GARNet Research Roundup: July 27th

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Published on: July 26, 2018

This GARNet research roundup includes papers that feature a number of different research areas. Firstly is work from Glasgow that investigates the photoactivation of the UVR8 light receptor. Second is work from the University of Cambridge that links the activity of the BIG protein to the circadian oscillator. The next paper has co-authors from Cambridge and looks at promotor sequences needed for expression in bundle sheath cells. The fourth paper from the University of Leeds documents an important role for peroxisomes in the drought response whilst the final manuscript includes co-authors from the University of Birmingham and looks at the role of the ASYNAPTIC4 protein during meiosis.


http://pubs.rsc.org/en/Content/ArticleLanding/2018/PP/C8PP00138C#!divAbstract

Díaz-Ramos LA, O’Hara A, Kanagarajan S, Farkas D, Strid Å, Jenkins GI. Difference in the action spectra for UVR8 monomerisation and HY5 transcript accumulation in Arabidopsis (2018) Photochem Photobiol Sci. doi: 10.1039/c8pp00138c

Open Access

Aranzazu Díaz-Ramos is first author on this research from the University of Glasgow that investigates the activation of photomorphogenic responses by the UVR8 photoreceptor. They show that two distinct UVR8 responses, either the monomerisation of UVR homodimers or accumulation of HY5 responsive transcripts, occurs at different wavelengths.


Hearn TJ, Marti MC, Abdul-Awal SM, Wimalasekera R, Stanton CR, Haydon MJ, Theodoulou FL, Hannah MA, Webb AA (2018) BIG regulates dynamic adjustment of circadian period in Arabidopsis thaliana. Plant Physiology pp.00571.2018. doi: 10.1104/pp.18.00571

Open Access

Timothy Hearn works with Alex Webb at the University of Cambridge and in this paper characterises how the multi-functional BIG protein impacts the circadian clock. This gene was isolated in a forward genetics screen to identify signaling components that alter the response to nicotinamide, which acts as a brake on the circadian oscillator. This finding allows the authors to better understand how altering the circadian oscillator can affect appropriate phasing during different environmental conditions.


Kirschner S, Woodfield H, Prusko K, Koczor M, Gowik U, Hibberd JM, Westhoff P. Expression of SULTR2;2 in the Arabidopsis bundle sheath and vein cells is mediated by a positive regulator. J Exp Bot. 2018 Jul 19. doi: 10.1093/jxb/ery263

Open Access

Sandra Kirschner is first author on this German-led study that includes Helen Woodfield (now Cardiff University) and Julian Hibberd (University of Cambridge). They are interested in the mechanisms that restrict gene expression to bundle sheath cells in C3 plants with a longer view of understanding the biology of these cells in C4 plants. They analyse the vascular-restricted SULTR2;2 promotor and identified a short region that is necessary for its expression pattern. Importantly they show that this sequence is evolutionarily conserved across Brassicaceae and a distantly related C4 plant.

https://academic.oup.com/jxb/advance-article/doi/10.1093/jxb/ery263/5056055

Ebeed HT, Stevenson S, Cuming AC, Baker A. Conserved and differential transcriptional responses of peroxisome associated pathways to drought, dehydration and ABA. J Exp Bot. 2018 Jul 19. doi: 10.1093/jxb/ery266

Open Access

Heba Ebeed is the lead author of this work conducted in Alison Baker’s lab at the University of Leeds. They take a comparative genomics approach to investigate the expression of peroxisome-localised genes in a moss (physcomitrella), monocot (wheat) and a dicot (arabidopsis). They show that members of three gene families are upregulated in each of these organisms following drought stress, demonstrating the importance of peroxisomes in this environmental response throughout plant evolution.


Chambon A, West A, Vezon D, Horlow C, De Muyt A, Chelysheva L, Ronceret A, Darbyshire AR, Osman K, Heckmann S, Franklin FCH, Grelon M (2018) Identification of ASYNAPTIC4, a component of the meiotic chromosome axis. Plant Physiol. pii: pp.01725.2017. doi: 10.1104/pp.17.01725

Chris Franklin and Alice Darbyshire from the University of Birmingham are co-authors on this French-led study that looks into the role of the ASYNAPTIC4 (ASY4) protein in the control of synapsis formation during meiosis. Plants without ASY4 activity have defective chromosomal axis formation and cannot undergo synapsis. Although the initiation of recombination is unaffected in asy4 mutants, later processes are altered, demonstrating the key role for ASY4 during meiosis

GARNet Research Roundup: May 17th

This weeks GARNet research roundup includes six excellent papers investigating many aspects of Arabidopsis cell biology. Firstly Eirini Kaiserli from Glasgow introduces a novel regulator of blue-light signaling. Second is a paper that analyses the circadian clock with single cell resolution and is led by James Locke (SLCU) and Anthony Hall (Earlham Institute). The next two papers investigate different aspects of hormone signaling, with Keith Lindsey’s group at Durham looking at the relationshop between the HYDRA protein and the auxin response whilst Ottoline Leysers group in Cambridge looks at the link between auxin and cytokinin during shoot growth. The fifth paper from Phillip Mullineaux (University of Essex) provides a genome-wide analysis into the role of HEAT SHOCK TRANSCRIPTION FACTORA1b protein. The final paper from the lab of Piers Hemsley (James Hutton Institute, University of Dundee) should be of interest to many plant molecular biologists as they assess the functional significance of different epitope tags.


Perrella G, Davidson MLH, O’Donnell L, Nastase AM, Herzyk P, Breton G, Pruneda-Paz JL, Kay SA, Chory J, Kaiserli E (2018) ZINC-FINGER interactions mediate transcriptional regulation of hypocotyl growth in Arabidopsis. Proc Natl Acad Sci U S A.. pii: 201718099. doi: 10.1073/pnas.1718099115

Open Access

Eirini Kaiserli (University of Glasgow) leads this study that identifies the ZINC-FINGER HOMEODOMAIN 10 (ZFHD10) as a novel regulator of light signaling. ZFHD10 physically interacts with TANDEM ZINC-FINGER PLUS3 (TZP) and these proteins coassociate at promotors that are blue-light regulated. These results reveal of novel mechanism of action for the key multiple signal integrator TZP in the light regulated growth of Arabidopsis hypocotyls.

