Arabidopsis Research Roundup: August 21st.

There are a wide array of topics included in this weeks Arabidopsis Research Roundup, ranging from studies on stomatal density, thylakoid transport, metabolic flux analysis, mutant detection and root development. We feature unlinked studies from three researchers from the University of Oxford Plant Science (Paul Jarvis, Lee Sweetlove and Nick Harberd), whilst the papers from Julie Gray and Brian Forde share the broad theme that investigates different mechanisms that might be used to improve nitrogen uptake, either by modifying the expression of a single gene involved in root development or by altering stomatal density.

Hepworth C, Doheny-Adams T, Hunt L, Cameron DD, Gray JE (2015) Manipulating stomatal density enhances drought tolerance without deleterious effect on nutrient uptake New Phytol. http://dx.doi.org/10.1111/nph.13598

Julie Gray (University of Sheffield) is an expert on both stomatal biology and on the potential for manipulating stomatal density to improve crop production. In this study drought tolerance and soil water retention were measured in four Arabidopsis mutants with defects in epidermal patterning and stomatal density. Nutrient uptake was measured by mass flow of 15N. Plants with less stomata had reduced transpiration and were drought-tolerant yet interestingly showed little reduction in shoot N concentrations, especially when water availability is restricted. In contrast, plants with extra stomata could take up more N except when access to water was reduced. Therefore the authors show that by altering stomatal density they can generate plants that are drought resistance yet maintain nutrient uptake or generate plants with enhancing nutrient uptake is conditions with plentiful water.

Trösch R, Töpel M, Flores-Pérez Ú, Jarvis P (2015) Genetic and Physical Interaction Studies Reveal Functional Similarities between ALB3 and ALB4 in Arabidopsis. Plant Physiol. http://dx.doi.org/10.1104/pp.15.00376

This German, Swedish and UK collaboration is led by Paul Jarvis at the University of Oxford and broadly investigates thylakoid protein targeting. The ALB3 complex has previously been shown to target light harvesting complex proteins (LHCP) to the thylakoid. A related Arabidopsis protein, ALB4, had been proposed to interact not the LHCPs but rather with the ATP synthase complex. However this study shows that ALB3 and ALB4 have some overlapping roles in addition to their specific functions and that they can engage with a similar set of interactor proteins to bring their substrates to the thylakoid membrane.

Cheung CY, Ratcliffe RG, Sweetlove LJ (2015) A method of accounting for enzyme costs in flux balance analysis reveals alternative pathways and metabolite stores in an illuminated Arabidopsis leaf Plant Physiol. http://dx.doi.org/10.1104/pp.15.00880

Lee Sweetlove (Oxford University) leads this study that looks at the Flux Balance Analysis (FBA) of plant metabolism across several metabolic pathways by attaching ‘flux weighting factors’ to allow for the variable intrinsic cost of supporting each flux. This model has been applied to the Arabidopsis leaf exposed to different light regimes to explore the flexibility of the network in meeting its metabolic requirements. The authors discover interesting trade-offs between use of different carbon storage forms and in the variable consumption of ATP and NADPH by different metabolic pathways.

Belfield EJ, Brown C, Gan X, Jiang C, Baban D, Mithani A, Mott R, Ragoussis J, Harberd NP (2014) Microarray-based optimization to detect genomic deletion mutations Genom Data Dec;2:53-54 http://dx.doi.org/10.1016/j.gdata.2014.04.005

GARNet Advisory Board member Nick Harberd (Oxford University) leads this short communication that highlights the development of a tool for detection of genomic deletion mutants in Arabidopsis. Using a NimbleGen whole genome custom tiling array they successfully identify five mutants with deletion ranging from 4bp to 5kb and therefore introduce a powerful tool for analysing this type of genetic lesion in Arabidopsis and other plant species with well-constructed genomes.

