Three Reviews: Phytochrome, shade avoidance and far-red light ($)

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shadeavoidancePlant Cell Environ. has a set of reviews on light responses. Ballaré and Pierik (10.1111/pce.12914) review The shade avoidance syndrome: Multiple signals and ecological consequences, Sheerin and Hiltbrunner (10.1111/pce.12915) review the Molecular mechanisms and ecological function of far-red light signalling, and Inoue et al. (10.1111/pce.12908) review the Evolutionary origin of phytochrome responses and signaling in land plants. Collectively, these reviews provide a comprehensive overview of how plants use far-red light information (not absorbed by chlorophyll) to direct their growth, from the molecular mechanisms to the evolutionary history in land plants and ecological consequences. As always, a complementary set of current reviews provide an excellent resource for teaching.

Review: Role of vacuoles in phosphorus storage and remobilization ($)

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PVacuolePhosphorus (P) is a non-renewable soil nutrient essential for plant growth. The vacuole serves as a crucial dynamic store of P that helps maintain cytosolic homeostasis. Yang et al. review vacuolar P stores, comparing P storage species and membrane proteins in yeast, algae and plants. In yeast, polyphosphate (PolyP) is a major storage form, whereas in plants the major forms are orthophosphate (PO43- or Pi) in vegetative cells and inositol phosphate (InsPs) in seeds. The contributions of SYG1/PHO81/XPR1 (SPX)-domain containing proteins are highlighted, including the channel-like vacuolar P influx transporter PHT5 and its rice orthologs OsSPX-MFS1, and the putative efflux transporter OsSPX-MFS3. The contributions during P starvation of autophagy-dependent recycling other forms of organic P such as RNA are also discussed.  J. Exp. Bot. 10.1093/jxb/erw481

Review: Cyanobacterial metabolites as a source of sunscreens and moisturizers

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algaeThe cosmetic industry uses a lot of different chemicals to produce the seven or so skin care products used by the average American every day. Efforts are underway to develop renewable sources for some of these. Derikvand et al. review the chemistry and potential applications behind compounds used by cyanobacteria both as UV-absorbing sunscreens and water-retaining humectants, which include extracellular polysaccharides. Eur. J. Phycol.   10.1080/09670262.2016.1214882

BotanyOnline: Shared learning-support resources for improving Botanical Literacy

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Guest post by Rosanne Quinelle, an Associate Professor in the School of Life and Environmental Science at the University of Sydney, Australia.

Proficiency in any discipline requires exposure to both breadth and depth, where “breadth” is akin to acquiring the vocabulary and “depth” is akin to an understanding of the prevailing patterns, the rules of grammar.

Developing botanical literacy in undergraduate sciences students requires exposure to the words we use in Botany, some of which can be different from their everyday meaning (e.g. pungent and habit) and can be challenging because of botanical literacy’s evil twin, plant blindness. Teaching approaches that embrace:

  1. the trend that learners ‘bring your own’ mobile devices to class and offering resources via these devices can be extremely useful for formal study during class and outside of class hours,
  2. the use of emerging research technologies in the classroom as powerful strategies to engage students (Twitter, Socrative, YouTube)

offer technically interesting resources which, because they are accessible via mobile devices, increase the likelihood of students engaging and learning.

There are lot of really interesting initiatives out there to make plants more ‘visible’ and the learning key concepts more accessible. Congratulations to Chris Martine for his award received last year and his stellar work as a botany educator and communicator and of course Teaching Tools in Plant Biology provides excellent resources to share with our students.

At the University of Sydney we have a collection of learning and teaching resources offered as Botany [Online]. Our Australian flora is different from the flora of northern continents and it is important to offer students examples from the plants that surround us from our biogeographical context. Our resources include:

  • image glossaries aimed to assist students with terminology, e.g. terms to describe habit, leaf arrangement, stipules, inflorescences etc.
 PlantDiversity stipules Picture13
Screenshots from BotanyOnline: each links to the page from which it was derived.
  • a virtual Botany slidebox. Virtual microscope slides are generated from scanning specimen slides and generating high resolution images. The resultant files are hosted on an image hub and can be examined in a browser in much the same way as one would with a microscope; users can manipulate magnification and interrogate all parts of the specimen at high and low power. The files generating from scanning are large and depending on how the images are served patience is required when loading. [A ‘secure site’ warning may popup; to view these scans you will need to accept the security certificate. If using an iPhone or iPad, I recommend the mobile browser Puffin to enable viewing, but note these files are large, and I tell my students that if accessing from home, to watch their download limits.]Picture14
  • eBot Plant Sciences Image Collection, which includes herbarium specimens from the John Ray Herbarium where Australian flora features. [See Quinnell et al., 2009 eBot: An image bank of Australian flora]

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  • eFlora, a digital rendering of an interactive, dichotomous key to all species of vascular plants in the Sydney Region. [See Henwood et al., 2006 Sowing the Seeds of a Digital Garden]
  • florathe CampusFlora app, which has turned the whole University into a learning space for Botany for all of our campus community. This project is using a “students as partners” model and our undergraduates have advised on the user interface (incl. icon design), contributed content (including photographs), developed the Google Play app and co-authored scholarly outputs. @CampusFloraOz
  • skills development: sectioning plant material at BotanyUSYD on YouTube.

