Program focuses on super fruit
In 1991, the fresh market apple industry hit a home run with consumers by introducing Honeycrisp. It was decades in the making. But while the texture and the flavor pleased palates, it wasn’t exactly producer- or handler-friendly.
What if scientists and breeders could develop an apple with desirable traits for everyone — an apple that handled and stored well, and had exceptional flavor and texture profiles. But why stop there? Why not satisfy McDonald’s, which buys 55 million pounds of sliced apples annually, by making them non-browning and higher in vitamin C. And what if you could develop these new cultivars in a matter of years vs. decades? Now you’re talking a grand slam!
The development of “super fruits” is the focus of RosBreed — a project
designed to speed up improvements of conventional fruit varieties with DNA-based, marker-assisted breeding. Ultimately, it’s hoped new cultivars will increase fruit consumption and human health, enhance industry competitiveness and sustainability, and decrease pesticide use.
• Project is designed to speed up conventional fruit variety improvement.
• RosBreed has 12 demonstration breeding programs, including two in Michigan.
• Project to survey industry and consumers on traits they deem most important.
Specifically, the project involves the genomes of four fruit-bearing species of Rosaceae — apples, peaches, cherries (tart and sweet) and strawberries.
“We’re not inventing the wheel, we’re playing catch-up,” says Amy Iezzoni, Michigan State University tart cherry breeder and lead researcher for RosBreed. “Through DNA analysis, genome sequencing has already been done for rice, wheat, barley and other crops,” she adds. “Row crops have had this for some time, but the fruit industry lacked the resources. The Specialty Crop Research Initiative has changed that.”
RosBreed is in its second year of a four-year, $14.4 million research project funded through the USDA’s Specialty Crop Research Initiative and matching funds.
It is a collaborative effort involving almost 50 scientists from across the U.S. and five countries. RosBreed has 12 demonstration breeding programs, including two in Michigan, with Iezzoni heading up the cherry research and Jim Hancock of MSU’s horticulture department focusing on strawberries.
Through RosBreed, the trait that determines the desirable texture of Honeycrisp has been identified and is being used to speed up the development of the next generation of good-tasting varieties.
Iezzoni calls individual genes that control desirable production and fruit quality traits “jewels in the genome.”
Fruit quality traits, including texture, flavor and appearance, are being evaluated for cultivars and breeding germplasm.
Going forward, a socioeconomic team has been assembled within RosBreed to survey breeders, producers, processors and handlers, and consumers on what traits they deem most important.
Last year, 146 scientists were surveyed, and following this year’s growing season, there will be a vast outreach to gain grower input through telephone interviews, mail and Internet surveys, and meetings.
“At the Great Lakes Fruit and Vegetable Expo, Dec. 6-8, we will have a short presentation and ask growers how they value traits,” Iezzoni says. “We’ll use a clicker survey, so it will be interactive, and growers will know the results right away. We want to target our resources appropriately and hone in on the high-impact traits. We think we know what growers want, but we still want to ask them and talk about it.”
Trait for cherry firmness sought
One must-have trait for tart cherries Iezzoni is trying to understand is the genetic control for fruit firmness, which has already been cracked for apples and peaches.
“Firmness impacts pitting, grade and, ultimately, payment for the grower. Breeders are also interested in disease resistance, and that’s on my radar, as well. We already have markers for the DNA regions that control fruit size of cherries, which will help eliminate small cherries and meet fruit size cutoff,” she says.
By identifying markers on chromosomes from either parent and by using correlations between fruits in the same family, a chromosome region is associated with performance for the trait. Seedlings are grown, and DNA is analyzed for that trait. Iezzoni calls it a pipeline, where at certain phases the hypothesis is tested.
“We continue to grow out more seedlings and test out those associations,” Iezzoni says.
In strawberries, researchers may try to use wild strawberry germplasm to improve flavor and produce a strawberry that bodes well in ice cream. They will also be testing for genotypes that perform well in certain climates, such as California.
Peaches have tremendous potential for improvement in the RosBreed project, partially because they are one of the worst fruits to market. Many fresh market peaches are picked under-ripe, Iezzoni says.
“A good peach is hard to beat, and a good peach is what we don’t have,” says John Clark, fruit breeder from the University of Arkansas, who is also participating in the RosBreed project. “We need to figure out how to make it better because we’re picking them green and then hauling them away, and they get mealy and don’t taste good.”
Through marker-assisted breeding, Clark is hoping to figure out the storage issue and “make it [peach] the noble fruit that it really is. We have a long way to go, but there is a lot of opportunity,” he adds.
This year, Iezzoni says the statistical team will be doing a lot of analyzing of new RosBreed-generated genotyping data of tart cherries grown at the MSU Clarksville Research Station and of strawberries grown at the MSU Southwest Michigan Research Station.
This article published in the May, 2011 edition of MICHIGAN FARMER.