How did weedy rice plants regain bristles after loss in domestication?

Rice is the most important agricultural crop for the majority of the world's population. Thousands of years ago, humans domesticated the Asian wild rice species, Oryza rufipogon. This resulted in the development of cultivated rice, Oryza sativa. Weedy rice (or red rice), its conspecific relative, is interestingly not a crop but a pest that invades rice paddies around the world. It can reduce crop yield by up to 80% and devalue the overall quality of the harvest.

One important trait that contributes to the success of weedy rice in crop fields is the presence of awns. An awn is the bristle-like appendage that extends from certain grains. The loss of awns was favored by artificial selection because awns make rice difficult to harvest and store. However, awns have reappeared in weedy rice and are advantageous to the pest due to their assistance in seed dispersal, burial, and protection from the environment.

Previous research has shown that the An-1 gene regulates the development of long awns in wild rice. In the Caicedo lab, we are interested in determining if this same gene is associated with awn morphology in weedy rice. By phenotyping this trait and sequencing the An-1 locus in samples of wild, cultivated, and weedy rice, we hope to discover more about the origin and evolution of awns in weedy rice. We believe that a better understanding of the evolutionary development of weedy rice will improve methods of weed control in agriculture.