Monthly Archives: September 2014

Genome of the robusta variety reveals that caffeine-making evolved more than once, in part because pollinators developed a caffeine habit

Caffeine evolved long before sleep-deprived humans became addicted to it, probably to defend the coffee plant against predators and for other benefits. Credit: Thinkstock

Caffeine's buzz is so nice it evolved twice. The coffee genome has now been published, and it reveals that the coffee plant makes caffeine using a different set of genes from those found in tea, cacao and other perk-you-up plants.

Coffee plants are grown across some 11 million hectares of land, with more than two billion cups of the beverage drunk every day. It is brewed from the fermented, roasted and ground berries ofCoffea canephora andCoffea arabica, known as robusta and arabica, respectively. An international team of scientists has now identified more than 25,000 protein-making genes in the robusta coffee genome. The species accounts for about one-third of the coffee produced, much of it for instant-coffee brands such as Nescafe. Arabica contains less caffeine, but its lower acidity and bitterness make it more flavourful to many coffee drinkers. However, the robusta species was selected for sequencing because its genome is simpler than arabicas.

Caffeine evolved long before sleep-deprived humans became addicted to it, probably to defend the coffee plant against predators and for other benefits. For example, coffee leaves contain the highest levels of caffeine of any part of the plant, and when they fall on the soil they stop other plants from growing nearby.

Caffeine also habituates pollinators and makes them want to come back for more, which is what it does to us, too, says Victor Albert, a genome scientist at the University of Buffalo in New York, who co-led the sequencing effort. The results were published on September 4 inScience.

Dual origin When the team looked for gene families that distinguish coffee from other plants, those that make caffeine topped the list. The genes encode methyltransferase enzymes, which transform a xanthosine molecule into caffeine by adding methyl chemical groups in three steps. Tea and cacao, meanwhile, make caffeine using different methyltransferases from those the team identified in robusta. This suggests that the ability to make caffeine evolved at least twice, in the ancestor of coffee plants and in a common ancestor of tea and cacao, Albert says.

The genome could be used to identify genes that help the plant to combat diseases, such ascoffee rust, and to cope with climate change.

Caffeine-making genes might also be inactivated to create a tastier decaf. A coffee cultivar that is genetically engineered to be caffeine-free could be a welcome development for the many people who cannot tolerate the buzz. The process of removing caffeine currently involves chemical processing, and also affects the flavour (see 'Plant biotechnology: Make it a decaf'). I have to have a cup every morning, but I usually dont drink during the day because it makes me shaky, says Albert.

This article is reproduced with permission and was first published on September 4, 2014.

Read the original:
Coffee's Caffeine Buzz Evolved Separately from Tea's

Wake up and smell the genome.

Researchers have pieced together the genetic atlas of the parent of the most commonly cultivated species of coffee plant and uncovered a rather independent streak in its evolution.

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FOR THE RECORD

An earlier version of this post said 39 countries had exported 5.3 metric tons of coffee last year. Those countries exported 5.3 million metric tons.

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Coffee developed its caffeine-generating capacity independently from its cousin, cacao, according to the first whole genome study of the plant behind the brew quaffed every morning by about 100 million Americans, published online Thursday in the journal Science.

Theres been a lot of genetic sleuthing on coffee, most of it far from the tree. We have a good idea about how caffeine affects animal (particularly human) genes and alters brain chemistry. We know which of our own genes seem to draw us toward consuming coffee, tea or chocolate as well. And theres also been a heady, if somewhat contradictory, brew of studies purporting to demonstrate caffeines beneficial and deleterious effects on humans.

But how caffeine production got started has been as hard to see as a spoon in a demitasse of espresso.

Coffee has been kind of an orphan crop," said UC Davis geneticist Juan F.Medrano, who was not involved in the study. "It has been kind of forgotten in terms of DNA research. Perhaps this opens the door to expand that area.

Read more:
Meet the genes in the beans of your coffee

Dimas Ardian/Bloomberg/Getty Images

Robusta coffee berries left to dry in the Sun on Sumatra, in Indonesia.

Caffeine's buzz is so nice it evolved twice. The coffee genome has now been published, and it reveals that the coffee plant makes caffeine using a different set of genes from those found in tea, cacao and other perk-you-up plants.

Coffee plants are grown across some 11 million hectares of land, with more than two billion cups of the beverage drunk every day. It is brewed from the fermented, roasted and ground berries of Coffea canephora and Coffea arabica, known as robusta and arabica, respectively. An international team of scientists has now identified more than 25,000 protein-making genes in the robusta coffee genome. The species accounts for about one-third of the coffee produced, much of it for instant-coffee brands such as Nescafe. Arabica contains less caffeine, but its lower acidity and bitterness make it more flavourful to many coffee drinkers. However, the robusta species was selected for sequencing because its genome is simpler than arabicas.

Caffeine evolved long before sleep-deprived humans became addicted to it, probably to defend the coffee plant against predators and for other benefits. For example, coffee leaves contain the highest levels of caffeine of any part of the plant, and when they fall on the soil they stop other plants from growing nearby.

Caffeine also habituates pollinators and makes them want to come back for more, which is what it does to us, too, says Victor Albert, a genome scientist at the University of Buffalo in New York, who co-led the sequencing effort. The results were published on 4 September in Science1.

When the team looked for gene families that distinguish coffee from other plants, those that make caffeine topped the list. The genes encode methyltransferase enzymes, which transform a xanthosine molecule into caffeine by adding methyl chemical groups in three steps. Tea and cacao, meanwhile, make caffeine using different methyltransferases from those the team identified in robusta. This suggests that the ability to make caffeine evolved at least twice, in the ancestor of coffee plants and in a common ancestor of tea and cacao, Albert says.

The genome could be used to identify genes that help the plant to combat diseases, such as coffee rust, and to cope with climate change.

Caffeine-making genes might also be inactivated to create a tastier decaf. A coffee cultivar that is genetically engineered to be caffeine-free could be a welcome development for the many people who cannot tolerate the buzz. The process of removing caffeine currently involves chemical processing, and also affects the flavour (see 'Plant biotechnology: Make it a decaf'). I have to have a cup every morning, but I usually dont drink during the day because it makes me shaky, says Albert.

Read more here:
Coffee got its buzz by a different route than tea