CAUGHT IN A MAIZE OF GENES.

• Author: Werner, Louis
• Position: History of corn varieties

SINCE PRE-COLUMBIAN TIMES, THE VERSATILE CORN PLANT HAS BEEN THE OBJECT OF EXPERIMENTATION AND GENETIC MANIPULATION WITH FAR-REACHING CONSEQUENCES

Of all the New World foods that so impressed the Europeans, it was maize they spread the fastest and farthest around the globe. From that sixth day of November 1492, when Columbus noted in his journal that "it tasted very good," only a brief moment in the ten-millennia-long history of agriculture needed to pass before maize was grown and eaten on every continent. A maize crop was planted in Spain the very next season. Within fifty years, Africans along the Congo River depended on it for their very life. Before the century's end, maize joined rice on the Chinese dinner table and became a favored subject of brush paintings. China today is the world's second largest maize producer.

Few other food crops are as versatile in the hands of the chef or adaptable to the circumstances of the farmer. In the kitchen, maize can be baked, boiled, and brewed or pickled, parched, and popped. In the field, it can be grown at sea level or twelve thousand feet, in the desert or the tropics, and from 50 degrees north latitude to 40 degrees south latitude.

But maize did not become this outstandingly successful crop by dint of creative cooks and cultivators alone. Ever since Columbus took his first discriminating bite, scientists too have played their part in observing, classifying, improving, and utterly reinventing--more than ever in the age of genetic engineering--this member of the grass family known taxonomically as Zea mays.

But just as scientists have helped maize to improve and diversify, so maize has helped science to progress and develop. As an object of study and a subject of experimentation, maize grows at the center of some of the century's great scientific breakthroughs.

Maize was the test organism in the 1906 discovery of directed hybrid vigor, which gave new insight into the rule of Mendelian genetics, and in the 1946 finding of transposable genes, which contradicted the very same Mendelian rule but won Barbara McClintock the Nobel Prize for Medicine. Indeed, maize plants are used in research as commonly as white mice and fruit flies.

One reason that maize is the scientists' favorite is that, thanks to its widely separated male (the tassel) and female (the corn silk) reproductive organs, breeding can be easily manipulated. By removing the tassel or bagging the ear during pollination, a plant can be hand...