Eirini discusses this paper on the GARNet YouTube channel.


Gould PD, Domijan M, Greenwood M, Tokuda IT, Rees H, Kozma-Bognar L, Hall AJ, Locke JC (2018). Coordination of robust single cell rhythms in the Arabidopsis circadian clock via spatial waves of gene expression. Elife. 26;7. pii: e31700. doi: 10.7554/eLife.31700 Open Access

https://elifesciences.org/articles/31700

This paper is led by James Locke (SLCU) and Anthony Hall (Earlham) and investigates the circadian clock at single cell resolution. They use Arabidopsis plants grown in constant environmental conditions to show two desynchronised yet robust single cell oscillations that move both up and down the root. Their results indicate that the clock shows cell-to-cell coupling and they they modeled this relationship to recapitulate the observed waves of activity. Overall their results are suggestive of multiple coordination points for the Arabidopsis clock, which is different from the mammalian system of regulation.


http://dev.biologists.org/content/145/10/dev160572

Short E, Leighton M, Imriz G, Liu D, Cope-Selby N, Hetherington F, Smertenko A, Hussey PJ, Topping JF, Lindsey K (2018) Epidermal expression of a sterol biosynthesis gene regulates root growth by a non-cell autonomous mechanism in Arabidopsis. Development . pii: dev.160572. doi: 10.1242/dev.160572 Open Access

This collaboration between the research groups of Keith Lindsey and Patrick Hussey at the University of Durham investigates the role of the HYDRA1 (HYD1) sterol Δ8-Δ7 isomerase in epidermal patterning. This tissue shows highest HYD1 expression and hyd mutants have major root patterning defects. Tissue-specific expression of HYD1 indicates that it is involved with some type of non-cell autonomous signaling. Analysis of PIN1 and PIN2 protein expression suggests that auxin might be this functional signal


http://www.plantphysiol.org/content/early/2018/05/01/pp.17.01691.long

Waldie T, Leyser O (2018) Cytokinin targets auxin transport to promote shoot branching. Plant Physiol. 2018 May 1. pii: pp.01691.2017. doi: 10.1104/pp.17.01691.Open Access

This study from the lab of Ottoline Leyser (SLCU) investigates the integration between the plant hormones cytokinin and auxin. They investigate the role of cytokinin in shoot branching through analysis of Arabidopsis Response Regulators (ARRs) mutants. They show arr mutant phenotypes correlate with changes in stem auxin transport mediated by the PIN3, PIN4 and PIN7 efflux carriers, the expression of each respond to cytokinin signaling. Overall this study identifies a novel alternative pathway by which cytokinin impacts bud outgrowth through alterations in auxin transport.


Albihlal WS, Irabonosi O, Blein T, Persad R, Chernukhin I, Crespi M, Bechtold U, Mullineaux PM (2018) Arabidopsis Heat Shock Transcription FactorA1b regulates multiple developmental genes under benign and stress conditions. J Exp Bot. doi: 10.1093/jxb/ery142 Open Access

Phillip Mullineaux (University of Essex) leads this collaboration with French colleagues in a study that investigates the genome-wide targets of the HEAT SHOCK TRANSCRIPTION FACTORA1b (HSFA1b) protein. Under non-stress ad heat-stress conditions they showed that 1000s of genes are differentially expressed with a smaller proportion of genes showing different levels of direct interaction. The indirect targets of HSFA1b are regulated through a network of 27 transcription factors and they also provide evidence for the role of hundreds of natural antisense non-coding RNA in the regulation of HSFA1b targets. Overall they show that HSFA1b is a key regulator of environmental cues to regulate both developmental genes and those involved in stress tolerance.


Hurst CH, Turnbull D, Myles SM, Leslie K, Keinath NF, Hemsley PA (2018) Variable effects of C-terminal tags on FLS2 function – not all epitope tags are created equal. Plant Physiol. doi: 10.1104/pp.17.01700 Open Access

This study from the Hemsley lab (James Hutton Institute, University of Dundee) is a cautionary tale on the use and interpretation of results obtained from experiments with commonly-used epitope tags. They assessed the activity of plants containing transgenic FLS2 proteins, which is a receptor-like kinase (RLKs) involved in the defence response. They show that various FLS2 C-terminal epitope fusions reveal highly variable and unpredictable outputs, indicating that the presence of different tags significantly alters protein function. This finding might require a reassessment of many experiments that rely on interpreting the function of epitope-tagged proteins and has significant for many if not all plant molecular biologists.

GARNet Research Roundup: April 27th

This weeks GARNet research roundup features four papers that include Malcolm Bennett (University of Nottingham) as an author. The first three are linked manuscripts that investigate the role of auxin on root hair development that is controlled by varying phosphate levels. Ranjan Swarup provides an audio summary of two of these papers on the GARNet YouTube and podcast feeds.

The fourth paper from Nottingham is a collaboration with GARNet PI Jim Murray (Cardiff University) that characterises the STM gene network and its influence on meristem development.

The fifth paper from the lab of Paul Dupree in Cambridge characterises the stem transcriptome whilst the next paper from Iain Johnston and George Bassel (University of Birmingham) identifies a bet-hedging network that influences seed germination. The final paper features Seth Davies (University of York) as a co-author and investigates the impact of changes in circadian rhythms on short architecture.


Researchers at the University of Nottingham are involved in three back-to-back papers that add a mechanistic framework to the relationship between phosphate and auxin signaling in root hairs.

Bhosale R, Giri J, Pandey BK, Giehl RFH, Hartmann A, Traini R, Truskina J, Leftley N, Hanlon M, Swarup K, Rashed A, Voß U, Alonso J, Stepanova A, Yun J, Ljung K, Brown KM, Lynch JP, Dolan L, Vernoux T, Bishopp A, Wells D, von Wirén N, Bennett MJ, Swarup R (2018) A mechanistic framework for auxin dependent Arabidopsis root hair elongation to low external phosphate. Nat Commun. 9(1):1409. doi: 10.1038/s41467-018-03851-3

https://www.nature.com/articles/s41467-018-03851-3

Open Access

The first paper is led by Ranjan Swarup and defines components of auxin biosynthetic, transport and signaling pathways that are involved in the change root hair development in response to different phosphate concentrations in Arabidopsis. Ranjan discusses this paper on YouTube.

