GARNet Research Roundup: November 1st 2018

This week’s GARNet research roundup again features papers on a variety of topics. First is work from the University of Leeds that investigates the physical properties of callose:cellulose hydrogels and the implication for cell wall formation. Second is work from the University of York that assesses the role of the HSP90.2 protein in control of the circadian clock. The third paper features GARNet committee member Sarah McKim and looks at the genetic control of petal number whilst the next paper from the Universities of Warwick and Glasgow includes a proteomic analysis of different types of secretory vesicles.

The next two papers look at different aspects of hormone signaling. Firstly Alistair Hetherington from the University of Bristol is a co-author on a study that looks at the role of the BIG protein whilst Simon Turner’s lab in Manchester investigates the role of ABA in xylem fibre formation.

The penultimate paper includes Lindsey Turnbull from the University of Oxford and looks at the stability of epialleles across 5 generations of selection. Finally is a paper that includes researchers from TSL in Norwich who have contributed to a phosphoproteomic screen to identify phosphorylated amino acids that influence the defence response.

Abou-Saleh R, Hernandez-Gomez M, Amsbury S, Paniagua C, Bourdon M, Miyashima S, Helariutta Y, Fuller M, Budtova T, Connell SD, Ries ME, Benitez-Alfonso Y (2018) Interactions between callose and cellulose revealed through the analysis of biopolymer mixtures. Nature Communications DOI: 10.1038/s41467-018-06820-y

Open Access
Radwa Abou-Saleh is lead author on this work from Yoselin Benitez-Alfonso’s lab at the University of Leeds. (1,3)-β-glucans such as callose play an important role in plant development yet their physical properties are largely unknown. This study analyses a set of callose:cellulose hydrogel mixtures as a proxy for different cell wall conditions. They show that callose:cellulose hydrogels are more elastic than those composed of only cellulose, providing evidence that the interactions between cellulose and callose are important for the structural features of cell walls.

Davis AM, Ronald J, Ma Z, Wilkinson AJ, Philippou K, Shindo T, Queitsch C, Davis SJ (2018) HSP90 Contributes To Entrainment of the Arabidopsis Circadian Clock via the Morning Loop. Genetics. doi: 10.1534/genetics.118.301586

Open Access
Amanda Davies is the first author on this study from Seth Davies’ lab at the University of York in which they assess the role of the molecular chaperone HSP90.2 on function of the circadian clock. The show hsp90.2-3 mutant plants have a lengthened circadian period with a specific defect in the morning. This data allows the authors to better understand the pathway through which HSP90.2 functions to entrain the circadian clock.

Monniaux M, Pieper B, McKim SM, Routier-Kierzkowska AL, Kierzkowski D, Smith RS, Hay A. The role of APETALA1 in petal number robustness. Elife. doi: 10.7554/eLife.39399

Open Access
GARNet committee member Sarah McKim is a co-author on this paper, that is led by Marie Monniaux, which includes research from her time at the University of Oxford. This work from the Hay lab in Cologne compares petal number in Arabidopsis thaliana, in which the number is invariant, and Cardamine hirsute, in which it varies. They show that petal number robustness can be attributed to the activity of the APETALA1 (AP1) floral regulator and that AP1 masks the activity of several genes in Arabidopsis but not in Cardamine.

Waghmare S, Lileikyte E, Karnik RA, Goodman JK, Blatt MR, Jones AME (2018) SNAREs SYNTAXIN OF PLANTS 121 (SYP121) and SYP122 mediate the secretion of distinct cargo subsets . Plant Physiol. doi: 10.1104/pp.18.00832

Open Access

This collaboration between the Universities of Glasgow and Warwick is led by Sakharam Waghmare, who works with Mike Blatt in Glasgow. This study uses proteomic approaches to characterise the secretory cargos within vesicles decorated with either of the SNARE proteins SYNTAXIN OF PLANTS 121 (SYP121) or SYP122. Genetic analysis suggests that SYP121 and SYP122 have redundant functions but this new research is able to identify cargo proteins that are either contained within both types of vesicle or that are specific to one or the other.

Zhang RX, Ge S, He J, Li S, Hao Y, Du H, Liu Z, Cheng R, Feng YQ, Xiong L, Li C, Hetherington AM, Liang YK (2018) BIG regulates stomatal immunity and jasmonate production in Arabidopsis. New Phytol. doi: 10.1111/nph.15568

Alistair Hetherington is a co-author on this China-based study led by Ruo‐Xi Zhang from Wuhan. This work adds to some recent interest in the BIG protein; in this study showing that it is involved in the interaction between JA and ethylene signaling during stress responses. In a complex set of interactions they show that the BIG protein differently alters opposing arms of the JA signaling pathway providing additional evidence that this protein is a key regulator of plant hormone signaling, albeit by a set of as yet unknown mechanisms.