In the interests of improving botanical literacy in the community generally, these resources are freely available. Feedback on how to improve these resources is most welcome.

Rosanne Quinnell is an Associate Professor in the School of Life and Environmental Science at the University of Sydney, Australia. Her science education research examines the effective use of existing and emerging information and communication technologies to support student learning, and with understanding the somewhat uncomfortable relationship many students in the life sciences have with mathematics and statistics. mailto:rosanne.quinnell[at]sydney.edu.au @ah_cue

Loose-Knit Family: Tracing the Evolution of Actin Depolymerizing Factors that Sever or Join the Actin Cytoskeleton

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IN BRIEF by Jennifer Lockhart [email protected]

Picture5The interior of a plant cell is supported by the actin cytoskeleton, a complex network of yarn-like fibers whose form changes as the cell develops, grows, and divides. Actin fibers readily come apart (sever) and join back together, depending on the needs of the cell. This process is carefully orchestrated by a myriad of proteins, such as actin depolymerizing factors (ADFs). ADFs can bind to both monomeric and filamentous actin (F-actin). Across the plant kingdom, ADFs play diverse, often unexplored roles in shaping the vegetative and reproductive actin cytoskeleton systems. The 11 ADFs of Arabidopsis thaliana have various tissue-specific gene expression patterns and activities. For example, ADF1, ADF2, ADF4, and ADF7 can sever actin filaments in vitro, whereas ADF9 shows actin-bundling and -stabilizing activity, especially at low pH (Tholl et al., 2011). Such findings prompted the intriguing hypothesis that ADF genes arose from a common ancestor through duplication and acquired diverse functions as actin fibers evolved (Kandasamy et al., 2007). The functional differences among ADFs might be due to changes in key amino acids or functional motifs, a challenging topic ripe for exploration.

Nan et al. (2017) rose to the challenge by exploring the evolution of ADF family members across various plant lineages and the amino acid changes that led to the diversification of their functions. The study began with an analysis of the effects of all 11 Arabidopsis ADFs on actin filaments in vitro based on a simple principle: Actin filaments are generally sedimented by high-speed centrifugation, whereas filaments severed by ADFs remain in the supernatant, especially at high pH. Most ADFs exhibited F-actin-severing activity. By contrast, low-speed co-sedimentation assays, which separated single actin filaments from actin filament bundles, revealed the F-actin bundling activity of ADF5 and ADF9. Fluorescence microscopy confirmed the diverse roles of the ADFs (see figure). The ADFs were divided into two categories based on activity: 1) D-type (depolymerizing F-actin) ADFs, which sever or depolymerize F-actin and 2) B-type (bundling F-actin) ADFs, which bind to and bundle F-actin. Phylogenetic analysis of ADFs across the plant kingdom suggested that an intron-sliding event (movement of an intron from one position in a gene to another) occurred during evolution. It appears that the ADF genes descended from a D-type common ancestor and expanded through various types of gene duplication events, which increased the chances of retaining these vital genes. The ADF genes were grouped into four ancient subclasses that have been conserved in angiosperms for approximately 250 million years. While most ADFs have completely retained the D-type function of their ancestors, a few B-type ADFs have completely lost this function and have undergone neo-functionalization.

The authors zeroed in on amino acid changes that led to the conversion of the original D-type function to B-type function by analyzing the F-actin severing and bundling activities of mutant, ancestral-like proteins. They identified several pivotal amino acid residues affecting the biochemical functions of these proteins; these residues are conserved in Arabidopsis and several other angiosperms. N-terminal extensions that arose from intron sliding events were found to be crucial for the change from D-type to B-type function. This mechanism appears to have remained fixed since the diversification of the angiosperm lineage, shedding light on this not so tight-knit family.

REFERENCES

Kandasamy, M.K., Burgos-Rivera, B., McKinney, E.C., Ruzicka, D.R., and Meagher, R.B. (2007). Class-specific interaction of profilin and ADF isovariants with actin in the regulation of plant development. Plant Cell 19: 3111-3126.

