Plant Physiology, Sainsbury Lab, University of Bath, University of Birmingham

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Published on: November 13, 2015

This weeks Arabidopsis Research Roundup presents a wide range of topics from researchers across the UK. Firstly we highlight a study that documents the early stages of a potential biotechnological/synthetic biology approach to improve higher plant photosynthesis using algal components. Corresponding author Alistair McCormick also takes five minutes to discuss this work. Secondly a team based mostly at Bath introduces the function of the PAT14 gene, which is involved in S-palmitoylation. Thirdly is a study that successfully transfers SI components between evolutionary diverged plant species and the final paper documents research that adds additional complexity to the signalling pathway that responses to strigolactones.

Atkinson N, Feike D, Mackinder LC, Meyer MT, Griffiths H, Jonikas MC, Smith AM, McCormick AJ (2015) Introducing an algal carbon-concentrating mechanism into higher plants: location and incorporation of key components. Plant Biotechnol J. http://dx.doi.org/10.1111/pbi.12497 Open Access

This work results from a collaborative effort between the four groups that make up the Combining Algal and Plant Photosynthesis (CAPP) consortium and include Howard Griffiths (Cambridge), Martin Jonikas (Carnegie Institute for Science), Alison Smith (JIC) and Alistair McCormick (Edinburgh). Here they attempt to express in higher plants a range of algal proteins that are involved in carbon-concentrating mechanisms (CCM). They initially confirmed the intracellular locations of ten algal CCM components and showed that these locations were largely conserved when the proteins were expressed transiently in tobacco or stably in Arabidopsis. Although the expression of these CCMs components in Arabidopsis didn’t enhance growth, the authors suggest that stacking of multiple CCM proteins might be needed to confer an increase in productivity.

Alistair takes five minutes to discuss this paper here:

Li Y, Scott RJ, Doughty J, Grant M, Qi B (2015) Protein S-acyltransferase 14: a specific role for palmitoylation in leaf senescence in Arabidopsis. Plant Physiology http://dx.doi.org/10.1104/pp.15.00448 Open Access

This Southwest-based study is led by Baoxiu Qi from the Plant-Lab at Bath University with input from Murray Grant (Exeter). They investigate Protein S-Acyl Transferase (PATs) protein, which are multi-pass transmembrane proteins that catalyze S-acylation (commonly known as S-palmitoylation). This process both confers correct protein localisation and is involved in signalling. These are 24 PATs in Arabidopsis and this study focuses on the novel PAT14, which they show has its predicted enzymatic role. Pat14 mutant plants show accelerated senescence that is associated with SA, but not JA or ABA-signaling. Therefore the authors suggest that AtPAT14 plays a pivotal role in regulating senescence via SA pathways and that this is the first published linkage between palmitoylation and leaf senescence.

Lin Z1, Eaves DJ1, Sanchez-Moran E1, Franklin FC1, Franklin-Tong VE1 (2015) The Papaver rhoeas S determinants confer self-incompatibility to Arabidopsis thaliana in planta Science 350(6261):684-7 http://dx.doi.org/10.1126/science.aad2983

University of Birmingham researchers led by Noni Franklin- Tong publish this study in Science in which they transfer the elements that confer self-incompatibility (SI) in Papever rhoeas (Poppy) to Arabidopsis. They find that Arabidopsis pistils that express the self-determinant PrsS protein reject pollen that expresses the PrpS protein. This leads to a robust SI response in these plants, demonstrating that these two components are sufficient for the establishment of this interaction. Poppy and Arabidopsis are evolutionarily separated by 140million years so the authors suggest that the successful transfer of SI determinants between these divergent species will have potential utility in future crop production strategies.

Soundappan I, Bennett T, Morffy N, Liang Y, Stanga JP, Abbas A, Leyser O, Nelson DC (2015) SMAX1-LIKE/D53 Family Members Enable Distinct MAX2-Dependent Responses to Strigolactones and Karrikins in Arabidopsis The Plant Cell http://dx.doi.org/10.1105/tpc.15.00562

Ottoline Leyser (SLCU) is the UK lead on this US-UK collaboration that investigates the plant response to butenolide signals, namely the plant hormone strigolactones and smoke-derived karrikins. It is known that these molecules are perceived by the F-box protein MORE AXILLARY GROWTH2 (MAX2) and that the Arabidopsis SUPPRESSOR OF MAX2 1 (SMAX1) protein acts downstream of this perception. This study documents an extensive genetic study that shows that the activity of the SMAX1-LIKE genes, SMXL6, SMXL7, and SMXL8 promote shoot branching. smxl6,7,8 mutant plants suppress several strigolactone-related phenotypes in max2, that focus on the response to auxin but not on germination or hypocotyl elongation responses, which are only suppressed in smax1 mutants. On a molecular level these responses are controlled by the MAX2-dependant degradation of the SMAX1/SMXL proteins, which result in changes in gene expression. Therefore this shows that the diversity of SMAX1/SMXL proteins allows the signaling pathway that responses to butenolide signals to bifurcate downstream of the initial perception.

