Category: Genetic diversity

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Tasteful breeding

A couple of days ago the Evil Fruit Lord complained — a little bit — about an article in a Ugandan newspaper which extolled the virtues of traditional crops and varieties over new-fangled hybrids. While not doubting the many attractive qualities of landraces and heirloom varieties, he quite rightly pointed out that there’s nothing to stop modern varieties and hybrids tasting just as good:

I get really sick of the tendency to talk about plant breeding as a process which makes crops into finicky, crappy tasting garbage in exchange for yield. You absolutely can create varieties which taste as good (or better) than traditional varieties, produce more, and resist pests. In fact, plant breeding is the only way to get to that.

Now there’s an article by Arthur Allen in Smithsonian magazine which basically says — not very surprisingly, I suppose — that both those things have happened in the tomato:

Flavor … has not been a goal of most breeding programs. While importing traits like disease resistance, smaller locules, firmness and thicker fruit into the tomato genome, breeders undoubtedly removed genes influencing taste. In the past, many leading tomato breeders were indifferent to this fact. Today, things are different. Many farmers, responding to consumer demand, are delving into the tomato’s preindustrial past to find the flavors of yesteryear.

Allen has a good word to say for the wild relatives:

The architect of the modern commercial tomato was Charles Rick, a University of California geneticist. In the early 1940s, Rick, studying the tomato’s 12 chromosomes, made it a model for plant genetics. He also reached back into the fruit’s past, making more than a dozen bioprospecting trips to Latin America to recover living wild relatives. There is scarcely a commercially produced tomato that didn’t benefit from Rick’s discoveries. The gene that makes such tomatoes easily fall off the vine, for instance, came from Solanum cheesmaniae, a species that Rick brought back from the Galapagos Islands. Resistances to worms, wilts and viruses were also found in Rick’s menagerie of wild tomatoes.

And he also plugs genebanks:

…we can take comfort in the tomato’s continuing, explosive diversity: the U.S. Department of Agriculture has a library of 5,000 seed varieties, and heirloom and hybrid seed producers promote thousands more varieties in their catalogs.

Not quite sure where he got that number, as the C.M. Rick Tomato Genetic Resources Center seems to have about 3,500 accessions, but anyway.

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Special publication on livestock genetic resources

Livestock Science has a special issue on animal genetic resources. Or it will have, it doesn’t seem to be out yet, although some corrected proofs are available. You can get a flavour of the thing with the introduction. Here are some of the highlights:

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Sunflower controversy hots up

ResearchBlogging.org More from the trenches in the sunflower wars. A few weeks ago I said I would be keeping an eye on the controversy over the possibility of a separate site of domestication for sunflower in Mexico, additional to the conventional locale in eastern North America. Now Hannes Dempewolf alerts me to an exchange of letters in PNAS that continues the discussion.

My earlier post was prompted by a paper by David Lentz (University of Cincinnati) and others which presented a range of archaeological, linguistic, ethnographic and ethnohistoric evidence for the domestication of sunflower in Mexico by 2600 BC. ((D. L. Lentz, M. D. Pohl, J. L. Alvarado, S. Tarighat, R. Bye (2008). Sunflower (Helianthus annuus L.) as a pre-Columbian domesticate in Mexico Proceedings of the National Academy of Sciences, 105 (17), 6232-6237 DOI: 10.1073/pnas.0711760105 This paper is behind a paywall but the supplementary material is available and gives a taste. The letters discussed here are also only available to subscribers, which is why I’ll go into some detail.)) Now that evidence comes under fire.

Cecil Brown, an anthropologist at Northern Illinois University, leads off. ((C. H. Brown (2008). A lack of linguistic evidence for domesticated sunflower in pre-Columbian Mesoamerica Proceedings of the National Academy of Sciences, (), – DOI: 10.1073/pnas.0804505105)) He points out that the local names for sunflower in 11 contemporary native Mexican languages which “do not phonologically resemble Spanish words,” and which Lentz et al. therefore quoted as evidence for local domestication, are mostly descriptive terms. “Such semantically transparent names are typically used as alternatives to loanwords to designate newly encountered introduced things.”

Then Loren Rieseberg (University of British Columbia) and John Burke (Indiana University) take on the molecular evidence. ((L. Rieseberg, J. M. Burke (2008). Molecular evidence and the origin of the domesticated sunflower Proceedings of the National Academy of Sciences, (), – DOI: 10.1073/pnas.0804494105)) Lentz had said that previous molecular studies had not included indigenous Mexican cultivars, but Rieseberg and Burke say that two samples purchased in markets in Jalisco have been analyzed, and were inferred to have arisen from wild populations in the eastern US.

Third up, Bruce Smith from the Smithsonian tackles the archaeology. ((B. D. Smith (2008). Winnowing the archaeological evidence for domesticated sunflower in pre-Columbian Mesoamerica Proceedings of the National Academy of Sciences, (), – DOI: 10.1073/pnas.0804434105)) He contends that out of more than 100,000 expertly identified archaeobotanical specimens from throughout Mesoamerica, only 3 are unambiguously sunflower, and all from one, late, site.

Finally, Charles Heiser at Indiana University deals with the early documents, suggests a number of misinterpretations on Lentz’s part and concludes that he has “yet to see any historical records than confirm the early presence of the sunflower in Mexico.” ((C. B. Heiser (2008). How old is the sunflower in Mexico? Proceedings of the National Academy of Sciences, (), – DOI: 10.1073/pnas.0804588105))

Lentz, Mary DeLand Pohl (Florida State University) and Robert Bye (UNAM) are of course given a chance to reply. ((D. L. Lentz, M. D. Pohl, R. Bye (2008). Reply to Rieseberg and Burke, Heiser, Brown, and Smith: Molecular, linguistic, and archaeological evidence for domesticated sunflower in pre-Columbian Mesoamerica Proceedings of the National Academy of Sciences, (), – DOI: 10.1073/pnas.0805347105)) They say a local name for sunflower referring to the Mesoamerican sun god is strong evidence for domestication in Mexico. And that material collected in a couple of markets is not an adequate sample of Mexican sunflowers. And they beg to differ with Smith and Heiser on the interpretation of the archaeological and historical evidence. So there we are: pretty much were we began. I suspect the bottom line is to be found in a sentence in Lentz’s reply dealing with the molecular studies:

This hypothesis will be tested most effectively by collecting sunflower germplasm directly from indigenous people in Mexico and running the same experiments with well provenienced and thoroughly documented material.