Campbell L, Etchells JP, Cooper M, Kumar M, Turner SR. An essential role for Abscisic acid in the regulation of xylem fibre differentiation. Development. doi: 10.1242/dev.161992

This work from Simon Turner’s lab at the University of Manchester is led by Liam Campbell and identifies a novel role for ABA in the formation of xylem fibres during secondary thickening of the Arabidopsis hypocotyl. The action of ABA doesn’t alter the xylem:phloem ratio but rather the activity focuses on the formation of fibres within the already defined xylem tissue.

Schmid MW, Heichinger C, Coman Schmid D, Guthörl D, Gagliardini V, Bruggmann R, Aluri S, Aquino C, Schmid B, Turnbull LA, Grossniklaus U (2018) Contribution of epigenetic variation to adaptation in Arabidopsis. Nat Commun. doi: 10.1038/s41467-018-06932-5

Open Access
Lindsey Turnbull (University of Oxford) is a co-author on this paper from Ueli Grossniklaus’ group in Zurich. Marc Schmid is lead author of the study that investigates the inheritance of Arabidopsis epialleles over 5 generations during conditions of simulated selection. The authors show that variations in methylation state are subject to selection and do indeed contribute to adaptive responses

Kadota Y, Liebrand TWH, Goto Y, Sklenar J, Derbyshire P, Menke FLH, Torres MA, Molina A, Zipfel C, Coaker G, Shirasu K (2018) Quantitative phosphoproteomic analysis reveals common regulatory mechanisms between effector- and PAMP-triggered immunity in plants. New Phytol. doi: 10.1111/nph.15523

Members of Cyril Zipfel’s group at The Sainsbury lab in Norwich are co-authors on this paper led by Yasuhiro Kadota from the RIKEN in Yokohama. They use a phosphoproteomic screen to identify a set of newly identified phosphorylation sites on membrane-associated proteins involved in effector-triggered immunity (ETI). Some of these phosphosites overlap with those known to be important for pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI), indicating a convergence of signaling control of both these pathways to certain key residues.

GARNet Research Roundup: October 19th 2018

This edition of the GARNet research roundup includes six papers that look at different areas of plant biology. Firstly is a Belgian-led study with co-authors from Nottingham that introduces adaptive Xerobranching, a cereal-root response that can be mimicked in Arabidopsis by modulating ABA signaling. Second is study from Juriaan Ton’s lab in Sheffield that investigates the extent of DNA methylation during transgenerational acquired disease resistance. Third is paper from the John Innes Centre that places the DET1/COP1-PIF4 signaling module as a key determinant of the plants decision to allocate resources toward growth or defence.

The fourth paper is from Siobhan Braybrook’s (now ex-) lab at SLCU and provides an extensive dataset of the shape of leaf pavement cells across plant lineages. The penultimate paper is from a group at the University of Birmingham investigating the role of TOPII in the removal of damaging chromosome interlocks that occur during meiosis. The final paper returns to the ABA signalling with a study from Rothamsted Research that looks at the impact of the N-end rule on the different growth responses that occur during seed germination.

Orman-Ligeza B, Morris EC, Parizot B, Lavigne T, Babé A, Ligeza A, Klein S, Sturrock C, Xuan W, Novák O, Ljung K, Fernandez MA, Rodriguez PL, Dodd IC, De Smet I, Chaumont F, Batoko H, Périlleux C, Lynch JP, Bennett MJ, Beeckman T, Draye X (2018) The Xerobranching Response Represses Lateral Root Formation When Roots Are Not in Contact with Water. Current Biology. doi: 10.1016/j.cub.2018.07.074

Open Access

Emily Morris and Beata Orman-Ligeza are co-authors on this Belgian-led study that includes authors from the Universities of Nottingham and Lancaster. They introduce a new adaptive response termed xerobranching that defines the repression of root branching when a root tip is not in contact with wet soil. This response occurs in cereal roots but can be mimicked in Arabidopsis by treatment with ABA as the authors show that the response is dependent on the PYR/PYL/RCAR-dependent signaling pathway. This response allows roots to respond to the realistically varied microclimate encountered through the soil and offers another excellent example of how using both cereals and Arabidopsis can provide answers that would not be possible from a single experimental system.

