Category: Wild relatives

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Ethiopia goes for decaf

Reuters reports that Ethiopian coffee farmers will soon be able to grow a variety which is naturally low in caffeine. Details are sketchy. The whole thing seems to be based on the following statement by Mr Abera Deressa, State Minister of Agriculture and Rural Development, at an unnamed coffee research conference:

“Coffee research centres are in the process of planting seedlings of natural coffee with low caffeine varieties, to enable Ethiopia to supply the world market within the shortest possible time.”

The article mentions the 2004 controversy between the Ethiopian government and Brazilian researcher Paulo Mazzafera, who

declared he had discovered a variety of naturally decaffeinated coffee from 6,000 specimens collected in Ethiopia in the 1980s. The find sparked a dispute with Ethiopian authorities who accused him of taking the bushes without permission.

However, it is not clear whether the low-caffeine variety now being planted in research centres has anything to do with the one Mazzafera identified.

Decaffeinated coffee accounts for 10 percent of total coffee sales in the world, a multibillion-dollar industry. Natural decaf brews could dominate over the current chemically caffeine-reduced options in today’s health-conscious market.

The story has been picked up all over the place. It should run and run. Hopefully we’ll get some more details soon.

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Wheats and gluten

Sometimes it takes some personal connection to get me motivated enough to try and understand something a little more fully. Laziness, I guess. Anyway, for example, I vaguely knew about the gluten seed storage proteins of wheat and the coeliac disease they cause in about 1% of the population. But I decided to delve a little deeper only when an old friend I hadn’t seen for a while visited today and told me that she was a sufferer, and that she needed to know how to describe the condition in italian so she wouldn’t get into trouble eating in restaurants here in Rome.

Having sorted that out, I was interested to know whether there are differences among wheat species in the “toxicity” of their glutens. You’ll remember that wheat comes in a polyploid series: diploid, tetraploids and hexaploids. And that three distinct genomes are involved: AA, BB and DD. Diploid einkorn (AA) and BB genome species got together to form tetraploid emmer and durum wheat (AABB). And these hybridized with wild diploid Triticum tauschii to make hexaploid (AABBDD) bread wheat.

It turns out that differences in gluten toxicity do exist. An analysis of the ancestral A, B and D genomes of wheat found that DNA sequences associated with 4 peptides that have been identified as triggering a response in coeliac patients are not distributed at random. For example, the B genome sequences analyzed did not reveal any of the “guilty” sequences.

On the basis of such insight, breeding strategies can be designed to generate less toxic varieties of wheat which may be tolerated by at least part of the [coelic disease] patient population.

Oh, and coeliac disease is called celiachia in italian.

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Fido decoded

An article by Elaine Ostrander in the latest American Scientist summarizes recent advances in canine genomics, which have been considerable:

The dog genome has been mapped and sequenced. A host of disease loci have been mapped, and in many cases the underlying mutations identified. Our understanding of how dog breeds relate to one another is beginning to develop, and we have a fundamental understanding of the organization of the canine genome. The issue of complex traits is no longer off-limits. We have begun to understand the genetic portfolio that leads to variation in body size and shape, and even some performance-associated behaviors.

Some snippets:

  1. Between-breed genetic variation is about 27.5% of the total, compared to about 5% between human populations.
  2. Dog breeds fall into 4 main groups: Asian and African dogs, plus grey wolves; mastiffs; herding dogs and sight hounds; and modern huntings dogs.
  3. 75% of the 19,000 genes that have been identified in the dog genome show close similarities with their human counterparts.
  4. Variation in a single gene (IGF1) explains a lot of the size differences among and within breeds.

What to do with all this information?

It is certainly hoped that the disease-gene mapping will lead to the production of genetic tests and more thoughtful breeding programs associated with healthier, more long-lived dogs. It will be easier to select for particular physical traits such as body size or coat color… Finally, canine geneticists will have a chance to develop an understanding of the genes that cause breed-specific behaviors (why do pointers point and herders herd?).

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Backyard domestication

There’s a “dump heap” hypothesis of agricultural origins which suggests that people first got interested in actively managing and manipulating plants for food or other products when they saw them sprouting out of piles of garbage in and about settlements. There they could observe them daily and experiment with them. A slight variation on this theme — involving corrals in pastoralist campsites rather than garbage dumps — has been proposed for the domestication of quinoa.

One of the things that might have happened in these fertile micro-environments in close proximity to human habitations is that different related species might have been brought accidentally together, leading to hybridization and the development of interesting new — polyploid — types. But there really hasn’t been much empirical evidence for this.

No more. A new paper ((Colin E. Hughes, Rajanikanth Govindarajulu, Ashley Robertson, Denis L. Filer, Stephen A. Harris, and C. Donovan Bailey. Serendipitous backyard hybridization and the origin of crops. PNAS published August 17, 2007, 10.1073/pnas.0702193104.)) looks at the domestication of the legume tree Leucaena in Mexico, where it is grown for food (it is also used as a fodder in some parts of the world). A variety of evidence is discussed which suggests that there has indeed been much hybridization among up to 13 different wild species of Leucaena in Mexican backyards. This has proved “a potent trigger for domestication.” The authors think a similar thing also happened in Mexico with two other perennial crops, Agave and Opuntia.

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Solanaceous information

There’s a global online monograph of the genus Solanum called Solanaceae Source. Each species treatment includes illustrations, a clickable list of specimens, links to molecular data and a dot distribution map (which mashes herbarium specimen locality data with Google Maps), among other things. The National Science Foundation (NSF) funds the project as part of the Planetary Biodiversity Inventories mission. Collaborators are eligible for small awards in support of their contributions to the completion of the worldwide Solanum monograph.