April 29, 2010

A cautionary tale for wheat domestication

What this paper shows is that an ancestral allele believed to have been lost during wheat domestication, was actually present in 19th century wheat cultivars. What this means is that (a) the derived allele may not be fixed (100% frequency) but may co-exist with the ancestral one, and (b) if it is indeed fixed, then this fixation did not occur in Neolithic times, but over the last century and a half or so.

Journal of Archaeological Science doi:10.1016/j.jas.2010.04.003

Re-evaluating the history of the wheat domestication gene NAM-B1 using historical plant material

Linnéa Asplund et al.


The development of agriculture is closely associated with the domestication of wheat, one of the earliest crop species. During domestication key genes underlying traits important to Neolithic agriculture were targeted by selection. One gene believed to be such a domestication gene is NAM-B1, affecting both nutritional quality and yield but with opposite effects. A null mutation, first arisen in emmer wheat, decreases the nutritional quality but delays maturity and increases grain size; previously the ancestral allele was believed lost during the domestication of durum and bread wheat by indirect selection for larger grain. By genotyping 63 historical seed samples originating from the 1862 International Exhibition in London, we found that the ancestral allele was present in two spelt wheat and two bread wheat cultivars widely cultivated at the time. This suggests that fixation of the mutated allele of NAM-B1 in bread wheat, if at all, occurred during modern crop improvement rather than during domestication. We also discuss the value of using archaeological and historical plant material to further the understanding of the development of agriculture.



pconroy said...

I wonder does this mean that different wheat varieties were being hybridized till recently?

BTW, I much prefer Spelt to other varieties, and eat it instead of Brown Rice with meals.

Maju said...

Important cautionary tale. Most of the homogenization in breeds, not just in wheat, should be pretty recent, caused by globalization and standarization of production methods.

Mrs. Watanabe said...

It looks like Norin 10.


Norin 10 is a short wheat variety that permitted fertilizer to be used (normal wheat would grow too large and fall over).

The "last half century" is right for Norin 10.

If we went back to an older variety, then we wouldn't be able to fertilize, yields would fall, and people would starve.

Maju said...

Chemical fertilizers are expensive and damage the soils in the long run. They also require of an industrialized agriculture that relies on too little diversity and may collapse at any moment.

In reality most countries used to be self-sufficient in food but now they are almost forced to buy US (and other large grain exporters') subsidized products because the IMF has forced them to recycle into single-crop mega-plantations (like with oil palm).

So things are not that simple, not at all. Industrialized agriculture requires standarization and global markets but people would probably face better their food needs if using more reasonable methods in ecologically-friendly small scale agriculture.

Marnie said...

Thank you Mrs. Watanabe for your comments about Norin 10 wheat.