Stassen JHM, López A, Jain R, Pascual-Pardo D, Luna E, Smith LM, Ton J (2018) The relationship between transgenerational acquired resistance and global DNA methylation in Arabidopsis. Sci Rep. doi: 10.1038/s41598-018-32448-5

Open Access

Joost Stassen and Ana Lopez are the lead authors of this study from Juriaan Ton’s lab in Sheffield that continues their work on mechanisms that explain transgenerational acquired resistance (TAR). TAR occurs in the progeny of heavily diseased plants and in this study they investigate the extent of DNA methylation in generations following exposure to pathogens. They find that the extent of TAR-induced methylation was in direct proportion to the number of previous generations that had been exposed to disease. The majority of this methylation was in the CG context in gene bodies and clearly shows that methylation is an important component of molecular changes that occur during TAR.

Gangappa SN, Kumar SV (2018) DET1 and COP1 Modulate the Coordination of Growth and Immunity in Response to Key Seasonal Signals in Arabidopsis. Cell Rep. doi: 10.1016/j.celrep.2018.08.096

Open Access

Sreeramaiah Gangappa performed this work with Vinod Kumar at the John Innes Centre in which they investigate the molecular pathways that regulate the environmental signals that feed into the balance decision between growth and defense responses. They show that De-Etiolated 1 (DET1) and Constitutive Photomorphogenic 1 (COP1) negatively regulate immunity during favourable growth conditions and that this response is coordinated through the PIF4 transcription factor. These findings lead the authors to conclude that the DET1/COP1-PIF4 module is a key determinant of the different growth requirements that are necessary to response to either environment and disease.

Vőfély RV, Gallagher J, Pisano GD, Bartlett M, Braybrook SA (2018) Of puzzles and pavements: a quantitative exploration of leaf epidermal cell shape. New Phytol. doi: 10.1111/nph.15461

Open Access

Work from Siobhan Braybrook’s lab features in the Research Roundup for the second consecutive edition, this time led by Roza Vofely at the Sainsbury Lab Cambridge University (SLCU). In this study they have investigated the shape of leaf epidermal pavement cells from a remarkable 278 plant taxa in order to ascertain whether certain lineages are characterized by different cell shapes and whether the presence of an undulating cell wall is common, as in both maize and Arabidopsis. Interestingly they found that these primary examples were the exception as strongly undulating cell walls were unusual. They found that different lineages were characterised by similar levels of undulation and the authors conclude that this study sets a quantitative benchmark on which future experiments can be based that aim to understand the underlying factors that control pavement cell shape.

Martinez-Garcia M, Schubert V, Osman K, Darbyshire A, Sanchez-Moran E, Franklin FCH (2018) TOPII and chromosome movement help remove interlocks between entangled chromosomes during meiosis. J Cell Biol. doi: 10.1083/jcb.201803019

Open Access
Marina Martinez‐Garcia is the lead author on this work conducted during her time working with Eugenio Sanchez-Moran and Chris Franklin at the University of Birmingham. Normal meiosis requires a lack of structural interlocks between entangled chromosomes that can result from inevitable collisions in an area so packed with nucleic acid. In this paper the authors confirm a previously developed hypothesis that topoisomerase II (TOPII) is needed to remove interlocks. However it is not the only determinant of the number of interlocks as in Arabidopsis mutants in which chromosome movement is reduced, interlocks occur irrespective of the presence of TOPII.

Zhang H, Gannon L, Jones PD, Rundle CA, Hassall KL, Gibbs DJ, Holdsworth MJ, Theodoulou FL (2018) Genetic interactions between ABA signalling and the Arg/N-end rule pathway during Arabidopsis seedling establishment. Sci Rep. doi: 10.1038/s41598-018-33630-5

Open Access

Hongtao Zhang is the lead author of this work from the lab of Freddie Theodoulou at Rothamsted Research that investigates the role of the PROTEOLYSIS6 (PRT6) N-recognin E3 ligase in the ABA response. PRT6 regulated degradation of Group VII of the Ethylene Response Factor superfamily (ERFVIIs) controls both sugar sensitivity and oil body breakdown in germinating Arabidopsis seedlings. They found that the former but not the latter response was enhanced by ABA signaling components when the ERFVIIs were stabilised. The authors conclude that during seed germination the N-end rule controls multiple layers of regulation, both in an ABA dependent and independent manner

GARNet Research Roundup: October 10th 2018

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Published on: October 10, 2018

This edition of the GARNet research roundup begins with a paper from Jose Gutierrez-Marcos’ lab in Warwick that investigates the functional significance of inherited epigenetics marks in clonally propagated plants. Second is work from Sara Simonini and Lars Ostergaard (John Innes Centre) that defines a domain in the ETTIN protein important for the auxin response. Next is work from SLCU from Siobhan Braybrook and Henrik Jonsson that experimentally defines and models the role of cell wall composition in anisotropic hypocotyl growth. The fourth paper is from Jonathan Jones’ lab (TSL, Norwich) that adds to our understanding of the activity of the RRS1-R-RPS4 NLR immune complex.

