Genomic analyses of weedy rice reveal historical connections between European and northwestern Chinese rice.

Rice (Oryza sativa) was domesticated in the Yangtze River basin of China and later spread across Asia into Europe; however, the route of its early introduction into Europe remains unresolved, as modern breeding and repeated introductions have obscured historical signals in cultivated varieties. Here, we use weedy rice-a feral derivative of cultivated rice that has undergone relatively limited artificial selection and retains clearer ancestral genomic features-as a genomic system to trace historical dispersal. By integrating whole-genome resequencing of 196 weedy rice accessions with analyses of photoperiod-related flowering genes, we investigated the evolutionary relationships between Asian and European rice populations. Population genomic and phylogenetic analyses reveal a close genetic affinity between European weedy rice and northwestern Chinese rice lineages, while also uncovering signatures of recent feralization and introgression from modern cultivars. Photoperiod-adaptive alleles enriched in northwestern Chinese weedy rice are also prevalent in modern European cultivars, consistent with repeated utilization of ancestral variation during adaptation to higher latitudes. Demographic modeling further suggests that these shared patterns likely predate modern breeding. Together, our findings demonstrate the value of weedy rice as a model for reconstructing crop evolutionary history and provide genetic evidence supporting a historical westward dispersal of rice into Europe, potentially along routes associated with the Silk Road.