October 03, 2012

Rice and Barley domestication news

Both papers are open access.

PNAS doi: 10.1073/pnas.1215265109

Tibet is one of the centers of domestication of cultivated barley

Fei Dai et al.

The Near East Fertile Crescent is well recognized as a primary center of barley origin, diversity, and domestication. A large number of wild barleys have been collected from the Tibetan Plateau, which is characterized by an extreme environment. We used genome-wide diversity array technology markers to analyze the genotypic division between wild barley from the Near East and Tibet. Our results confirmed the existence of Tibetan wild barley and suggested that the split between the wild barleys in the Near East and those in Tibet occurred around 2.76 million years ago (Mya). To test the concept of polyphyletic domestication of barley, we characterized a set of worldwide cultivated barley. Some Chinese hulless and six-rowed barleys showed a close relationship with Tibetan wild barley but showed no common ancestor with other cultivated barley. Our data support the concept of polyphyletic domestication of cultivated barley and indicate that the Tibetan Plateau and its vicinity is one of the centers of domestication of cultivated barley. The current results may be highly significant in exploring the elite germplasm for barley breeding, especially against cold and drought stresses.


Nature (2012) doi:10.1038/nature11532

A map of rice genome variation reveals the origin of cultivated rice

Xuehui Huang et al.

Crop domestications are long-term selection experiments that have greatly advanced human civilization. The domestication of cultivated rice (Oryza sativa L.) ranks as one of the most important developments in history. However, its origins and domestication processes are controversial and have long been debated. Here we generate genome sequences from 446 geographically diverse accessions of the wild rice species Oryza rufipogon, the immediate ancestral progenitor of cultivated rice, and from 1,083 cultivated indica and japonica varieties to construct a comprehensive map of rice genome variation. In the search for signatures of selection, we identify 55 selective sweeps that have occurred during domestication. In-depth analyses of the domestication sweeps and genome-wide patterns reveal that Oryza sativa japonica rice was first domesticated from a specific population of O. rufipogon around the middle area of the Pearl River in southern China, and that Oryza sativa indica rice was subsequently developed from crosses between japonica rice and local wild rice as the initial cultivars spread into South East and South Asia. The domestication-associated traits are analysed through high-resolution genetic mapping. This study provides an important resource for rice breeding and an effective genomics approach for crop domestication research.


1 comment:

Annie Mouse said...

Barley is a very important grain crop for Europeans. The earliest breads found in Europe, so far as I am aware, are all flat breads, and they are mostly barley flat breads. Oetzi I think ate einkorn wheat.

So I had a look at this paper looking for a neolithic expansion signal. Happily there is a very nice phylogentic tree in the paper. But I am damned if I can spot a clear neolithic expansion signal in it. I expected a sudden expansion of strains at about 10kya for the neolithic or post glacial warming..

I dont know what to make of this, but it looks to me like Barley was NOT spread in the neolithic with post glacial warming.

There is what looks like a very early expansion out of central asia, and thereafter it looks random. Northern European barley was connected to southern Tibet, Southern European barley was connected to North Africa (basically mediterranean).