Giri J, Bhosale R, Huang G, Pandey BK, Parker H, Zappala S, Yang J, Dievart A, Bureau C, Ljung K, Price A, Rose T, Larrieu A, Mairhofer S, Sturrock CJ, White P, Dupuy L, Hawkesford M, Perin C, Liang W, Peret B, Hodgman CT, Lynch J, Wissuwa M, Zhang D, Pridmore T, Mooney SJ, Guiderdoni E, Swarup R, Bennett MJ (2018). Rice auxin influx carrier OsAUX1 facilitates root hair elongation in response to low external phosphate. Nat Commun. 9(1):1408. doi: 10.1038/s41467-018-03850-4

https://www.nature.com/articles/s41467-018-03850-4

Open Access

This paper led by Malcolm Bennett uses a rice model to investigate the relationship between auxin and root hair elongation in response to low concentrations of phosphate. They show rice aux1 mutants have significant changes in root architecture.

Dindas J, Scherzer S, Roelfsema MRG, von Meyer K, Müller HM, Al-Rasheid KAS, Palme K, Dietrich P, Becker D, Bennett MJ, Hedrich R (2018) AUX1-mediated root hair auxin influx governs SCF(TIR1/AFB)-type Ca(2+) signaling. Nat Commun. 9(1):1174. doi: 10.1038/s41467-018-03582-5

Open Access

The third paper includes Malcolm Bennett as a co-author and investigates how the auxin transport and signaling pathways stimulate calcium signaling during root hair elongation.


Scofield S, Murison A, Jones A, Fozard J, Aida M, Band LR, Bennett M, Murray JAH (2018) Coordination of meristem and boundary functions by transcription factors in the SHOOT MERISTEMLESS regulatory network. Development pii: dev.157081. doi: 10.1242/dev.157081

http://dev.biologists.org/content/early/2018/04/12/dev.157081.long

Open Access
GARNet PI Jim Murray is the corresponding author on this manuscript that is led by Dr Simon Scofield and includes collaborators from the University of Nottingham. They have explored the gene regulatory network that is regulated by the key meristem identity gene SHOOT MERISTEMLESS (STM). This network includes an over-representation of transcription factor families, each of which have distinct roles in meristem development. They use in planta experimentation and in silico modeling to investigate the relationship between STM and CUC1 in more detail. Overall this study confirms that STM is a central regulator of shoot meristem function.


Faria-Blanc N, Mortimer JC, Dupree P (2018) A Transcriptomic Analysis of Xylan Mutants Does Not Support the Existence of a Secondary Cell Wall Integrity System in Arabidopsis. Front Plant Sci. 9:384. doi: 10.3389/fpls.2018.00384

Open Access

Paul Dupree (University of Cambridge) is the corresponding author of this study that uses a range of Arabidopsis cell wall mutants to investigate the stem transcriptome. In plants with defects in xylan synthesis the authors found surprisingly few transcriptional changes. This indicates that once plants have committed to a terminal secondary cell wall program there is little need for transcriptional changes even after cell wall damage.


Johnston IG, Bassel GW (2018) Identification of a bet-hedging network motif generating noise in hormone concentrations and germination propensity in Arabidopsis. J R Soc Interface. 15(141). pii: 20180042. doi: 10.1098/rsif.2018.0042.

Open Access
Iain Johnston (University of Birmingham) leads this study that has identified a bet-hedging network that links hormone signaling during Arabidopsis germination. This type of network allows plants to more easily adapt to varying environmental conditions but can preclude maximum growth. In this system the network is based upon the regulation of ABA synthesis, activity and degradation, which is maintained at a constant mean level even though it exhibits significant noise. They investigate the parameters that might be tweaked to reduce variation in germination rate and therefore might be targets for modification in order to maximise responses under particular environmental conditions.

George Bassel who is a co-author on this paper will be speaking at the GARNet2018 Meeting in York in September.

http://rsif.royalsocietypublishing.org/content/15/141/20180042.long

Rubin MJ, Brock MT, Baker RL, Wilcox S, Anderson K, Davis SJ, Weinig C (2018) Circadian rhythms are associated with shoot architecture in natural settings. New Phytol. doi: 10.1111/nph.15162.

Seth Davies (University of York) is a co-author on this study that assesses the effect of circadian rhythms on aerial phenotypes that lead to fruit production in field grown Arabidopsis. This was assessed over two growing seasons and they show that variation in clock function significantly impacts shoot architecture.

GARNet Research Roundup: April 11th 2018

This weeks GARNet research roundup begins with a microscopy-based study led by Lorenzo Frigerio from the University of Warwick that investigates the origin of Protein Storage Vacuoles. The second paper from John Doonan at Aberystwyth University looks at how differential splicing of cyclin-dependent Kinase G1 effects the thermosensory response. Reiner van de Hoorn from Oxford leads the next paper that characterises the use of activity-based protein profiling (ABPP) to identify novel α-glycosidases in model and non-model plants. Simon McQueen-Mason from York is corresponding author of the next paper that identified a new QTL from Brachypodium that is involved in cell wall formation. The fifth paper is led by Anthony Dodd from Bristol and characterises the role of the SnRK1 complex in hypocotyl elongation whilst the penultimate manuscript from Julia Davies’s lab in Cambridge performs patch clamp analysis of dorn1 mutant plants. The final paper from Brendan Davies at the University of Leeds characterises the SMG kinase, a gene that is lacking from the Arabidopsis genome, in Physcomitrella patens.


http://www.plantphysiol.org/content/early/2018/03/19/pp.18.00010.long

Feeney M, Kittelmann M, Menassa R, Hawes C, Frigerio L. Protein storage vacuoles originate from remodelled pre-existing vacuoles in Arabidopsis thaliana (2018) Plant Physiol. 2018 Mar 19. pii: pp.00010.2018. doi: 10.1104/pp.18.00010 Open Access

