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KNOWLEDGE


B E


By Zoe Dunford from the John Innes Centre and The Sainsbury Laboratory


FEELING THE HEAT!


Some summers can be too hot to handle. In 2003, 35,000 people in Europe died as a result of a record heat wave. Too much sun, too much heat and not enough water makes us sick. The same goes for plants. Including ones that feed us and our livestock.


Leaves grow more slowly, less water means less productivity and cereals produce smaller, lighter grains because the grain- filling period is reduced.


Higher temperatures can also make plants more vulnerable to attack. Pests and diseases can become more virulent or are able to survive in new locations. Others become less virulent but the crops become more susceptible to their effects.


Heat shock


In 2003 French wheat yields were down by a fifth and Italian maize yields were down by over a third. Nothing like it had been seen since 1540, the year that Henry VIII got hitched to wives four and five, when a heatwave beginning in April lasted seven months. Such extreme temperatures are likely to become more frequent according to IPCC climate model projections.


In the tropics and subtropics, the highest temperatures recorded so far are highly likely to be below the summer average that will be experienced by 2100.


It is also predicted that every 1ºC temperature rise will cause direct losses in crop yields of 2.5-16%. Further losses are expected from rising sea levels, increased salinity and decreased soil moisture.


Plant scientists are starting to gather evidence on the exact ways in which plants will be affected. Researchers at the John Innes Centre and The Sainsbury Laboratory on Norwich Research Park are starting to unravel how plants respond to temperature and how their interactions with pests and diseases are likely to change.


This knowledge will show us if anything can be done to help plants cope. It may show us if it’s possible to breed crop varieties that are able to adapt.


Plants that glow


Scientists at the JIC have being doing research with plants that emit a gentle glow under heat. One plant luminesced whether it was hot or cold, and this led them to identify the gene that plants use to measure temperature.


They also found that plants change the way their DNA is wrapped according to temperature. As it becomes warmer, plant DNA becomes less tightly packed. This allows genes to be switched on in response to temperature. What they are trying to find out next is whether this is a direct effect of temperature on DNA or is more indirect.


If they can develop a deep enough understanding of the process they hope to be able to breed plants that respond to temperature differently and are less sensitive to temperature shocks.


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