Yu C, Liu Y, Zhang A, Su S, Yan A, Huang L, Ali I, Liu Y, Forde BG, Gan Y (2015) MADS-box Transcription Factor OsMADS25 Regulates Root Development through Affection of Nitrate Accumulation in Rice PLoS One http://dx.doi.org/10.1371/journal.pone.0135196

Brian Forde (Lancaster University) is the UK lead on this Chinese collaboration that focuses on nitrate accumulation and how it regulates root development in rice. This occurs via a MADS-box transcription factor OsMADS25 that, when overexpressed in Arabidopsis, promotes primary and lateral root development. Altered expression of this gene also affects root development in transgenic rice and includes significant changes in nitrate accumulation. Therefore this gene might prove to be an important target for future attempts to improve plant growth in regions with altered nitrate concentrations.

Arabidopsis Research Roundup: July 11th

A couple of weeks since the last update as it’s been quiet for UK Arabidopsis Research publications. However we now see a variety of publications that address some important questions in different signaling pathways. Firstly a multinational collaboration performs a genome-wide analysis of DELLA binding, followed by two studies looking different aspects of light signaling, specifically the link with the production of protective carotenoids and also with the tight control of protein degradation. Elsewhere there is the description of a systems biology approach developed to aid the definition of signaling pathways in non-model organisms and finally a commentary piece about some work on Arabidopsis Arenosa.

 

Genome Wide Binding Site Analysis Reveals Transcriptional Coactivation of Cytokinin-Responsive Genes by DELLA Proteins (2015) Marín-de la Rosa N, Pfeiffer A, Hill K, Locascio A, Bhalerao RP, Miskolczi P, Grønlund AL, Wanchoo-Kohli A, Thomas SG, Bennett MJ, Lohmann JU, Blázquez MA, Alabadí D PLoS Genet. 11(7):e1005337. http://dx.doi.org/10.1371/journal.pgen.1005337

The Centre for Integrative Biology in Nottingham and Rothamstead Plant Science partner with groups from Sweden, Germany, Spain and Saudi Arabia in this truly international collaboration. They investigate the role of DELLA proteins in the relay of environmental cues to multiple transcriptional circuits. The primary experimentation in this study uses ChIP-Seq to analyse the DNA-binding sites of one DELLA protein. Perhaps as expected the DELLA protein binds multiple promotor regions yet with a particular enrichment in regions upstream of cytokinin-regulated genes, where they interact with type-B ARABIDOPSIS RESPONSE REGULATOR (ARR) proteins. The biological relevance of this mechanism is underpinned by the requirement for both DELLAs and B-type ARRs in the control of root growth and photomorphogenesis.

 

Regulation of carotenoid biosynthesis by shade relies on specific subsets of antagonistic transcription factors and co-factors (2015) Bou-Torrent J, Toledo-Ortiz G, Ortiz-Alcaide M, Cifuentes-Esquivel N, Halliday KJ, Martinez-Garcia JF, Rodriguez-Concepcion M Plant Physiol.

Karen Halliday at the University of Edinburgh is part of this UK-Spanish team that studied the regulation of carotenoid biosynthesis via a light signaling module formed by PIF1 and HY5. In shade conditions, PIF proteins signal for a decrease in carotenoid accumulation, thus saving the plant unneeded energy consumption. The PIF1 response focusses on the phytoene synthase (PSY) biosynthetic gene and is antagonised by the PAR1 transcriptional co-factor. However this is not a universal response carried out by known antagonisers of PIF1 function, demonstrating that carotenoid biosynthesis is finely regulated by a precise subset of regulatory proteins.

 

High-level expression and phosphorylation of phytochrome B modulates flowering time in Arabidopsis (2015) Hajdu A, Ádám É, Sheerin DJ, Dobos O, Bernula P, Hiltbrunner A,, Kozma-Bognár L, Nagy F Plant Journal http://dx.doi.org/10.1111/tpj.12926

Professor Ferenc Nagy has dual appointments in Edinburgh and in Hungary and this output results from work performed in Hungary. This study looks at control of flowering via phytochrome B signalling, which has been previously shown to rely on the degradation of the CONSTANS (CO) protein that in turn delays flowering by attenuating FLOWERING LOCUS T (FT) expression. Therefore phyB mutants show accelerated flowering, yet this is unexpectedly also true following PHYB overexpression. The novelty of this study comes from showing that PHYB overexpression induces FT without affecting CO transcription but rather acts by causing accumulation of the CO protein, due to an affect on a COP1-ubiquitin ligase complex. This article adds further detail to the already complex relationship between light signaling, the circadian clock, protein degradation and de novo transcription in the control of flowering in Arabidopsis.

