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Wild Plants to the Rescue

Efforts to domesticate new, high-yield, perennial grain crops require patience and persistence—but such plants could transform agriculture

David Van Tassel, Lee DeHaan

The Kernza Story

2013-05VanTasselF3.jpgClick to Enlarge ImageWhen we embarked on our breeding program, our primary approach was to develop perennial grain crops by hybridizing current annual crops with perennial relatives. We saw this method as a shortcut that would allow us to begin with domestication genes that had accumulated over thousands of years. All that was needed, we figured, was to introduce the key lifestyle trait of perenniality from a related species. The approach has promise, and for some crops, we are continuing along this path.

But back in 2001 we were also intrigued by the possibility of improving the wild perennial species themselves in order to develop entirely new perennial grain crops. With this strategy we could avoid the genetic complications that arise when two species are crossed (sterility, for instance), and we would be assured of having a strongly perennial plant to work with.

We started side projects to investigate the potential of numerous wild perennial species. One of these was intermediate wheatgrass (Thinopyrum intermedium), a species that had been studied by another nonprofit organization, the Rodale Institute, since 1987. The species is, as the name suggests, a grass; but it is no more closely related to wheat than barley or rye. After about six years of giving the wheatgrass part-time attention, we began to see signs that we could make good progress through breeding. Although our best estimates showed that it would take about 30 years to match the yield of wheat, we also saw that it would be possible to obtain a crop that farmers could successfully grow and market in much less time.

At this point we encountered one of the less scientific problems with domesticating a new species: the name. “Intermediate wheatgrass” just doesn’t have the ring of any of our current grains’ names—corn, rice, or wheat. So we came up with a name that we hoped would be unique and catchy, and remind people of Kansas. We called this crop-in-the-making kernza.

The Land Institute also decided to give domestication full standing as an approach for obtaining perennial grain crops. DeHaan and a technician were assigned to work on the project, which allowed us the time and attention to develop larger programs and collaborations. This step was critical: We knew that the introduction of a new crop would require a lot more than just breeding and genetics.

2013-05VanTasselF4.jpgClick to Enlarge ImageThe University of Minnesota now has an interdisciplinary project to develop kernza as a perennial grain and to use the residue for biofuels or animal feed. The research team, of which DeHaan is a member, includes researchers from the fields of agronomy, food science, plant breeding, soil science, plant pathology and economics. Plots are established at six sites around the state of Minnesota. Additional plantings in other states and in Canada are helping us evaluate the crop’s performance in diverse environments.

Because kernza is a relative of wheat and other grains, genomic approaches may allow us to transfer the knowledge gained from the study of these crops to the development of this new grain. Rather than transferring genes from wheat to kernza, we are studying the genomes in an effort to identify useful genes from wheat that are already present in kernza, but need only be discovered. We are also hopeful that marker-assisted selection will be helpful in sorting out some of the complexities involved in breeding a species that is both outcrossing—it can’t pollinate itself and thereby doesn’t breed true—and polyploid—having multiple genomes, which can result in complex gene segregation patterns. To these ends, sequencing work is now beginning at several institutions.

2013-05VanTasselF5.jpgClick to Enlarge ImageAll of this work is valuable, but we still believe that domestication comes down to evaluating very large numbers of plants in the field and selecting the best to intermate. This activity requires sustained, long-term commitment. In a conventional plant breeding program, 10 to 15 years may be required from the time a first cross is made to when a variety resulting from that cross is offered to farmers. But when the breeding pipeline is full—when new crosses are made every year—varieties can be released on a regular basis. Everyone from farmers to administrators to plant breeders can be satisfied that there is good evidence of progress. The case for breeding programs that are more experimental and that are not connected to a commercial program is more tenuous: Even if a new domestication program is sustained for a decade, the plants it is developing may not yet have economic value, and any value they have accumulated will be quickly lost if the program is discontinued.

In the case of kernza, we measured 14,000 individuals in the field last year. We intermated the best plants and, based on past experience, we expect that the yield will increase by about another 20 percent. This is a truly amazing rate of progress—but varieties that are usable by farmers remain a goal for the future.

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