Cutting-edge technology leads to variety improvement


Geneticist Chad Finn identifies best-performing plants and evaluates berry appearance and flavor to see whether the fruit has the characteristics that growers, processors and consumers want.
PHOTO BY STEPHEN AUSMUS, ARS.

What do apples, sweet and tart cherries, peaches and strawberries have in common? All are members of the Rosaceae family. Now, these fruits are benefiting from a project that focuses on their genetic similarities to help speed crop improvement.

What is RosBREED?

The project, called RosBREED (www.rosbreed.org), was launched in 2009 with funds from the USDA’s National Institute of Food and Agriculture Specialty Crops Research Initiative. The nationwide, collaborative effort is pooling resources, infrastructure and top scientists to develop improved plant materials more quickly and efficiently than in the past. The key to that benefit is using marker-assisted breeding. This technique employs genetic markers used to identify the desired characteristics in a plant while it is a seedling, reducing the time needed to select individuals with those traits. Although the method has been used with other crops, it is new to the Rosaceae family. Less expensive and regulated than some breeding methods, the procedure will deliver better fruit more quickly and with less red tape.

RosBREED’s mission is to blend cutting-edge genomics tools with traditional breeding techniques to reach a new level in crop improvement. For growers, this means more profitable crops that are in higher demand. In addition to advances in research, the group seeks to improve training and outreach.

“This is a watershed year for Rosaceae with the peach, apple and strawberry genomes being sequenced,” project director Amy Iezzoni said. “Yet a huge gap exists because this DNA-based information is rarely applied to improve plant breeding for the development of new fruit cultivars. These crops provide vital contributions to human health and well-being, and the associated production and processing industries collectively make up the economic backbone of many U.S. rural communities.”

Goals

To achieve its goals, RosBREED is taking a broad-based approach. In addition to evaluating the scientific and grower needs, the project is looking at consumer preferences to help guide breeding of highly marketable fruit. Drawing on the genetic similarities of the fruits in the Rosaceae family, the team is creating a sustainable technical infrastructure to facilitate its end goals. The program is merging breeding and genomics resources by establishing a user-friendly statistical and breeding information management system. Cultivar development will become more sustainable by marker-assisted breeding training and closer relationships between producers, processors, marketers, scientists and consumers.

RosBREED’s activities

To develop optimal fruit and engage all the stakeholders, the project is conducting specific activities aimed at identifying and breeding the crops of the future. To determine which traits are most valued by growers, processors, consumers and other stakeholders, interviews, surveys and taste tests will be conducted.

“Imagine ultra-crisp, tasty apples, sweet peaches that don’t get mealy, and aromatic and flavorful strawberries consistently available from your local grocery store,” said Cameron Peace, Washington State University horticulturist and RosBREED co-director. “These are the kinds of fruit that consumers want, [the] industry needs, and that we can help develop using new genetics and genomics technologies.”

Scientists plan to develop a genome-scanning capability for the targeted fruits, looking most closely at the shared traits. This resource will facilitate training and breeding for years to come.

The four-year, $14.4 million project offers a cooperative extension service-based educational component for those involved in breeding, producing and marketing.

The RosBREED team

The project involves scientists from 11 U.S. institutions, USDA labs and six international partners from the Netherlands, South Africa, New Zealand, Chile, France and the United Kingdom.

Amy Iezzoni, Michigan State University, leads RosBREED. Under her management are a number of team leaders directing specific functions. The University of Minnesota’s Chengyan Yue is overseeing the socioeconomic studies, while Jim McFerson, from the Washington Tree Fruit Research Commission, heads up the stakeholder component.

Crucial to bringing those improved cultivars to the farm are breeders such as Chad Finn. He is involved with blackberries, blueberries, raspberries and strawberries at the Oregon Agricultural Experiment Station in Corvallis, which is affiliated with Oregon State University. As the Pacific Northwest fruits typically are processed, rather than directed to fresh markets, his work focuses on that market segment.

To develop fruit suitable for such purposes, Finn looks at uniform fruit size, excellent color and flavor and low drip loss. Drip loss refers to the amount of moisture that is retained after fruit is frozen and thawed. Processing strawberries must tolerate efficient hand picking and be easy to cap. Growers in Finn’s region look for hardy plants that are virus-resistant.

Finn evaluates up to 8,000 seedlings annually and manages a large germplasm collection. He makes scores of crosses each spring, using advanced selections and wild germplasm. He released the Tillamook and Firecracker strawberries and collaborated with Washington State University scientists on Puget Summer strawberries.

Strawberry has the shortest generation time of the fruits in the RosBREED program, making it a good study crop. Cultivars will be evaluated in Oregon, Michigan and California.

Although Finn’s breeding program currently does not use DNA markers, it is moving toward working with selections based on marker-assisted selection. He believes that the work of RosBREED will make breeders more efficient, as inferior seedlings can be weeded out more quickly and at less expense.

Mapping the peach genome


Peach growers will benefit from RosBREED’s early work, as the peach genome was mapped in early 2010.
PHOTO COURTESY OF MORGUEFILE.COM

Isolating, comparing and cataloging genetic content and transferring that knowledge to better fruit cultivars may sound like a decades-long endeavor. However, as promised, working with common genetic traits within a fruit family is speeding up the breeding and crop improvement processes.

A major accomplishment of RosBREED was announced on April 1, 2010. The peach genome, its entire genetic pattern, has been isolated. This demonstrates the power of the project.

Scientists consider the peach as one of the most well-characterized species, genetically speaking, in the Rosaceae family, making it well-suited to serve as a model. Its genes for vital characteristics, such as fruit and flower development, tree growth habit, dormancy, cold hardiness, and disease and pest resistance, have been identified. Mapping its specific genetic makeup is a giant step in breeding better fruit.

More discoveries

In other findings, an important step in tackling the crucial element of fruit size has been achieved. In Iezzoni’s “Jewels in the genome” column in the RosBREED newsletter, she says that, in the case of sweet cherries, even a difference of 2 millimeters in diameter can dictate profit or loss. Scientists also isolated a genetic region that controls cherry fruit size and even narrowed down the DNA responsible for small, medium and large dimensions. The bad news is that trees bearing large cherries tend to offer soft fruits, while those producing firm fruits generally are small in size. Through the RosBREED project, using data from Washington State University seedlings, the magical DNA type resulting in large, firm and sweet cherries was identified. This discovery paves the way for breeders to develop the ideal sweet cherry and will also help improve the tart cherry.

“Being a peach breeder and part of the RosBREED team is very exciting,” Clemson University researcher Ksenija Gasic said. “RosBREED focuses on bridging a gap between genetics and genomics technologies and their practical application in breeding programs, with the ultimate goal of delivering fruit that is desirable by consumers and more profitable for fruit growers. It’s all about delivering the best product to the final consumer using the latest techniques guided by stakeholders’ needs and consumer preferences.”

Current and future findings, combined with the expanded breeding and educational branches of RosBREED, promise fruit growers highly marketable cultivars that will enhance profitability. Stay abreast of the latest developments online at www.rosbreed.org.

Based in Greensboro, N.C., the author writes articles about horticulture, landscaping, agriculture and travel.