- Colony collapse disorder: where are we now?
- Weedkiller diversity essential to maintain weed susceptibility.
- Eat the streets.
- Ancient Grains Flour Blend. A baker asks: Whatever next?
- Bumblebee beauty.
Natural selection at work
“This new forage has great insect resistance”, effused a former colleague, “we just need to eliminate the toxins that keep sheep from eating it.”
Genetically engineered drought-tolerant crops are introduced with great fanfare, only to disappear when they turn out to have low yield under nondrought conditions.
Fascinating post from R. Ford Denison, about how silly old natural selection (apparently) fails to make simple changes that would “obviously” be good for the organism concerned. Denison is very clear, in this post and elsewhere on his blog, about just how hard it is for even clever people to improve on the countless experiments that natural selection has had to work on, especially in agriculture. That’s why I for one am not holding my breath waiting for anyone anywhere to transform a C3 plant into a C4 plant.
Making that haystack smaller
Germplasm collections can be very large, and that can put off potential users. What breeder really wants to screen thousands of accessions, when only a dozen might end up being useful? It’s not surprising, therefore, that people have looked for short-cuts. One approach is to make a “core collection.” You use the available data on the collection to select a sub-set which you hope will contain most of the original genetic diversity in a fraction (20%, say) of the total number of accessions. And then you evaluate that subset, rather than the whole collection, and use the results to delve back into the remaining 80% of the material, with hopefully a better chance of finding what you’re looking for.
That’s been done for lots of large collections now, with a certain amount of success in increasing their use — and usefulness. But breeders are not really satisfied. They want to shorten the odds even more. And the application of Geographic Information Systems (GIS) technology in something called the Focused Identification of Germplasm Strategy (FIGS) provides a potentially effective way of doing just that.
Jeremy described recently over at Bioversity how FIGS was used to increase the chances of finding a needle in a haystack by “start[ing] with a smaller haystack.” The haystack was 16,000 wheat accessions. The needle was resistance to powdery mildew.
It works like this: take 400 genebank samples known to have some resistance to powdery mildew and use the geographical location where they evolved and were collected to determine the environmental profile that can be associated with resistance. Then apply that profile to a further 16,089 samples with location data, using the profile as a template to identify those that were found in places that share the conditions associated with resistance. The result is a group of 1320 wheat varieties, mostly from Turkey, Iran and Afghanistan. This much more manageable subset was screened by growing them with diverse strains of powdery mildew. About 16% of the samples (211 of 1320) showed some resistance.
These varieties then moved to the next phase, molecular screening for the presence of different alleles of the Pm3 gene. More than half (111 of the 211) had Pm3 resistance, some in previously unknown forms. In the end the group isolated and identified 7 new functional alleles of the Pm3 gene. It took scientists 100 years to find the first 7 Pm3 alleles. FIGS doubled the number in a fraction of the time.
Very good. But is it always going to work? Another recent paper — in fact, a series of papers — counsels caution.
Mango to get the encyclopedia treatment
I heard about this last week when I was at NBPGR in New Delhi, but it’s quite surprising to see it in the popular press. Just goes to show how important mango is in India. With funding from the Sultanate of Oman, the Indian Council of Agriculture Research (ICAR) is going to produce a catalogue of all the mango varieties of the world. Sounds like a monumental enterprise. But, given the news lately about loss of varieties, very timely. Hope the wild relatives will be included.
Around the world in a grain of rice
A great image of agrobiodiversity from Italian Grazia magazine, with thanks to Linda for cutting it out and saving it for me. It’s not online, so this is a scan. Click on the image to enlarge it. The spoonfuls are, from the top:
1. arboreo rice for risotto
2. long-grain basmati rice
3. mixture of rice, oats and Khorasan wheat
4. Sisa rice for sushi
5. black Venere rice
6. long-grain red rice
7. basmati again
8. mixture of unmilled rices