This collaboration between the Universities of Warwick and Oxford Brookes is led by Lorenzo Frigerio and Chris Hawes. They have investigated the origin of seed Protein Storage Vacuoles (PSV) using a two-pronged approach using confocal and immunoelectron microscopy. They looked at embryo development as well as in leaf cells that have been reprogrammed for embryonic cell fate by overexpression of the LEAFY COTYLEDON2 TF. These studies indicate that PSVs are formed following the reprogramming of pre-existing embryonic vacuole (EV) rather than from de novo assembly.


https://onlinelibrary.wiley.com/doi/abs/10.1111/tpj.13914

Cavallari N, Nibau C, Fuchs A, Dadarou D, Barta A, Doonan JH. The Cyclin Dependent Kinase G group defines a thermo-sensitive alternative splicing circuit modulating the expression of Arabidopsis ATU2AF65A (2018) Plant J. doi: 10.1111/tpj.13914 Open Access

John Doonan (Aberystwyth University) is the corresponding author on this UK-Austrian collaboration that presents the role of the cyclin-dependent Kinase G1 (CDKG1) in thermosensing in Arabidopsis. Ambient temperature change causes altered gene expression of the spliceosome component, ATU2AF65A. Interestingly the CDKG1 gene is differentially spliced and to produces two protein isoforms that are both needed to complement the expression of ATU2AF65A across a temperature range. This alternative splicing is dependent on CDKG2 and CYCLIN L1 and is a novel control mechanism in the temperature control response.


Husaini AM, Morimoto K, Chandrasekar B, Kelly S, Kaschani F, Palmero D, Jiang J, Kaiser M, Ahrazem O, Overkleeft HS, van der Hoorn RAL (2018) Multiplex fluorescent, activity-based protein profiling identifies active α-glycosidases and other hydrolases in plants. Plant Physiol. pii: pp.00250.2018. doi: 10.1104/pp.18.00250 Open Access

Renier Van de Hoorn (University of Oxford) leads this pan-european study that uses novel cyclophellitol aziridine probes that label α-glycosidase enzymes. They identified two novel α-glycosidases in Arabidopsis as well as using the technique in non-model saffron crocus. Finally they showed that this multiplex fluorescent labelling in combination with probes for serine hydrolases and cysteine proteases can be used to identify changes in hydrolase activity in response to pathogen infection.


Whitehead C, Ostos Garrido FJ, Reymond M, Simister R, Distelfeld A, Atienza SG, Piston F, Gomez LD, McQueen-Mason SJ (2018) A glycosyl transferase family 43 protein involved in xylan biosynthesis is associated with straw digestibility in Brachypodium distachyon. New Phytol. doi: 10.1111/nph.15089 Open Access

Simon McQueen-Mason (University of York) leads this study that use QTL mapping to identify a gene in Bracypodium that is involved in cell wall architecture, which might then be a target to develop plants with improved cellulose digestibility. This glycosyl transferase family (GT) 43 protein is an orthologue of Arabidopsis IRX14, which is involved in xylan biosynthesis. When RNAi was used to reduce expression of this gene the resulting plants showed increased digestibility, indicating that this BdGT43A will be a good target for future breeding plans.


Wang L, Wilkins KA, Davies JM (2018) Arabidopsis DORN1 extracellular ATP receptor; activation of plasma membrane K(+) -and Ca(2+) -permeable conductances New Phytol. 2018 Mar 25. doi: 10.1111/nph.15111. Open Access

This letter to New Phytologist from the lab of Julia Davis (University of Cambridge) outlines some experiments to determine whether the DORN1 plasma membrane receptor is responsible for transmitting a signal from extracellular ATP (eATP). They performed patch clamp analysis on isolated protoplasts and showed that DORN1 is involved in the activation of Ca+ and K+ pumps by eATP as, in contrast to wildtype, dorn1 mutant protoplast showed no voltage changes after incubation with eATP.


Simon NML, Sawkins E, Dodd AN. Involvement of the SnRK1 subunit KIN10 in sucrose-induced hypocotyl elongation (2018) Plant Signal Behav. 27:1-9. doi: 10.1080/15592324.2018.1457913.

Anthony Dodd (University of Bristol) is the corresponding author of this follow-on study from one that previously featured on the GARNet YouTube channel. This study measures sucrose-induced hypocotyl elongation in two T-DNA mutants of the SnRK1 subunit KIN10 gene. These mutants had altered responses to sucrose leading to the hypothesis that the SnRK1 complex suppresses hypocotyl elongation in the presence of external sugar.


Lloyd JPB, Lang D, Zimmer AD, Causier B, Reski R, Davies B (2018) The loss of SMG1 causes defects in quality control pathways in Physcomitrella patens. Nucleic Acids Res. doi: 10.1093/nar/gky225 Open Access

Brendan Davis (University of Leeds) is the corresponding author on research that investigates the role of the SMG1 kinase during nonsense-mediated mRNA decay (NMD) in the moss Physcomitrella patens. This kinase plays a critical role in animals but as it is not present in Arabidopsis, its function is not well studied in plants. However moss smg mutants show expression changes in genes involved in a variety of processes indicating that NMD is a common control mechanism in moss. In addition these plants have increased susceptibility to DNA damage, which suggests that the SMG1 kinase is a key player in quality control mechanisms in plants.

https://academic.oup.com/nar/advance-article/doi/10.1093/nar/gky225/4955258

GARNet Research Roundup: March 29th

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Published on: March 29, 2018

This edition of the GARNet research roundup begins with an analysis of the CELLULOSE SYNTHASE COMPLEX led by Simon Turner in Manchester. Next are two papers from Ian Henderson at Cambridge who, in collaboration with Rob Martienssen in the USA, has investigated the epigenetic factors that control meiotic recombination. Next are two papers led by Hugh Nimmo (Glasgow) who is researching alternative splicing of the LATE ELONGATED HYPOCOTYL transcript. Marc Vendrell and Karl Oparka at the University of Edinburgh are co-authors in the next paper that investigates the binding specificity of the AtSUC2 protein. The seventh paper includes David Salt (Nottingham) as a co-author in an investigation in the plants response to zinc. The final three papers are methods papers on gravitropism, ChIP-Seq and calcium sensing from Nottingham University, SLCU and the John Innes Centre respectively.