The final three papers are each from the University of Edinburgh and look at different aspects of the relationship between light quality and the circadian clock. First is a paper from Karen Halliday’s lab that investigates the role of PHYA; next Andrew Millar is a co-author on a manuscript that looks at control of FT expression during seasonally realistic conditions. Finally Ference Nagy and Mirela Domijan (University of Liverpool) co-author a paper that assesses the role of HY5 in the response to blue-light.

Wibowo A, Becker C, Durr J, Price J, Spaepen S, Hilton S, Putra H, Papareddy R, Saintain Q, Harvey S, Bending GD, Schulze-Lefert P, Weigel D, Gutierrez-Marcos J (2018) Partial maintenance of organ-specific epigenetic marks during plant asexual reproduction leads to heritable phenotypic variation. Proc Natl Acad Sci U S A doi: 10.1073/pnas.1805371115

Open Access
Anjar Wibowo and Claude Becker are first authors on this UK-German collaboration from the labs of Jose Gutierrez-Marcos (University of Warwick) and Detlef Weigel (Max Planck Institutem, Tübingen). In this work they clonally propagate Arabidopsis and show that organ-specific epigenetic marks are maintained across generations. Interestingly these changes are then maintained through multiple rounds of sexual reproduction. These epigenetic marks provide heritable molecular and physiological phenotypes that can alter the response to pathogens, allowing progeny to maintain a beneficial epigenome that was generated in their parents.

Simonini S, Mas PJ, Mas CMVS, Østergaard L, Hart DJ (2018) Auxin sensing is a property of an unstructured domain in the Auxin Response Factor ETTIN of Arabidopsis thaliana. Sci Rep. doi: 10.1038/s41598-018-31634-9

Open Access

This UK-France collaboration is led by Sara Simonini from the John Innes Centre and continues the Ostergaard lab’s work on the role of the auxin response factor ETTIN in the auxin response. In this paper they analyse the C-terminal ETT specific domain (ES domain) across plant lineages, showing that it does not directly bind auxin but could functional response to a dose response of auxin in a Y2H assay. Understanding more about this ES domain will increase our understanding of auxin sensing by ETTIN and more broadly about auxin-dependent gene regulation.

Bou Daher F, Chen Y, Bozorg B, Clough J, Jönsson H, Braybrook SA. Anisotropic growth is achieved through the additive mechanical effect of material anisotropy and elastic asymmetry. Elife.  doi: 10.7554/eLife.38161

Open Access

Firas Bou Daher is the first author on work from Siobhan Braybrook’s lab conducted both in the Sainsbury Lab Cambridge University and at its new home in California. In this work they look at anisotropic growth in the Arabidopsis hypocotyl and the relationship between cellulose orientation and pectin deposition in the control of this process. They provide experimental evidence that growth parameters are influenced by pectin biochemistry in processes that begin immediately after germination.

Ma Y, Guo H, Hu L, Martinez PP, Moschou PN, Cevik V, Ding P, Duxbury Z, Sarris PF, Jones JDG (2018) Distinct modes of derepression of an Arabidopsis immune receptor complex by two different bacterial effectors. Proc Natl Acad Sci U S A. doi: 10.1073/pnas.1811858115

Yan Ma and Hailong Guo are lead authors on this study from Jonathan Jones’ lab at The Sainsbury Lab, Norwich. They perform a detailed examination of the RRS1-R-RPS4 NLR protein complex, which is necessary to respond to at the bacterial effectors, AvrRps4 and PopP2. Deletion of a WRKY transcription factor domain in the RRS1-R protein causes constitutive activation of the defense response, indicating that this domain maintains the complex in an inactive state in the absence of pathogens. Indeed AvrRps4 does interact with this WRKY domain but interestingly PopP2 activation requires interaction with a longer C-terminal extension of RRS1-R. This demonstrates that although these bacterial effectors are recognised by the same complex the interactions occurs in a subtly but functionally distinct ways.

