Article suitable for older students

Question for October 2018

Does the different colour of maize depend on where it’s grown?? Asked by Green Park School. Chosen and answered by Professor Michael Heinrich

The story of maize or corn brings together many disciplines, an attention this important crop most certainly deserves. In 1983 and more than 30 years after her initial discoveries the botanist Barbara McClintock (1902 - 1992) received the Nobel Prize in Physiology or Medicine for discovering “mobile genetic elements” and for this studies in maize (Zea mays L.) were essential. Early in her career (in the 1930s) she developed methods to visualize and characterize maize chromosomes.

And this then answer the questions: Some of these genes code for the colours of maize. Very important in this context are her systematic studies on mosaic colour patterns of the seeds, and specifically the genetic mechanisms inheritance. This was called jumping genes and later transposons. Later in her career Barbara McClintock also looked at the origin of maize and the genetic differences between the varieties and cultivars* of maize.

Let’s go back to México: In Nahuatl cintli means “dried maize still on the cob” and elote means a corncob – so the language is rich in names for what we just call maize or corn. And they even had a god – Centeotl, who is the son of the earth goddess Tlazolteotl and of the planet Mercury Piltzintecuhtli. Centeotl was one of the most important gods of the Aztecs and of course his head was adorned with maize. All this tells us how important maize was to the Aztecs and they developed (bred) many cultivars also differing in their colour.

So, no it does not depend on where it is grown, but the colour tells us a lot about genetics and the ingenuity of the Aztecs in breeding new varieties of maize.

* A ‘cultivar’ means a variety cultivated by selective breeding.

Picture sources:-
• Pix 1 & 2: photos from Wikipedia (Barbara McClintock)
• Pic 3: Illustration by and courtesy of Gwendal Uguen
• Pic 4: photo from Wikipedia (List of sweetcorn varieties).

‘Why did the Aztecs worship maize?’

Professor Michael Heinrich has answered 2 questions altogether.

Does the different colour of maize depend on where it’s grown?

How many different colours of maize are there?