The corn's new clothes

Leggi questo post in Italiano.

If you never imagined to see a multicolor corn cob in your life, you'll change your mind after reading this post.

Believe it or not, coloured corn does exist. To be precise, it was crafted not too long ago, thanks to the patience and a certain degree of experience with corn growing of a US farmer, Carl Barnes.

Mr Barnes, a man with Cherokee roots, still living in Oklahoma, wanted to trace back his origins growing ancient varieties of corn, which had sunken into oblivion, replaced by hardy and pest resistant cultivars.

While his corn was growing, he imagined that he might have the possibility to create a brand new variety of corn with multicoloured kernels, all in the same hue, or beautiful rainbow cobs.

Do not fear, I am not talking about GMO; there's already plenty of people saying everything, usually talking out of turn. I would like to talk about a man who devoted a great part of his life to the selection of plants with particular cob colours. As a result, he planted this crops again, observing what would happen in the next generation.

To be complete, we have to keep in mind that the cob's colour is a characteristic which is not influenced by the environment, unlike, for example, the height of the plant. Thus, the multicolor cob only derives from man-made hybridization.

We do not know precisely for how many years Barnes worked to obtain the Glass Gem Corn, picking the cobs with the vividest colours, however the result is really striking and eye-catching.

Most of the corn diversity existing in the past is now gone, probably due to the diffusion of one-crop cultivation, more resistant varieties with a better yield. This has inevitably caused a restriction in plant biodiversity; in fact every plant which was not productive or resistant, became an endangered species.

You can have a look at the Glass Gem Corn in the photos below. The cobs are edible, though is preferable to use them for flour and pop corn than to eat the corn directly from the cob. However, I'm afraid you won't be able to show your friends a coloured pop corn, as it is white, just like the “normal” one.

Of course, the kernels can be used to grow a new generation of corn!

Glass Gem Corn - via Seeds Trust Facebook Page

There's an obvious question to ask: what is the purpose of a multicoloured cob, if the yellow ones are edible?

In my opinion, adding a little more diversity in a constantly uniformating world wouldn't be bad.

Furthermore, the rainbow cob honours the job of a passionated man, with a unique perseverance we all should keep in mind.

Carl Barnes was only the first of professional and amateur farmers who began growing Glass Gem Corn. The precious kernels were donated to the Seeds Trust, a little family-run company in Arizona, who is in charge for the preservation of this variety of corn. Later on, the company evolved into the NATIVE Seeds/Search, a nonprofit organization preserving seeds of particular plant species (www.nativeseeds.org).

On their website you can find an online shop, from where you can order a variety of plant seeds, among which, of course, the famous Glass Gem Corn.

In 1983 Barbara McClintock was awarded with the Nobel prize for her research about transposable elements in corn genome.

The transposable elements are parts of the DNA which jump here and there inside the genome (even the human genome) and alter in some different ways the genetic expression: as a result of the insertion of a transposon in its sequence, a gene can stop producing proteins.

The great discovery in McClintock's work was that the genome was not static. We could say, just keeping it simple, that there are two types of transposable elements: the ones which can move by themselves and the ones which cannot.

It is very similar to the story of the two kinds of people in the world: those on the driver's seat going wherever they want and those on the passenger's seat, always needing someone to drive them anywhere.

Unlike genetic recombination, which is aimed to a determined position on the genes, transposition is casual and it can happen on each of the 10 corn chromosomes.

A kernel has three layers: endosperm, the internal part, pericarp, the middle layer, and aleurone, the external part.

The kernel's colour is regulated by the overlapping of these three layers. They can have different hue or even show no colour, as it happens in the endosperm when the transposon interrupts the gene that usually produces the protein responsible for the yellow colour.

After reading this text, a friend of mine asked a question that made me deepen my researches. I'll write it here for you.

Most of the colours displayed by the cobs are secondary; they are formed by the overlapping of different coloured layers. Even to me, a total ignorant about drawing and painting, that sounds right.

Yellow and red, primary colours, are pretty normal even in common experience: you saw plenty of yellow cobs and the red ones are composed of kernels with a white endosperm and red external layers, rich in anthocyanins and phlobaphenes.

But how do you explain the blue kernels? It is a primary colour, so the overlapping game does not work anymore; furthermore, the external layers are usually reddish, so how do you get this colour?

Well, blue corn does exist, dear readers, and it is simply corn with a high concentration of anthocyanins in the external layers of the kernel, which turn blue from the usual red hue.

It is one of that ancient varieties of corn we were talking about at the beginning of this post. It was once grown by the native american tribes of Hopi and it is still grown today in some US states, like Arizona and New Mexico, as well as in Mexico. You would be surprised to find blue corn chips in the United States!

So, even for blue kernels we can speak about overlapping of anthocyanin-rich layers on a white endosperm.

If you want to widen your knowledge about this topic, you can check this post, that was really revealing for me: Jumping genes make fall come alive from Kirk Maxey's Blog.

I would also like to personally thank the author of this blog for his kind helpfulness and dedicate this post to him.