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英语新闻:科学家成功解决黄瓜发苦难题

2014-11-28    来源:新华网    【      美国外教 在线口语培训
英语新闻:科学家成功解决黄瓜发苦难题
英语新闻:
 
An international team led by Chinese researchers said Thursday they have identified the genes responsible for the intense bitter taste of some cucumbers, a plague to lovers of this vegetable.
 
The research, published in the U.S. journal Science, revealed how cucumbers, believed native to India, were domesticated from their wild ancestors that have extremely bitter fruits to make them more edible.
 
"Wide cucumbers have been used as a purgative in India and because their fruits are as bitter as wormwood they are not sold on the market," Huang Sanwen of the Chinese Academy of Agricultural Sciences, who led the study, told Xinhua. "No one wants to eat wide cucumbers."
 
Today's domestic cucumbers are delicious, stress conditions such as a lack of water or temperatures too cold or too hot, however, are still able to cause them to bear bitter tasting fruits, Huang said.
 
In the new study, Huang and colleagues performed genomic and biochemical analyses on 115 diverse cucumber lines to unravel the biosynthetic pathway involved in domesticating cucumbers to the non-bitter fruits people eat today.
 
They were able to identify nine genes involved in making cucurbitacins, which confer a bitter taste in cucumbers, and showed that the trait can be traced to another two genes that switch on these nine genes to produce the compounds.
 
In short, bitterness is controlled by two "master switch" genes, "Bl" which confers bitterness in leaves and "Bt", which leads to bitter fruit, Huang said.
 
The study also found that a mutation in the Bt gene is able to keep domestic cucumbers from becoming bitter even when exposed to stress conditions such as cold temperatures.
 
Cucurbitacins protect wild plants against predators and have also been showed to have the ability to kill or suppress growth of cancer cells.
 
"The new knowledge on cucurbitacin biosynthesis laid a solid foundation for biological manufacturing and engineering of the compounds as antitumor drugs," Huang said.
 
The study also involved researchers from Nanjing Agricultural University, Hunan Agricultural University, Hunan Academy of Agricultural Sciences and Chinese Academy of Sciences, as well as researchers from universities of the United States, Japan and the Netherlands.
 
domesticate: v.引进,驯养
edible: adj.可食用的
purgative: n. 泻剂
wormwood: n.苦艾, 苦恼;萩;蒿草
biosynthetic: adj.[医]生物合成的
cucurbitacin: n.葫芦素;葫芦苦素
predator: n.捕食其他动物的动物,食肉动物
antitumor: adj.抗癌的
 
相关内容:
黄瓜是许多家庭餐桌上的常客,但难免会有“苦黄瓜”影响胃口。中国科学家主导的一项最新研究发现了一个与黄瓜发苦有关的基因,解决了长期影响黄瓜生产的一个难题,也将有助于培育抗病的黄瓜品种。
 
黄瓜原产于印度,其野生祖先和黄连一样苦,在印度常作为泻药使用。经过长期人工驯化,如今黄瓜已成为可口蔬菜,但部分黄瓜在高温和干旱等条件下依然会发苦。
 
研究人员27日在美国《科学》杂志上报告说,他们采用基因组、分子生物学和生物化学等多种技术手段研究黄瓜苦味合成、调控及驯化的分子机制。研究表明,黄瓜的苦味物质葫芦素由9个基因负责合成,而这9个基因受到2个“主开关”基因Bl和Bt的直接控制,其中Bl控制叶片苦味,Bt控制果实苦味。
研究负责人、中国农业科学院研究员黄三文告诉新华社记者:“在野生极苦黄瓜向栽培黄瓜驯化过程中,Bt基因受到选择,导致无苦味黄瓜的出现。但这个驯化过程并不完全,在逆境条件下黄瓜仍会变苦。”
 
但黄三文也指出,只要让Bt基因发生某个突变,那么黄瓜即便在高温、干旱等逆境中也不会变苦。
 
他解释说:“通过精确调节果实和叶片中Bt和Bl的表达模式,就可确保黄瓜果实中不积累苦味物质,保证黄瓜的品质,同时提高叶片中的葫芦素含量用于抵御害虫的侵害,减少农药的使用。”
 
此外,黄瓜苦味物质葫芦素具有很好的药用价值。现代医学发现,葫芦素能抑制癌细胞的生长,可与其他抗癌药物一起用于癌症治疗。葫芦素合成和调控机制的破解也为将来开发和合成治疗癌症药物也提供了新思路。
 
(新华网)


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