Resilient Rice on the Rise

Plant geneticist Susan McCouch taps into wild grains for traits to help rice survive in a changing environment.

Rice in Hands
Photo courtesy of Cornell University

Plant geneticist Susan McCouch has been studying rice and how it grows for three decades, first mapping its genome in 1988. But she never ceases to be amazed by the attributes that rice varieties develop so they can persevere in adverse conditions.

Consider two major discoveries just this year. McCouch, a professor of plant breeding and genetics at Cornell University, and a research team discovered a gene in rice that is critical to surviving flood conditions. She also developed a new breed of nutritious Scarlett rice that incorporates the best qualities of its wild cousin, red rice—considered a “noxious weed”—resulting in a high-yielding rice variety resilient to weather extremes.

Susan McCouch
Susan McCouch
Photo courtesy of Cornell University

Water, Water Everywhere
Being able to thrive in flood conditions is important for rice varieties grown in Southeast Asia, where the water depth in the fields can reach several feet and remain for several months during the rainy summer and fall monsoon season. Farmers there plant roughly 6,000 varieties of deep-water rice. The grain plants grow in a normal manner in shallow water, but in heavy floods they increase their height in keeping with the rising water levels. This enables the plants to ride out the lengthy floods.

“To keep its head above water, the rice can grow up to 20 feet and stay there,” says McCouch, adding that until now researchers did not know which gene signaled the plant to respond to the flood. “What’s interesting is that if the floods don’t reach that high, the plant can grow 7 feet tall or 1 foot extra. It won’t grow at all extra if the floods don’t come.”

Working with a research team from Japan and the United States, McCouch and her co-investigators identified a gene in rice that enables it to survive in flood conditions. The research has also shed light on the gene’s molecular function and evolutionary history. The team identified the SD1 gene (SEMIDWARF1) as the gene responsible for deep-water rice’s dynamic response to being able to sense its environment.

“The farmers who can plant this rice and harvest it in their boats would otherwise get nothing,” says McCouch. “You value something more when you understand it, and the magic of this organism is that it senses its environment and responds appropriately, and that has a certain fundamental value in physics and chemistry.”

The deep-water varieties are not the highest yielding, however, because they put so much energy into just growing up to meet the water levels. So now researchers are focusing on improving breeding of deep-water rice to increase yields. They know they have to retain this fundamental survival mechanism, and then they can work on improving yields, McCouch explains.

Taming Red Rice’s Wild Ways
McCouch says she has always seen the value in studying mechanisms that tell a plant to adapt to its extreme environments and discovering the genetic potential of wild species. Understanding diversity is a key point of this work, both in the field and in gene banks, she says.

“What is fascinating about gene banks is that the kinds of things sitting in them are available for research and available for farmers,” she says. “So we try to take a lesson from what nature has given us and see how that might be translated into a different form of rice.”

The nutritious Scarlett rice that McCouch developed is one example. It’s a whole-grain rice with a nutty, rich flavor—much like brown rice—that grows well under organic conditions and is disease resistant. To create it, McCouch and collaborator Anna McClung, director of the USDA Agricultural Research Service’s Dale Bumpers National Rice Research Center in Arkansas, crossed a cultivated rice variety with a strain of red rice. The resulting cross retained none of the unfavorable “weedy” characteristics of seed dormancy and of seeds falling off the plant before they can be harvested. The new Scarlett variety keeps its red pericarp, a part of the hard outer layer that is rich in micronutrients and antioxidants, resulting in a high-yielding rice with a nutritious red bran layer.

Scarlett rice is currently being grown for seeds so it can go commercial. It can thrive in the southern United States and in similar environments in Uruguay and Argentina, and it is being released as a public variety with no intellectual property restrictions and royalty free. McCouch says she is also working with chefs in South Carolina to develop new recipes that showcase the flavorful rice as a central feature in a meal.

“The public is becoming more interested in food and food diversity, going back to how it’s grown, where it’s grown, and what the varieties are,” McCouch says. “The Scarlett rice is very interesting for consumers because it has a different texture when you eat it. It’s much chewier and nutty, and it has a lot of oils in cell layers, and so it’s an experience that differs completely from a cuisine point of view.”


Lisa Palmer is author of “Hot, Hungry Planet” (St. Martin’s Press, 2017) and a freelance journalist in Maryland. She reports on food, the environment and sustainable business for publications such as Slate, Scientific American, Nature, Yale e360, and The Guardian. She is a senior fellow for socio-environmental understanding at the National Socio-Environmental Synthesis Center (www.sesync.org) in Annapolis, Md.