From Teosinte to Maize A Genetic Journey
From Teosinte to Maize
A Genetic Journey
Scientific name:
Zea mays spp. parviglumis
How did we get from this…
www.historyforkids.org/learn/food/corn
To this….?
http://soilcrop.tamu.edu/photogallery/cornsorghum+/images/corn%20ears.jpg
A significant difference
http://www.nsf.gov/news/mmg/media/images/corn-and-teosinte_h1.jpg
Morphological Differences Between Maize and Teosinte
Maize:• rigid, 3-12 ranked rachis with solidly attached
grains grains require human intervention for dispersal and propagation.
• Rachis segments bear pairs of grain bearing spikelets oriented perpendicular to rachis axis.
• Open fruit case
Cont. Morphological Differences
• Teosinte:• Two-ranked rachis that naturally disarticulates.• Single grain-bearing spikelet per rachis,
oriented parallel to rachis axis.• Grains are protected inside closed fruit case.
Comparison
http://teosinte.wisc.edu/morphology.html
Which traits were chosen?
• Early “farmers” did not want seeds to fall off easily. So they chose those individuals that had very attached seeds.
• They wanted many seeds per ear. chose those with mutations having several rows and ranks.
• They wanted big seeds chose individuals with the largest seeds.
When and where did it begin?
• Earliest evidence of cultivation 6,250 years B.P.• Earliest evidence found in Guila ‘ Naquitz,
Oaxaca Mexico• Earliest cultivators: Pre-ceramic hunter-
gatherers using cave shelters.
Photograph of three Guilá Naquitz archaeological cobs.
Benz B F PNAS 2001;98:2104-2106
©2001 by The National Academy of Sciences
Cultural Significance of MaizeProject
http://tvnoticias.files.wordpress.com/2008/04/maiz.jpg
-Pair up for this project-Use the internet to complete your research-You will have three class periods to work on this-Compile your findings into a power point presentation-Be prepared to present your project!-Follow your rubric closely!
References• Benz, Bruce, F. (2001). Archaeological evidence of teosinte domestication
from Guila’ Naquitz, Oaxaca. The National Academy of Sciences. Retrieved from http://www.pnas.org/content/98/4/2104.full on 9/3/2010.
• http://www.koshland-science-museum.org/exhibitdna/crops02.jsp• http://teosinte.wisc.edu/morphology.html