English Russia is an “entertaiment blog devoted to the events happening in Russian speaking countries.” Quite often fun but not, you would have thought, likely to feature much of agrobiodiversity interest. And you’d be right. For 99% of the time at any rate. Because there was a post a few days ago with truly amazing colour photographs of the Russian Empire from a hundred years ago, and many show farming products and activities. They’re by Sergei Mikhailovich Prokudin-Gorskii, according to one of the comments, and he had a Library of Congress exhibition devoted to him in 2003, whose website is where it seems most of the images in the English Russia post originated. Well worth exploring. I wonder if some of these images could be used to compare with the present. For example, are these melons still to be found in Samarkand?
Modern rice varieties (can sometimes) increase genetic diversity
People say that introducing high-yielding crop varieties threatens agricultural biodiversity. Farmers adopt the modern varieties and abandon their traditional varieties, so that the overall genetic diversity falls as a result. They’re right, but not every time. A new paper published online in Field Crops Research ((Steele, K., Gyawali, S., Joshi, K., Shrestha, P., Sthapit, B., & Witcombe, J. (2009). Has the introduction of modern rice varieties changed rice genetic diversity in a high-altitude region of Nepal? Field Crops Research DOI: 10.1016/j.fcr.2009.04.002)) shows that genetic erosion need not be the unintended consequence of high-yielding varieties, especially if the modern varieties count farmer varieties among their parents.
In the early 1990s, while a PhD student at Bangor University in the UK, our friend Bhuwon Sthapit, now a senior scientist at Bioversity International, was instrumental in breeding three new varieties of rice suitable for upland rice farms in Nepal. This was no ordinary breeding programme, however. Sthapit worked closely with farmers, who both set the goals of the breeding programme and participated in the selection of the final varieties from the many crosses. The varieties were selected from crosses of Chhomrong Dhan, a local landrace well adapted to the cold conditions of high-altitude rice farms in Nepal, with Fuji 102 and IR36, more productive material from international breeding programmes.
Farmers selected three lines: Machhapuchhre-3 (M3), Machhapuchhre-9 (M9, which is similar to M3 but with lower cold tolerance) and Lumle-2 (L2, like M3 with better grain quality and easier threshing). Only M3 was officially released, but M9 and L2 have been adopted widely thanks to informal seed exchanges among farmers. By 2004 about 60% of the land in the study villages was sown to one of the three COB (client-oriented breeding) varieties, while traditional varieties occupied the remaining 40%. In adopting the COB varieties, many farmers had dropped traditional landraces, but there was no clear pattern to which landraces were dropped in which villages. The variety dropped most commonly was Chhomrong Dhan, one parent of all three COB varieties.
To assess genetic diversity, Sthapit and an international team of the researchers from Bangor and Nepal analyzed DNA from the three COB varieties, a random selection of landraces and a control group of modern varieties. Overall, genetic diversity was greatest in the landraces, and least in the COB varieties. However, there was no loss of genetic diversity across the district as a whole, at least as long as the three COB varieties were adopted on less than about 65% of the land. Indeed, because the high-yielding parental varieties contribute alleles not previously known in the area, there is an increase in diversity as the COB varieties are adopted .
Another crucial result is that although some farmers grow COB varieties on 100% of their land, nevertheless, at least 11 diverse landraces survived on some 40% of the land. These landraces clearly meet needs not fulfilled by the COB varieties. For example, although the most commonly dropped variety was Chhomrong Dhan, farmers in the Gurung community continued to grow that variety.
“It is the preferred rice for preparation of the dish Madeko Bhat used during funerals and other ritual and social ceremonies,” Sthapit told us.
“The conclusion is clear,” Sthapit added. “Participatory breeding and client-oriented breeding programmes should choose locally adapted varieties as parents for breeding. It ensures that landrace genes are conserved and increases the likelihood that the breeding programme will succeed.”
How to rescue a sunflower wild relative
A paper by Jennifer R. Ellis and David E. McCauley of Vanderbilt University, just out in Biological Conservation, tries to answer a couple of quite controversial questions for conservationists: ((Ellis, J., & McCauley, D. (2009). Phenotypic differentiation in fitness related traits between populations of an extremely rare sunflower: Conservation management of isolated populations. Biological Conservation. DOI: 10.1016/j.biocon.2009.03.029)) How do you prioritize populations for conservation? And when does genetic pollution become genetic rescue? Both answers depend on something most gene-jockeys don’t do much of: growing plants and seeing how they perform.
To add piquancy, the paper deals with a crop wild relative, and a very rare one at that: Helianthus verticillatus, which is known from only four sites in the southeastern United States. The authors worked on populations from two of these, in Tennessee (fewer than 100 individuals) and Alabama (several hundred individuals). They collected seeds from sixteen of what they had previously identified as genetically distinct individuals from each population, and then made a whole bunch of crosses, both within populations and also between the two populations, for two generations. They grew the progeny of these crosses in the same environment and measured how well they did in terms of fruit viability, germination, survival and pollen quality.
So, first, to the prioritization question. Genetic markers are now routinely used to identify populations that are particularly low in diversity and thus in need of immediate in situ protection or collecting for ex situ conservation. Often, genetic diversity is positively correlated with fitness, but this is not always the case. For H. verticillatus, in fact, it was known from previous marker studies that the two populations had comparable levels of genetic diversity and only moderate genetic differentiation. However, the results of the common environment study on the offspring of the intra-population crosses showed that they different significantly in their overall “fitness,” with the Tennessee material having lower germination rates and fruit viability. In other words, molecular markers on their own would not have raised a particular concern about the long-term viability of the Tennessee population. In the words of the authors, “contrary to genetic marker information, these populations are not interchangeable with regard to quantitative fitness characters.”
Next, the genetic rescue question. The conventional wisdom of course is that conservation should strive to maintain the genetic integrity of populations. Bringing in material from elsewhere constitutes genetic pollution and is BAD. The introduction of new genetic material into relatively homogeneous populations with low fitness can of course result in heterosis and increased fitness. But it can also lead to lower fitness — inoutbreeding depression — “owing to the dilution of local adaptations or disruption of co-adapted gene combinations.” Enter the inter-population crosses. Crossing Tennessee individuals with those from Alabama resulted in offspring that were more fit, with no sign of outbreeding depression, at least for the two generations of the study. This “offers great promise” as an active conservation strategy for the Tennessee population, the authors say.
Given people’s sqeamishness about messing around with rare species, I wonder if such activism will be given a chance.
Supporting local breeds in the UK
Our friend Danny over at Rurality has been on a bit of a rare livestock breeds hobbyhorse lately. First he noted that the UK’s new biodiversity indicators include consideration of native livestock breeds but not crop landraces. And that prompted him to sing the praises of the Rare Breeds Survival Trust. Quite right too.
Melaku Worede speaks
And this is what the veteran crop conservationist says:
Gene banks like the SADC gene bank, the Svalbard gene bank, and many others, focus only on collecting and preserving. How can you think you are conserving diversity when the very source upon which the seeds depend is not included? You can capture only so much, and in 100 years it will be useless because the planet will have changed. Perhaps you will be able to incorporate some genetic material into varieties and release them, but who is going to benefit from that? That is the big question.
I know what he means. You need to conserve the process, as well as the product. But I have another big question. If the world — read the climate — is changing as fast as many now fear, don’t you need the insurance policy that genebanks provide all the more?