Kumar M, Mishra L, Carr P, Pilling M, Gardner P, Mansfield SD, Turner SR (2018) Exploiting CELLULOSE SYNTHASE (CESA) class-specificity to probe cellulose microfibril biosynthesis. Plant Physiol. doi: 10.1104/pp.18.00263 Open Access

Simon Turner (University of Manchester) leads this study that investigates the subunit specificity of the CELLULOSE SYNTHASE COMPLEX, which is composed of many CESA components. Mutant cesa plants were used to probe the specificity of these subunits. Overall the authors found that CESA classes have similar roles in determining cellulose microfibril structure but that the rates of cellulose synthesis might be altered in a subunit-specific manner.


Choi K,, Zhao X, Tock AJ, Lambing C, Underwood CJ,, Hardcastle TJ, Serra H, Kim J, Cho HS, Kim J, Ziolkowski PA, Yelina NE, Hwang I, Martienssen RA, Henderson IR (2018) Nucleosomes and DNA methylation shape meiotic DSB frequency in Arabidopsis thaliana transposons and gene regulatory regions. Genome Res. doi: 10.1101/gr.225599.117
The research groups of Ian Henderson (University of Cambridge) and Rob Martienssen (CSHL) co-lead back-to-back papers that investigate the factors that influence meiotic recombination frequencies. The Henderson led-paper focuses on the position of the SPO11 topoisomerase and the epigenetic factors, such as H3K4me3 and DNA methylation that reside in those areas. They discovered some surprising relationships between SPO11 binding and different transposon classes.


Underwood CJ, Choi K, Lambing C, Zhao X, Serra H, Borges F, Simorowski J, Ernst E, Jacob Y, Henderson IR, Martienssen RA (2018) Epigenetic activation of meiotic recombination near Arabidopsis thaliana centromeres via loss of H3K9me2 and non-CG DNA methylation. Genome Res. doi: 10.1101/gr.227116.117

Open Access

The Martienssen–led paper focuses on epigenetic marks, such as H3K9me2 and non-CG DNA methylation that reside at pericentromeric regions. By altering the distribution of these marks, the amount of pericentrometric recombination can be changed and that the number of double stranded breaks increase in H3K9me2/non-CG mutants.


James AB, Sullivan S, Nimmo HG (2018) Global spatial analysis of Arabidopsis natural variants implicates 5’UTR splicing of LATE ELONGATED HYPOCOTYL in responses to temperature. Plant Cell Environment. doi: 10.1111/pce.13188

James AB, Calixto CPG, Tzioutziou NA, Guo W, Zhang R, Simpson CG, Jiang W, Nimmo GA, Brown JWS, Nimmo HG (2018) How does temperature affect splicing events? Isoform switching of splicing factors regulates splicing of LATE ELONGATED HYPOCOTYL (LHY). Plant Cell Environ. doi: 10.1111/pce.13193

The first of these back-to-back papers is led by Hugh Nimmo (Glasgow) in a study that characterises a set of 5’UTRs in the LATE ELONGATED HYPOCOTYL (LHY) gene and how they change in response to temperature. This is linked to a correlation of how these LHY haplotypes are global distributed.

The second paper is an extension of this study and includes Hugh Nimmo (Glasgow) and John Brown (JHI, Dundee) as co-corresponding authors. They that show RNA-binding splicing factors (SFs) are necessary for temperature-induced changes in the LHY transcript. LHY might be considered a molecular thermostat whose splicing can response to changes as little as 2°C.


De Moliner F, Knox K, Reinders A, Ward J, McLaughlin P, Oparka K, Vendrell M (2018) Probing binding specificity of the sucrose transporter AtSUC2 with fluorescent coumarin glucosides. J Exp Bot. doi: 10.1093/jxb/ery075 Open Access

Marc Vendrell and Karl Oparka (University of Edinburgh) are the corresponding authors on this bioimaging study that probes the specificity of the AtSUC2 phloem sucrose transporter. They use structural varieties in coumarin glucosides to precisely define the binding characteristics of AtSUC2.


Chen ZR, Kuang L, Gao YQ, Wang YL, Salt DE, Chao DY (2018) AtHMA4 Drives Natural Variation in Leaf Zn Concentration of Arabidopsis thaliana. Front Plant Sci. doi: 10.3389/fpls.2018.00270

Open Access

David Salt (University of Nottingham) is a co-author on this Chinese study that characterises the role of the Heavy Metal-ATPase 4 (HMA4) in the respond to zinc.


Muller L, Bennett MJ, French A, Wells DM, Swarup R (2018) Root Gravitropism: Quantification, Challenges, and Solutions. Methods Mol Biol. doi: 10.1007/978-1-4939-7747-5_8

Ranjan Swarup (University of Nottingham) leads this methods paper that describes techniques for the automated measurement of root gravitropic responses.


Cortijo S, Charoensawan V, Roudier F, Wigge PA (2018) Chromatin Immunoprecipitation Sequencing (ChIP-Seq) for Transcription Factors and Chromatin Factors in Arabidopsis thaliana Roots: From Material Collection to Data Analysis. Methods Mol Biol. doi: 10.1007/978-1-4939-7747-5_18

Phillip Wigge (SLCU) leads this methods paper that outlines the technical details for the now common and important technique of ChIP-Seq from Arabidopsis roots.


Kelner A, Leitão N, Chabaud M, Charpentier M, de Carvalho-Niebel F (2018) Dual Color Sensors for Simultaneous Analysis of Calcium Signal Dynamics in the Nuclear and Cytoplasmic Compartments of Plant Cells. Front Plant Sci. doi: 10.3389/fpls.2018.00245 Open Access

Miriam Charpentier (John Innes Centre) is a co-author on this work that uses fluorescent protein-based Ca2+ sensors, the GECOs, to successfully monitor the calcium response to a range of biotic and abiotic elicitors. These GECO-based sensors represent an exciting new tool for the study of calcium dynamics.

Arabidopsis Research Roundup: March 2nd.

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Published on: March 2, 2018

The first two papers in this weeks Arabidopsis Research Roundup investigate different aspects of the plants response to temperature fluctuations. Firstly Lars Ostergaard (JIC) looks at the influence of temperature in the control of fruit dehiscence whilst Phil Wigge (SLCU) investigates crosstalk between chloroplast and nuclear signaling.

