How do plants cope with changing temperature?

By Dr Lindsey Atkinson (@LJA_1)

Plants have evolved many specialised adaptations to enable them to live in a wide range of conditions but what happens when their environment changes?

Plants are sessile organisms, literally rooted to the spot, so if the conditions where they live become unfavourable they cannot move to a more favourable area.  For instance, they may be subject to changes in water or nutrients supply, light or temperature:  here I want to focus on temperature in particular. Plants experience climate with some seasonal variation but they may also be exposed to short-term fluctuations in temperature due to local weather conditions. These changes in temperature impact on the plant’s growth, function and development (phenology). In the long term adaptation may occur, or there may be a change in the range in which the species can live. However, in the short term, plants need to adjust to the local conditions to ensure survival, growth and ultimately reproduction.

It is important to understand how plants will respond to climate change as this will have impacts on biodiversity and also on crop productivity and quality, and hence food security.   In addition plants are major determinants of CO₂ turnover in the atmosphere (Schimel et al. 2001) through the processes of photosynthesis and respiration.  Both of these processes are sensitive to temperature, with rates increasing with increased temperature. However, there may be an adjustment in the rate of the process to compensate for the initial change in temperature; this is known as acclimation and may moderate the response.

We can use our knowledge of how changing temperatures will affect photosynthesis and respiration at the leaf level of individual leaves to scale these processes up to predict the responses of ecosystems to global change.  For example, we incorporated thermal acclimation of respiration into a coupled-global climate vegetation model. The results indicated that while incorporating acclimation of respiration had little effect on predicted global atmospheric CO₂ levels, the response varied between biomes which could have land use management implications (Atkin et al. 2008).

Arabidopsis thaliana  grown at 23^oC in
controlled environment conditions

Even in a warmer world plants may experience a sudden drop in temperature: this could occur in the autumn at the onset of winter, or due to a late cold-spell in spring.  We wanted to know whether plants could continue to grow in these conditions so we grew Arabidopsis thaliana plants at 23^oC and then shifted them to 5^oC (Atkinson et al., 2014):  following the shift the growth rate was initially reduced to less than one third of that of warm grown plants.  However, growth subsequently recovered with the development of new leaves in the new conditions after about 14 days.  These new leaves had a cold phenotype which was important in the recovery in carbon metabolism in the cold.  The development of the new tissues was supported initially by use of stored nitrogen and relocation from pre-existing tissues but later by nitrogen obtained from the growth medium. This indicates that both the nitrogen status of the plant and the external nitrogen supply may be important in the acclimation of photosynthesis and respiration in the cold. 

The paper is available online at http://onlinelibrary.wiley.com/doi/10.1111/pce.12460/abstract

References

Atkin OK, Atkinson LJ, Fisher RA, Campbell CD, Zaragoza-Castells J, Pitchford JW, Woodward FI, and Hurry VM (2008) Using temperature-dependent changes in leaf scaling relationships to quantitatively account for thermal acclimation of respiration in a coupled global climate-vegetation model.   Global Change Biology 14: 1-18 

Atkinson LJ, Sherlock DJ and Atkin OK (2014) Source of nitrogen associated with recovery of relative growth rate in Arabidopsis thaliana acclimated to sustained cold treatment. Plant, Cell and Environment Article first published online: 7 Dec 2014 | DOI: 10.1111/pce.12460

Schimel DS, House JI, Hibbard KA et al. (2001) Recent patterns and mechanisms of carbon exchange by terrestrial ecosystems.  Nature, 414, 169–172.

High school students as research partners: working with Nuffield Placement Students

 by Jane Bunting (@DrMJBunting) and Rebecca Williams (@Volcanologist)


Meanwhile, back in the lab...

This week, the blog is back indoors, where Jane and Rebecca are spending August helping some Sixth Form students get a taste of 'real science' in the summer before they apply for University.  Five students have placements with us in GEES through the Nuffield Foundation Research Placements Scheme, which will enable them to be assessed for a British Science Association CREST Gold Award.