 

Inferring orthologous gene regulatory networks using interspecies data fusion (2015) Penfold CA, Millar JB, Wild DL. Bioinformatics. 31(12):i97-i105. http://dx.doi.org/10.1093/bioinformatics/btv267

This study was led by David Wild from Warwick Systems Biology Centre. The authors have used two related Bayesian approaches to network inference that allow Gene Regulatory Networks (GRN) to be jointly inferred in, or leveraged between, several related species, for example between Arabidopsis and related crop species. Inferring gene function is achieved with more accuracy when GRNs are compared between species rather than attempting to use stand alone inference. The manuscript uses data from the yeast S.pombe but the broader principles could be applied to other experimental systems.

 

The High Life: Alpine Dwarfism in Arabidopsis (2015) Bomblies K Plant Physiol. 168(3):767. http://dx.doi.org/10.1104/pp.15.00745

This commentary piece about high altitude growth of Arabidopsis aernosa is the first published work from Kristen Bomblies since she moved her lab to the John Innes Centre from Havard (together with the lab of Levi Yant). Having these two talented young researchers relocate to the UK is be great for UK plant science so I sure everyone in the community wishes them all the best. Watch Kristen talk about her work at a New Phytologist conference from 2014.

Levi Yant also has two postdoctoral posts currently available in his lab.

 

The TREE of plant science education

Aurora Levesley is the Project Officer for the Gatsby Plant Science TREE. The TREE grew out of the Gatsby Plant Science Summer Schools as a means of sharing the valuable resources produced for and during the Schools. Here she discusses the value of the TREE’s online lectures, which are the subject of a current New Phytologist paper. 

David Beerling at the Gatsby Plant Science Summer School
David Beerling gives a lecture at the Gatsby Plant Science Summer School. This is one of many lectures that have been edited for interactive online delivery and shared on the Plant Science TREE.

The Plant Science TREE is a free online central repository of plant science educational resources. More than 90 research academics and publishers have contributed over 2000 resources, including online research lectures, research-led lecture slides, practicals, video clips and other resources on topical plant science. It was developed by the University of Leeds with funding from the Gatsby Charitable Foundation, and is currently used by scientists, educators and students from over 320 institutes worldwide.

Many students enter biological sciences courses with little interest in or knowledge of plants, and engaging students with plant science early in their studies is arguably an important step in reversing the decline in uptake of this vulnerable yet strategically important subject linked to food security and other globally important issues. Prof Alison Baker of the Centre for Plant Sciences at the University of Leeds, says of the TREE: “The aim is to put a tool in the hands of educators that will engage students in plant science and research, especially where expertise is becoming limited.”

Our recent study, published in New Phytologist, showed the online research lectures that form a large part of the TREE successfully engage undergraduates with plant science (Levesley et al 2014, New Phytologist Early View).

In this study, undergraduates from four UK universities were provided with links to online research lectures as part of their course. The lectures, filmed at the Gatsby Plant Science summer schools, were given by research leaders but pitched at a level to engage undergraduates and provided a first-hand insight into how discoveries are made and science is carried out.

Not only were the online lectures successful in engaging students with plant science and research in general, but students were unanimous in the opinion that they were a good way to learn about a subject. Interestingly the study also showed that the online viewing experience was comparable to watching the research lectures live.