The third paper from Ian Henderson (University of Cambridge) studies the genetic elements that control rates of meiotic recombination. The next paper from the University of Leeds looks at the potential of using MET1 in the induction of novel epi-alleles whilst the penultimate paper includes the GARNet PI Jim Murray (Cardiff University) as a co-author and defines the role of CYCD7;1 in guard cell formation.

The final paper focusses on an enzyme involved in chlorophyll biosynthesis and includes Guy Hanke (QMUL) as a co-author.


https://linkinghub.elsevier.com/retrieve/pii/S1674-2052(18)30023-6

Li XR, Deb J, Kumar SV, Østergaard L (2018) Temperature Modulates Tissue-Specification Program to Control Fruit Dehiscence in Brassicaceae. Molecular Plant doi: 10.1016/j.molp.2018.01.003 Open Access

Lars Ostergaard (John Innes Centre) is the corresponding author that continues his groups work on the function of the INDEHISCENT protein, on this occasion looking at its involvement in the link between temperature and fruit dehiscence. They show that fruit valve margin development is accelerated at higher temperatures, facilitated by the activity of IND. This activity is associated with the changes in the induction dynamics of the known thermosensory histone H2A.Z and demonstrate a molecular framework for the response to changing temperature during fruit ripening.


http://www.cell.com/cell-reports/references/S2211-1247(18)30103-7

Dickinson PJ, Kumar M, Martinho C, Yoo SJ, Lan H, Artavanis G, Charoensawan V, Schöttler MA, Bock R, Jaeger KE, Wigge PA (2018) Chloroplast Signaling Gates Thermotolerance in Arabidopsis. Cell Rep. doi: 10.1016/j.celrep.2018.01.054 Open Access

Phil Wigge (SLCU) is the corresponding author on this study of the link between light-induced chloroplast signaling and thermotolerance. A forward genetic screen allowed the authors to identify two genes that demonstrated a key role for chloroplast signaling in controlling the activity of heat shock factors (HSFs), which enable the plant to cope with temperature variations. Subsequently they show that altering the binding activities of the HSFA1a protein can mimic heat shock response independent of any changes in temperature.


Serra H, Lambing C, Griffin CH, Topp SD, Nageswaran DC, Underwood CJ, Ziolkowski PA, Séguéla-Arnaud M, Fernandes JB,, Mercier R, Henderson IR (2018) Massive crossover elevation via combination of HEI10 and recq4a recq4b during Arabidopsis meiosis. PNAS doi: 10.1073/pnas.1713071115

Ian Henderson (University of Cambridge) is the corresponding author on this collaboration with French colleagues in a study that investigates the factors that control recombination frequency in meiosis. During normal meiotic recombination the majority of double stranded breaks will not form crossovers (over 90%) so to increase this frequency they altered the active dosage of genetic elements that are either pro-crossover or anti-crossover control. This strategy results in a massive increase in crossovers and provides a genetic framework for increasing recombination, a strategy that can be critically important for increasing variation during crop breeding.


Brocklehurst S, Watson M, Carr IM, Out S, Heidmann I, Meyer P (2018) Induction of epigenetic variation in Arabidopsis by over-expression of DNA METHYLTRANSFERASE1 (MET1). PLoS One. doi: 10.1371/journal.pone.0192170 Open Access

This study from the University of Leeds is led by Peter Meyer and investigates how overexpression of the METHYLTRANSFERASE1 (MET1) gene might generate novel epi-alleles that result in altered gene expression. This strategy indeed generated novel epi-alleles that increased expression at loci encoding TEs, non-coding RNAs and protein coding genes. Importantly any altered expression can be transmitted to the next generation, independent of the presence of a MET1 expressing transgene. However the long term stability of these epi-alleles differs in an loci-specific manner.


Weimer AK, Matos JL, Sharma N, Patell F, Murray JAH, Dewitte W, Bergmann DC (2018) Lineage and stage-specific expressed CYCD7;1 coordinates the single symmetric division that creates stomatal guard cells. Development. doi: 10.1242/dev.160671

GARNet PI Jim Murray and Walter DeWitte (Cardiff University) are co-authors on this US-led study that adds complexity to our understanding of the molecular players that control guard cell specification. The authors show that the D-type cyclin CYCD7;1 is expressed during a short time window prior to the symmetry division that forms two guard cells. This activity is controlled by cell-type specific transcription factors acting in the appropriate time period.

http://dev.biologists.org/content/early/2018/02/14/dev.160671.long

Herbst J, Girke A, Hajirezaei MR, Hanke G, Grimm B (2018) Potential Roles of YCF54 and Ferredoxin-NADPH Reductase for Magnesium Protoporphyrin Monomethylester Cyclase. Plant J. doi: 10.1111/tpj.13869

Guy Hanke (QMUL) is a co-author on this German-led study that investigates an enzyme reactions that occur during chlorophyll biosynthesis. Specifically they showed that plants lacking the LCAA/YCF54 subunit of the enzyme MgProto monomethylester (MgProtoME) cyclase causes accumulation of MgProtoME and destabilization of the entire cyclase enzyme. This disrupts chlorophyll synthesis and negatively effects photosynthetic activity.

Arabidopsis Research Roundup: February 12th

This weeks Arabidopsis Research Roundup begins with a study from SLCU that investigates the interaction between nitrate and cytokinin signaling in the shoot meristem. Next is research from Sheffield that studies changes to the macromolecular composition of the photosynthetic apparatus following the transition from dark to light. Third are three papers that include University of Edinburgh faculty members as co-authors; Gary Loake is involved in a global study on NO signaling, Karen Halliday is included on a study into the relationship between clock components and the PIF-mediated hypocotyl elongation and Naomi Nakayama contributes to the development of a model that explains PIN protein localisation. Cyril Zipfel (TSL) is a co-author on the fifth paper, which introduces a new signaling component in the defence response and whilst the penultimate paper includes Denis Murphy (University of South Wales) and investigates the effect of dioxins on seed development. The final paper documents research from Manchester and Nottingham that uses a cress endosperm as a model to test the elastic properties of thin biological membranes.


Landrein B, Formosa-Jordan P, Malivert A,, Schuster C, Melnyk CW,, Yang W, Turnbull C, Meyerowitz EM, Locke JCW,, Jönsson H (2018) Nitrate modulates stem cell dynamics in Arabidopsis shoot meristems through cytokinins. PNAS doi: 10.1073/pnas.1718670115.

