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Wheat disease genes

Fusarium graminearum is the fungus that causes Fusarium head blight, a serious disease of wheat and barley. FHB infects the flowers and makes itself at home in the seed, which ends up shrunken and white and loaded with toxins that can have a harmful effect on people and animals that eat the grain. A study just published in Science decoded the DNA sequence of the fungus and sheds some light on its virulence and variability ((The Fusarium graminearum Genome Reveals a Link Between Localized Polymorphism and Pathogen Specialization. Science: 317:1400 – 1402 DOI: 10.1126/science.1143708)).

The sequence of one strain is interesting enough, but the surprises emerged when the researchers, led by Corby Kistler at the University of Minnesota, compared two different strains. There were more than 10,000 differences between the two sequences. Those differences, however, were not spread evenly along the DNA; more than half of the differences were concentrated in just one eighth of the sequence.

So some regions of the genome are much less stable than others. And what genes are in those regions? Mostly ones concerned with infection and virulence, among them the genes for compounds that dissolve the host cell walls and others that digest host molecules so that the fungus can make use of them.

Just why the variability in Fusarium graminearum is concentrated in some areas of the DNA is not yet clear. These areas seem to be hotspots for recombination, which shuffles the DNA during sexual reproduction and so promotes diversity, but this particular fungus doesn’t go in for sexual reproduction all that often. A mystery, then, but one that may still yield new approaches to breeding resistant wheat and barley and perhaps to new kinds of treatment.

You may remember that a joint team of Israeli and US researchers recently reported that a wild relative of wheat, Sharon Goatgrass (Aegilops sharonensis), is loaded with resistance genes that protect it against seven of the most important fungal diseases of wheat. Alas, none of the samples tested was resistant to Fusarium head blight. How about some other wild relative species, though? We shall see.

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Danny goes solo

You may remember some of Danny Hunter’s excellent contributions to this blog, for example his take on the importance of mentoring in helping to enhance scientific research capacity in developing countries. He also recently kicked off a fascinating discussion on the worldwide distribution of the practice of floating-bed cultivation.

Well, no doubt inspired by our example, Danny’s got a brand new blog of his own now. It’s called Rurality, and its mission is to:

collect and share information relevant to rural development in an Irish context by exploring commonalities between global and local experiences and practices. By generating discussion and debate, it hopes to construct information that will be accessible in one place, and of value, to people with an interest in rural living.

Do check it out, it’s really great. We’ve added Rurality to our blogroll, and we’ll be visiting Danny regularly for his thoughts on agrobiodiversity.

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Pigs didn’t fly, walked to Europe

We know that agriculture began in the Fertile Crescent about 12,000 years ago and then spread across Europe between 9,000 and 6,000 years ago. But what exactly was it that spread? Was it the idea of agriculture or agriculturalists themselves? Just-published work on the DNA of modern and ancient pigs says it was probably a bit of both. It seems that Middle Eastern farmers migrated into Europe carrying their agrobiodiversity with them — crops and domesticated animals. But, as far as the pig was concerned anyway, they soon adopted a locally domesticated version in preference to the Middle Eastern type they had brought along.

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Mini-watermelons

I had no idea there was such a thing as a mini-watermelon, let alone a mania about them, as suggested by a piece in FreshPlaza. But apparently, in addition to being easier to carry, they’re also good for you. I haven’t been able to find information on how these nutritious, small-fruited varieties were developed, but it does seem to have been through conventional breeding.

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Use monoculture to pay for diversity

Palm oil plantations destroy the biodiversity of the forests they replace. But high-falutin’ ideas of paying farmers not to plant oil palms are doomed to failure for two reasons. First, as developing countries rush to point out, Europe and America destroyed their own forests to power their development, so who are they to ask developing countries to forego similar development? Secondly, palm oil is so profitable that very little else is likely to appeal to farmers. Lian Pin Koh and David Wilcove have a nifty idea in a recent Nature. Conservationists should invest in small palm oil plantations and use the profits to buy — and protect — rainforest.

Koh and Wilcove say that a typical mature oil-palm plantation in Malaysia makes an annual net profit of roughly $2,000 per hectare. Existing oil palm-cultivated land sells for about $12,500 per hectare, so the capital investment could be recovered in just 6 years. Thereafter, the profits from a 5,000-hectare oil palm plantation would be about $10 million, which could buy 1,800 hectares of forest each year. The forest would be set aside as private nature reserves. Furthermore, new and more sustainable palm plantations could then be established on degraded land, which is feasible, but currently not as cheap as chopping down forest.

Sounds to me like a plan.

The Nature paper is behind a paywall; more details at Biopact and Mongabay.