Phytochromes act as internal brakes for plants. When phytochromes are activated by sunlight, they bind to a plant's DNA to slow its growth. When a plant receives adequate sunlight, it does not recognise a need to grow faster. When a plant is in too much shade for its needs, the phytochromes decouple from the DNA, and growth accelerates so that the plant can reach new sources of light.
Until recently, researchers believed this process to be the only function of phytochromes and that when the sun set, the molecules were simply deactivated. However, this new study suggests that instead, phytochromes gradually deactivate in direct proportion to the temperature in a process called "dark reversion." In cold weather, the molecules return to their inactive state more slowly and plant growth is slowed. In warmer weather the dark reversion is sped up and faster growth is recorded.
The research was conducted using a mustard plant called Arabidopsis, which is frequently used in scientific studies (and the first plant to have its genome sequenced), but the researchers say that other crops have phytochromes as well, and understanding the complete picture of how they work could help us battle difficult growing conditions brought about by climate change.
"It is estimated that agricultural yields will need to double by 2050, but climate change is a major threat to such targets," said lead researcher Dr. Philip Wigge from Cambridge University's Sainsbury Laboratory. "Key crops such as wheat and rice are sensitive to high temperatures. Thermal stress reduces crop yields by around 10 percent for every one-degree increase in temperature."
"Discovering the molecules that allow plants to sense temperature has the potential to accelerate the breeding of crops resilient to thermal stress and climate change." This study could prove a major breakthrough in developing crucial crop resistance in the face of changing climates and farming patterns and potentially help ease issues of food scarcity.