Open Access

http://www.pnas.org/content/early/2018/01/22/1718670115

Henrik Jonsson and James Locke (SLCU) are corresponding authors on this investigation into the relationship between nitrate and cytokinin signalling in the Arabidopsis shoot meristem (SAM). They show that nitrate availability determines the size of the SAM, which is controlled by the transport of cytokinin precursors from the root to the shoot. A discussion about this paper with lead author Benoit Landrien and Professor Jonsson is available on the GARNet YouTube and iTunes channels.


Wood WHJ, MacGregor-Chatwin C, Barnett SFH, Mayneord GE, Huang X, Hobbs JK, Hunter CN, Johnson MP (2018) Dynamic thylakoid stacking regulates the balance between linear and cyclic photosynthetic electron transfer. Nature Plants. doi: 10.1038/s41477-017-0092-7

Open with this link

This research in this manuscript has come from the University of Sheffield with Matthew Johnson as the corresponding author. They have used atomic force microscopy (AFM) to investigate how the transition from dark to light affects the macromolecular architecture of the photosynthetic apparatus within the thylakoid membrane. This transition does not alter the antenna size of either photosystem yet increases the number of thylakoid grana. Overall these changes serve to regulate the balance between light harvesting, CO2 fixation and enabling the protection of PSII activity from the destructive effects of non-photochemical quenching.


Imran QM, Hussain A, Lee SU, Mun BG, Falak N, Loake GJ, Yun BW (2018) Transcriptome profile of NO-induced Arabidopsis transcription factor genes suggests their putative regulatory role in multiple biological processes. Sci Rep. doi: 10.1038/s41598-017-18850-5.

https://www.nature.com/articles/s41598-017-18850-5

Open Access

Gary Loake (University of Edinburgh) is a contributor to this Korean-led manuscript that has performed expression analysis on plants treated with S-nitrosocysteine (CySNO). They have identified many novel NO-responsive transcription factors and were able to confirm the role of three random TFs in this response following analysis of loss of function mutants. This paper provides new insights into the molecular components that contribute to NO signalling during plant defence and immunity.


Martín G, Rovira A, Veciana N, Soy J, Toledo-Ortiz G, Gommers CMM, Boix M, Henriques R, Minguet EG, Alabadí D, Halliday KJ, Leivar P, Monte E Circadian Waves of Transcriptional Repression Shape PIF-Regulated Photoperiod-Responsive Growth in Arabidopsis. Curr Biol. doi: 10.1016/j.cub.2017.12.021

Karen Halliday (University of Ediburgh) is a co-author on this Spanish-led study that investigates how the expression of PHYTOCHROME-INTERACTING FACTORS (PIFs) genes is controlled. The activity of PIFs are responsible for determining the rate of hypocotyl elongation in different light conditions and this paper demonstrates that PSEUDO-RESPONSE REGULATORS PRR9/7/5 proteins act antagonistically to the PIFs by interacting at the promotor of the CDF5 transcription factor. This provides a mechanism to explain the circadian-controlled regulation of hypocotyl cell elongation.


Hernandez V, Barrio RA, Benítez M, Nakayama N, Romero-Arias JR, Villarreal Lujan C (2018) A physico-genetic module for the polarisation of auxin efflux carriers PIN-FORMED (PIN). Phys Biol. doi: 10.1088/1478-3975/aaac99

Naomi Nakayama (University of Edinburgh) is a co-author on this Mexican-led study that proposes a physico-genetic model that explains the localization of PIN auxin transporter proteins to the Arabidopsis plasma membrane. This model confirms experimental observations and allows the prediction that mechanical forces can predominate over molecular components.


www.cell.com/molecular-cell/fulltext/S1097-2765(17)30983-8

Wang J, Grubb LE, Wang J, Liang X, Li L, Gao C, Ma M, Feng F, Li M, Li L, Zhang X, Yu F, Xie Q, Chen S, Zipfel C, Monaghan J, Zhou JM (2018) A Regulatory Module Controlling Homeostasis of a Plant Immune Kinase. Mol Cell. doi: 10.1016/j.molcel.2017.12.026

This Chinese-led paper includes Cyril Zipfel (TSL) as a co-author and identifies the U-box proteins PUB25 and PUB26 as E3 ligases for the cytoplasmic kinase BIK1, which is a key rate limiting component of the plant defence response. This multi-protein regulatory module provides another level of complexity to our understanding of the molecular factors involved in plant immunity.


Hanano A, Almousally I, Shaban M, Murphy DJ (2018) Exposure of Arabidopsis Plants to Dioxin Results in a Wrinkled Seed Phenotype that is likely due to 20S Proteasomal Degradation of WRI1. J Exp Bot. doi: 10.1093/jxb/ery027

Denis Murphy (University of South Wales) is a co-author on this Syrian-led study that uses Arabidopsis seeds to test the negative effects of dioxins. Seeds treated with dioxins have a wrinked phenotype that corresponds to changes in the expression of genes related to lipid and carbohydrate metabolism. Overall this study reveals a novel set of genetic changes effects caused by dioxins that explain the profound effects on seed development.


S. P. Pearce, J. R. King, T. Steinbrecher, G. Leubner-Metzger, N. M. Everitt, M. J. Holdsworth (2018) Finite indentation of highly curved elastic shells Proceedings of the Royal Society A doi: 10.1098/rspa.2017.0482

Open Access

Plant scientist Mike Holdsworth (University of Nottingham) is a co-author on this paper that has used the endosperm from garden cress (Lepidium sativum) as the experimental model to define the elastic properties of a thin biological surface. Indentation experiments have been classically used to measure these properties and then develop mathematically models that explain their characteristics. These models rely on an assumed flat surface whereas in reality any surface will often be curved. By obtaining measurements from identations studies on the cress endosperm they are able to better refine the models that explain the properties of the membrane in this context.

Arabidopsis Research Roundup: December 8th.