Seaton DD, Toledo-Ortiz G, Ganpudi A, Kubota A, Imaizumi T, Halliday KJ (2018) Dawn and photoperiod sensing by phytochrome A. Proc Natl Acad Sci U S A. doi: 10.1073/pnas.1803398115

Open Access

This research from Karen Halliday’s lab in Edinburgh is led by Daniel Seaton and provided a detailed assessment of the role of phytochrome A (phyA) in photoperiod sensing, which is defined as the relationship between the circadian clock and external light signals. They show that PHYA activity, controlled by the transcription factors, PIF4 and PIF5, is a key regulator of morning activity, particularly in short photoperiods. PHYA protein accumulates during the night and responds to light by promoting a burst of gene expression that prepares the plant for the upcoming daylight and places this light receptor as a key detector of dawn.

Song YH, Kubota A, Kwon MS, Covington MF, Lee N, Taagen ER, Laboy Cintrón D, Hwang DY, Akiyama R, Hodge SK, Huang H, Nguyen NH, Nusinow DA, Millar AJ, Shimizu KK, Imaizumi T (2018) Molecular basis of flowering under natural long-day conditions in Arabidopsis. Nat Plants. doi: 10.1038/s41477-018-0253-3

Andrew Millar is a co-author on this US-led paper that investigates the circadian regulation of the Arabidopsis florigen gene FLOWERING LOCUS T (FT) within an annual context, showing that during the spring FT shows a morning peak is absent in their usual lab experiments. By adjusting growth-room conditions to mimic natural seasonal variations they show that phytochrome A and EARLY FLOWERING 3 regulate morning FT expression by stabilizing the CONSTANS protein. This manuscript highlights the importance of providing seasonal-specific conditions in order to understand field-relevant regulation of plant growth.

Hajdu A, Dobos O, Domijan M, Bálint B, Nagy I, Nagy F, Kozma-Bognár L. ELONGATED HYPOCOTYL 5 mediates blue light signalling to the Arabidopsis circadian clock (2018) Plant J. doi: 10.1111/tpj.14106

Ferenc Nagy (University of Edinburgh) is a co-author on this Hungarian-led study that looks the effect of light quality on the function of the key signaling hub transcription factor ELONGATED HYPOCOTYL 5 (HY5). They show that hy5 mutants show shorter period rhythms in blue but not in red light or darkness. Even though the pattern and level of HY5 alters its binding to downstream promotor elements, subsequent gene expression is only altered in a few genes. In collaboration with Mirela Domijan (University of Liverpool) they model this response to suggest that clock feedback mechanisms mask HY5-induced changes. Ultimately they show that HY5 is important in decoding the blue:red mix of white light and that it at least partially informs activity of the circadian oscillator.

High Value Chemicals from Plants Annual Meeting 2018

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Published on: October 3, 2018
Naomi Nakayama discusses plant cell factories

The final annual meeting in Phase I of the BBSRC-funded HVCfP NIBB network was held on October 1st in the delightful Royal College of Physicians, close to Regents Park in London. This single day meeting was a byte-size mix of invited talks and those provided by researchers who had received Proof of Concept (PoC) or Business Interaction Voucher (BIV) funding from the network.

From a GARNet perspective it was gratifying to hear presentations that included preliminary work conducted in Arabidopsis, demonstrating the importance of model organisms in the development of ideas that can lead to industrial biotechnology projects. Naomi Nakayama from the University of Edinburgh described her labs work aimed at optimising use of Arabidopsis cell cultures as well as in developing plant stem cells as ‘single cell factories’. Secondly Peter Eastmond from Rothamsted Research described the initial characterisation of the Sugar Dependent1 hydrolase enzyme that they are now developing as a potential industrial biocatalyst.

Paul Fraser from RHUL and Mike Roberts from Lancaster University introduced very different research projects that both use tomato plants. Long-term establishment of RIL lines have allowed the Fraser lab to identify tomato plants with increased levels of B-carotene in the fruit. This project has similarity to other attempts at vitamin A biofortification yet takes advantage of many years expertise working specifically with this plant. These B-carotene fortified lines are now ready for the field and should be particularly important in regions with high food insecurity and vitamin A deficiency.

Mike Roberts has a nascent industrial collaboration with greenhouse tomato producer APS Salads. Their soil-free growth of tomatoes generates a large amount of waste biomass, which is currently used for a variety of applications that rely on downstream anaerobic decomposition. It is known that mechanical disruption of plant tissue causes the release of protective defence chemicals so the Roberts lab have used HVCfP BIV funding to investigate whether macerated tomato waste has protective anti-pathogen properties. The initial characterisation of liquid fractions taken from the waste pipeline have given promising protective effects indicating that the mechanical disruption of the tissue generates an as-yet-unknown defense-promoting compound.

Michael Marsden discusses co-products, not plant waste.

