Apr 19, 2016

RosBREED prioritizes disease resistance

The focus of RosBREED 2, a program to produce better-tasting fruit that resists storage problems and other challenges, is disease resistance.

A $10-million, five-year grant from USDA is driving the wide-ranging national fruit-breeding project. The program is using advanced breeding and DNA techniques – not GMO technology.

The second phase of RosBREED, which began in 2015, has a sharper focus than the initial program, which started in 2009. The focus now is on developing better horticultural quality with improved disease resistance through better genetics and breeding.

Breeders working on the project recently gathered for a meeting in East Lansing, Michigan. Project Director Amy Iezzoni of Michigan State University (MSU) and a national team of scientists discussed the importance of disease resistance work and what they’ve learned about the genomics, genetics and breeding of rosaceous crops and what they hope to learn in the next few years.

Iezzoni and co-director Cameron Peace of Washington State University (WSU) are now leading a group of 35 scientists from 14 U.S. institutions, along with international cooperators. The team has added new scientists and expanded to include additional crops that are part of the rosaceae family, Iezzoni said.

RosBREED 1 focused on apples, sweet and tart cherries, peaches and strawberries. RosBREED 2 has added pear, blackberry, prunus rootstock for armillaria resistance and rose, Iezzoni said.

Jay Norelli, research plant pathologist with USDA in Kearneysville, West Virginia, is the pathology team leader overseeing disease resistance management.

“Disease resistance is a very important production trait for growers,” Norelli told Fruit Growers News. “They lose a lot of profit to disease. In addition, they have to spray a lot of pesticides to control diseases. By incorporating resistance, we’ll be able to both reduce pesticide loads, which should save money and time for growers, and produce fruit that is probably more desirable for consumers as well.

“We’re working with a lot of important disease traits in RosBREED for different crops,” Norelli said. “We’re attempting to develop breeding parents that we can use in breeding programs that will be carrying resistance to many different diseases so that breeders will be able to start to incorporate the disease resistance into the new cultivars they’re going to be producing.
“Time is a big impediment,” he said.

“A lot of time, resistance may be coming from wild species that may not have great flavor, so developing the sort of DNA tools to be able to select resistance is really allowing us to speed up that incorporation into crops, because we don’t have to spend a lot of time evaluating the fruit for its resistance. We can use a DNA test to quickly evaluate things at a seedling stage rather than have to plant a tree, grow it up, get the fruit and then start to evaluate it. We can now do that evaluation usually in the greenhouse before it ever goes out to the field.”

Ksenija Gasic, associate professor of horticulture at Clemson University, is RosBREED’s stone fruit team leader.

“My peach breeding program for Clemson University is the youngest one that participates in the RosBREED project,” Gasic said. “I was here from the start of the first project, and now into the second. The beauty of this project is it encompasses so much expertise and so many experiences in the programs that are running for 50 or 60 years, down to mine that is seven years old.

“What that makes for me is I can actually see the history of the breeding and how breeders, in not actually knowing in the DNA level what they’re doing, made certain progress and advanced their selections,” she said.

“When I came into the picture, I needed to learn all that knowledge at once and apply it in my program to get at least closer to the final stage where they are,” Gasic said. “That was not really easy. The main guidance I got from the industry was the disease resistance.

“Within the first RosBREED project we focused on the fruit quality, because that’s still an issue in many of our crops, because we want to develop the best products so consumers will want to buy to eat and the industry will be happy and successful. But the disease is a big part
of it.

“In this project, we actually have a chance to combine the disease resistance with food quality and actually deliver that to our consumers,” Gasic said. “One of the biggest issues is we don’t know what we are looking at. Even though in the field some trees might look good, we don’t know what is in the background. What do we have there? If we choose to use those trees as a parent in our further crosses, there is no guarantee that the resistance will transfer to the seedlings.

“Now, with the DNA tools that we are developing, we can actually track the resistance that comes from the ancestors and see how that applies to the children and know how many of them are actually having a chance to get the resistance that trickles down to the money – everything revolves around the money and how much you have to do it,” Gasic said.

“We can allocate our resources much better and focus on the seedlings that have a chance to get to the goal that we want,” she said. “That excites the industry really well. We also added the rootstock breeding to the effort, although it’s kind of on the orphan side of all these efforts because it’s not so showy. You cannot just go around and show the fruit to people, but it’s a really important part of our industry, especially since we don’t have any new land. We need to replant our orchards, for the cherry and peach industries in particular.

“Armillaria is one of the biggest issues that is killing our orchards and decimating our industry,” Gasic said. “This was the biggest push from our stakeholders – to address that issue.

“This is a first known concerted effort to do something about it and to move forward, especially since some of the issues with the diseases take several years, so you can actually see the effect and evaluate it,” she said. “If you apply the tools at the molecular level you can increase your chances of finding something that’s important, combined together in one unique individual tree with markers, and then evaluate it for seven, eight years, and then at the end have a final cultivar. Before it was more serendipity, as one of my colleagues would say, where, if you’re lucky, among the thousands of seedlings you evaluate you’ll find that one that combines all the traits that you want.”

For more on RosBREED, visit www. rosbreed.org.

See videos on RosBREED research.

— Gary Pullano, associate editor