Waxy corn

Waxy corn (maize) was found in China in 1909. As this plant showed many peculiar traits, the American breeders long used it as a genetic marker to tag the existence of hidden genes in other maize breeding programs. In 1922 a researcher found that the endosperm of waxy maize contained only amylopectin and no amylose starch molecule in opposition to normal dent maize varieties that contain both. Until World War II, the main source of starch in the USA was tapioca but when Japan severed the supply lines of the States, they forced processors to turn to waxy maize. Amylopectin or waxy starch is now used mainly in food products, but also in the textile, adhesive, corrugating and paper industry.

When feeding trials later on showed that waxy maize could produce more efficient feed gains than normal dent maize, interest in waxy maize suddenly expanded. Geneticists could show that waxy maize has a defect in metabolism precluding the synthesis of amylose in the endosperm. It is coded by a single recessive gene (wx). Waxy maize yield about 3.5% less than their normal dent counterparts and has to be isolated from any nearby normal maize fields by at least 200 meters.

The exact history of waxy maize is unknown. The first mentions of it were found in the archives of the U.S. Department of Agriculture (USDA). In 1908, the Rev. J. M. W. Farnham, a Presbyterian missionary in Shanghai, sent a sample of seeds to the U.S. Office of Foreign Seed and Plant Introduction. A note with the seeds called it: “A peculiar kind of corn. There are several colours, but they are said to be all the same variety. The corn is much more glutinous than the other varieties, so far as I know, and may be found to be of some use, perhaps as porridge.” These seeds were planted on May 9, 1908, near Washington, D.C., by a botanist named Guy N. Collins. He was able to grow 53 plants to maturity and made a thorough characterisation of these plants, including photographs, which were published in a USDA bulletin issued in December 1909.

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