VOA慢速英语--美国考虑基因工程树

US to Consider Genetically³ Engineered Tree

American scientists are harvesting chestnuts⁵ like no other found in nature. These researchers work at New York State's College of Environmental Science and Forestry⁶ in Syracuse, New York. About half the nuts they collect have a gene¹ that provides resistance to a condition known as blight⁷. The disease killed nearly all American chestnut⁴ trees during the 20th century.

The researchers will soon ask United States officials for permission to give out thousands of genetically engineered chestnut trees. Their hope is to return the American chestnut to many communities across the country.

The plan could expand the world of genetically engineered plants from farmland into forests. It also raises the question that scientists and others have been asking: Should genetic² engineering be used in the wild to help save trees?

Some people are afraid of starting what they call an "irreversible experiment" in a highly complex ecosystem⁸. Others see a technology already used in food production, one that could help save forests under attack from invasive organisms and diseases.

"We have this technology, it's a very powerful technology, and we can use that now to save a species," said William Powell, a molecular⁹ plant biologist. Powell directs the American Chestnut Research and Restoration Project at the college.

The researchers will ask the U.S. Department of Agriculture (USDA) to consider approving an American chestnut tree with a gene from wheat. The gene helps the tree resist cryphonectria parasitica, a fungus¹⁰ accidentally brought to the United States over 100 years ago.

The blight destroyed a tree species once found in forests from Maine to Georgia. Nuts from up to 4 billion trees were fed to farm animals, and its wood was used to build homes for American settlers. Then came the blight.

Creating a blight-resistant tree

Efforts to create American chestnut trees with an ability to fight the blight, like Chinese chestnut trees, are very complex. The genetically engineered method is easier, scientists say.

Powell and his research partner Charles Maynard began working many years ago at the request of the New York office of the American Chestnut Foundation. The added wheat gene enables the trees to make an enzyme¹¹ that breaks down the fungus.

About half the chestnuts will have the gene, researchers say.

The researchers will ask the USDA's Animal and Plant Health Inspection¹² Service to examine the risks of the new tree. They want the agency to change its rules.

The USDA commonly approves genetically engineered crops. Most corn and soybean fields in the United States are used to grow crops engineered in some way.

But engineered trees have not been planted in the forests for environmental reasons. That could change as genetic changes become more common and trees are increasingly threatened by climate change and blight.

"If the chestnut is approved ... I think it's accurate to say that it does help pave the way for other biotech trees," said Jason Delborne. He is an associate professor of science, policy and society at North Carolina State University.

Long-term effects

Some scientists are concerned about the long-term effects of adding planting trees that can live for more than 200 years.

Forest eco-systems are complex and the current system of rule-making is not up to the job of studying the environmental and societal risks, said biotechnology expert Doug Gurian-Sherman.

"I think we have to step back and ask whether our ability to manipulate things is getting ahead of our ability to understand their impacts," he said. Gurian-Sherman is a former senior scientist with the Union of Concerned Scientists.

Yet trees are dying from newly identified diseases and some scientists say biotech could help where other efforts have failed.

"Compared to what's happening in the world...I think the risks of making a mistake due to (changing) a gene wrong are so small compared to the risks of doing nothing," said Steven Strauss. He is a forest biotechnologist at Oregon State University in Corvallis.

Words in This Story

irreversible - adj. unchangeable

invasive – adj. spreads quickly and kills other plans

fungus – n. a living organism that spreads and lives on dead things

species – n. a group of individuals having the same physical and genetic qualities

manipulate – v. to change on purpose

1 gene   

n.遗传因子，基因

参考例句：

• A single gene may have many effects.单一基因可能具有很多种效应。
• The targeting of gene therapy has been paid close attention.其中基因治疗的靶向性是值得密切关注的问题之一。

2 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。

3 genetically   

adv.遗传上

参考例句：

• All the bees in the colony are genetically related. 同一群体的蜜蜂都有亲缘关系。
• Genetically modified foods have already arrived on American dinner tables. 经基因改造加工过的食物已端上了美国人的餐桌。 来自英汉非文学 - 生命科学 - 基因与食物

4 chestnut   

n.栗树，栗子

参考例句：

• We have a chestnut tree in the bottom of our garden.我们的花园尽头有一棵栗树。
• In summer we had tea outdoors,under the chestnut tree.夏天我们在室外栗树下喝茶。

5 chestnuts   

n.栗子( chestnut的名词复数 )；栗色；栗树；栗色马

参考例句：

• A man in the street was selling bags of hot chestnuts. 街上有个男人在卖一包包热栗子。 来自《简明英汉词典》
• Talk of chestnuts loosened the tongue of this inarticulate young man. 因为栗子，正苦无话可说的年青人，得到同情他的人了。 来自汉英文学 - 中国现代小说

6 forestry   

n.森林学；林业

参考例句：

• At present, the Chinese forestry is being at a significant transforming period. 当前, 我国的林业正处于一个重大的转折时期。
• Anhua is one of the key forestry counties in Hunan province. 安化县是湖南省重点林区县之一。

7 blight   

n.枯萎病；造成破坏的因素；vt.破坏，摧残

参考例句：

• The apple crop was wiped out by blight.枯萎病使苹果全无收成。
• There is a blight on all his efforts.他的一切努力都遭到挫折。

8 ecosystem   

n.生态系统

参考例句：

• This destroyed the ecosystem of the island.这样破坏了岛上的生态系统。
• We all have an interest in maintaining the integrity of the ecosystem.维持生态系统的完整是我们共同的利益。

9 molecular   

adj.分子的；克分子的

参考例句：

• The research will provide direct insight into molecular mechanisms.这项研究将使人能够直接地了解分子的机理。
• For the pressure to become zero, molecular bombardment must cease.当压强趋近于零时，分子的碰撞就停止了。

10 fungus   

n.真菌，真菌类植物

参考例句：

• Mushrooms are a type of fungus.蘑菇是一种真菌。
• This fungus can just be detected by the unaided eye.这种真菌只用肉眼就能检查出。

11 enzyme   

n.酵素，酶

参考例句：

• Above a certain temperature,the enzyme molecule will become unfolded.超过一定温度，酶分子将会展开。
• An enzyme that dissolves the fibrin of blood clots.能溶解血凝块中的纤维的酶。

12 inspection   

n.检查，审查，检阅

参考例句：

• On random inspection the meat was found to be bad.经抽查，发现肉变质了。
• The soldiers lined up for their daily inspection by their officers.士兵们列队接受军官的日常检阅。