POPcorn

The maize genetics community needs your help! POPcorn a special resource being developed with the goal of putting all maize-related information in one easy-to-use place. To help make POPcorn the best possible resource, they need feedback on ease of use.

Not a maize geneticist or breeder? The resource might still be of use to you if you study another crop or if you are just interested in learning more about a particular plant gene and what it does.

Any feedback that you can provide would be a big help to the POPcorn team. POPcorn is funded by NSF.

Corn has been king for a long time

University of Calgary archaeologists found corn starch residues in ancient pottery shards. “Their discovery shows the spread of maize out of Mexico more than 9,000 years ago occurred much faster than previously believed and provides evidence that corn was likely a vital food crop for villages in tropical Ecuador at least 5,000 years ago (U of C website, EurekAlert).” As described in the paper “Directly dated starch residues document early formative maize (Zea mays L.) in tropical Ecuador”, residues of maize with both soft and hard endosperm were found on cooking pots and grinding tools, indicating that both types were grown by the people there.

Importantly, although we do not deny that maize played a significant role in Andean ceremonial life, our results show that it was indeed consumed as food as part of a diverse subsistence system. Our results indicate that a greater percentage of hard endosperm versus soft endosperm maize was cooked in the pots analyzed from Loma Alta. The higher percentage of soft endosperm maize present on the grinding stones may indicate extensive milling of soft endosperm maize to produce flour, resulting in a higher recovery rate from those artifacts. Other starches identified in the ceramic residues show that maize was one of a complex of crops exploited [including manioc, arrowroot, chili peppers, and jackbeans].

In other words, the evidence shows that early Ecuadoreans started using the traditional ingredients of Central American cooking from a very early date. The authors of this paper remind us that “There are dietary reasons why maize, beans, and chili peppers would be cooked together. Whereas maize is deficient in the essential amino acids lysine and tryptophan, and in niacin, legumes contain these essential dietary components and the consumption of maize and beans together complement each other and are nutritionally complete; chili peppers are high in vitamin C, which increases the absorption of iron.” The evidence also shows that the Ecuadoreans had been farming crops such as squash and beans well before the arrival of maize.  To me, this shows that these people were willing to adopt new farming strategies, even if they had not seen them before.
The residues also show that the people were cooking in very sophisticated ways, such as “the addition of lime (calcium hydroxide) Ca(OH)2, lye (sodium hydroxide) NaOH, or wood ash (potassium hydroxide) KOH” to “increase the temperature at which starches gelatinize, as does the addition of salts and/or sugars to the water.” This is known as alkali or alkaline cooking, and is a good way to improve the amount of bioavaliable iron in maize tortillas. Lactic acid works too, as described by Amy Proulx in her interesting paper “Fermentation and Lactic Acid Addition Enhance Iron Bioavailability of Maize”.
It so amazing that these people knew what were the best ways to obtain nutrients from their available plant foods over 5000 years ago! We might all be better off if we took their advice.

Teosintes are a puzzlebox of genes

Teosinte is a so-called primitive version of corn. Basically it’s corn’s version of our monkey, but corn and teosinte can still interbreed. To a corn breeder, teosinte is a puzzle box of genes that have been lost from maize cultivars. What secrets wait for us to discover? We could find disease resistance, drought resistance, improved nutrients… we only have to find the genes.

To date, there haven’t been many studies on what useful traits hide in teosintes. There have been studies in Mexico on their local corn varieties, and on Native American varieties, but fewer than you would think. This week, I’m embarking on an exciting study that, to my knowledge, no one has done before. I’m going to measure the storage proteins in 55 varieties of the genus Zea. Some are teosintes, some are modern cultivars, some are found only in small plots in places like Mexico.
I’m hoping that some of the varieties have storage proteins that are really different from the ones found in modern corn. Modern corn has been bred for yield (and yield it does) but has pretty much no nutritional value. Hopefully some of these varieties will have lots of amino acids that are essential for humans, cattle, pigs, and chickens. I can find the responsible genes, then use them to improve modern lines. Then, instead of growing for quantity, we can grow for quality!
The anti-GM crowd has brought up the issue of gene flow. They say that genes like BT could spread via pollen to non-transgenic crops, including rare cultivars and even wild teosintes. It’s true, it has happened, but very little. The irony is that modern varieties contain many mutations that aren’t found in nature. Modern non-GM corn is just as strange and different as GM corn, and its pollen is just as likely to drift on a breeze. It doesn’t matter much, because a hybrid plant is much more likely to loose a new gene over subsequent generations than to keep it, unless selective pressure is involved. Even if the transgene is retained, it doesn’t turn the plant into something new, as the gene can just be bred back out again if desired.
While I’m on the subject of new genes, I’d like to share two interesting articles that talk about plant breeding via radiation. It’s been done for decades now, but strangely, hasn’t met any resistance. This is surprising, because genetic engineering is confined to one or a few genes, while radiation could change anything, so is inherently riskier. Check out “Useful Mutants, Bred with Radiation” from the NY Times, and “GMOs: Making the Earth Say Beans,” by an awesome female geneticist working on improving stress resistance in crops. She worked with Barbara McClintock!
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