The humble lettuce has been shown to hold the key to producing a new form of natural rubber thanks to seven years of painstaking research by scientists at the University of Calgary. Associate professor Dae-Kyun Ro and PhD student Yang Qu, from the university’s department of biological science, made the breakthrough they believe will eventually lessen the world’s need for petrochemicals in the large-scale production of products such as tires. The researchers discovered that once a lettuce plant bolts the elongated stem produces milky latex containing a biopolymer from which they identified a key enzyme that can synthesize natural rubber. Those accepted findings, which were published in the prestigious Journal of Biological Chemistry last week, represent the first natural biosynthetic model for rubber production in more than half a century.

“Nobody knew how natural rubber is synthesized in plants so we decided to use lettuce as a model system. We found it produces very high quality natural rubber but of a very low quantity,” said Ro. “When lettuce bolts and you prick the stem with a pin you will find a white, milky liquid. We analyzed this and found that the quality is almost the same as that from the Brazilian rubber tree, which is where natural rubber is found today,” he added. Natural rubber comprises almost half of all the world’s consumption with the rest produced synthetically by the petrochemical industry. Ro said the Brazilian rubber tree is now rare in its native country because of disease with the world’s supply now concentrated in South East Asia. “Replantation occurred in areas such as Indonesia and Thailand, but those countries have only one species and it is located in one geographical area so they are very susceptible for a disease outbreak. If that happens we won’t have a proper supply of natural rubber,” added Ro. Such supply is vital as synthetic rubber made by the petrochemical industry is not as high in quality — for example about 20 per cent of the rubber in a regular car tire needs to be natural to allow for elasticity while high performance tires, such as those on aircraft, need to be almost entirely made of the natural product. “Natural rubber is also carbon neutral. Increasing our use will have significant benefits on the environment by reducing reliance on petrochemicals,” added the Korean-born scientist, who has lived in Calgary for nine years. Though the researchers made the breakthrough using lettuce they believe future commercial production will require a different plant to ensure quantities large enough to make it economically viable. “We cannot grow lettuce in the garden to produce a car tire,” said Ro. In the 1930s, Thomas Edison, Henry Ford and the Firestone Tire Company set up a joint business venture to look into producing natural rubber from plants other than the Brazilian rubber tree. They settled upon a Canadian weed called goldenrod because of its high quantity of natural rubber. There was a problem, one that the U of C scientists think their work on lettuce will solve. “The quality from the goldenrod plant was very low. But we have identified the important genes from the lettuce and we can make the goldenrod produce high quality rubber and we can grow that in Canada,” said Ro. There are other rubber producing plants native to Canada, the researchers are keen to do more work on the dandelion, which contains rubber in the root. They are also hoping to produce a prototype plant that is commercially viable both in quality and quantity within five to ten years. “The question is ‘can you produce natural rubber for a cheap cost.’ That is challenging. Quantity and yield are important if we want to compete commercially with synthetic rubber,” said Ro, who credits his student Qu with doing 80 per cent of the work leading to the breakthrough.

Source: Calgary Herald