Thousands of years before modern crop breeding jumpstarted the "green revolution," ancient humans had already manipulated genes to improve crop characteristics, researchers find.
Focusing on the evolution of one crop in particular, Masanori Yamasaki and colleagues analyzed the genomes of wild rice and two rice subspecies with distinctly different domestication histories.
Genetic tests showed that the length of rice stems during the domestication process was shortened by mutations in the "Semi-dwarf1" (SD1) gene, one of the most important genes in modern rice breeding, according to the authors.
Over time, the mutations in SD1 yielded rice with shorter stems, sturdier stalks, and greater grain output. The researchers found that these mutations are fixed in one subspecies of modern domesticated rice, but not in wild rice.
In addition, much lower levels of genetic diversity were observed in the SD1 gene of the domesticated subspecies compared with wild rice, which suggested to the authors that the SD1 gene had been subjected to artificial selection during early rice domestication.
The authors propose that ancient humans took an interest in the height of rice plants and selected shorter plants with specific SD1 gene characteristics.
Source: Proceedings of the National Academy of Sciences via EurekAlert! [June 07, 2011]
Focusing on the evolution of one crop in particular, Masanori Yamasaki and colleagues analyzed the genomes of wild rice and two rice subspecies with distinctly different domestication histories.
Genetic tests showed that the length of rice stems during the domestication process was shortened by mutations in the "Semi-dwarf1" (SD1) gene, one of the most important genes in modern rice breeding, according to the authors.
Over time, the mutations in SD1 yielded rice with shorter stems, sturdier stalks, and greater grain output. The researchers found that these mutations are fixed in one subspecies of modern domesticated rice, but not in wild rice.
In addition, much lower levels of genetic diversity were observed in the SD1 gene of the domesticated subspecies compared with wild rice, which suggested to the authors that the SD1 gene had been subjected to artificial selection during early rice domestication.
The authors propose that ancient humans took an interest in the height of rice plants and selected shorter plants with specific SD1 gene characteristics.
Source: Proceedings of the National Academy of Sciences via EurekAlert! [June 07, 2011]