How do plants remember winter?

Martin Howard is a Professor at the John Innes Centre, one of a small cluster of research institutes in Norwich. In the fourth of our Celebrating Basic Plant Science series, he explains how he uses mathematical modelling to understand how plants remember winter cold and respond to it throughout the year. 

How do plants ‘know’ the correct time to flower? Getting this timing right is vital for reproductive success; flowering in the middle of winter is unlikely to be optimal! Many factors are integrated together to make this critical decision, including the day length.

We have been studying one aspect of this question: How the plant Arabidopsis thaliana perceives and then remembers exposure to winter cold. This fundamental mechanism ensures that flowering doesn’t occur until winter has passed. Interestingly, this memory is quantitative – a longer winter means flowering is faster once it starts (see the image below).  This process is a very nice example of what’s called an epigenetic phenomenon, as the plants store information about winter cold exposure even after the environmental stimulus (cold) has been removed.

So how is this information about cold stored? In Arabidopsis, this is centred on a gene called FLC (Flowering Locus C). When the plant is cold, the FLC gene is turned off. The products of this gene prevent flowering, so turning it off actually stimulates the plant to flower. Over recent years, we have learned a great deal about the operation of FLC and associated genes through genetics and biochemistry, in large part through the work of my experimental collaborator, Caroline Dean. However, despite all this knowledge it was still not clear overall how the epigenetic memory system worked. This was partly due to feedback among the different components, which made arriving at an intuitive understanding a very difficult task. For these reasons, we began to model the dynamics of FLC mathematically in the hope of making sense of these interactions and, we hoped, revealing some underlying simplicity in how the system operated.

Mathematical modelling turned out to be very informative and suggested that FLC gene silencing occurred in an all or nothing fashion inside each cell. (more…)

Celebrating Basic Plant Science: Siobhan Braybrook

The first in our series of Celebrating Basic Plant Science articles comes from Siobhan Braybrook, a Career Development Fellow at the Sainsbury Laboratory at the University of Cambridge. She explains her work on plant development and discusses why she thinks basic plant science is value for money. 

In parts of India people have built ‘living bridges’ with traditional methods. Could developmental biology build the living bridges of the future?

How do we measure the importance of scientific works? Do we require immediate applications? Do we simply need to know? Both basic and applied science are important and vital for our sociological and scientific progress, but we tend to measure their impact with a very immediate and short ruler, one which is biased towards applied outcomes. Basic science is concerned with knowledge for knowledge’s sake, the desire to know. Applied science is directed towards a specific problem and it’s solution. Here, I propose that is impossible to anticipate the value of a basic scientific work beyond its immediate context, and that attempting to do so might just force us to narrow our field of imagination and innovation.

My group focuses on a basic scientific question- we would like to know how plants grow shapes. Our research definitely falls into the category of basic science as we pursue the answer to this question, not with a specific application in mind, but with a simple desire to know. But that does not mean that we don’t find applied directions during our pursuits.

Plant cells are pretty special to me because they exist in a box; the plant cell wall contains all of the other cell contents, allowing the cell to attain high pressures and also being the regulator of cell shape. We use biology, genetics, biochemistry, and materials science to understand how the cell wall controls cell, organ, and whole plant shape. As an example, we have shown with collaborators in France that new organ formation strictly requires a particular change in the cell wall, altered pectin chemistry. It was surprising that something as simple as pectin, the same thing used to make jellies set, was able to control whole plant shape by limiting new organ growth. These experiments have directed us to look at other growth processes that might be controlled, in part, by pectins in the cell wall.

From a basic science standpoint, our findings were very satisfying- we had found out something new and interesting. But they have also led us down some less familiar paths, into the realm of applied science. Can we take what we have learned about a biological material, the cell wall, and design man-made materials that also have the potential to grow? Could we one day place a small block of material on the ground and have it grow into a house? A car? Alternatively, if we understand how the cell wall controls growth, could we plant a seed that grows into a house frame? A chair? It is unlikely that any company would touch this idea without a very, very, very long pole at this time. It is too speculative, maybe even too crazy. But within the realm of basic science, we can continue to chip away at the possibility- with a freedom that does not require a final product right away, a freedom that allows us to grow our ideas along side our plants.

In closing, it is probably highly simplistic to separate basic and applied science. There is cross talk between the two, research projects that exist in a continuum, and research questions that are entangled. However, there are some very special things about basic science: you don’t need to know exactly where you are going in order to end up somewhere cool; you can explore things for the sake of knowledge which gives a lot of freedom; and sometimes you find out unexpected things that end up having massive applied impacts that you might never have anticipated. It is essential that we create a place for such scientific freedoms, that we don’t assume which pursuits have value before they have been investigated, and that we allow for the possibility of novel discoveries.

You can read Siobhan Braybrook’s research about pectin and new organ formation in Braybrook and Peaucelle 2013, PLoS ONE 8(3): e57813 and Peaucelle et al. 2001, Curr. Biol. 21:1720

Image credit: Screwtape via Flickr

 

Celebrating basic plant science with David Baulcombe

Categories: UKPSF
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Published on: May 10, 2013

 

Barbara McClintock discovered transposable elements when investigating irregular colouring in maize.

It’s now nearly a month since UK PlantSci 2013, and high time I wrote something about it on this blog. Rebecca Nesbit has written two posts about it already on the Society of Biology blog, and a New Phytologist meeting report will be coming out soon. The Weeding the Gems contribution to this collection of UK PlantSci nostalgia is a write-up of the second keynote talk by David Baulcombe.

David Baulcombe’s talk was a rallying cry in defence of basic research and plant science. He kicked it off with a whistle-stop history of important scientific achievements, all by scientists carrying out basic research on plants: Robert Hooke, who identified and labelled ‘cells’ for the first time when studying woody plant biomass in 1665; 19th century monk Gregor Mendel, whose peas were the first genetic model system; Russian botanist Dmitri Iwanowsk, who in 1892 was the first scientist to identify and characterise a virus; and Barbara McClintock, who discovered transposable elements in maize. More recently even than McClintock’s work, Argonaute proteins, tumour formation, and cellular totipotency were all identified first in plants (Bohmert et al. 1998, EMBO 17:170; Sussex 2008, Plant Cell 20:1189).

The scientists involved in the discoveries listed above were carrying out what they presumably viewed as interesting work, simply because they wanted to know the answer – pure science, but all with far-reaching consequences. Baulcombe commented than in the 21st Century research is impact-driven, so some of these pioneers may have struggled to get funding via today’s funding mechanisms.

Now, it is unfair to say that research today is all end-product focussed and impact driven. I know that the BBSRC and other funders worldwide fund basic plant science research regularly, and I highlight some of it here on this blog. Baulcombe’s main point in this first half of the talk was that basic excellent plant science research has to be celebrated in its own right rather than as a half-way point to a useful product in the future. (more…)

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