Category: Breeding

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Hot cocoa

fairtrade.jpgThe Fairtrade Foundation licenses this special mark to distinguish products that have been certified as meeting certain producer and trading standards, meant to ensure that small-scale producers and plantation workers in the developing world get a better deal. The producers “receive a minimum price that covers the cost of sustainable production and an extra premium that is invested in social or economic development projects.” And farmers are thus given an incentive to maintain agrobiodiversity on farm. However, as an article in last week’s Economist points out, this model is not particularly popular among the large corporations that control the global trade in agricultural commodities: “Fairtrade’s price-adjustment mechanism is intended to insulate small producers from volatile commodity markets and the free-trading, no-holds-barred capitalism that multinational companies espouse.”

And yet, Fairtrade-like strategies — The Economist calls them “Fairtrade lite” — are increasingly popular: “firms are finding ways to improve the lot of small farmers, and burnish their own reputations, without signing up to Fairtrade’s rules.” The article describes the latest example.

It is called the “Cadbury Cocoa Partership,” and it commits that multinational to investing US$87 million over 10 years in increasing cacao yields in Ghana. That country provides Cadbury Shweppes with 70% of its global needs (100% of its UK needs), amounting to 10% of Ghana’s production. A recent study showed that yields have been decreasing and youngsters leaving the farms, imperilling supply. Cadbury does use a Fairtrade-certified cocoa (from Belize), but in this case it decided that the problem was not so much price as productivity, and came up with its own scheme.

Intercropping will be encouraged (peppers, mangoes, coconuts) as an additional income option, wells dug to free up the time of women and girls, and schools and libraries built, equipped and staffed. But it is unclear how productivity is to be increased. The article says that “the aim of the venture is to show cocoa farmers how to increase yields using fertilisers and by working with each other.” Surely that’s not going to be enough. Hopefully cacao genetic resources conservation, evaluation and breeding work will also be supported. ((There’s a good summary of the importance of diversity in a New Agriculturalist focus feature on cacao, but it is from a few years back.))

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Soybeans and its bottlenecks (or lack of them)

All too often crop genetic diversity studies — even ones published in peer-reviewed journals – are not really testing a clearly set out hypothesis. Markers are chosen and scored for each accession in a germplasm collection, and that’s basically it. Oh sure, estimates of various genetic parameters for the collection as a whole are provided, and there are dendrograms aplenty to illustrate the relationships among accessions. Which is fine, that sort of information can be useful. But one sometimes wishes that more focused questions had been asked — and answered.

Which is why recent work on soybean from USDA and visiting scientists from China and Korea is so interesting. I saw it reported in the February issue of Biodiesel magazine, but the original news item goes back to late last year. What the USDA team did is not just fingerprint material from the 17,000-strong USDA Soybean Germplasm Collection maintained at Urbana, Illinois and publish a nice dendrogram showing how Chinese accessions are related among themselves and to Korean ones, for example. ((Although someone probably did that as well!)) They defined four distinct sets of germplasm, each of which was derived from the one before, and tested the specific hypothesis that each process of derivation caused significant narrowing of genetic diversity, i.e. was associated with a “genetic bottleneck.” The sets of material were:

  1. 26 accessions of wild soybeans 
  2. 52 Asian landraces derived from them
  3. the 17 Asian landraces introduced to the US in the 20th century
  4. 25 elite modern cultivars which have been bred from them

What they found is that genetic diversity (as measured by gene sequencing) in wild soybeans was much greater than in landraces, which is fair enough. Most crops go through a very strong genetic bottleneck at domestication. What was more surprising is that the loss of genetic diversity caused by the introduction of only a few landraces to North America, followed by intensive breeding, amounted to only about 25%. This was much less than expected. The genetic base of US soybeans is narrow, yes, but not that narrow, it turns out.

What this means is that randomly introducing more landraces into soybean breeding programmes will not be very effective. The authors suggest that landraces should instead be carefully selected from the Urbana collection based on what the specific breeding objectives are at any one time. So, if breeding for resistance to the Asian aphid is the aim, landraces from areas of Asia where this pest is found should be the ones to be thawed out of genebank and crossed with the elite material.

All very logical. But I wonder. Was all that gene sequencing really necessary to reach this conclusion? I mean, wouldn’t you want to be somewhat selective in the landraces you introduce into a breeding programme even if the genetic base of the crop had been narrower? Maybe a breeder will help me out here. But anyway, it was good to see a real hypothesis of practical significance clearly set out and tested through specific comparisons in a crop molecular diversity study.

