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Super-hairy plants to battle global warming
Research news and discovery
ANDREW BAILEY/FLPA
In brief– Fine vine
Autumn leaves cling to the secret of colour change WE ALL enjoy the view as autumn leaves change colour, but why does it happen? The late William Hamilton, a biologist at the University of Oxford, suggested that the colour change was a warning – a signal to parasitic pests of a toxic chemical arsenal. After all, the tree actively synthesises anthocyanins, the red molecules in autumn leaves. Why go to all that trouble? If Hamilton was right, insects like aphids, whose eggs laid in autumn become leaf-muching larvae in spring, should steer clear of toxin-rich trees. His initial study showed that insects do apparently
prefer to feed on green rather than red autumn leaves, supporting the theory. Now Marco Archetti at Oxford and his colleagues at the University of Talca in Chile have studied aphid egg-laying preferences on a number of different-coloured beech trees. They found that aphids on average preferred green leaves. In spring, however, no difference was seen between the success and growth of aphids from eggs laid on red or green leaves (Journal of Evolutionary Biology, DOI: 10.1111/j.1420-9101.2007.01469.x). So if pest control was the trees’ aim, it doesn’t work very well. Archetti says that perhaps the chemical deterrents are there in autumn, not spring, but either way, the thorny question of why leaves change colour in autumn remains unsolved.
Why fur coats are cooler than shades PLANTING extra-reflective crops that bounce sunshine back into space is the latest proposal to help cool our warming world. The notion of modifying Earth’s climate with sunshades or a blanket of reflective aerosols to counteract global warming – known as geoengineering – has been around for years. But climate models suggest that this would significantly reduce rainfall. 12 | NewScientist | 5 January 2008
Now Christopher Doughty at the University of California, Irvine, and colleagues think they can get around that problem. Models show that geoengineering near the equator hits rainfall hardest, but focusing on latitudes between 30 and 60 degrees would produce a much smaller drop in rainfall. Planting crops bred or genetically modified to be more reflective could cool these regions
by an average of 1 °C. Doughty presented the research last month at the American Geophysical Union meeting in San Francisco. The key, Doughty says, is to deploy leaves that sport a thick layer of hairs, which reflect nearinfrared wavelengths back out into space. Super-hairy strains of soya have already been bred, and these reflect 3 to 5 per cent more sunlight. Doughty calculates that this would be enough – if planted in huge amounts – to generate the cooling effect.
WOULD you drink wine made from genetically engineered grapes if it had extra benefits? Such wine could be on the menu, thanks to a grape variety six times richer than normal in resveratrol, the compound in red wine associated with increased longevity, decreased heart disease and a host of other benefits. Yuejin Wang and colleagues at the Northwest Agricultural and Forestry University in Yangling, Shaanxi province, China, made the supervine by equipping it with an extra gene from a wild Chinese vine. Vitus pseudoreticulata has an unusual variant of the stilbene synthase gene, which triggers resveratrol production (Plant Cell, Tissue and Organ Culture, DOI: 10.1007/ s11240-007-9324-2). The team plans to make wine from the GM vine, though their main goal is to make grapevines more resistant to fungus, which is kept in check by resveratrol.
Earth and sun tell story on moon HERE’S another reason to go back to the moon: it may help settle a climate change controversy. Climate modellers use ice cores, tree rings and sunspot data to see how much solar energy reached Earth centuries ago and whether it affected global temperatures. Such methods are far from reliable, though: sunspot data is incomplete, while conditions on Earth can skew results. Bob Cahalan at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and colleagues calculated that boreholes on the moon just 10 metres deep would provide a temperature record stretching back to the 1600s, and so help researchers gauge solar energy in the past more accurately (Geophysical Research Letters, DOI: 10.1029/2007GL032171). www.newscientist.com
ANDREW BAILEY/FLPA
In brief– Fine vine
Autumn leaves cling to the secret of colour change WE ALL enjoy the view as autumn leaves change colour, but why does it happen? The late William Hamilton, a biologist at the University of Oxford, suggested that the colour change was a warning – a signal to parasitic pests of a toxic chemical arsenal. After all, the tree actively synthesises anthocyanins, the red molecules in autumn leaves. Why go to all that trouble? If Hamilton was right, insects like aphids, whose eggs laid in autumn become leaf-muching larvae in spring, should steer clear of toxin-rich trees. His initial study showed that insects do apparently
prefer to feed on green rather than red autumn leaves, supporting the theory. Now Marco Archetti at Oxford and his colleagues at the University of Talca in Chile have studied aphid egg-laying preferences on a number of different-coloured beech trees. They found that aphids on average preferred green leaves. In spring, however, no difference was seen between the success and growth of aphids from eggs laid on red or green leaves (Journal of Evolutionary Biology, DOI: 10.1111/j.1420-9101.2007.01469.x). So if pest control was the trees’ aim, it doesn’t work very well. Archetti says that perhaps the chemical deterrents are there in autumn, not spring, but either way, the thorny question of why leaves change colour in autumn remains unsolved.
Why fur coats are cooler than shades PLANTING extra-reflective crops that bounce sunshine back into space is the latest proposal to help cool our warming world. The notion of modifying Earth’s climate with sunshades or a blanket of reflective aerosols to counteract global warming – known as geoengineering – has been around for years. But climate models suggest that this would significantly reduce rainfall. 12 | NewScientist | 5 January 2008
Now Christopher Doughty at the University of California, Irvine, and colleagues think they can get around that problem. Models show that geoengineering near the equator hits rainfall hardest, but focusing on latitudes between 30 and 60 degrees would produce a much smaller drop in rainfall. Planting crops bred or genetically modified to be more reflective could cool these regions
by an average of 1 °C. Doughty presented the research last month at the American Geophysical Union meeting in San Francisco. The key, Doughty says, is to deploy leaves that sport a thick layer of hairs, which reflect nearinfrared wavelengths back out into space. Super-hairy strains of soya have already been bred, and these reflect 3 to 5 per cent more sunlight. Doughty calculates that this would be enough – if planted in huge amounts – to generate the cooling effect.
WOULD you drink wine made from genetically engineered grapes if it had extra benefits? Such wine could be on the menu, thanks to a grape variety six times richer than normal in resveratrol, the compound in red wine associated with increased longevity, decreased heart disease and a host of other benefits. Yuejin Wang and colleagues at the Northwest Agricultural and Forestry University in Yangling, Shaanxi province, China, made the supervine by equipping it with an extra gene from a wild Chinese vine. Vitus pseudoreticulata has an unusual variant of the stilbene synthase gene, which triggers resveratrol production (Plant Cell, Tissue and Organ Culture, DOI: 10.1007/ s11240-007-9324-2). The team plans to make wine from the GM vine, though their main goal is to make grapevines more resistant to fungus, which is kept in check by resveratrol.
Earth and sun tell story on moon HERE’S another reason to go back to the moon: it may help settle a climate change controversy. Climate modellers use ice cores, tree rings and sunspot data to see how much solar energy reached Earth centuries ago and whether it affected global temperatures. Such methods are far from reliable, though: sunspot data is incomplete, while conditions on Earth can skew results. Bob Cahalan at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and colleagues calculated that boreholes on the moon just 10 metres deep would provide a temperature record stretching back to the 1600s, and so help researchers gauge solar energy in the past more accurately (Geophysical Research Letters, DOI: 10.1029/2007GL032171). www.newscientist.com