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Arabidopsis Research Roundup: October 12th

by Geraint

Categories: Arabidopsis, Exeter University, GARNet, Global, John Innes Centre, plant hormone, plant pathogens, QMUL

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Published on: October 11, 2015

The Arabidopsis Research Roundup is ‘defense-focused’ this week. We present three papers that highlight different aspects of plant immunity, two of which result from UK-US-China collaborations. Firstly a team from the Sainsbury Lab, Norwich looks at two molecular mechanisms that control stomatal closure. There are then two studies that involve University of Exeter researchers that investigate either the role of plant hormones in the response to bacterial pathogens or the role that the physical barrier of the cell wall plays in the prevention of infection. Next a group of JIC researchers present a Large Scale Biology investigation of microtubule interacting proteins. Finally a study from QMUL looks at the interaction between NPQ and photoinhibition in controlling the activity of Photosystem II.

Gou M, Zhang Z, Zhang N, Huang Q, Monaghan J, Yang H, Shi Z, Zipfel C, Hua J (2015) Opposing effects on two phases of defense responses from concerted actions of HSC70 and BON1 in Arabidopsis. Plant Physiol. http://dx.doi.org/10.1104/pp.15.00970

GARNet Advisory Board Member Cyril Zipfel is the UK lead on this US-China-UK collaboration that looks at two aspects of the plant immune response that are regulated by the same proteins, albeit in an antagonistic way. The heat shock protein HSC70 and the calcium binding protein BON1 both are involved in stomatal closure, the formers effect mediated by the SNC1 protein and the latter (BON1) via the activitation of SGT1 that in turn inhibits HSC70. These new functions demonstrate opposing roles for HSC80 and BON1 in the immune response and further highlight the complexity of the signaling pathways that ultimately feed into the gross phenotypic change of stomatal closure.

de Torres Zabala M, Zhai B, Jayaraman S, Eleftheriadou G, Winsbury R, Yang R, Truman W, Tang S, Smirnoff N, Grant M (2015) Novel JAZ co-operativity and unexpected JA dynamics underpin Arabidopsis defence responses to Pseudomonas syringae infection New Phytol. http://dx.doi.org/10.1111/nph.13683

This is another UK-USA-China collaboration led by Murray Grant at the University of Exeter, in which the role of the plant hormones is assessed in the response to bacterial pathogens. The defence response is mediated by both the hormones salicylic acid (SA) and jasmonic acid (JA) which antagnise many of each others activity. Pathogens have been shown to produce a JA-mimic cornatine (COR) in order to stall SA-mediated effects. In this study the authors use a systems-biology based approach that involved targeted hormone profiling, high-temporal-resolution micro-array analysis, reverse genetics and mRNA-seq to introduce a complex network of regulation that involves JAZ proteins, which are repressors of the JA signal. In short they show that JAZ5 and JAZ10 specifically co-operate to inhibit pathogen growth by restricting COR cytotoxicity by novel mechanisms, which do not involve previously well-defined signaling proteins.

Marcos R, Izquierdo Y, Vellosillo T, Kulasekaran S, Cascón T, Hamberg M, Castresana C (2015) 9-Lipoxygenase-derived oxylipins activate brassinosteroid signaling to promote cell wall-based defense and limit pathogen infection Plant Physiol. http://dx.doi.org/10.1104/pp.15.00992

This work was performed in Madrid under the supervision of Carmen Castresana but includes the work of Satish Kulasekaran who is now at the Exeter. The focus of the work is the oxylipins, which are oxygenated lipid derivatives that regulate plant development and immunity. Using a variety of noxy mutants (non-responding to oxylipins) they show that the effect of the oxylipins is mediated via changes in the cell wall and this is signalled via the Brassinosteriod response pathway. Suspectibility to bacterial and fungal infection was enhanced in noxy mutants but plants were resistance when BR signalling was switched on. Therefore this manuscript introduces an important interaction between the oxylipins and BR signalling and helps to clarify their role in modulating plant defense.

Derbyshire P, Ménard D, Green P, Saalbach G, Buschmann H, Lloyd CW, Pesquet E (2015) Proteomic Analysis of Microtubule Interacting Proteins over the Course of Xylem Tracheary Element Formation in Arabidopsis Plant Cell. http://dx.doi.org/10.1105/tpc.15.00314

The experiments in this Large Scale Biology paper were performed in the lab of Clive Lloyd (John Innes Centre) which included the work of Eduoard Pesquet, who now has his own lab in Sweden. They looked the microtubule patterning that defines the nature of tracheary element (TEs) thickening in plant vascular tissues. They used Arabidopsis cell suspension culture to isolate microtubule interacting proteins present during TE differentiation. One protein of interest was CELLULOSE SYNTHASE-INTERACTING PROTEIN1, associated with primary wall synthesis, which was enriched during secondary cell wall formation of TEs. The authors knocked-down the expression of some of their identified proteins and indeed showed that they were important for this differentiation. A take-home message is that the proteins that interact with microtubules and link them to different metabolic compartments do indeed specifically vary during TE differentiation, regulating different aspects of cell wall patterning.

Giovagnetti V, Ruban AV (2015) Discerning the effects of photoinhibition and photoprotection on the rate of oxygen evolution in Arabidopsis leaves J Photochem Photobiol B. http://dx.doi.org/10.1016/j.jphotobiol.2015.09.010

Arabidopsis Research Roundup Regular Alexandre Ruban (QMUL) again looks at the mechanisms that lessen the amount of photoinhibition (when photosystem II is damaged by being exposed to too much light). An opposing response is Non-photochemical quenching (NPQ) of chlorophyll a fluorescence which serves to protect PSII from high light conditions. In this study they confirm that a recently devised procedure that aims to discern between the effect of NPQ and photoinhibition works well as a measurement for the efficiency of PSII activity.

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