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https://www.economist.com/science-and-technology/2009/12/30/blow-out
New sources of rubber
Blow out
The tyres of the future may be made from dandelions
Dec 30th 2009
OTHER than being an ingredient of the more recherché sorts of salad, herbal tea or wine, dandelions are pretty useless plants. Or, at least, they were. But one species, a Russian variety called Taraxacum kok-saghyz (TKS), may yet make the big time. It produces molecules of rubber in its sap and if two research programmes, one going on in Germany and one in America, come to fruition, it could supplement—or even replace—the traditional rubber tree, Hevea brasiliensis.
Despite the invention of synthetic rubbers, there is often no good substitute for the real thing, for nothing artificial yet matches natural rubber's resilience and strength. This is because natural-rubber molecules, the product of a stepwise synthesis by enzymes, have a more regular structure than the artificial ones made by chemical engineering. Around a fifth of an average car tyre is therefore made of natural rubber. In an aeroplane tyre that figure can be more than four-fifths. Moreover, the price of synthetic rubber is tied to that of the oil from which it is made, rendering it vulnerable to changes in the oil price. Because oil is likely to become more costly in the future, natural rubber looks an attractive alternative from an economic point of view as well as an engineering one.
Natural rubber has problems, though. Growing Hevea in the Americas is hard. A disease called leaf blight means the trees have to be spaced widely. Even in Asia, currently blight-free, planting new rubber trees often means cutting down rainforest, to general disapproval. And trees, being large, take time to grow to the point where they can yield a crop. A smaller plant that could be harvested for its rubber therefore has obvious appeal.
P1. (synthetic rubber)人工合成橡胶没有天然/传统（Natural/Traditional）的橡胶好，但两年才能割一次胶；人工合成橡胶耗原油（Oil）比较多（补充知识，非本文出现，仅仅为了加深理解：合成橡胶是以石油、天然气为原料,以二烯烃和烯烃为单体聚合而成的高分子材料。）……（中间断片，好像还有内容）后面说了天然橡胶树在种植时需要间隔一定的距离，这个苛刻的种植条件使得天然橡胶树变少/人们不愿意去种天然橡胶树？（这块后面记着紧跟着一个XX Risk，看了好几遍没看明白），然后后面是说找替代方法/解决问题的方法
One proposal is to use guayule, a shrub that grows in arid regions and produces rubber that is free from allergenic proteins, which makes it useful for items such as surgical gloves. Desert plants, however, tend to be slow growing—guayule takes two years to mature. Yulex, a firm that has commercialised guayule, gets an annual crop of 400 kilograms per hectare. Hevea can yield four or five times that figure. Which is where TKS could come in. Dandelions are regarded as weeds for a reason—they are robust, fast-growing plants that can be pulled up for processing and resown easily, possibly yielding two harvests a year. If they could be turned into usable crops, they could outstrip even Hevea.
To this end, Christian Schulze Gronover of the Fraunhofer Institute for Molecular Biology and Applied Ecology in Aachen, Germany, and his colleagues have identified the genes that allow TKS to produce usable rubber. In particular, they have discovered an enzyme called polyphenoloxidase that is responsible for making its rubbery sap coagulate.
P3. 第三段是最难读的一段，里面涉及到了很多technical的术语，开始准备硬啃，扫了两三句发现难度有些大，就开始跳读，出现的词确定有enzyme, 好像有像RNA之类一些比较复杂的术语（实在记不得了呀..），不过我好像没遇到关于这段的题，但这段真的是最难读的
From the plant's point of view this coagulation is a good thing. The evolutionary purpose of rubber, and the reason why it has appeared independently in plants as diverse as trees, guayule and dandelions, is that it gums up the mouthparts of herbivorous insects. Human users, however, do not want it to coagulate too soon, and Dr Schulze Gronover has found a way to switch polyphenoloxidase off, using a technique called RNA interference. This intercepts and destroys the molecular messengers that carry instructions from the polyphenoloxidase gene to make the enzyme, meaning that rubber can be extracted more easily from the plant.
Meanwhile, in America Matthew Kleinhenz of Ohio State University is working on increasing the yield of rubber from TKS. Dr Kleinhenz is doing things the old-fashioned way, growing different strains of TKS, grinding up the roots (where most of the sap is found) to see which have the highest rubber content, and crossbreeding the winners. His aim is to create a plant that is both high-yielding and has roots chunky enough to be harvested mechanically by the sort of device now used to pick carrots.
P4. 我记得是有P4的，而且比P3短很多，大概就是一些总结性话语；很清楚地记得全文最后又去和前面人工合成橡胶用Oil多的问题进行了勾连（本以为会考关于这个的细节，但是并没有）（Oil 这个点是全文的结尾）
Combining the two approaches—high-tech bioengineering and low-tech plant breeding—may produce that rarity in the modern world, a whole new crop species. It would also mark a step on a journey that some see as the way forward: a return to the use of plant-based products that have, briefly, been overshadowed by the transient availability of cheap oil.
https://forum.chasedream.com/thread-1281895-1-1.html
https://forum.chasedream.com/thread-1326607-1-1.html
3.rubber橡胶树以及新技术rna什么的，看考古吧
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发表于 2018-7-30 13:51:33
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