Posts

Posted on

Lactose tolerance: independent origins and strong selective pressure

Michael Kubisch has submitted another post, based on an article in Nature Genetics. Unfortunately the full article and a News and Views piece about it are behind a paywall. However, I’ve done some sleuthing to find a few links that give more details on the story, which I’ve added at the end. As Michael noted, the article is “not about genetic diversity of agricultural species, but how agriculture has affected human genetic diversity”. That’s good enough for us.

The ability to digest lactose, one of the primary carbohydrates in milk, varies widely among adult human populations. In some European countries nearly 90% of individuals can tolerate lactose, while the incidence in some Asian countries is as low as 1%. The inability to digest lactose is caused by a decline in lactase, the enzyme that breaks down lactose into sugars that can be absorbed into the blood stream. This decline starts shortly after weaning and most likely reflects the fact that until animals were domesticated, milk was simply not a staple of human diets. Lactose tolerance, or lactase persistence as it is sometimes called, in turn is facilitated by a continuous production of lactase throughout adulthood. Not surprisingly, lactase persistence appears to be closely linked to whether a population has traditionally practiced a pastoral or an agricultural lifestyle.

This new study examined the incidence of lactase persistence in several African populations. Based on analysis of genetic markers the authors of the study conclude that the trait appears to have evolved not only independently from Europe, but also more than once in Africa itself. Given that the prevalence of the trait is so high in some populations and domestication of milk-producing animals only goes back 12000 years or so, which is a mere blink of an eye in evolutionary times, milk consumption must have provided a significant benefit for human survival.

Those links:

 

Posted on

Chinese fungi and tea

I’m killing a few hours at Hong Kong International Airport, so I pick up the latest issue of China Today. There’s a number of really interesting articles, but two little snippets jumped out at me. The first is a short note on the Chinese Caterpillar Fungus, Cordyceps sinensis. No, I’d never heard of it either, but it turns out that it is important in Chinese traditional medicine, and that it has not been possible to grow it in the lab. Until just now that is, hence the note in the Sci-tech Info section announcing the possibility of mass-production.

The other really nifty piece of sino-information occurs in the opening section of an Around China piece on the Zhenyuan Yi-Hani-Lanu Autonomous County. It seems that this ancient tea-growing area, with its tea-dominated forests, boasts what is considered the oldest and largest tea plant in the world. At 25 metres tall, almost 3 metres in diameter and an alleged 2,700 years of age, it is apparently quite the tourist attraction, and “its fleshy, glossy leaves produce a strong and lasting flavour.”

Posted on

More sorghum for Zimbabwe

A press release from the Netherlands Organisation for Scientific Research is creating tiny ripples in the blogosphere because it suggests that fertilizer, rather than water, is what poor farmers in semi-arid regions of Zimbabwe need to improve their crops. That’s certainly one conclusion from the research of Dr Bongani Ncube, who successfully defended her doctoral dissertation 10 days ago. (Congratulations, Bongani.) More important, I think, is the demonstration that almost regardless of water, sorghum crops benefit enormously from a preceding grain legume. There’s an interaction with rainfall to be sure. In a dry year, cowpea yields more than groundnut or bambara groundnut, but sorghum is always better after a nitrogen-fixing legume. That’s not to say that farmers shouldn’t make use of a little artificial fertilizer if they can afford it. But a better strategy might be to grow a variety of grain legumes, to buffer any possible effects of rainfall, and then plant sorghum, using agricultural biodiversity instead of cash to increase the harvest.

Posted on

What’s so special about Oidium neolycopersici?

It’s a disease that affects mostly tomatoes, more commonly known as tomato powdery mildew. It has only recently been identified as a separate species. And it is the 1000th disease to be mapped by CABI, a fact we noted from CABI’s blog.

Oidinl

Distribution Maps of Plant Diseases is a series that has been going since 1942. To view the maps you need to subscribe, although CABI has generously made map no. 1000 available free ((Which is why we have no hesitation about duplicating it here)). There’s also a collection of Distribution Maps of Plant Pests. Apparently, many of the maps have been drawn up more than once. What I’d really like to see would be time series animations showing how pests and diseases have moved around the world in recent years, what with climate change, air travel and a host of other contributory factors. How about it CABI?

Posted on

Cereals databases

Before I disappear for a few days of immersion in the First International Breadfruit Symposium back in Fiji, let me point to two somewhat complementary online resources on cereals genetic resources that I have come across – no doubt Jeremy will say and about time too – in the past couple of days.

The FIGS database brings together passport and evaluation data on bread wheat landraces from a number of the major genebanks and “allows the user to efficiently interrogate the data associated with this collection and provides the capacity to identify custom subsets of accessions with single and multiple trait(s) that may be of importance to breeding programs.” FIGS stands for “Focused Identification of Germplasm Strategy,” and the focus is on identifying material with resistance to abiotic and biotic stresses.

The other database is that of Israel’s Institute of Cereal Crop Improvement, which includes information on accessions of wild cereal relatives collected over the past 30 years. Again, there’s a particular focus on data on disease resistance.