John Browse uses the biochemistry of the castor bean to develop a better vegetable oil for biodiesel production. Photo by Shelly Hanks.

If we’re going to get serious about reducing our dependence on imported oil and producing car and truck fuel from plants, there’s a bit more work to do. Although it’s true that you can make biodiesel out of almost any oil, even if it’s been used in a fast-food fryer vat, using any old oil as fuel for your car or truck can lead to problems, says John Browse, professor at the Institute for Biological Chemistry. One of his lab’s research projects, undertaken about six years ago, concerns the production of biofuels from crop plants.

Ethanol, made from corn, is an eco-friendly fuel for gasoline engines. Biodiesel, made from vegetable oil, is the equivalent alternative fuel for diesel engines. The problem is that, as is the case for humans, you don’t want to put just any vegetable oil in your fuel tank. Oils that are high in the smaller polyunsaturated fats, like the ones you and I aren’t supposed to eat, make a bit of a mess in an internal combustion engine too, says Browse. Studies in other laboratories have shown that those fats tend to produce nitrous oxide, a harmful component of smog, and diesel made from them is unstable and can clog fuel lines or damage engine parts.

Luckily, some plants do make fats that can work well in your vehicle or have other uses in the chemical industry. One is made by the castor bean plant, and a gene involved in its production has been introduced into Arabadopsis thaliana, the small mustard-family plant that is the plant researchers’ workhorse organism.

While it might seem more straightforward either to grow castor beans and harvest the oil from them or to take the less desirable oils made by standard crop plants such as canola and change them via chemical manipulation or refining, neither would work well. Castor is a poor crop plant, says Browse. And altering oils chemically is extremely expensive and would have to be done for each new batch of oil. An appropriately engineered oil-seed plant will yield the desired oil each time.

The initial work such as Browse’s is done in Arabadopsis instead of crop plants, because Arabadopsis is well studied and understood. It has served as an excellent model system for oil-seed crop species, proving true between 80 and 90 percent of the time, says Browse.

The good news is that the Arabadopsis transformed with the castor gene makes the desirable fat. The bad news is that the plant doesn’t make much of it. “We believe it’s because the plant doesn’t know what to do with the unusual fat,” says Browse.

Browse and his lab are using three different approaches to try to increase the amount of desirable fat that the transformed plant makes, from the current 17 percent of the oil its seeds produce to 80 or 90 percent. They’ve already managed an almost two-fold increase.

The first approach involves the production and testing of a large number of other castor bean genes in a relatively short period of time. It’s a novel approach based on pulling together for the first time several new developments in plant biology, says Browse.

The second approach is to produce mutant plants, an approach Browse has used for 25 years. This time they’re mutating the plant that produces the17-percent-desirable oils and looking for improvements.

Finally, the Browse’s research team is using what they now know about the biochemistry of seed oil production to target genes likely to make a difference in the amount of the desired oil produced. They have introduced a half dozen such genes into plants and found that some of these genes can, in fact, make a large difference.

All of this work, as well as the work done by the rest of Browse’s group on the biochemistry of plant membranes, involves using basic science while considering long-term, practical goals. The ultimate aim is to find an industrial partner who will move the technology out of Arabadopsis and into a crop plant such as canola, something that makes sense because it takes a lot of work and a long time to get from a perceived practical application to a marketable product.

That the entire process is time consuming even before an industrial partner is on board is evidenced by the 25 years of fundamental research in labs like Browse’s that it’s taken for work on plant-oil biochemistry to begin to yield benefits we will be able to use. The first should be available soon in the form of soybeans and soybean oil with an altered, healthier oil content. Others will follow shortly, whether for food uses of oils, biodiesel, neutraceutical applications, or the use of plant oils as chemical feed stocks for industry.

“If that’s an advertisement for research in higher educational institutions and for focusing on feeding the engine of basic research, then it’s a very good one,” says Browse.

--Mary Aegerter 

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