London: If you think genetically-modified rice is a modern day practice, think again -- even cavemen were growing the GM variety more than 10,000 years ago, a new
study has found.
The research by a team from the Kobe University in Japan showed that the ancient humans selected different strains of the rice and mixed their genes to create an ideal
version of the crop, which had led to higher yields and better cultivation.
The discovery was made after researchers carried out a genome analysis of wild rice alongside two sub-species with different histories. This showed that the lengths of stems was shortened by variants in a gene called SD1, the Daily Mail reported.
According to lead researcher Dr Masanori Yamasaki, SD1 is one of the most important genes in modern rice breeding over the last fifty years. Over time the mutations in SD1 yielded rice with shorter stems, sturdier stalks and greater grain output.
Dr Yamasaki and his team found these are fixed in one sub-species 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 sub-species compared with wild rice.
This suggests that the SD1 gene had been subjected toartificial selection during early rice domestication, the researchers reported in the journal Proceedings of the
National Academy of Sciences.
Dr Yamasaki and his colleagues believe that ancient humans took an interest in the height of the rice plants and selected shorter ones with specific SD1 gene characteristics.
Plant domestication, according to the researchers, involves the genetic modification of wild species to create a new plant to meet human needs.
They said: "During this domestication ancient humans subjected common agronomic traits to artificial selection, thereby increasing the seed or fruit size, synchronisation of growth and flowering, loss of seed dispersal, changes in plant
architecture and other characteristics comprising the `domestication syndrome`.
"These traits have contributed to more efficient cultivation, higher yields and more valuable products for human use.
"Consequently crop species have undergone extensive selection for these agronomically important traits and genes impacted by artificial selection can be essential genetic factors in the domestication process.
"These findings indicate SD1 has been subjected to artificial selection in rice evolution -- suggesting ancient humans already used the green revolution gene."