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Barbara McClintock in the year 1983 received the Nobel Prize for the discovery of transposons in maize.
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The kernel of wild variety of maize are purple, blue or black.
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This colour is the result of a molecule called anthocyanin.
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If the anthocyanin pathway in corn is disabled, the corn kernels are yellow.
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Yellow corn is a mutant.
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The molecule which gives corn its yellow colour belongs to the class Carotenoids.
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Corn kernels which are deficient in both, anthocyanins as well as carotenoids are white.
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During her studies on maize development and chromosomal breakages in maize, McClintock discovered that maize plants which develop patched kernels do not inherit this phenotype in a Mendelian fashion.
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Instead, they develop their colour patterns due to the action of transposons moving in and out of the genome.
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McClintock realized that the jumping genes whose effect she observed consisted of a two-component system - An activator element (Ac) and a dissociator element (Ds).
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Ac is able to transpose by itself, but transposition of Ds requires the presence of Ac; otherwise, Ds would be unable to move.
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Ds is derived from Ac by means of a truncation removing its transposase.
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Many Transposon insertions remain “silent”, though, because they are located within non-coding regions of the maize genome.
[Reference: http://bytesizebio.net/wp-content/uploads/2011/06/indian_corn_cobs.png]
