Genomic revolution of US weedy rice in response to 21st century agricultural technologies

Weedy rice is a close relative of cultivated rice that devastates rice productivity worldwide. In the southern United States, two distinct strains have been historically predominant, but the 21(st) century introduction of hybrid rice and herbicide resistant rice technologies has dramatically altered the weedy rice selective landscape. Here, we use whole-genome sequences of 48 contemporary weedy rice accessions to investigate the genomic consequences of crop-weed hybridization and selection for herbicide resistance. We find that population dynamics have shifted such that most contemporary weeds are now crop-weed hybrid derivatives, and that their genomes have subsequently evolved to be more like their weedy ancestors. Haplotype analysis reveals extensive adaptive introgression of cultivated alleles at the resistance gene ALS, but also uncovers evidence for convergent molecular evolution in accessions with no signs of hybrid origin. The results of this study suggest a new era of weedy rice evolution in the United States. Whole-genome re-sequencing of weedy rice accessions reveals recent genetic introgression and adaptation that is altering crop-weed dynamics across southern USA.

Automated summary

This study investigates the genomic consequences of crop-weed hybridization and selection for herbicide resistance in weedy rice using whole-genome sequences. The results reveal recent genetic introgression and adaptation that is altering crop-weed dynamics across southern USA.