Multiple domestications of Asian rice

Area of Science:

• Agricultural Science
• Genetics
• Evolutionary Biology

Background:

• The origin of domesticated Asian rice (Oryza sativa L.) is a long-standing debate.
• Key hypotheses include a single domestication event in China versus multiple events in separate regions.
• These hypotheses predict different evolutionary histories for domestication-related genes.

Purpose of the Study:

• To investigate the geographic origin and evolutionary history of Asian rice domestication.
• To resolve the debate between single versus multiple domestication events.
• To identify genes and alleles selected during rice domestication.

Main Methods:

• Amassed a large dataset of 1,578 resequenced Asian rice genomes.
• Included an expanded sample of wild rice from its entire geographic range.
• Analyzed selected genes and constructed phylogenetic trees to infer origins.

Main Results:

• Identified 993 selected genes involved in rice domestication.
• Phylogenetic analysis indicated japonica and indica rice formed a monophyletic group.
• Domestication alleles for approximately 80% of selected genes originated in China.
• A substantial minority (~20%) of domestication alleles originated from wild rice in South and Southeast Asia.

Conclusions:

• Asian rice domestication was not a single event but involved multiple geographic origins.
• Evidence supports both a primary domestication center in China and secondary centers in South/Southeast Asia.
• This finding clarifies the complex evolutionary trajectory of Oryza sativa L.