Author: Jeremy Cherfas

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Many routes to stayfresh cassava

Luigi wondered whether there was a connection between my recent report of a cassava that did not show post-harvest physiological degradation (PPD, or rotting for the rest of us) and his own post on the same subject in March of this year. So we asked the CIAT blogger.

So what’s the story? Did the high carotene trait come from M. walkerae? Or some other place? It would be great if you could tie these loose ends up for us.

And he did, by asking the CIAT researcher.

There is a connection as Luigi suggests. In the article we have just submitted there are four different sources of tolerance to PPD:

1) High carotenes

2) Induced mutations

3) Tolerance from a wild relative (Manihot walkerae)

4) Waxy starch genotypes.

The tolerance from high carotene clones is not coming from M. walkerae. It is an entirely different source and an entirely new chemical basis for the tolerance as well. As it turns out the tolerance from M. walkerae (which is real and is there) is not as good as the one we have seen in yellow rooted cassava.

Thanks to Neil, and to Hernán, and to Luigi’s elephantine memory. We’ll be on the lookout for that paper.

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Dog fight over canine origins

We’ve pointed briefly to recent studies on the origins of the domestic dog, where two schools of thought hold sway. The conventional version offers east Asia — China, more or less — as the centre of dog diversity and, by implication, the place where dogs were first domesticated. An apostate view is that dogs were domesticated in Africa and perhaps in Europe too.

There’s no clear resolution in sight yet, but it looks as if the Chinese dog may be on top. A news report in Science gives details of (and links to) a new and more detailed study from Peter Savolainen and his team:

The data reaffirm a single site for domestication and pinpoint the origin of the domesticated dog to a region south of the Yangtze River, where wolf taming was quite common, Savolainen’s team reports today in Molecular Biology and Evolution. That’s where the largest number of similar groupings of DNA, called haplogroups, is found. As the researchers looked at dogs farther from this region, they saw fewer haplogroups; Europe had only four, for example. “The gene pool we are finding in Europe and Africa are a subset of the South Chinese gene pool,” says Savolainen.

But the African dogs aren’t rolling over yet.

Carles Vilà of the Biology Station of Doñana-CSIC in Seville, Spain … points out that other genetic studies suggest dogs date back at least 20,000 years and that archaeological remains of dogs in Europe are almost as old. … “I’m not convinced by the results,” he says, “and I do not think this is the last that we will hear about the time and place of the domestication of dogs.”

That seems certain. Back in the days before DNA a multiple-origins theory was all the rage, but then, it was for H. sapiens too.

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Good news from Zimbabwe?

“I’m looking for maduni, my son. This millet variety was grown for ages by our ancestors, but it’s gone,” she says. “We grew it in our fields when we were young. We liked it because it had a good taste unlike some of the new varieties we have now.”

Long piece by Sifelano Tsiko in the Zimbabwe Herald about the search for forgotten varieties of traditional crops and wild species.

“If humanity mourns the loss of wild plants, we should really worry about the extinction of cultivated ones. These plants sustain our lives,” one renowned agricultural development activist once remarked.

I wonder who that was?