Kenneth Olsen, the George William and Irene Koechig Freiberg Professor of Biology, frequently works with international colleagues to study the evolution and genetics of plants. Much of his focus is on rice, a crop that has been grown under human control for 10,000 years. Olsen explained that domesticated crops are like prolonged experiments in natural selection. Twenty years ago, rice became the first plant to have its entire genome decoded. “That opened up a world of possibilities for studying the connection between genes and traits,” Olsen said.

Weedy rice is a feral form of rice that aggressively outcompetes cultivated rice. Here, the researchers visit rice fields in Arkansas to inspect fields and talk with farmers about this aggressive weed.

In a 2023 study published in BMC Biology, Olsen and a team of researchers from China and the Philippines examined the genomes of 13 varieties of wild and domesticated rice to identify genes that were lost during domestication. In many cases, they were able to connect the genetic change to a specific trait. For example, in japonica rice, the most common variety grown in East Asia, the deletion of the gene Os03g27510 improved grain length.

Understanding the genetic basis of specific traits could help boost crop production through selective breeding or genetic engineering, Olsen said. Rice is a crucial component of global food supply, so any insight into its growth and cultivation could have significant repercussions. “I’m a basic research scientist, but I definitely recognize and value the potential impacts that our research could have on crop improvement,” he said.

Kenneth Olsen

Olsen and his team are also working to understand “weedy” rice, a feral form of the crop that has become a scourge to rice farmers in the United States and other parts of the globe. Marshall Wedger, a postdoctoral researcher in Olsen’s lab, has visited rice fields in Arkansas to inspect them and talk with farmers about this aggressive weed. “Farmers can lose up to 80% of their harvest to weedy rice,” Olsen explained. The farmers, he said, are eager to share their observations and get help. “It can be so incredibly valuable to interact with farmers and get the insights of people who really understand the biology of a given species in its natural environment,” he said.

In 2022, Olsen, Wedger, and Nilda Roma-Burgos, a professor of weed physiology and molecular biology at the University of Arkansas, published a study that explored the genomes of weedy rice samples collected from five Arkansas rice fields. They found that most plants are actually hybrids of domestic crops and weedy ancestors, a radical shift from just 20 years ago, when hybrids were rare. The researchers speculated that the widespread use of herbicides over the last two decades has created a new generation of hybrid weeds that are relatively resistant to chemicals. “It’s incredibly easy for these weeds to adapt and evolve,” Olsen said. The findings, he added, underscored the dangers of using just one method — in this case, a single type of herbicide — to control weeds.