Coffee plants that produce much reduced levels of caffeine have been created by genetic engineers.
Hiroshi Sano and colleagues at the Nara Institute of Science and Technology in Japan used a technique called RNA interference to silence a key gene for making caffeine in coffee plants.
This technique cut caffeine in young coffee plants by up to 70 per cent. They now hope to develop this technology in the world鈥檚 most popular Arabica coffee.
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The demand for decaffeinated coffee is growing globally, say the team, because of the possible adverse health effects of caffeinated coffee. Caffeine can trigger palpitations and increase blood pressure in sensitive individuals.
Sano believes consumers will not be put off by the idea of genetically modified coffee. 鈥淚t鈥檚 actually a good GM organism for health,鈥� Sano told 快猫短视频. 鈥淚n this case, you will have coffee beans which are quite normal except in their caffeine content 鈥� it will be of practical good for some people.鈥�
The other key advantages of GM decaffeinated coffee, say the researchers, are that it should be cheaper and retain all the taste of regular coffee. The expensive processes currently used to extract caffeine from normal beans also strip other flavour compounds from the coffee.
Interfere and destroy
The team鈥檚 achievement is the result of seven years work on the coffee plant variety Coffea canephora.
Caffeine is produced in coffee plant cells from a natural plant chemical called xanthosine in three steps. Each step involves a chemical process called methylation. The team has now managed to silence the second gene involved in this process so that caffeine cannot be produced.
Proteins are produced from genes in living cells via complementary molecules called messenger RNA. This mRNA, which is a mirror image of the gene鈥檚 DNA, is 鈥渞ead鈥� to produce a protein, but RNA interference switches off this process.
鈥淲ith RNAi you introduce a small fragment of RNA complementary to the mRNA ,鈥� says Sano. 鈥淭hey interfere and destroy each other.鈥�
Knock-out efficiency
Modified one-year old seedlings showed a reduction in caffeine content of 50 to 70 per cent in their leaves. It will be at least four years before these GM plants blossom and therefore produce beans, says Sano. 鈥淯ntil then, of course, we cannot evaluate the caffeine content in the beans,鈥� he says.
Previous attempts to genetically alter the caffeine content of coffee plants have involved a less efficient technique than RNA interference, says Sano.
In 1998, researchers at the University of Hawaii produced decaffeinated coffee plants using a gene 鈥渁ntisense鈥� method. 鈥淓xperimentally, plant biologists have found knocking out efficiency much higher with RNAi than with antisense,鈥� says Sano.
Journal reference: Nature (vol 423, p 823)