- Farmers headed into Europe. As it were.
- BBC slideshow on drought in NE Kenya and its effect on pastoralists.
- Might they have something to learn from the Sedillo Cattle Association at Laguna Pueblo, NM?
- The script of a radio programme about drought-resistant sorghum in Karamoja, northern Uganda. I can’t find the programme itself.
- The genetics of red-fleshed apples.
- Just 3 genes account for all dog fur phenotypes. But “[w]hat’s important for human health is the way we found the genes involved….rather than the genes themselves.”
- Pear cider makes a comeback.
Upstream blast
Blast is one of the worst rice diseases. I believe that, thanks to the breeders, most modern varieties have decent levels of resistance. After all, they can be used in varietal mixtures to protect traditional glutinous rice varieties from blast. ((Zhu, Y., Chen, H., Fan, J., Wang, Y., Li, Y., Chen, J., Fan, J., Yang, S., Hu, L., Leung, H., Mew, T., Teng, P., Wang, Z., & Mundt, C. (2000). Genetic diversity and disease control in rice. Nature, 406 (6797), 718-722 DOI: 10.1038/35021046 Also see this post.)) Unfortunately, much of this resistance is not durable, because the pathogen overcomes it with time.
For a long time, durable resistance has been known to exist in some Japanese varieties. But these varieties have not been useful for resistance breeding, as the resistant parent also brought along undesired characteristics: the offspring always had poor eating quality.
Shuichi Fukuoka and colleagues have found out why. They report in Science ((Fukuoka, S., Saka, N., Koga, H., Ono, K., Shimizu, T., Ebana, K., Hayashi, N., Takahashi, A., Hirochika, H., Okuno, K., & Yano, M. (2009). Loss of Function of a Proline-Containing Protein Confers Durable Disease Resistance in Rice Science, 325 (5943), 998-1001 DOI: 10.1126/science.1175550
see also Normile, D. (2009). New Strategy Promises Lasting Resistance to a Rice Plague Science, 325 (5943), 925-925 DOI: 10.1126/science.325_925)) that it is because of a tight genetic linkage. Resistance is conferred by the Pi21 locus, and:
The eating quality of plants carrying the elite cultivar’s chromosomal sequence from a point less than 2.4 kb downstream of the Pi21 locus was equivalent to that of the elite cultivar, and the plants showed a high level of blast resistance. In contrast, plants carrying the donor chromosomal sequence up to 37 kb downstream of the Pi21 locus showed inferior eating quality.
By crossing in just the right bit of the chromosome, and making sure that the neighboring areas do not tag along, resistance can now be transferred, without spoiling the taste.
Nibbles: Agroforestry, Korean fruit, Sami knowledge, Date palm, Havana
- World Agroforestry Congress has a blog. Welcome to the blogosphere!
- Evil Fruit Lord does Korea. Korea still reeling.
- Sámi herders have lots of words for reindeer pastures. No, wait…
- UAE boffins fingerprinting their dates. Why, what have they done?
- Yet more on Cuban urban/organic agriculture from the BBC.
Nibbles: Cacao, Soil mapping, Rice terraces, Maize, Cereus
- “USDA’s Bourlaug International Science Fellows Program has partnered with non-profit and for-profit organizations to identify new agricultural techniques for cocoa cultivation and to control cocoa diseases.” And do some conservation and breeding, surely.
- Big shots call for a decent global digital soil map. Seconded.
- Cool photos of rice agricultural landscapes.
- Roasting maize, Mexico style. Oh yeah, there’s also a nifty new maize mapping population out.
- Peruvian apple cactus doing just fine in Israel.
Wild cassava genetics used to document past changes in vegetation
Was southern French Guiana always forested, a refugium for forest species, or was it dominated by more open vegetation during drier, glacial times? A recent paper in Molecular Ecology tries to decide between these competing hypothesis, and the interesting thing for us at the Agricultural Biodiversity Weblog is that it does so through a genetic study of a crop wild relative. ((DUPUTIÉ, A., DELÊTRE, M., DE GRANVILLE, J., & MCKEY, D. (2009). Population genetics of Manihot esculenta ssp. flabellifolia gives insight into past distribution of xeric vegetation in a postulated forest refugium area in northern Amazonia. Molecular Ecology, 18 (13), 2897-2907. DOI: 10.1111/j.1365-294X.2009.04231.x.))
Manihot esculenta ssp. flabellifolia is the closest wild relative of cassava. It is “distributed on an arc partly encircling the Amazon basin, from eastern Bolivia and Peru eastward to northeastern Brazil, northward to the Guianas and then westward to Venezuela.” Its habitat is the transition zone between forest and cerrado in the south, and open environments such as savannas and rocky outcrops in the north. In French Guiana, which was the focus of the study, it is found both in the coastal strip, and on isolated granitic outcrops (inselbergs) in the forested south, with a large gap in between.
Seven microsatellite loci were used to investigate the genetic relationships among 14 populations, 4 from inselbergs and the rest from the coast. The results are pretty easily summarized. First, the inselberg populations were very similar to each other. Second, they were quite different as a group from the coastal populations. Finally, the coastal populations were highly differentiated among themselves.
So, what do these results tell us about the past vegetation history of the region? One conclusion was that the coastal populations (which incidentally, in contrast to the inselberg populations, showed some evidence of introgression from the crop) are relatively recent, and arrived from savannas to the west through a series of bottlenecks, rather than from the south. As for the southern inselberg populations, given the limited range of pollen and seed flow, they seem to be the remnants of a formerly more extensive, fairly homogeneous population. ((Conservation question: Does that mean that seed of the 4 inselberg populations could be bulked and kept as a single accession? Answers on a postcard, please.)) That suggests that southern French Guiana was drier and had a more open vegetation before the Late Glacial Maximum 10,000 years ago. There was probably a forest refugium in the central part of the country, but not in the south.
Assuming, of course, that the adaptation of the species hasn’t changed much along the way. It remains to be seen whether the same pattern will be found in other taxa. Perhaps other species of agrobiodiversity interest will be investigated in the same way.