Rebecca did a Nuffield Placement herself in the summer after her first year of A Levels.  Neither the Nuffield scheme or the CREST Awards had been done before at Rebecca’s school. An eager biology teacher, Dr Bridgeman, had heard of the scheme and so started it up that year with Rebecca and two of her school friends being the first students to go through it. They weren’t provided with placements, but rather had to find them for themselves. At the time, Rebecca knew she enjoyed Geography, Science and Maths. She was also a bit obsessed with Time Team and she has blogged before about how her journey into geology really started by wanting to be a geophysicist. The only company she could find locally which did geophysics was a consultancy company for the oil and gas company, TGS-Nopec (as they were then known). Rebecca wrote a letter (no email back then!) asking if they would take her on as a work experience student and was delighted when they did. It was a phenomenal experience. Rebecca worked on a project called ‘Hydrocarbon prospectivity along the eastern seaboard, offshore northwest Europe’. She doesn’t have a good memory, but the report is sat next to her as she types this – a testament to how important the experience was. Rebecca found that the geophysical interpretation of the seismic lines wasn’t what interested her. Rather, it was the geology – how is the oil formed, where does it come from, where is it stored, how is it trapped and where can it be found? When Rebecca then had to fill out her UCAS application a month or so later, it was geology degrees she applied to, and not the geophysics that she thought she was going to do, and the rest, as they say, is history. The Nuffield Scheme really did change Rebecca’s path in life. The results from that project were eventually presented by TGS-Nopec at the PETEX Conference – the premier oil and gas conference!

Students doing placements work with a supervisor for 4-6 weeks on a 'real' research project - one where the supervisor doesn't know what will happen or be found out.  The students are expected to read around their topics, contribute to discussions about the design of experiments or studies, plan their own time, learn to use different pieces of equipment, collect data and interpret it, and produce a report and a talk or poster at the end of the placement - of course there is lots of help available, from the supervisor, from technical staff, from other students and researchers in related fields, but it is still quite a challenge.  This year's students all seem to be making the most of it, and are filling their lab notebooks with lots of lovely data.

Tinashe weighing an ear of wheat

surface of a wheat leaf: the 'squashed donuts' are the stomata

Jordan, Leah, Charlotte and Tinashe from local sixth forms at Wyke and Sirius Academy are all working with Jane and Lindsey Atkinson (@LJA_1), who also blogs here, on a pilot study of the effects of small climate changes on spring wheat, which is linked to a bigger project being run by the Network Ecology Group called "The impacts of climate-warming on farmland food-webs and ecosystem services".  In this project, 24 plots are marked out in a field of spring wheat.  Half of these are warmed by 2 ^oC, the sort of change in summer temperature which we are likely to see in our region within the next century according to predictive models.  Since the warming will dry out the soil, half of the warmed plots and half of the non-warmed plots are also given some extra water, so some plots are warmer and drier, and some are just warmer.  We're studying wheat plants collected from the different plots in the field experiment, and also growing our own in the controlled environment rooms in the GEES building, where special lights on timers mimic day and night cycles, the room temperature is controlled, and neither rabbits nor aphids can snack on the growing leaves - the indoors experiment should therefore help us understand how the plants respond to the climate changes without the rest of the food web complicating the picture.  Jordan is studying how biomass allocation varies (essentially 'plant budgeting', looking at how plant resources are divided between light capture, water capture and reproduction).  Charlotte is looking at the effects of the climate changes on the grain yield of the wheat plants.  Leah and Tinashe are looking in more detail at whether the plants can adapt to grow in different conditions by varying the number of stomatal cells in their leaves (an introduction to studying stomata aimed at students can be found here). 

Jordan and Leah cutting up wheat plants

These data, along with other aspects of the plants being measured by Jane and Lindsey, will form the basis for an initial paper on the response of this important crop plant to anticipated climate changes (which of course will get blogged about here) and for a grant application to extend the work; we need to show that our experiments will produce interesting results before we can ask for funding, so these projects are playing an important role in helping us develop this research area.

Jodie uses a digital camera to photograph her thin sections

Jodie joins us from Hessle High School and Sixth Form College. Jodie is interested in geology and chemistry so we’re convincing her that volcanology is an excellent subject! Jodie is doing a research project on the Green Tuff Ignimbrite from Pantelleria with Rebecca. In particular she is looking at thin sections of the ignimbrite to look for features that she can use to interpret how the ignimbrite was formed. This project is a continuation of a long-running project that started with Rebecca’s PhD in 2006. It’s a small, but important part of a much bigger research jigsaw, and the results look promising! We’ll be blogging more about the project next week. If the results look good, Jodie and Rebecca will be presenting the research at the UK’s volcanology conference which this year is hosted in Norwich; Jodie is getting real experience of working on a research project at the cutting-edge of Rebecca’s science.

