An international team of researchers, including some from NYU Abu Dhabi, have identified a global cooling event 4,200 years ago, as a key factor in the evolution of rice. The study indicates that the cooling may have created new varieties of rice, and driven the subsequent spread across Asia of this global staple.
Using a multidisciplinary approach, the research, published in Nature Plants, reconstructs the evolutionary history of rice and its migration throughout Asia. While rice is now ubiquitous in global diets, its development, which began 9,000 years ago in China’s Yangtze Valley, is not well understood. By understanding rice’s development, new varieties can be developed which meet environmental challenges, helping secure global food supplies.
The study indicates that the japonica subspecies of rice diversified into temperate and tropical varieties as a result of a major climate cooling about 4,200 years ago, which brought civilization collapse in regions including Mesopotamia, China, and the Arabian Peninsula.
Researchers reconstructed the development of rice across Asia using whole-genome sequences of over 1,400 varieties in the two main subspecies of rice, japonica and indica, as well as geographic, archaeological, and historic climate data.
Tropical varieties of japonica continued evolving after the cooling event - likely supported by trade and travel networks – and the study finds tropical japonica reached Southeast Asian islands 2,500 years ago. However, the evolution of indica was more recent, migrating into China approximately 2,000 years ago, having originated in India’s lower Ganges Valley around 4,000 years ago.
Genomic differences between tropical and temperate varieties of japonica uncovered in the study suggest that temperature was the most significant factor in rice’s evolutionary development.
The study involved researchers from across the world, including members of the Purugganan laboratory at the NYUAD Center for Genomics and Systems Biology, alongside experts at Pennsylvania State University, Universidade Nova de Lisboa in Portugal, the Crow Canyon Archaeological Center, Carnegie Mellon University, the University of Manitoba, University College London, North-West University in China, University College Dublin, and the University of California San Diego.