These online undergraduate research lectures are freely available through the Plant Science TREE. Our study shows they represent a valuable plant science education tool to help lecturers and teachers introduce cutting-edge research examples that address globally relevant applied initiatives – as well as curiosity-driven research – to their students. As such they have the potential to change student attitudes to plant science, engage students in research and are able to reach a large and wide global student audience.

The full reference for the Plant Science TREE paper is: Levesley A, Paxton S, Collins R, Baker A and Knight CD. “Engaging students with plant science: the Plant Science TREE”, New Phytologist http://dx.doi.org/10.1111/nph.12905, published online ahead of print in June 2014.

 

Plant science – making an impact on scientific publishing

Categories: Arabidopsis, resource
Comments: No Comments
Published on: September 5, 2013

This year is proving to be a good year for plant science publications. So far there have been special plant science issues in Science and Genome Biology (and I have it on good authority that there will be plant synthetic biology special issue of another journal coming soon) as well as a landmark birthday for New Phytologist.

Special Issues for Plant Science

The open access journal Genome Biology published their Plant Science Special Issue in June 2013. It was guest edited by Mario Caccamo, acting director and Head of Bioinformatics at The Genome Analysis Centre. He discusses the issue and explains the importance of plant genomics, alongside Dale Sanders and other experts, in this podcast from Biome, BMC’s online magazine. The special issue itself features a whole host of UK researchers, including  Cristobal UauySebastian SchornackAnna Amtmann and Edgar Huitema.

The Science Special Issue, published just last month, unsurprisingly had a much broader focus – Smarter Pest Control. The featured reports take a global look at issues surrounding crop protection from pests, including RNAi-based pesticides, possible health problems caused by traditional pesticides, and tracking the effects of pesticides in wild animal populations.

New Phytologist Celebration

The Lancaster based journal New Phytologist, founded in 1902, is celebrating 200 volumes in October. By my reckoning, it’s the second oldest plant science journal in the world, after Annals of Botany which began life in 1887 as the Journal of Botanical Science (special mention for strictly botany journal, Flora). There is an incredible celebratory Virtual Special Issue of New Phytologist available here, featuring historic articles from throughout the journal’s lifetime including a 1904 critique of the then fashionable field of plant-based ecology from the great man himself, Sir Arthur Tansley.

Arabidopsis UK research roundup

On a related more local note, our new team member Lisa has been searching the literature each week for publications from UK Arabidopsis or other basic plant science researchers. She’s posting the Arabidopsis Research Round-up to the GARNet News pages, so check it out if you want to keep up with new research from your UK colleagues. If you’ve been published and want to make sure we spot your paper (we’re not perfect!), feel free to email Lisa at lisa@garnetcommunity.org.uk to let her know.

The genetics of broad-spectrum resistance

Downy mildew infection of Arabidopsis thaliana seedlings

Highlighted article: Dmitry Lapin, Rhonda C. Meyer, Hideki Takahashi, Ulrike Bechtold, Guido Van den Ackerveken (2012) Broad-spectrum resistance of Arabidopsis C24 to downy mildew is mediated by different combinations of isolate-specific loci. New Phytologist DOI: 10.1111/j.1469-8137.2012.04344.x

It is a mark of how effective plant immune systems are that most bacteria, fungi, and viruses do not affect plants at all either because plant tissues are not suitable for them to live in, or they are fended off. Of course there are pathogens that are compatible with plants – and within species that share compatibility, there are pockets of resistance. Some sub-groups are resistant to specific pathogen isolates, and this is caused by dominant resistant genes. A much broader, more complicated, and less common form of resistance occurs when a particular accession is resistant to a whole pathogen species, or several species. This is broad-spectrum resistance, and it can be caused by a simple dominant gene or multiple genes. Natural broad-spectrum resistance is not simple to transfer from its origin to a commercial crop because it can come from a complex set of genes which are not necessarily all dominant. (more…)

The cost of glucosinolate biosynthesis

Highighted article: Michaël Bekaert, Patrick P. Edger, Corey M. Hudson, J.Chris Pires, Gavin C. Conant (2012) Metabolic and evolutionary costs of herbivory defense: systems biology of glucosinolate synthesis. New Phytologist 196:596–605.