This weeks Research Roundup begins with two papers from the University of Edinburgh on very different topics of Arabidopsis research. Firstly Alistair McCormick and Sofirtios Tsaftaris introduce a new low-cost phenotyping platform whilst Gerben Ooijen’s group has analysed the role of SUMOylation in the control of the circadian clock. The next three papers each involve wide UK collaborations and either look at plant nutrient composition (Nottingham, Dundee, York), the role of N-end rule pathway in the control of seed storage mobilisation (Rothamsted, Nottingham, Oxford, Birmingham, Cambridge) or the development of a new tool for the study of phloem sieve elements (Leeds, Rothamsted, Cambridge, Newcastle). The penultimate paper from Daniel Zilbermann (JIC) highlights the global mechanisms of methyltransferase function in Arabidopsis and mice whilst the final paper from Alexandre Ruban (QMUL) and co-authors continues his groups work to unpick the specifics of NPQ.


Dobrescu A, Scorza LCT, Tsaftaris SA, McCormick AJ (2017) A “Do-It-Yourself” phenotyping system: measuring growth and morphology throughout the diel cycle in rosette shaped plants. Plant Methods. doi: 10.1186/s13007-017-0247-6

Open Access

University of Edinburgh colleagues Alistair McCormick and Sofirtios Tsaftaris lead this work that presents a low cost phenotyping system for the analysis of the growth rate and phenotypic characteristics of Arabidopsis thaliana rosettes. The software that they have developed allows the accurate segmentation of multiple rosettes within a single image and overall offers a straightforward solution for automated phenotyping across a range of growth environments.


Hansen LL, van den Burg HA, van Ooijen G (2017) Sumoylation Contributes to Timekeeping and Temperature Compensation of the Plant Circadian Clock. J Biol Rhythms. doi: 10.1177/0748730417737633

Gerben van Ooijen (University of Edinburgh) is the corresponding author of this work that has identified SUMOylation as a novel mechanism of regulating circadian clock genes in Arabidopsis. Plants with defects in sumoylation have altered circadian periods that exhibit incorrect temperature compensation. Overall these results indicate that sumoylation importantly buffers clock function in response to changing temperatures.


Alcock TD, Havlickova L, He Z, Bancroft I, White PJ, Broadley MR, Graham NS (2017) Identification of Candidate Genes for Calcium and Magnesium Accumulation in Brassica napus L. by Association Genetics. Front Plant Sci. doi: 10.3389/fpls.2017.01968

Open Access

Neil Graham and Martin Broadley (University of Nottingham) are the corresponding authors of this study that has taken advantage of the Brassica napus Associative Transcriptomes RIPR diversity panel developed by Ian Bancroft’s lab in York. Novel loci involved with an altered response to calcium and magnesium were identified in B.napus before mineral composition was analysed in Arabidopsis mutants defective in orthologous genes. The analysed plants exhibited alteration in mineral composition, meaning that the associated Brassica loci might be targets for future breeding strategies aimed at improving plant nutrient compositions.


Zhang H, Gannon L, Hassall KL, Deery MJ, Gibbs DJ, Holdsworth MJ, van der Hoorn RAL, Lilley KS, Theodoulou FL (2017) N-terminomics reveals control of Arabidopsis seed storage proteins and proteases by the Arg/N-end rule pathway. New Phytol. doi: 10.1111/nph.14909

Freddie Theodoulou (Rothamsted Research) is the corresponding author of this research that involved a collaboration with colleagues in Cambridge, Birmingham, Nottingham and Oxford. They have performed a proteomic analysis on etiolated seedlings to identify those proteins designated for degradation by the N-end rule pathway. They analysed prt6 mutant plants that lack the function of the E3 ligase PROTEOLYSIS6 (PRT6) and discovered that N-terminal peptides from 45 protein groups were upregulated in this mutant, corresponding to the equivalent downregulation of several known N-end rule proteases. Overall the authors show that PRT6 plays an important role in the regulation of seed storage mobilisation in young seedlings and is therefore a possible future target to manipulate the plant responses to adverse environmental conditions. Dr Kirsty Hassall, a statistician at Rothamsted, is an author on this paper and in the latest edition of the GARNish newsletter explains how she interacts with plant scientists during her work.


Torode TA, O’Neill RE, Marcus SE, Cornuault V, Pose-Albacete S, Lauder RP, Kracun SK, Gro Rydahl M, Andersen MCF, Willats WGT, Braybrook SA, Townsend BJ, Clausen MH, Knox JP (2017) Branched pectic galactan in phloem-sieve-element cell walls: implications for cell mechanics. Plant Physiol. doi: 10.1104/pp.17.01568 Open Access

Paul Knox (University of Leeds) is the corresponding author of this study that includes contributions from researchers at SLCU, Newcastle and Rothamsted. This work is based around the development of a monoclonal antibody, LM26 that is able to recognize a β-1,6-galactosyl substitution of β-1,4-galactan. LM26 has allowed the identification of this unusual branched galactan that is specific to phloem elements and the authors hope that it can be a useful tool in future studies on the biology of phloem elements


Lyons DB, Zilberman D (2017) DDM1 and Lsh remodelers allow methylation of DNA wrapped in nucleosomes. Elife. doi: 10.7554/eLife.30674 Open Access

Daniel Zilberman has recently moved to the John Innes Centre and is the lead author of this work that was conducted when he was working in US. This research is a cross-kingdom analysis showing that nucleosome-free DNA is the preferred target for methyltransferases in both Arabidopsis and mice, and that nucleosomes appear to be a barrier to the function of these enzymes. Furthermore they demonstrate that linker-specific methylation that is usually absent in Arabidopsis can be introduced by removal of histone H1. This shows that flowering plants still possess this ability despite its loss, during the evolution of H1, over a billion years ago.


Tutkus M, Chmeliov J, Rutkauskas D, Ruban AV, Valkunas L (2017) Influence of the Carotenoid Composition on the Conformational Dynamics of Photosynthetic Light-Harvesting Complexes. J Phys Chem Lett. doi: 10.1021/acs.jpclett.7b02634

Alexandre Ruban (QMUL) is a co-author on this study that investigates the role that carotenoid composition plays in the control of Non-photochemical quenching (NPQ), a mechanism that protects the photosynthetic apparatus from light-damage. Arabidopsis mutants with differing carotenoid compositions were analysed for the dynamics of the conformation switches that occur during NPQ. Interestingly they show that LHCII has robust function  that is resistant to different carotenoid concentrations.

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