Climate-proof food plants are coming

What if we could create a food plant that defied all those doomsday scenarios where extreme temperatures take us all to oblivion, and instead kept growing and fruiting regardless of whether it got very hot or very cold?

"We would never run out of food!" remarked Philip Wigge, a scientist at the Norwich-based John Innes Centre, a member institute of Britain's Biotechnology and Biological Sciences Research Council.

That day could come sooner than we think - perhaps in the next 10 to 15 years - because Wigge and co-scientist Vinod Kumar have had a crucial breakthrough. They have isolated a "thermometer" gene that helps plants sense temperature, and this could provide a shortcut to creating plants that fruit in any temperature.

Their findings have been published in the current edition of Cell a US-based scientific journal that is peer-reviewed.

Scientists across the world have been working to create food crops tolerant to extreme temperatures, some of which are already being grown in Asia. They evolved from a long of process subjecting grain plants to stresses such as drought conditions, and then isolating genes from those that survived to create new variants.

Often only conventional breeding processes are used, as many Asian and African countries do not accept genetically modified products, said Baboucarr Manneh, a molecular biologist and coordinator of the Africa Rice Centre's Abiotic Stresses Project in Benin, which is working on developing varieties of rice that will tolerate extreme heat and cold.

Wigge and Kumar's discovery could potentially push agricultural microbiology forward by leaps and bounds in much the same way that early medicine, which depended on empirical methods to treat diseases, was revolutionized by an increased understanding of bacteria.

Time is a critical factor. The impact of extreme temperatures and water stress on food production, brought on by climate change, could be felt in the next 10 years, according to the Intergovernmental Panel on Climate Change (IPCC), which projects that food production in Africa could be severely compromised by 2020.

Manneh said the discovery would "cut down" the time it took to find varieties that were more tolerant to extreme temperatures, and "will lead to precision breeding - we won't have to tamper with all the genes."

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"thermometer" gene

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So how does the thermometer gene work?

Wigge and Kumar's research was spurred by a fundamental question: "How do plants sense temperature?" Wigge pointed out that they could sense temperature variations of just one degree Celsius, "and yet no one had asked how plants were able to do this".

They took the Arabidopsis plant - a member of the mustard family and the equivalent of a "lab rat" in plant research laboratories - and studied all its genes to see which were affected by warmer temperature. The sensitive genes were then used in new plants.

It took five years for the scientists to create a mutant plant that had lost its ability to sense temperature correctly - it grew as if the temperature was optimal all the time.

Whenever plants are subjected to extreme stress, such as very high or low temperatures, they do not flower and grow because they divert their food to their embryo. "Their instinct is to protect the next generation," said Wigge.

The scientists discovered that plants use a specialised histone protein to measure temperature. Histone proteins bind to the plant's DNA and wrap it around them, and control which genes are switched on.

"The histone variant works as a thermometer by binding to the plant's DNA more tightly at lower temperatures, blocking the gene from being switched on," said a statement from the John Innes Centre. "As the temperature increases, the histone loosens its grip and starts to drop off the DNA, allowing the gene to be switched on."

The mutant had no specialized histone, so the plant reacted as if the temperature was conducive to growth even when it was cold, but its ability to sense very high temperatures was still functioning.

The next step

"What we'd like to do next is to have a constitutive lack of high temperature perception, particularly in the grain. In this way, we may be able to prevent some of the detrimental effects of climate change on yield," said Wigge.

Photo: Jane Some/IRIN
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"To do this, we want to create plants that express special versions of the H2A.Z [the specialised histone] that don't respond to temperature. That way we should keep the high temperature genes off, even at high temperatures. There is clearly a lot of work in the future, but having the molecular mechanism provides some light at the end of the tunnel!"

Africa Rice Centre's Manneh pointed out that institutes using genetic engineering could transfer the Arabidopsis genes implicated in this mechanism into rice cultivars, shortening the development process even more.

However, he said it would take time for the findings to be assessed and made accessible to all the scientists, and "it could two or three years for farmers to have access to it."