Author: Luigi Guarino

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Agrobiodiversity everywhere, if you look

My weekend reading included two pieces that I felt sure would prove well written and engaging, but which I frankly did not think would yield much in the way of agrobiodiversity fodder. Turns out I was wrong, at least on the latter point.

Felipe Fernandez-Armesto’s review of the Encyclopedia of Exploration 1850 to 1940 by Raymond John Howgego is indeed a model of its type: informative, stimulating and charming. It also includes a reference to the late nineteenth-century Swiss ethnobotanist of Paraguay Moisés Bertoni, who described Stevia rebaudiana, a controversial sugar substitute. And another to the Société Impériale Zoologique d’Acclimatation, which had a famous birthday boy as a loyal member in its early days. ((It’s now the Société nationale de protection de la nature.)) A Colonel Henry Wayne apparently won the society’s gold medal for his efforts to introduce camels to the US.

The second piece that intrigued me over the weekend was an article by Matt Jenkins in the Smithsonian Magazine about the elite pilots who guide ships through the treacherous, sand-barred mouth of the Columbia River in Oregon. What’s the agrobiodiversity angle? Well, Portland and other upriver ports are the the main gateway in the US for its wheat and barley exports. The river pilots can shut down the entrance to the river if conditions are too bad, but, to quote one of them:

“When we shut down the bar for two days, trains are backed up all the way into the Midwest. And just like a traffic jam on the freeway, once you clear the wreck, it takes a long time for it to smooth out again.”

It’s a great image. The world’s interdependence for agricultural products ((And coincidentally I came across a great graphical representation of that yesterday, thanks to blogging machine Tom Barnett.)) resting on the judgement of a dozen or so salty sea dogs in the Pacific Northwest.

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Maize aguafiestas

From Jacob van Etten.

Uncorking a big bottle of agrobiodiversity, that is what Mexico’s first farmers did when they domesticated maize. Not only is maize enormously malleable, genetic diversity also goes everywhere through cross-pollination. That is in traditional farming systems. Modern maize improvement has been about sorting out this abundance by “freezing” it into breeding lines, to get some control over the diversity feast. But what happens when the hybrids are released into the dance room again?

An Italian study just out quantifies the gene flow from hybrids to traditional varieties. It finds different degrees of purity in the traditional varieties, but no genetic erosion. This is an interesting finding in the light of writings about “creolisation” in Mesoamerican agriculture. Creolisation, the mixing of modern and traditional varieties, is thought to lead to plants that combine their benefits. I have always wondered if the creolised varieties of Mesoamerica are not modern varieties “creolised” by selection instead of mixing with traditional varieties. Something similar to the Italian study would be needed to find this out.

The question is only one step removed from the issue of gene flow from transgenic crops to traditional varieties. Perhaps you remember the Quist and Chapela paper published in Nature in 2001 on the presence of transgenes in Mexican traditional maize, and the controversy it generated. A new study confirms the presence of transgenes in Mexico with an improved study design. Through genetic population simulations it also explains why detection of transgenes is erratic and prone to giving false negatives. The distribution of the transgenes is likely to be very skewed. A few fields will have much of them, but most will have very few. This has to be taken into account and therefore authors call for more rigorous sampling methods to detect transgene presence.

There is little discussion or speculation about the effects of transgenes on maize diversity. Will the transgenes just add to the existing diversity, like the hybrids in Italy? Will they perhaps produce some benefits, like the creolized varieties? Or will, in some Monty Python-like scenario, the big seed companies pick up the message about rigorous sampling and start to trace transgenes in Mexico in order to charge farmers for unlicensed use of their technology?

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A citrus species in need of research?

It seems that citrus canker, a nasty bacterial disease, has been officially eradicated in Australia. Good news, but there is a bit of a dark lining. Along with 495,000 commercial citrus trees and 4000 residential trees, the eradication programme has included destroying a lot of trees of native Citrus glauca in the affected area. Desert Lime is well-known bush tucker, as well as a potential resource for Citrus breeding. It’s not currently considered endangered, but there’s not really all that much research about it ((That’s a bit of a casual way of introducing the fascinating Australian New Crops Web Site. Thanks to Danny for the tip.)), so that might be optimistic. There are only 8 germplasm accessions worldwide (page 29), apparently. That sounds inadequate to me. Especially given the historic proportions of the current drought, which is affecting the whole of SE Australia, including areas of C. glauca.

LATER: See also a map of the latest spate of bushfires in Australia. A threat to this and other crop wild relatives?

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Nibbles: Wolf, Conservation agriculture, ODI, Food policy, Stress, Sustainability