On a related note, Michael Marsden provided an invited talk and asked delegates to re-think the idea of ‘plant waste’. His company AB Connect labels waste as ‘co-products’ and it was extremely informative to learn about all the possible uses of crop co-products across a range of industries. However there certainly remains additional potential in this area as technologies continue to develop for degradation of cellulosic material and improvement of manufacturing pipelines.

Sweet smelling success story of Oxford BioTrans.

Jason King from Oxford Biotrans provided the opening invited talk that was a real success story of activities that have taken place since he last presented at the 2015 annual HVCfP meeting. Their main product is the grapefruit flavour nootkatone that they produce from oranges using patented P450 enzymes. This industrial project was recently highlighted as a success story by the BBSRC. Oxford BioTrans are now investigating options for producing a range of other products using their set of novel P450s. Pleasingly Jason King reported that they have not had significant difficulties in obtaining funding for this project both from national funding bodies and local angel investors.

The afternoon invited speakers provided a different perspective on some wider issues surrounding the research environment. Kelly Vere is working with the Science Council on the establishment of the Technicians Committment, which is an initiative to provide recognition for the vital yet often underappreciated support provided by technical staff in higher education. Over 50 universities have signed up to the charter and many are taking steps to provide this extra support.

Alison Prendiville (University of the Arts London) and Sebastian Fuller (St George’s, University of London) described their involvement with the EU-funded Pharma-Factory project. This involves the input of numerous stakeholders associated with the use of the products generated by plant-based biofactories. These include potential patients, clinicians, regulators and researchers. They described how they are using the process of co-design to create partnerships that take into account stakeholder priorities in order to facilitate new methods of knowledge exchange. Intuitively it seems that this type of project might be challenging for bench scientists to fully appreciate so it will be interesting to observe where this project leads and to learn about their conclusions.

Due to the obvious links between the GARNet community and the type of PoC/BIV projects funded by the HVCfP network, the GARNet coordinator has attended and participated in a number of HVCfP events over the past four years. Although this annual meeting only highlighted a small set of supported projects it seems clear that the HVCfP network has succeeded in bringing together academics and industrial partners as well as supporting research in its early stages.

The decision regarding Phase II of the NIBBs will be announced over the next month so hopefully this plant-based network will gain follow-on funding to continue the progress they have made during Phase I.

Andrew Millar talks Open Data at GARNet2018

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Published on: October 2, 2018

Andrew Millar (University of Edinburgh) speaks at the GARNet2018 conference about ‘Being more Open by being more Productive’

GARNet Arabidopsis Roundup: September 13th

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Published on: September 13, 2018

The latest GARNet Research Roundup includes two papers led by Cyril Zipfel from The Sainsbury lab, Norwich (who has since moved his lab to the University of Zurich). The first paper demonstrates the potential for cross-species strategies for developing disease resistance whilst the second is a phosphoproteomic dissection of the BAK1 immune co-receptor. Third is work from the lab of Liam Dolan (University of Oxford) that has discovered a novel type of regulation for RSL Class I bHLH transcription factors in Marchantia. Finally is research from Paul Dupree’s lab in Cambridge that investigates the structure of galactoglucomannan polysaccharides in the Arabidopsis cell wall.

Pfeilmeier S, George J, Morel A, Roy S, Smoker M, Stransfeld L, Downie JA, Peeters N, Malone JG, Zipfel C (2018) Expression of the Arabidopsis thaliana immune receptor EFR in Medicago truncatula reduces infection by a root pathogenic bacterium, but not nitrogen-fixing rhizobial symbiosis. Plant Biotechnol J. doi: 10.1111/pbi.12999

Open Access

Sebastian Pfeilmeier and Jeoffrey George lead this work from the labs of Jacob Malone and Cyril Zipfel at the John Innes Centre and the Sainsbury lab, Norwich. In this study they have expressed the Arabidopsis PRR ELONGATION FACTOR-THERMO UNSTABLE RECEPTOR (EFR) immune reception in Medicago truncatula. They show that these transgenic plants remain able to form root nodules with the bacterial symbiont Sinorhizobium meliloti. However they are resistant to the bacterial pathogen Ralstonia solanacearum. This study shows the potential of cross-species approaches to develop broad-spectrum pathogen resistance. It will be interesting to learn more about future developments in this area.

