An international team of scientists has found that severe global cooling that occurred 4,200 years ago can have led to the evolution of recent rice varieties and the spread of rice to each northern and southern Asia.
Their study, published in Nature plants and run by New York University’s Center for Genomics and Systems Biology, uses a multidisciplinary approach reconstruct history Rice and trace its migration throughout Asia.
Rice is probably the most essential crops on the planet, providing the idea of food for over half of the world’s population. It was first cultivated 9,000 years ago within the Yangtze Valley in China and later spread to the east, southeast and South Asia, after which to the Middle East, Africa, Europe and the Americas.
In this process, rice evolved and adapted to recent conditions different environmentsbut little is understood concerning the routes, timing, and environmental forces involved on this dispersal.
In their study, scientists reconstructed the historical movement of rice across Asia using whole-genome sequences of greater than 1,400 rice varieties – including japonica and indica varieties, the 2 fundamental subspecies of Asian rice – combined with geography, archeology and historical climate. data.
For the primary 4,000 years of its history, rice cultivation was mainly confined to China, with japonica being the subspecies cultivated. Then the worldwide cooling that occurred 4,200 years ago – also often called the 4.2K event, which is believed to have had widespread consequences, including the collapse of civilizations from Mesopotamia to China – coincided with the diversification of japonica rice into varieties temperate and tropical. The newly evolved temperate varieties spread to northern China, Korea and Japan, while tropical varieties spread to Southeast Asia.
“This sudden climate change has forced plants, including crops, to adapt,” said Rafal M. Gutaker, a postdoctoral fellow at New York University’s Center for Genomics and Systems Biology and lead creator of the study.
“Our genomic data, as well as our collaborators’ paleoclimate model, show that the cooling occurred at the same time as the rise of temperate japonica, which grows in milder regions. This cooling may also have led to the migration of rice crops and farming communities in Southeast Asia.”
“These findings were further supported by data from archaeological rice stays excavated in Asia, which also showed that after the 4,200-year-old event, tropical rice migrated south, while rice also adapted to northern latitudes as temperate varieties,” said Michael D. Purugganan, a Silver Professor of Biology at New York University who led the study.
After global cooling, the production of tropical Japanese rice continued to diversify. It reached the islands of Southeast Asia about 2,500 years ago, probably due to extensive trade networks and the flow of products and folks within the region – a discovery also confirmed by archaeological data.
The spread of indica rice got here later and was more complicated; it originated within the Ganges Valley in India about 4,000 years ago, and scientists have traced its migration from India to China about 2,000 years ago.
Understanding the spread of rice and its associated environmental pressures also can help scientists develop recent varieties to satisfy future environmental challenges equivalent to climate change and drought, which could help address emerging food security issues.
“Armed with knowledge of rice dispersal patterns and the environmental factors that influenced its migration, we can study the evolutionary adaptations of rice as it spreads into new environments, which could allow us to identify traits and genes that will aid future breeding efforts.” Gutaker said.
Source : Phys.Org