Nan, Q., Qian, D., Niu, Y., He, Y., Tong, S., Niu, Z., Ma, J., Yang, Y., An, L., Wan, D., and Xiang, Y. (2017). Plant actin-depolymerizing factors possess opposing biochemical properties arising from key amino acid changes throughout evolution. Plant Cell 29: doi:10.1015/tpc16.00690.

Tholl, S., Moreau, F., Hoffmann, C., Arumugam, K., Dieterle, M., Moes, D., Neumann, K., Steinmetz, A., and Thomas, C. (2011). Arabidopsis actin-depolymerizing factors (ADFs) 1 and 9 display antagonist activities. FEBS Lett. 585: 1821-1827.

 

FIGURE LEGEND

Direct visualization of F-actin severing and bundling by ADFs. Representative micrographs of actin filaments in the absence (upper panels) or presence of Arabidopsis ADFs at pH 6.6 and pH 7.4 showing their differential actin severing (middle panels) and bundling (lower panels) activities. (Adapted from Nan et al. [2017], Supplemental Figure 5A.)

 

Jay Keasling. Engineering Microbes to Solve Global Challenges

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Filmed for iBiology 2016

Talk Overview

Picture12Dr. Jay Keasling discusses the promise of biological systems to create carbon-neutral products for a range of applications, including fuels, chemicals and drugs. Keasling discusses the application of these principles to the development of a microbial platform for the synthesis of the anti-malarial drug, artemisinic acid. This platform has helped stabilize the global supply. He also discusses additional applications of these techniques to fuel production, as well as some of the current challenges and possible solutions facing the metabolic engineering community.

About the Speaker: Jay Keasling

Jay Keasling is a Professor of Chemical engineering and Bioengineering at the University of California, Berkeley, an Associate Laboratory Director for Biosciences at Lawrence Berkeley National Laboratory, and also chief executive officer of the Joint BioEnergy Institute (JBIE). He received his PhD in Bernhard Palsson’s lab at University of Michigan and was a post-doc with Arthur Kornberg at Stanford University. The Keasling lab focuses on the bioengineering of microorganisms to enhance biofuel extraction from plant biomass and improve environmental clean-up strategies. Keasling has received numerous honors for his work over the years, including most recently the Heinz Award for Technology, the Economy and Employment (2012), the George Washington Carver Award (2013), and the ENI Renewable Energy Prize (2014). Dr Keasling was also elected a Fellow of the National Academy of Inventors in 2014.

Alistair Fritter. People, plants and planet

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Filmed at Gatsby Summer School, 2011

Picture10Abstract: Population issues are receiving renewed attention from both scientists and policy-makers and well-founded predictions of likely global population growth have given new urgency to concerns about food security and loss of ecosystem services.  Plant science has a central role to play in making it possible to feed the entire human population properly and to put an end to the scandal of global poverty.  One of our biggest challenges is to learn how to manage land in such a way that it delivers multiple services, especially to make enhanced food production compatible with other ecosystem services such as carbon sequestration, water supply and the maintenance of biodiversity

Speaker Profile: Alastair Fitter is Professor of Ecology at the University of York.  His research focuses on plant-soil interactions and mycorrhizal symbioses, especially in relation to the biological impacts of climate change, and on ecosystem services.  He is a Fellow of the Royal Society and Vice-President of the International Association of Ecology (INTECOL).  He was appointed CBE in 2009.  He chaired the European Academies Science Advisory Council group on Ecosystem Services and Biodiversity in Europe and was a member of the expert review group for the UK National Ecosystem Assessment and of the Royal Society group on People and Planet. He is an author of numerous popular natural history books, principally on plant identification.

http://www.gatsbyplants.leeds.ac.uk/tree/uploads/Lectures/Fitter_A_SS12/player.html

Giles Oldroyd. Engineering the nitrogen symbiosis for smallholder farmers in Africa

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Filmed at the Gatsby Summer School, University of Cambridge 2015

Western agricultural systems are reliant on the application of inorganic nitrogen fertilisers to greatly enhance yield. However, production and application of nitrogen fertilisers account for a significant proportion of fossil fuel usage in food production and the major source of pollution from agriculture.

Prof Giles Oldroyd studies the mechanisms by which some species of plants are capable of forming beneficial interactions with nitrogen-fixing bacteria, which provide a natural source of nitrogen for plant growth. In this lecture, filmed at the Gatsby Plant Science Summer School 2014 (for 1st year undergraduates from UK universities), Prof Giles Oldroyd discusses the potential to reduce agricultural reliance on nitrogen fertilisers.

http://sms.cam.ac.uk/media/1914136