Proteins found in buckwheat ((Fagopyrum esculentum, a pseudo-cereal of Himalayan origin)) grain seem to cut down the absorption of cholesterol, at least in vitro, according to a recent study. Is there genetic variation in this property? Well, I don’t suppose anyone has looked yet, but a paper just out in GRACE does point to significant variation in protein profiles among varieties and species.
Is the kouprey a species?
The kouprey is a very elusive wild bovid that is said to roam the Southeast Asian jungle. It was only discovered by outsiders at the beginning of the last century, but it has seldom been seen since and there are concerns that it may, in fact, already be extinct. (It is currently listed on the IUCN Red List of Endangered Species). As if that wasn’t bad enough, there is now a vigorous debate about whether the kouprey is — or was — in fact, a separate species at all, or merely some type of feral hybrid.
A report published some months ago in the Journal of Zoology showed that a comparison of mitochondrial DNA obtained from several banteng revealed some homology — similarity — with a previously published DNA sequence from a kouprey. ((Galbreath et al., 2006. J. Zool. 270:561)) The banteng is another bovid that has to some degree been domesticated, but can also still be found in the wild in several Southeast Asian countries. Based on their analysis, the authors concluded that the kouprey is more than likely just a hybrid originating from crosses between zebu cattle and the banteng. Now, some might argue that it is pretty bold to reach such a profound conclusion based on a very small sample size, and not surprisingly some have indeed so argued. They have pointed out that anatomical and even DNA evidence from their own studies did not support stripping the kouprey of its species status. ((Grigson, 2007. J Zool. 271:239; Hassanin and Robiquet, 2007. J. Zool. 271:246)) An alternative explanation might simply be that there has been introgression of DNA from one species into the other by occasional matings. And there is ample evidence that this has happened in other species. Cattle DNA is commonly found in the American bison, for example, because of past attempts by cattle breeders to generate what they thought would be more viable bison-cattle hybrids. ((Rasmussen et al., 2005. Mol. Reprod. Dev. 70:228))
What is clearly needed to settle the matter is additional analysis of nuclear DNA obtained from more than one kouprey. But if the animal has, indeed, already disappeared, that may prove to be difficult. ((Contributed by Michael Kubisch))
Cassava genes flow
Cassava exchanges precious bodily fluids with wild relative in French Guiana.
Italian fruits and nuts
The latest issue of Genetic Resources and Crop Evolution (GRACE to the cognoscenti) has no less that three papers which use DNA markers to say interesting things about the agricultural biodiversity of Italy, my country of birth and (coincidentally) current abode. I want to talk briefly about two of these today — focusing on opposite ends of the peninsula — because they’re kind of unusual among molecular diversity studies in actually trying to answer a question, rather than just fingerprinting a load of stuff for the sheer thrill of it. In other words, they’re a little bit more than stamp-collecting. No offence to the philatelists among us.
In the first paper, Italian and American researchers wanted to know whether the “Sorrento” walnut variety is really always the “Sorrento” walnut variety. Sorrento is a beautiful little seaside town south of Naples, in the south of Italy. We used to go near there on our summer holidays when I was small. Walnuts are everywhere once you get up into the surrounding hills, and the local variety — or, better said, population or landrace, as it shows a lot of morphological variation — is one of the most famous in Italy. It is now widely planted, and the researchers compared two sets of trees, all commercially labelled as “Sorrento,” from areas 50 km apart: one around Sorrento itself, and one further north near Caserta.
It turned out that, although they looked roughly similar and were called the same thing, the walnuts from these two areas were genetically distinct. It seems that the farmers of the Sorrento region have carried out strong selection for particular yield and quality traits, but the original ancient stock still survives in Caserta. And some walnuts sold as “Sorrento” are probably nothing of the kind at all.
In the second study, conducted way up in the north, an Italo-Swiss team asked itself: what modern wine grape varieties are the descendants of Pliny’s famous “Raetica”? Caius Plinius Secundus (23-79 AD), better known as Pliny the Elder, says in his Naturalis Historiae that before Tiberius experimented with African wines, “Rhaetian” was considered one of the best tipples in the Empire. Rhaetia “comprised the districts occupied in modern times by eastern and central Switzerland (containing the Upper Rhine and Lake Constance), southern Bavaria and the upper Danube, Vorarlberg, the greater part of Tirol, and part of Lombardy.”
The researchers started with the observation that a Swiss cultivar known as “Reze” is very close to “Raetica” etymologically and comes from the right geographical area. They then searched molecular databases for its closest relatives, and came up with four varieties from Switzerland and northern Italy, again all from roughly the right place. Sorting out the possible relationships gets complicated, but it is unlikely that any of these are parental to “Reze”, and much more likely that they are siblings or offspring. Incidentally, one of these varieties — “Arvine Grande” — is no longer grown and is only available in genebanks.
So actually we are not much closer to answering the original question, because we can’t be sure about the “Raetica”/”Reze” connection. But, as they say, the journey is the destination. And for their next step on this journey back in time, the authors are now trying to extract DNA from ancient pips.
Up a gum tree
Eucalypts decoded and hybridized.