Zea mays

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IMG_3531Maize_600.JPG

Zea mays – maize, or Indian corn.

6 Comments

People should know that the (dried-out, inedible) “Indian corn” that you see in the supermarkets in the U.S. around Thanksgiving is not really a separate, ancient strain of maize. It is just ordinary maize that has various color mutants and has been crossed randomly so the kernels differ randomly in color.

The ears that are used in genetics classes as examples of Mendelian segregation have some of the same mutants, but with care taken that each ear has only one pollen parent so that its kernels show the outcome of the cross of two individuals.

Joe Felsenstein said:

People should know that the (dried-out, inedible) “Indian corn” that you see in the supermarkets in the U.S. around Thanksgiving is not really a separate, ancient strain of maize. It is just ordinary maize that has various color mutants and has been crossed randomly so the kernels differ randomly in color.

The ears that are used in genetics classes as examples of Mendelian segregation have some of the same mutants, but with care taken that each ear has only one pollen parent so that its kernels show the outcome of the cross of two individuals.

Felsenstein should know that the color of Indian corn kernels is due to transposons (things he considers junk DNA). When they insert themselves near pigment production genes, they can either disable or reduce the expression of that gene. This is an interesting example of how random mutation (in this case insertion) can produce phenotypic diversity simply by switching things off. Let us not forget that blue eyes and blond hair in humans is due solely to reduced expression of eumelanin.

That corn is beautiful, thanks for posting. And all the amazing varieties came from teosinte, I believe? What I really like is making cornbread with blue corn meal. Anyway, happy Thanksgiving everyone!

Karen S. said:

That corn is beautiful, thanks for posting. And all the amazing varieties came from teosinte, I believe? What I really like is making cornbread with blue corn meal. Anyway, happy Thanksgiving everyone!

Many years ago I heard a lecture by George Beadle. After having retired from being President of the University of Chicago, he was doing corn crosses to verify that maize had its origin in teosinte. Up to that point, the leading theory for the origins of maize was by Paul Mangelsdorf, who argued that a now-extinct wild maize had hybridized with Tripsacum and produced teosinte. Beadle’s argument has prevailed.

As we walked away from the lecture, a friend of mine said to me “It’s nice to see George Beadle finally getting to do what he always wanted to do – destroy the reputation of Paul Mangelsdorf.”

This looks like what we used to call flint corn. My grandmother would make hominy from it.

I heard Beadle’s lecture also as a student at U Chicago. The problem was the teosinte kernels are too hard to eat. Native Americans could not have done selective breeding on a plant which was inedible, in the hope that it would become corn. Classic natural selection “can’t get there from here” problem. When making popcorn Beadle noticed that popcorn looks like teosinte kernels. So he tried popping teosinte and it worked! He and his grad students found by experiment that teosinte is edible, so problem solved!

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This page contains a single entry by Matt Young published on November 24, 2011 12:00 PM.

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