Issue link: https://read.dmtmag.com/i/751050
68 DECEMBER 2016 GOOD FRUIT GROWER www.goodfruit.com C onsumers want great tasting fruit with few or no blemishes. Growers want that, too, but they also need fruit trees to be easier to grow and, specifi cally, to be resistant to diseases that can decimate an orchard. A national team of scientists aims to tie those goals together by applying modern genomics to deliver new cultivars that carry both the disease resistance desired by producers and the horticultural qualities demanded by the marketplace. It is no simple task, but researchers have some success with which to build upon their efforts: The RosBREED project enabled researchers to develop the infrastruc- ture to conduct DNA-informed breeding to improve the effi ciency of the breeding process. By using molecular markers, researchers are able to identify and keep plants that contain multiple desirable traits — a process called gene pyramiding — and discard those that don't. From that project, researchers now have access to genetic markers for some ideal horticultural traits, such as fruit color or crispness, and are using these DNA mark- ers to select for those traits early in the breeding process. The next generation of the project, called RosBREED 2, goes a step further by combining those efforts with new research to increase the effi ciency of breeding new cultivars that have excellent horticultural traits and disease resistance. Two years into the fi ve-year project, many of the researchers have finished phenotyping, which means they've established which trees are disease resistant in their respective research blocks for different crops. The next step is to gather genetic data from those plants and use this information to locate the positions of the genes responsible for the disease resistances on the plant's chromosomes. "The goal is to, in future generations, use DNA infor- mation to choose parents more effectively and choose seedlings more effectively," said Amy Iezzoni, cherry breeder for Michigan State University and the project's co-leader. "And ultimately, to choose seedlings that are resistant for not just one disease but two." Pyramiding disease resistance is most effi ciently done using DNA markers, Iezzoni said. "Many times you can't subject the same seedlings to multiple diseases. Then if it is a fruit disease you are breeding for, with DNA markers you don't have to wait for the seedling to fl ower and fruit to know whether it is disease resistant. Using DNA infor- mation to predict its phenotype is the next step." RosBREED history A $14 million grant from the Specialty Crop Research Initiative created the first RosBREED project, which involved nearly three dozen scientists from 14 U.S. insti- tutions to focus on fi ve crops: apple, peach, strawberry, sweet cherry and tart cherry. RosBREED 2 has been expanded to include blackberry, pear, rose and prunus rootstock, as well as the efforts of a team of plant pathol- ogists to help research diseases. As with the fi rst project, information gleaned from individual projects will be shared across crops. Jim McFerson, director of Washington State University's Tree Fruit Research and Extension Center, said the standardized approach allows researchers for each crop to benefi t from the synergies in their research techniques. RosBREED, part II Scientists build on DNA-informed breeding efforts with research into disease resistance. by Shannon Dininny COURTESY KRISTEN ANDERSEN The tree on the left is an MSU breeding selection where one of its great-grandparents was sweet cherry, which has a tolerance for cherry leaf spot. The tree on the right is a susceptible Montmorency tart cherry. ONLINE See a chart of disease threats and affected crops targeted by the RosBREED 2 project at goodfruit.com