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Pussy Galore

A paper appeared in Science last year which used mitochondrial DNA and microsatellites to determine the geographic origin of the domesticated cat. We blogged about it back in June, albeit briefly. The major conclusion was that the cat was domesticated once, in the Fertile Crescent, about 9000 years ago, at about the time that agriculture started to take off. A paper just out in Genomics now takes the story on from there, by looking in more detail at the relationship among pure breeds and random-bred local populations from all over the world. ((Monika J. Lipinski, Lutz Froenicke, Kathleen C. Baysac, Nicholas C. Billings, Christian M. Leutenegger, Alon M. Levy, Maria Longeri, Tirri Niini, Haydar Ozpinar, Margaret R. Slater, Niels C. Pedersen and Leslie A. Lyons. (2008) The ascent of cat breeds: Genetic evaluations of breeds and worldwide random-bred populations. Genomics 91:12-21. doi:10.1016/j.ygeno.2007.10.009))

Using microsatellites, which are best suited to resolving more recent changes in genetic diversity, the authors of this latest study tried to reconstruct what happened when domestic cats left their Middle Eastern cradle and spread all over the world, presumably with the first agriculturalists and then with merchants and other travellers. It turns out that the diversity of the genepool has not decreased much overall during the past several thousand years. But it has fragmented. So now you have quite genetically differentiated groupings among the world’s cats: in the Mediterranean, Western Europe (+ the Americas), Asia and East Africa. The Asian group is particularly interesting, being the most distinct and the one with the most internal patterning. This shows that cats went to Asia early, and became relatively isolated there, from the rest of the world and from each other. ((Don’t I remember something similar for wheat? Must look it up. Later: ok, it was barley.))

There’s interesting stuff in the paper on the relationship among pure-bred breeds. They’re apparently mostly relatively young (less that 150 years old), and there’s not really that many of them (41 are recognized by cat enthusiasts), certainly compared to dogs and livestock like cattle and sheep. And it seems they’re all derived from 16 so-called “foundation” breeds, such as the Persian, for example. These in turn mostly — there are some exceptions — originated from random-bred cats from their region of origin, i.e. Persia, in the case of the Persian. Unsurprisingly, the development of pure-bred breeds from local common-or-garden cats has been associated with a narrowing of genetic diversity. And with the accumulation of deleterious mutations. It’s only in pure-bred cats that genetic disorders have been spotted. This study should lead to better plans for breed management, that could avoid such problems, the authors hope.

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Scary climate change story

ResearchBlogging.orgA paper ((Lobell, D.B., Burke, M.B., Tebaldi, C., Mastrandrea, M.D., Falcon, W.P., Naylor, R.L. (2008). Prioritizing Climate Change Adaptation Needs for Food Security in 2030. Science, 319, 607-610.)) and commentary ((Brown, M.E., Funk, C.C. (2008). Food Security Under Climate Change. Science, 319, 580-581.)) in the latest Science make pretty compelling reading for anyone with an interest in how climate change will affect agriculture and food security. Long-standing readers will remember a little round-up that included the work of our chums Andy Jarvis and Annie Lane. They predicted the effect of climate change on the suitability of different areas for different crops. David Lobell and his colleagues at Stanford University take a different tack, to answer a slightly different question: what are the top priorities for investing in agriculture to cope with climate change.

They isolated 12 regions where most of the world’s malnourished people are concentrated. Then they analyzed 20 different climate change models to get a feel for how temperature and rainfall would change in those areas. And finally, they looked at the specific crops that people in those regions eat and used past correlations between yield and temperature and yield and rainfall to predict how those crops might respond to the predicted changes in climate. This is an important step. As the researchers point out, “Rice, maize and wheat contribute roughly half of the calories currently consumed by the world’s poor and only 31% of the calories consumed by those in sub-Saharan Africa”. There’s a whole bunch more jiggery-pokery in there that ends up allowing the researchers to come up with best and worst case scenarios for each of the regions they consider, and some sharp conclusions.

Southern Africa and South Asia are going to be hit hard. Maize in Southern Africa and wheat and millet in South Asia are likely to show large declines. But there are also regions with large uncertainty, with some models predicting an increase and others a decrease. Groundnut in South Asia and sorghum in Southern Africa are examples of these, probably because the historical data on yield correlations are poor.

The results are summed up in a table that, the authors point out, could help agencies decide where to invest scarce resources. Those that are really risk averse might focus on wheat in South Asia, rice in Southeast Asia and maize in Southern Africa, all of which are predicted to drop by all the models. An investment in those crops is most likely to generate “some benefits”. A different view would be that investment should focus on crops and regions where at least some of the models predict strong depression of yields, because even if the projection is unlikely, if it does happen the consequences will be great. Many crops in South Asia, along with sorghum in the Sahel and maize in Southern Africa fall into this group.

The bigger question is, what form should those investments take? This is where the commentary adds its 2 cents worth. Molly Brown and Christopher Funk point out a double-whammy awaiting poor farmers:

In food-insecure regions, many farmers both consume their product and sell it in local markets. This exposes farmers to climate variations, because when they produce less their income goes down while their costs go up to maintain basic consumption. Large-scale hunger can ensue, even when there is sufficient food in the market that has been imported from elsewhere.

The solution that Brown and Funk see is largely technological; irrigation, fertilizers, improved varieties. Indeed, they aver that “technological sophistication determines a farm’s productivity far more than its climatic and agricultural endowments,” and of course at one level they are right. They also say that “poor farmers in the tropics will be less able to cope with changes in climate because they have far fewer options in their agricultural systems to begin with”.

I wonder whether that is correct. For the most marginal farmers, without irrigation or fertilizers or improved varieties, options — in the form of agricultural biodiversity — is all they do have. Development agencies are again starting to pay attention to agricultural research, and the Lobell paper and others on climate change are going to help them focus their efforts. It is clear that all approaches will need to be explored, among them helping people to adopt new foods in their diets and cultures. Will that include helping the most marginal farmers to use agrobiodiversity — local and exotic — to secure their food supplies in the face of climate change?