VOA慢速英语:Steps Toward Drought-Resistant Crops, 'Designer' Rice

A discovery in a laboratory could help lead to new generation of drought-resistant crops. Drought conditions cause plants to produce a stress hormone called abscisic acid. This chemical activates a set of protein molecules called receptors. These receptors then activate a series of changes to help the plant survive.
一项实验室发现可能有助于发现新一代耐旱作物。干旱状况会导致作物产生一种被称为脱落酸的应激激素。这种化学物质会激活一套被称为受体的蛋白质分子。这些受体随后会激活一系列变化，以帮助植物存活。

The natural reaction of the receptors is to close so-called guard cells on and inside the leaves. That closure decreases water loss and stops the plant from growing to save water during a drought.
受体的自然反应就是关闭植物叶子内外的所谓保卫细胞。关闭后会减少水分流失，使植物在干旱时期停止生长以节约水分。
 
Researchers say they have discovered a way to "supercharge," or increase, this reaction. Sean Cutler at the University of California, Riverside, led the team. The scientists engineered abscisic acid receptors that can be turned on at will and stay on. They tested hundreds of versions of engineered receptor genes until they found ones that worked right together.
研究人员称，他们已经发现一种“增压”的方式，来加强这种反应。加州大学河滨分校的Sean Cutler领导该研究小组。科学家人工改造的脱落酸受体可以随意开启并保持这一状态。他们检测了数百种人工改造受体基因直到发现可行的一种。
 

The team worked with Arabidopsis, a plant often used in experiments.  The results recently appeared in the Proceedings of the National Academy of Sciences.
该小组采用了南芥，一种实验常用的植物。研究结果最近发表在《美国国家科学院学报》上。

Professor Cutler says testing the new receptors in the field may take several years. He also points out that drought is not the only cause of plant stress.
Cutler教授表示，测试在该领域的新的受体，可能需要几年的时间。他还指出，干旱不是植物抗逆性的唯一原因。

SEAN CUTLER: "If a plant grows in the deserts normally, like a cactus, what would be stressful for a crop plant is not stressful for a cactus because it has evolved to live in that ecological niche where the water is very rare. So it would really mean, you know, any significant deviation from the normal or ideal growth conditions for an organism."
SEAN CUTLER：“如果一种植物常年生长在沙漠里，例如仙人掌。对这种植物来说可能会产生巨大抗逆性，但对仙人掌来说不会。因为仙人掌已经进化到在那种极度缺水的生态小生境中存活。所以它可能意味着一种有机体在正常和理想生长环境的显著偏差。”

In another development, scientists have produced a new system for analyzing genetic markers in rice plants. A genetic marker is a DNA sequence with a known location. It can help scientists identify nearby genes linked to individual qualities, or traits.
另据报道，科学家已经制造出分析水稻遗传标记的新系统。遗传标记是一种位置已知的DNA序列。它可以帮助科学家确定与特质或性状相关的附近基因。

Anna McClung and Georgia Eizenga are genetic scientists with the United States Department of Agriculture. Their new system will let researchers genetically "fingerprint" rice varieties and gain a better understanding of the markers.
Anna McClung和Georgia Eizenga是美国农业部的遗传学家。他们的新系统可以让研究人员从基因上鉴别水稻品种，并能够更好地了解标记。

Until now, breeders have been limited to using perhaps two hundred markers. But modern technology lets scientists identify differences throughout the plant's genome, its genetic map.  Ms. McClung says that means the ability to identify new genes that control biological pathways.
到现在为止，育种者限于使用两百种左右的标记。但是，现代科技让科学家确定植物的整个基因组的差异，也就遗传图谱。麦克朗女士说，这意味着有能力识别控制生物途径的新基因。

ANNA McCLUNG: "You know, biological pathways in the plant that may control yield, disease resistance, nutritional quality ... "
ANNA McCLUNG：“你知道的，植物的生物途径可以控制产量，抗病性，营养品质...”

The finding could make it easier in the future for farmers to grow "designer rice," rice bred to meet their specific needs.
这一发现可能使农民将来更容易种植出"专门设计的水稻 "，以满足他们特定的需求。