Grapevines and rice yield clues on early agriculture and civilizations
Geneticists sequence the grapevine genome, and archaeologists may have found where rice was first cultivated in China.
For the first time, geneticists have sequenced the genome of the grapevine. Their first reading of this information already has revealed significant changes that millenniums of selective breeding have made in this fruitful plant. Meanwhile, archaeologists have found what appears to be a site where rice was first cultivated in China.
Whether seen through the lens of 21st-century genetics or uncovered by traditional dig-and-sift archaeology, the story of the development of agriculture is becoming clearer. It is synonymous with the rise of civilization.
The grapevine geneticists made this point when they described their work in Nature last month. They quote the ancient Greek historian Thucydides' assertion "that Mediterranean people began to emerge from ignorance when they learnt to cultivate olives and grapes."
The specific grapevine studied is a variety of Pinot Noir. It has been inbred in a way that makes its genome easier to sequence. A large team carried out the research for the French-Italian Public Consortium for Grapevine Genome Characterization. Thus the consortium is listed as the author of the scientific paper, not the individual scientists. So far, it is only the fourth flowering plant, the second woody plant, and the first fruit crop plant to have its genome sequenced.
Two research findings stand out: Grapevine shares a common ancestor with a group of plants that include poplar, legumes, cotton, and other useful species. Knowing the grapevine sequence sharpens scientists' understanding of what still is shared genetically throughout this plant group. Also, the grapevine genome is enriched to favor production of terpenes and tannins that influence the quality, aroma, and flavor of wines. The hand of the husbandman is evident here.
This is just preliminary analysis. Going forward, the consortium hopes that public access to the grapevine genome "will help in the identification of genes underlying the agricultural characteristics of the species, including domestication traits." This will aid modern breeders to develop more pest-resistant and drought-tolerant varieties.
More is known genetically about another important crop plant – rice. But the places and circumstances of the first rice domestications are unclear.
Last month, Y. Zong at Britain's Durham University and colleagues reported in Nature what they call "detailed evidence" that "reveals the precise cultural and environmental context of rice cultivation at this earliest known Neolithic site in eastern China."
The site at Kuahuqiao has well-preserved sediments containing microscopic bits of pollen, algae, fungal spores, and charcoal. Together with artifacts and other archaeological materials, they allow the scientists to reconstruct both the cultural and ecological circumstances of the time some 7,700 years ago when rice was grown there. It was a postglacial seashore swamp. The inhabitants cleared it by fire and then maintained rice paddy conditions, probably by regular flooding with slightly brackish water.
The inhabitants grew rice there for 200 years until the rising sea level drowned them out.
The strategy of using fire to turn wetlands into productive rice paddies may have been used at other seashore or, perhaps, lake shore sites. This gives a new focus for research into the domestication of one of the most important food crops on our planet.
As the archaeologists note, "this was one of the most important cultural processes in history."