Perraki A, DeFalco TA, Derbyshire P, Avila J, Séré D, Sklenar J, Qi X, Stransfeld L, Schwessinger B, Kadota Y, Macho AP, Jiang S, Couto D, Torii KU, Menke FLH, Zipfel C (2018) Phosphocode-dependent functional dichotomy of a common co-receptor in plant signalling. Nature doi: 10.1038/s41586-018-0471-x

This second study from the lab of Cyril Zipfel is led by Artemis Perraki and includes wide range of collaborators from across the globe. They have used phosphoproteomics and targeted mutagenesis to perform a detailed characterisation of the immune co-receptor BRASSINOSTEROID INSENSITIVE 1-ASSOCIATED KINASE 1 (BAK1). This protein interacts with many leucine-rich repeat receptor kinases (LRR-RKs) yet they find that specific phosphosites discriminate between subsets of BAK1 functions that are linked to hormone or immune signaling. This study reveals new complexity in the regulation of this multi-facted protein and has broad importance regarding our understanding of how the phosphocode allows separation of the different signaling outputs.

Honkanen S, Thamm A, Arteaga-Vazquez MA, Dolan L (2018) Negative regulation of conserved RSL class I bHLH transcription factors evolved independently among land plants. Elife. doi: 10.7554/eLife.38529

Open Access

This study looks at the role of RSL class I basic helix-loop-helix transcription factors in the control of development in the lower plant Marchantia polymorpha. This work is led by Suvi Honkanen from Liam Dolan’s lab at the University of Oxford. In Arabidopsis RSL genes are negatively regulated by the GLABRA transcription factor yet in this study the authors identify a novel microRNA-based regulatory mechanism. Although RSL1 class I genes are evolutionarily conserved across land plants the miRNA regulatory module is only present in Marchantia, demonstrating that conserved genes can have divergent modes of regulation to control lineage-specific developmental requirements

Yu L, Lyczakowski JJ, Pereira CS, Kotake T, Yu X, Li A, Mogelsvang S, Skaf MS, Dupree P (2018) The patterned structure of galactoglucomannan suggests it may bind to cellulose in seed mucilage. Plant Physiol. doi: 10.1104/pp.18.00709

Open Access
This work is led by Li Yu from the lab of Paul Dupree at the University of Cambridge. They have investigated the detailed structure of mannose-based (mannan) polysaccharides within the Arabidopsis cell wall. These have previously been shown to be important in maintaining seed mucilage architecture, which has a glucose-mannose (glucomannan) backbone. The authors assess the contribution of the Cellulose Synthase-Like A2 (CSLA2) and Mannan α-Galactosyl Transferase 1 (MAGT1) enzymes in the construction and decoration of a galactoglucomannan backbone and provide data for molecular stimulations to predict as to how these might interact with cellulose microfibrils.

GARNet talks to Ari Sadanandom

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Published on: September 4, 2018

GARNet talked to Professor Ari Sadanandom from Durham University about a recent paper published in The Plant Cell entitled ‘SUMO Suppresses the Activity of the Jasmonic Acid Receptor CORONATINE INSENSITIVE 1

GARNet Research Roundup: August 22nd

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Published on: August 22, 2018

This week’s GARNet research roundup highlights outstanding science from across the UK. First are a group of three papers led by researchers in Cambridge and Bristol that investigate the role of either sugar or calcium signaling on control of the plant circadian clock. Secondly is work from Durham that provides an elegant link between SUMOylation and the jasmonate-responsive arm of the defence response. The biotrophic arm of defence signaling is the focus of the next paper from University of Nottingham that investigates the role of the N-end rule pathway in that response. Finally is a paper from the John Innes Centre that identifies a key determinant of planar cell polarity across the Arabidopsis leaf.

Frank A, Matiolli CC, Viana AJC, Hearn TJ, Kusakina J, Belbin FE, Wells Newman D, Yochikawa A, Cano-Ramirez DL, Chembath A, Cragg-Barber K, Haydon MJ, Hotta CT, Vincentz M, Webb AAR, Dodd AN (2018) Circadian Entrainment in Arabidopsis by the Sugar-Responsive Transcription Factor bZIP63. Current Biol. doi: 10.1016/j.cub.2018.05.092

Open Access

This research comes from the labs of Anthony Dodd (University of Bristol) and Alex Webb (University of Cambridge) and is led equally by Alexander Frank, Cleverson Matioli, Americo Viana, Timothy Hearn and Jelena Kusakina. They investigate how the Arabidopsis circadian clock is entrained to respond to changing metabolic rhythms, measured by assessing sugar signaling. The molecular factors that control changes in the circadian oscillator were previously unknown but they show that the transcription factor BASIC LEUCINE ZIPPER63 (bZIP63) is required to alter expression of the oscillator gene PSEUDO RESPONSE REGULATOR7 (PRR7). They also show that the SnRK1 sugar sensing kinase and TREHALOSE-6-PHOSPHATE SYNTHASE1 (TPS1) gene are required for sugar-mediated circadian adjustment. This study provides important information about additional layers of regulation controlling the relationship between the circadian clock and plant metabolism.

