Plants hibernate too!

It's often forgotten that plants are also hibernators, but without nerves to sense, how to they know when to change their behaviour?
19 January 2016

Interview with 

Dr Philip Wigge, University of Cambridge


Had you just awoken from an extra-long, grizzly bear-like hibernation, you would be forgiven for thinking that it was spring time in the UK: daffodils blooming and buds on trees are not usually associated with the depths of winter. Like animals, plants have also adapted to a seasonal planet but how do they do this? Connie Orbach went to the Cambridge Botanic Gardens to speak to plant scientists Dr Philip Wigge...

Philip - Plants need to know what the season is, so they measure how long the day is and that will often help them now whether it's spring, or autumn, or summer, or winter.  They can use that information to plan their life cycle and make decisions about when they should flower.  And the other thing they also use is temperature, and these unfortunate daffodils have really been relying and temperature information.  So, we had a really warm December and, as a result of that, these daffodils probably thought it was springtime and so they've actually started to flower, and now we've got a very cold patch and the frost will probably kill these flowers.

Connie - Humans may be carb load in the winter, some animals migrate, some animals go underground or sleep.  What do plants do in the year in response to temperature?

Francis - Plants can't move so they are stuck in one place, so they have to be really smart about the decisions they make. The reason for that is when you are a growing plant or making flowers, those growing structures are really sensitive to extremes of temperature, so either heat or cold.  So, if you are a plant, you really need to fine tune your lifecycle so that you're growing and flowering at those times of year when the temperatures are not too high and not too low.

Connie - We don't usually think of plants being maybe able to feel or see light, or temperature.  We don't think of them as sensory organisms, so how on earth are they doing this?

Philip - Yes, that's remarkable isn't it.  So you often look at a plant; you might think it's sitting there rather passively but, actually, they are constantly looking and sensing the environment and they integrate that information to change gene expression, and that's what we do in our research laboratory.  We try to understand the molecules that are controlling these responses of plants to the seasons.

Connie - Oh Wow!  Can you show me a bit of what you're doing here?

Philip - Great, so we should maybe go over to the growth rooms where we can see some of the plants we use in our research to understand how plants grow.

Connie - That sounds great - let's go...

Keen to get into the warm, we went underground to find a series of doors, each leading to a room heated at a different temperature and all filled with plants... Now be warned all this heating can get a little noisy...

Philip - Exactly.  These are the walk in chambers.  So I'll open this one here...

Connie - Oh Wow!  It feels so futuristic - it's really bright in here, it's quite noisy and it's got kind of a few rows of trolleys with lots of different plants on them.  What have we got here?

Philip - So this a room that's kept at low temperature.  If you look at these plants here, they're growing quite slowly and then these plants, by comparison, are growing very fast.  So we've tricked these plants into thinking it's actually warmer than it really is, so that just shows you that by changing a single gene in the plant, we can change what season the plant thinks it's growing in, which is quite interesting.

Connie - The plants were all the same species but looked so different that you would never guess.  Some were tiny and cress-like, others were huge and overflowing.  This shows how important the plant's environment is to their growth pattern and, also, that if  only a couple of genes are involved, the pathway for environmental responses of this kind must be really, really, specific.  I had lots more questions, but all that noise isn't that great for radio so it seemed best to continue the conversation elsewhere...

We mentioned this outside, but what we saw was all those plants blooming early due to a very warm winter.  What does this mean in the long run if we have a changing environment for the plants?  Can they adapt it or is it something that's going to cause us problems?

Philip - Well it's very interesting; we're sort of in the middle of a huge sort of global experiment and it's caused very large changes in the behaviour of plants.  What we've already seen is with a 1OC change, plants flower earlier when it gets warmer and the distribution of plants is moving.  And what's very important, also, is that plants are not all responding equally; so some plants will do relatively better than other plants and so it does seem that plants that mainly use temperature to make decisions about their lifecycle, they seem to be doing better than mainly use photoperiod.  And you can imagine that a plant that mainly uses the day length to determine when to flower or when to start growing, they might lose out.  If you have a warm spring, other plants might come up earlier they'll compete with plants that waiting for long days when, actually, they could have started growing earlier.  So wild plants have already changed and they're changing a lot. 

Then on top of that you've got to think about what's going to happen to crops.  On average, it's estimated that for every 1OC increase in temperature, crop yields they go down by about 10%, so that's something we've really got to watch out for.

Connie - And I guess that's something your work here will be important for in the future if we have to adapt to these changing climates?

Philip - Well, it's certainly a very interesting time to being doing this sort of research and our lab, and many labs around the world, are really interested in this question of how you identify the actual genes that are enabling the plant to sense temperature. So, if we identify these genes, then that has a great opportunity to enable us to breed plants that have a better response to warm temperature stress.


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