This was a well attended, fascinating meeting. Dr Jim Beynon, a lecturer at Wye (Agricultural) College in Plant Pathology, talked on research and development of genetically modified crops over the last 15 years.

What is Genetic Engineering?

A human cell contains 46 chromosones, each chromosone being a different strand of DNA. Each strand of DNA in turn is made up of a chain of genes and gene presenters. A cell will contain hundreds of thousands of genes. The presenter is an enzyme (a biological catalyst) which senses the local environment (eg temperature) and "switches" its gene on. Most genes are inactive most of the time. Different genes will be active in different parts of the body (or animal or plant).

Genes are protein. An active gene provides a "template" for the creation of copies or "clones" (an unfortunate word) of identical protein. Insulin, for example, is a protein made from a gene template. Interestingly, though each individual (except for identical twins etc) has a unique genetic make up, there are many specific genes common to humans, animals and plants. Many of the most common genes act to ensure basic survival.

Nature has provided a way to cut strands of DNA and stick them, or different strands together again. Here then we have the basic route to genetic engineering. We can "snip" bits of DNA out and replace them with something different. This means looking at a strand of DNA; discovering where individual genes (and their presenters) start and finish; and working out what those genes do. This incredible technology means we can for example replace defective genes such as that causing cystic fibrosis.

Modification of Crops

Jim Beynon concentrated on work on crops. Given a growing global population, the world had to find ways to provide more food either by increasing yields, or reducing the wastage from field to consumer. However, whereas formerly yields had been increased by using more fertilizer, herbicide and pesticide, the aim now was to reduce these due to the pollution caused. Jim explained how Monsanto had modified soya so that it was resistant to the toxicity of one of its weed killers, Round Up Ready. This made weed control cheaper and easier, reducing costs and increasing yields. Transgenic soya seed contributed 2% of the 1996 USA harvest.

In another case cotton was made resistant to the bore weevil insect. Unmodified cotton crops cause substantial pollution because much insecticide is needed to keep the bore weevil at bay. The new variety cuts pollution. In a third case tomatoes had been modified to slow the rate at which they ripen . Tomatoes can now be picked later and will last longer on supermarket shelves. Average weight is 35% up, waste is reduced, and a 170 gm tin of modified tomato puree is no more expensive than a 140 gm tin of conventional fruit.

The downside?

But how, said questioners, do we know a rogue crop, through the drift of its pollen, or other means,will not spread out of control - like rabbits taken in to Australia? Could things "go wrong faster?" This seems unlikely. Modified crops are highly specialized and specialism is vulnerable. Oneís garden rapidly returns to nature without attention. With genetic engineering at least we know scientifically what is happening. Previously cross breeding was a hit and miss affair. As to commercial monopoly and loss of diversity, these are political, not scientific problems.

The future

Scientists are only at the beginning of an exciting journey. There is a need for legislation, and there will be a need for tight ethical control especially in the animal and human fields. It is imperative too for the public to be kept up to date. Nevertheless, the potential is incredible. Food scientists are now trying to find which genes detect pathogens to improve plant defence. Other agricultural scientists are working on how to grow plastic as well as fuel from crops.