by Noel Kingsbury
Copyright © 2009 The University of Chicago Press
Published by The University of Chicago Press

From Chapter 11

CORNUCOPIA – genetics opens up the horn of plenty

Anyone today marketing a food called ‘Nuclear Rice’ would face severe marketing problems. But in the 1950s and early 1960s, nuclear energy was part of the technological revolution which, it was widely hoped, would transform the world. Despite its role in the immensely destructive power of the atomic bomb, nuclear energy was generally seen as good, to the extent that it could be used to sell products as modern and efficient; the author once had a set of kitchen scales called the ‘Nuclear Scales’ from this period, with the name surrounded by a stylized explosion. It was the Hungarians who came up with the high-yielding ‘Nucleoryza’ – during the 1960s it covered 80% of the Hungarian rice growing area. It was the result of radiation breeding, one of the most extraordinary chapters in the whole history of plant breeding. If it had never been invented, and someone suggested it today, the outcry would be enormous; popular fears of radiation and chemical residues would combine with all the arguments raised against genetic modification. Unlike GM, the change induced in the genetic material is random and unpredictable, although the technique has greatly improved its level of precision over the years. The fact that almost no-one outside the world of the plant sciences knows about it illustrates just how little popular (or pressure group) interest there was in plant breeding until relatively recently. A basic knowledge of the story of induced mutation can do much to put the alarmist fears raised by some in the GM debate into a very different perspective.

Mutations, or sports, have long been recognized as a source of sudden and spontaneous variation in plants - of all kinds. Breeders were often frustrated – Mendelian genetics enabled them to work with the level of variation they already had, and what they had could perhaps be increased by new introductions or crossing with more distant relatives. But breeders have always on the lookout for that extra level of variation, that magic trait which could enable them to transform the plant and raise a new variety that would take the world by storm. Mutations offer a source of novelty – but natural mutations are rare. Any method had to be seized which offered the possibility of improving on the rather ungenerous hand that nature had given.

Ancient Chinese texts record mutant cereal crops as early as 300BCE. Hugo de Vries (see Chapter 6) coined the term in 1901 with the publication of his first researches on mutations, which he believed played a major part in evolution. De Vries also predicted that mutations might be generated artificially. That chromosomes can be changed by X-rays, and that these changes are permanent, was made in 1927, by Hermann J.Muller (1890-1967), an associate of Thomas H.Morgan (1866-1945), the American geneticist who had, earlier in the century, shown that it was chromosomes which were the carriers of heredity. The obvious next step was to speed up the natural slow rate of mutation - using X-rays and other forms of radiation which increases the natural frequency of mutation. The first results were obtained with the geneticist’s favourite subject, the fruit fly, but corn and barley were soon tried.

Initially, X-rays and gamma rays were used to bombard seeds in order to stimulate mutations. Later, cutting material, or other plant parts which could be used for vegetative propagation were used. During the 1940s, it was discovered that a variety of chemical reagents could be used to induce mutations; compounds with highly reactive alkyl groups for example which react with DNA. The most useful has been Ethylmethane sulfonate (EMS) – a compound related to mustard oils.

Mutation breeding’s high point was probably the early 1990s – before GM technology began to threaten its hard-earned position as a viable source of variation. A survey conducted in 1990 showed that a total of around a thousand commercially-viable crop varieties had originated through induced mutation: of the 998 whose origin could be definitely traced, gamma rays were overwhelmingly the source of most (68% of seed propagated crops, 44% of vegetatively), X-rays next (12% and 49%), while chemical mutagens for only a small minority (15% and 3%).

Swedish researchers were amongst the early enthusiasts, with Nilsson-Ehle and Åke Gustafsson (1908-1988) beginning to work with a variety of crops in the 1930s. Gustafsson became known as the ‘father of mutation breeding’; he was a gifted speaker, which stood him in good stead in debates with skeptical colleagues. Barley was a particular interest and focus of his researches; he was also instrumental in establishing a gamma field at the Bålsgard Fruit Breeding Station – from which came many useful cultivars. Intriguingly, he was also noted as an essayist and poet. The International Atomic Energy Agency, established in Vienna in 1957 has played a major role in promoting radiation breeding. Mutation breeding’s first commercial success was a tobacco, ‘Chlorina’, achieved with X-rays in 1934 by a Dutch worker at a research station in the then Dutch colony of Java. By 1936 it or plants bred from it, was grown on 10% of the total tobacco area – its success being its light leaf color, useful for use as a wrapper for cigars. Barley has responded particularly well, the first commercial variety being released in the Soviet-satellite German Democratic Republic in 1955, ‘Jutta’, also the result of bombardment with X-rays. By 1981, a total of 61 barley varieties had been released; many were early maturing, had increased yield, shorter and stiffer straw, increased drought-resistance or higher protein content. Perhaps one of the greatest individual successes has been the durum wheat ‘Creso’, which covered about one third of the total acreage for the crop in Italy in the early 1990s. Those who might be worried about ‘irradiated genes’ will by now be choking on their spaghetti. Accountants were certainly not choking – it has been calculated that during ten years of production ‘Creso’ generated $1,800 million in additional value for Italian farmers – the total costs of the mutation breeding program on durum at the Casaccia centre near Rome over a fifteen year period came to only $3.5million.

excerpts from chapter 12 >>