Research published in a current New Phytologist paper uses a systems biology approach to demonstrate the metabolic and evolutionary costs of producing glucosinolates for defence.  Bekart et al. used AraGEM (Oliveira Dal’Molin et al., 2010) as a starting point. They collected data on Arabidopsis glucosinolate genes by scouring published papers and downloading their expression patterns from AtGenExpress. This information was integrated into the basic dataset from AraGEM. The complete list of genes involved in glucosinolate reactions, including references, is in Supplementary Table S1 of the paper.

The team performed flux balance analysis on the integrated database to estimate metabolic and energy flux through reactions in the system both with glucosinolate biosynthesis activity and with none. They found that glucosinolate biosynthesis affected flux incidentally through 241 reactions in addition to the 196 reactions which are only active when glucosinolates are being produced.

The main finding of the research is the heavy cost of glucosinolate biosynthesis. Sulphur import dramatically increased when glucosinolates were being synthesised, and demand for water, carbon dioxide, ammonia, and photons increased too. Despite the increase in substrate import, biomass synthesis fell by around 15% during glucosinolate production. This cost is reflected in other studies demonstrating that the evolutionary competitive edge glucosinolates give to plants is a disadvantage when there are no predators around (Mauricio, 1997), and reduces the number of seeds and flowers produced per plant compared to non-producers (Stowe and Marquis, 2011). (more…)

Views on synthetic plant products at the New Phytologist Synthetic Biology Workshop

The three day 4th New Phytologist Workshop on Synthetic Biology started on Wednesday 6th June, and we waited until after the Thursday afternoon coffee break to hear a presentation on plant synthetic biology. It was obvious that plant synthetic biology is not yet as sophisticated as synthetic chemistry and microbiology, and the reasons were implied in many of the talks. Plants are multi-cellular, have weeks-long life cycles and their products cannot simply be skimmed off or distilled from a vat of cells.

Rob Edwards (University of York) was quick to defend plant synthetic biology when I put this to him, pointing out that plant plastids are a means both of expressing a transgene and storing its possibly toxic product, all without affecting the rest of the cell. Plants can be grown cheaply, particularly if engineered to do so, although extracting the product may be expensive and difficult. On the other hand, synthetic biology may be used to enhance the flavor, fragrance or appearance of a fruit or flower and in that case the plant itself is a high-value product which requires no extraction.

While Rob Edwards’ SPPI-net focuses on synthetic biology for non-food plant products, he stated that genetically improved food crops can have great effects. Golden rice has the potential to help prevent blindness in areas where communities living on rice-based diets suffer from vitamin A deficiency, and soybean containing high omega-3 fatty acids can improve cardiovascular health. (more…)

New Phytologist Synthetic Biology Workshop: SynBio toolboxes for your lab!

Categories: synthetic biology
Comments: No Comments
Published on: June 28, 2012

Of more immediate practical use to the GARNet community than the technology described here are toolkits presented at the 4th New Phytologist Workshop by Susan Rosser (University of Glasgow) and Keith Saunders (John Innes Centre).

Violacein

Susan Rosser presented a soon-to-be-published multi-gene assembly kit based on synthetic integrons – ‘Syntegron’. Like existing kits for manipulating DNA, it involves cassettes which top and tail each gene or section of DNA. Unlike other kits, it will be open source and allows for many genes, even a whole pathway, to be assembled, shuffled if required, and expressed. It has been demonstrated to work on the 5-gene violacein pathway which was put, complete and functioning, into E. coli in just 5 days. I’m pretty sure this protocol will be a hit, and it will be an excellent method for a group to use when they try out synthetic biology for the first time.

Keith Saunders presented another gene transfer method, the CPMV-HT expression system which won the BBSRC Innovator of the Year award for Professor George Lomonossoff and Dr Frank Sainsbury. Their system is based on empty virus-like particles (eVLPs), made from modified cow pea mosaic virus (CPMV). (more…)

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