July 8, 2010
Source: SciDev.Net
by Jacob Aron
Farmers may one day be able to target pesticides to only those parts of their fields that are at risk of disease simply by noting which ones are glowing, according to researchers.
Scientists have genetically engineered the natural immune system of the tobacco plant to make it change colour or glow in the presence of viruses, bacteria and other pathogens known to reduce crop yields, which normally force farmers to apply costly pesticides.
In laboratory tests, these 'photosensory' plants turn red or produce a fluorescent glow when infected.
Although the system has so far been tested only in tobacco plants, lead researcher Neal Stewart, a plant scientist at the US-based University of Tennessee, told SciDev.Net it could easily be adapted to other crops.
Instead of planting entire fields with these plants, he suggested they could be strategically placed throughout the field. This would introduce only a small number of GM plants into the environment, so farmers could choose not to harvest them while still benefiting from their pathogen-detecting ability.
"If we know something bad is happening, the farmer can treat certain areas rather than the whole field," he said.
Stewart's sensory plants could also be adapted to detect landmines by changing their leaf colour.
The next step, said Stewart, is to conduct field tests to discover exactly how the new plants respond to different pathogens in a field setting.
"It would be very exciting to partner with research groups in developing countries that might not have access to a lot of pesticides," he said. "Knowing early on that a plant disease could sweep through might make a big difference to [those] farmers."
But Andrija Finka, a biologist at the University of Lausanne, Switzerland, expressed concerns that farmers in developing countries would not be able to grow the high-tech plants. "It will be really hard to maintain them," he told SciDev.Net.
And Janice Lake, a plant physiologist at the University of Sheffield, United Kingdom, said that plant responses to different stresses may be too similar to distinguish, because the same types of molecules can signal a range of problems.
"I'm not sure how you would identify exact stresses," she said.
The researchers presented their work at the 12th World Congress of the International Association for Plant Biotechnology, in the United States, last month (6–11 June).
Photo credit: Mary Rudis, Mitra Mazarei and Wusheng Liu
发光的作物可以将杀虫剂使用降到最小化
科学家有朝一日可能只要通过观察哪些作物正在发光就可以对田间面临病害风险的植物有针对性地施用杀虫剂。
科学家对烟草植株的天然免疫系统进行了遗传改造，从而让它能够在病毒、细菌和其他已知能减少作物产量的病原体存在的情况下改变颜色或者发光，这些病原体通常会迫使农民施用昂贵的杀虫剂。
在实验室测试中，这些“光感”植物受到感染的时候变成了红色或者产生了荧光。
尽管这个系统迄今为止只在烟草上进行了测试，美国田纳西大学的植物科学家、领导该研究Neal Stewart告诉本网站说，它可以很容易地用于其他作物。
他提出，不需要在整个大田中种植这些植物，可以把它们策略性地种植在大田中。这只需要把少量转基因作物引入到环境中，因此农民可以选择不收获它们，同时仍然享受它们的病原体探测能力的益处。
“如果我们知道不好的事情正在发生，农民就可以处理特定区域而非整片农田。”他说。
Stewart的传感植物还可能通过改变叶片颜色而探测地雷。
Stewart说，下一步是进行大田测试从而发现这种新植物究竟如何对田间环境的各种不同的病原体做出反应。
“与无法获取许多种杀虫剂的发展中国家的研究团体进行合作将是非常令人激动的，”他说，“及早了解一种植物疾病可能大规模流行，这对于农民很重要。”
但是瑞士洛桑大学的生物学家Andrija Finka表达了一些担忧，即发展中国家的农民可能无法种植这些高技术植物。“维护它们实在太困难了。”他告诉本网站说。
英国谢菲尔德大学的植物生理学家Janice Lake说，植物对不同胁迫的响应可能太相似而无法区分，因为同种类型的分子可能表明一大批问题。
“我不知道你究竟如何辨明具体的胁迫类型。”她说。
这组科学家在上个月（6月6-11日）在美国举行的国际植物生物技术协会第12届世界大会上公布了他们的研究。
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