Martí Ruiz MC, Hubbard KE, Gardner MJ, Jung HJ, Aubry S, Hotta CT, Mohd-Noh NI, Robertson FC, Hearn TJ, Tsai YC, Dodd AN, Hannah M, Carré IA, Davies JM, Braam J, Webb AAR (2018) Circadian oscillations of cytosolic free calcium regulate the Arabidopsis circadian clock. Nat Plants. 2018 Aug 20. doi: 10.1038/s41477-018-0224-8

This second paper from the labs of Alex Webb and Anthony Dodd also features work from Isabelle Carre’s and Julia Davis’s lab in Warwick and Cambridge respectively. This work led by María Carmen Martí Ruiz, Katharine Hubbard and Michael J. Gardner looks at the how oscillations of cytoplasmic calcium influence the central circadian clock. They show that calcium influences the clock through the activity of the CALMODULIN-LIKE24 (CML24) gene and further genetic analysis links these activities through the action of the central clock gene TIMING OF CAB2 EXPRESSION1 (TOC1). This paper is also a clear lesson in persistence as it was first received by Nature Plants back in May 2016.

Ohara T, Hearn TJ, Webb AAR, Satake A. Gene regulatory network models in response to sugars in the plant circadian system. J Theor Biol. doi: 10.1016/j.jtbi.2018.08.020

The research includes members of Alex Webb’s group and develops a theoretical model to predict the response of the gene regulatory network that links the circadian clock to metabolic signals. This model predicts that the targets of sugar signaling could be both members of the PSEUDO-RESPONSE REGULATOR gene family as well as evening complex components. These findings are experimental confirmed in the paper by Frank et al in this edition of the GARNet response roundup.

Srivastava AK, Orosa B, Singh P, Cummins I, Walsh C, Zhang C, Grant M, Roberts MR, Anand GS, Fitches E, Sadanandom A (2018) SUMO Suppresses the Activity of the Jasmonic Acid Receptor CORONATINE INSENSITIVE 1. Plant Cell. doi: 10.1105/tpc.18.00036

Open Access

Lead author on this paper from the labs of Elaine Fitches and Ari Sadanandom at the Unversity of Durham is Anjil Kumar Srivastava and includes co-authors from Lancaster University. In the study they reveal a feedback loop between the jasmonic acid receptor CORONATINE INSENSITIVE 1 (COI1) and its targets for degradation; the JASMONATE ZIM (JAZ) domain-containing repressor proteins. The authors show that SUMOylated JAZ proteins inhibit the COI1-dependent degradation of non-SUMOylated JAZ proteins. In addition they identify a SUMO-responsive element within the COI1 protein and that necrotrophic bacteria specifically target SUMO protease in order to modulate JA-responsive defense responses.

Vicente J, Mendiondo GM, Pauwels J, Pastor V, Izquierdo Y, Naumann C, Movahedi M, Rooney D, Gibbs DJ, Smart K, Bachmair A, Gray JE, Dissmeyer N, Castresana C, Ray RV, Gevaert K, Holdsworth MJ (2018) Distinct branches of the N-end rule pathway modulate the plant immune response. New Phytol. doi: 10.1111/nph.15387

Open Access
Jorge Vicente leads this work from the lab of Mike Holdsworth in Nottingham that includes collaborators from Belgium, Spain, Germany and Austria. They investigate the role of the N-end rule degradation pathway in the plant immune response. Indeed they show that portions of this response mediated by the E3 ligase PROTEOLYSIS (PRT)6 are important for expression of a specific set of defense-related genes and basal resistance to a biotropic pathogen. They also show this response is also important in the monocot barley where plants with reduced expression of HvPRT6 have enhanced resistance to different pathogens.

Mansfield C, Newman JL, Olsson TSG, Hartley M, Chan J, Coen E (2018) Ectopic BASL Reveals Tissue Cell Polarity throughout Leaf Development in Arabidopsis thaliana. Curr Biol. doi: 10.1016/j.cub.2018.06.019

Open Access
Catherine Mansfield leads this study from the lab of Enrico Coen at the John Innes Centre that investigates the factors that control cell polarity during leaf development. They show that BASL (BREAKING OF ASYMMETRY IN THE STOMATAL LINEAGE) is essential for establishment an organ-wide polarity field across the Arabidopsis leaf. They show this polarity field is aligned with the proximodistal axis of the leaf (base to tip) and is independent of stomatal patterning. Like in animals this demonstrates that planar plant organs have a tissue-wide cell polarity field that might be critical for guiding growth and differentiation.
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