Category: DNA

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Radicchio diversity

Following in Luigi’s footsteps, the botanic gardens at Padua beckoned. The oldest botanic gardens in the Old World (Wikipedia is wrong; the New has older) they have operated continuously in the same place since 1545. A freezing February day was not ideal to see plants, and precious few of the labels denoted anything directly edible as food. I was not, however, entirely disappointed, for in a sunny bed in the lee of a building was a display of perhaps the region’s most famous crop: radicchio.

The picture above shows an old local variety, Variegato di Castelfranco, and Otello, a modern cultivar. Which, naturally, sent me scurrying to discover more about their history and breeding. There isn’t, actually, a huge amount. One study, of which I’ve seen only the abstract, examined DNA diversity of the five major types. Turns out that if you compare pooled bulk DNA from six individuals of each type, the different types are easy to distinguish. If, on the other hand, you look at DNA from individuals, the distinctions disappear. The variation within a single type is much greater than the variation among the different types. This, the researchers say, indicates that the types have maintained their “well-separated gene pools” over the years. An earlier paper (available in full) had come to a similar conclusion about the populations, with what seems like an ulterior motive: ((Although they were also concerned to enable breeders “to select inbred lines suitable for the production of commercial F1 hybrids”.))

The molecular information acquired, along with morphological and phenological descriptors, will be useful for the certification of typical local products of radicchio and for the recognition of a protected geographic indication (IGP) mark.

And lo, it came to pass. Four types (I think early and late Rosso di Trevisos are included in one designation) got their Protected Geographical Indication in 2008 and 2009. That’s late — tardivo — in the photograph below.

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Nibbles: Vegetables training, Genebanks and genomics, Kew and CWR, AnGR ABS

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Is lack of sex really the problem for grapes?

There’s a very interesting article in the New York times reporting on a major investigation of the molecular diversity among grape cultivars.

The report is based on a big paper in PNAS, which I confess I have not had time to read carefully. That said, a few things about the NYT’s coverage confuse me. One is the whole depiction of “relatedness”.

Thus merlot is intimately related to cabernet franc, which is a parent of cabernet sauvignon, whose other parent is sauvignon blanc, the daughter of traminer, which is also a progenitor of pinot noir, a parent of chardonnay.

This web of interrelatedness is evidence that the grape has undergone very little breeding since it was first domesticated, Dr. Myles and his co-authors report in the Proceedings of the National Academy of Sciences.

So how did those varieties arise? Maybe breeding means only “deliberate crosses made by a breeder”. Are they saying that the molecular data support the breeding records? Or are actual breeding records, especially for the older and better-known varieties, too sketchy to know? There’s more too, but I’m going to have to find time to read the PNAS paper properly. Or maybe you already have, in which case, feel free to comment.

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Nibbles: IK, Fragaria, Citrus, Millet breeding, Vitis, Agricultural biodiversity, Satellite imagery, Subsistence

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Of cattle and people. And barley

Dienekes, a blogger who specializes in molecular anthropology, has a quick note today on a paper on the molecular genetics of cattle in Europe. The main story is one of distinction between North and South.

Apparently, the expansion of the dairy breeds have created, or largely maintained, a sharp genetic contrast of northern and southern Europe, which divides both France and Germany. It may be hypothesised that the northern landscapes, with large flat meadows, are suitable for large-scale farming with specialised dairy cattle (Niederungsvieh, lowland cattle), whilst the mixed-purpose or beef cattle (Höhenvieh, highland cattle) are better suited to the smaller farms and hilly regions of the south. However, it is also remarkable that in both France and Germany the bovine genetic boundary coincides with historic linguistic and cultural boundaries. In France, the Frankish invasion in the north created the difference between the northern langue d’oïl and the southern langue d’oc. The German language is still divided into the southern Hochdeutsch and northern Niederdeutsch dialects, which also correlates with the distribution of the Catholic and Protestant religions. On a larger scale, it is tempting to speculate that the difference between two types of European cattle reflects, and has even reinforced, the traditional and still visible contrast of Roman and Germanic Europe.

It doesn’t seem that the strong latitudinal genetic differentiation in cattle is matched by one in human populations. Here the pattern is much more gradual and clinal. ((Maybe there’s more interbreeding among human populations than between cattle breeds?)) However, there may be a similar “sharp genetic contrast of northern and southern Europe” (or at least between the Mediterranean and the rest of Europe) for barley. ((Yeah, I know it’s an old paper, but it’s the only map of barley genetic diversity in Europe I could find online at short notice. No doubt our readers will send in better examples.))

I’d dearly love to have the time to find out whether other livestock and crops show a similar pattern.