The Nuffield Schemes offer a wonderful opportunity for students to try out real science; it's very different from school!  For us, it's an excellent way to communicate with the next generation of scientists and consumers of scientific findings, and gives the students involved a taste of scientific work, a boost for their university or job applications and helps them make better course and career choices.  If you're a student reading this, ask your teachers about the scheme or go to this link.  If you're a scientist, we urge you to consider taking on placement students through the scheme - it might even help you get that crucial bit of data to progress your research next summer.

Of gribbles and fish oil: plants and future security

By Lindsey Atkinson (@LJA_1)

In the week that the latest report of the Intergovernmental Panel on Climate Change (IPCC) was issued (31.03.2014) with its emphasis on risks and the importance of adaptation, the UK Plant Sciences Federation  (UKPSF) held their 2014 conference ‘Plant Science – Sustaining Life on Earth’ at the University of York.  This conference brings together a wide range of plant scientists from ecologists to molecular biologists and gives them the opportunity to share their knowledge across disciplines.

A key theme of the conference was food security¹ and how plant science may help to meet some of the challenges we face.  The conference was opened with a keynote lecture from Prof Tim Benton (University of Leeds) on ‘Feed, food and fuel: plants and future security’ where he gave us an overview of some of these challenges.  Drivers of change include the growth in global demand for food, globalization and the changing climate.  Combine this with soil degradation and these things add up to make future food supplies look very uncertain!  On the other side of the coin, it’s not just about food supplies, but also about waste.   Some of these themes were echoed in Prof Peter Gregory’s (East Malling Research/University of Reading) talk in which he looked at the importance of sustainable agriculture and reducing waste and loss. 

Some of the headline figures from the recently published UKPSF report Status of UK Plant Science: Current Status and Future Challenges include:

•  ‘There will be 2.4bn extra people to feed by 2050’
•    ‘Global food production must increase by 60-110% to meet this demand’
•    ‘Up to 40% of global crop yields are lost to plant pests and diseases each year’
•    ‘Agriculture accounts for 70% of the world’s fresh water use’
• ‘By 2030, global energy demand is predicted to rise by 40%’

At one level these challenges need to be tackled through politics and economics but plant scientists are using their knowledge and creativity to contribute too, which brings us back to gribbles and fish oil…

Gribbles are small, marine, wood-boring crustaceans and wouldn’t normally make an appearance at a plant science conference.  However, understanding and using their digestive enzymes may increase the efficiency with which we can break down woody materials to produce biofuels (read more). 

We also learned that fish oil isn’t made by fish – yes, you guessed it – it is made by plants (in this case marine algae) and accumulated by the fish.   Using fish as a source of these fish oils for fish farming is not sustainable but using transgenic crops could be… (read more).  

There were many more examples of how plant scientists are working to improve crop yield and yield stability, water and nutrient use in agriculture and the nutritional value of crops.  There is also a lot of current research on using plants as factories to produce additional nutrients and biofuels.  You can find more details of all the topics covered at the conference at http://plantsci2014.org.uk/programme/

The future for plant scientists in the UK was the topic for a debate chaired by Dr Sandy Knapp of the Natural History Museum.  Although great strengths were recognized in the plant science research community, it was noted that it has an ageing population and skills shortages are predicted.  The importance of inspiring students from an early age was emphasized with calls for greater inclusion of plant science in the curriculum at both school and in higher education.  The next challenge is once inspired, providing the opportunities to keep scientists in this area.

The panel (from L to R): Sarah Gurr (University of Exeter), Jim Beynon (University of Warwick),  Sandy Knapp (Natural History Museum, London),  Mark Chase (Royal Botanic Gardens, Kew), Mike Bushell (Syngenta) and Dale Sanders (John Innes Centre).

The conference closed with a final talk from Prof Jackie Hunter, Chief Executive of the Biotechnology and Biological Sciences Research Council (BBSRC), who gave her view of a 21^st Century Vision for Plant Science to tackle challenges in sustainable crop production.

¹Food Security was defined at the World Food Summit of 1996 as occurring “when all people at all times have access to sufficient, safe, nutritious food to maintain a healthy and active life” (http://www.who.int/trade/glossary/story028/en/).