Good Fruit Grower

July 1

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12 JULY 2014 GOOD FRUIT GROWER New peach TEXTURES I n the future, peaches may be more like apples—identifiable by vari- ety name—and as different from each other as Honeycrisp is from Granny Smith. They will not be "just peaches" any more. And the biggest difference may be texture. The ideal peach may be hard at harvest, resistant to bruising, easy to pick and ship, yet taste sweet and smell good right off the tree. It can be eaten in that crunchy state, which some consumers like. Later, that same peach will melt into the juicy flesh most Americans identify as making a peach a peach. But several textures are possible. All this is coming clearer as the breeders involved in the $14.4-million RosBREED project consider what they have learned over the past four years. Of all the Rosaceae fruits that came together for genetic studies under the RosBREED project, peaches possibly profited the most. In future work, breeders will have a sound footing in the genetics of a broad range of traits, but most especially fruit texture. For Dr. John Clark, the peach breeder at University of Arkansas, Ros- BREED provided an opportunity to sort out "some curiosities," as he called them. Generally, breeders had worked with traits called melting and nonmelting, freestone and clingstone, but they knew there was something else going on. Now, they know there are genes for other kinds of textures—called slow melting, nonsoftening, slow ripening, and stony hard. In a presentation last winter at the Mid-Atlantic Fruit and Vegetable Convention in Hershey, Pennsylvania, Clark talked about consumer frustration that is likely responsi- ble for the low level of consumption of peaches compared to other fruits. While nearly everyone loves a perfect peach, "there are a lot of scary peaches out there I don't want to eat," he said. "Since consumer frustrations with peaches often are based on unripe fruit being har- vested, resulting in low quality and mealiness, it appears that flesh types that can allow for more mature fruit harvested can have potential," he said. Texture in context In the early 1980s, Clark said, Dr. Fred Hough, the peach breeder from Rutgers Uni- versity in New Jersey, sent three sacks of seeds from crosses he had made to the Univer- sity of Arkansas, where Clark had just come on board to work alongside Dr. Jim Moore to breed grapes, blackberries, blueberries, and peaches. "These populations contributed new genes for flesh types," he said. "I was not sure what these were, but they were different from the melting and nonmelting flesh types we had been working with." One type produced offspring that were freestone but very firm, which then softened when they became fully ripe. These are now called slow melting. Another produced offspring that were clingstone and firmer than nonmelting, having what is now called nonsoftening flesh. Clark, using traditional breeding methods, was able to release several new varieties with unusual textural qualities. "I had a hunch something was going on with these flesh types, but did not know what genes were involved, how they were inherited, or how the genes interacted among themselves to produce these differences." Enter RosBREED When the RosBREED project came along, Clark was quick to see the potential, but also realized he was not positioned to capitalize. "I didn't know nuttin' about how to do this new technology," he told his Mid-Atlantic audience about the use of molecular biology and DNA tests. "Molecular methods allow one to look behind the curtain to see what genes or alleles are present without the confusion of maturity and other factors," he said. "In theory, it Future breeders have the tools to make ideal peaches. by Richard Lehnert takes the guesswork out of determining what is present or not genetically. It also allows predicting the performance of a seedling way before the tree matures." The major focus has been on the endopolygalacturo- nase molecular marker. The breeders now know that a particular grouping of alleles at that location can pro- duce freestone or clingstone peaches with melting flesh or nonmelting flesh (although nonmelting can be cling- stone only). Breeders have long known that melting flesh is a dominant trait. It is still not known what the genetic underpinnings of slow-melting flesh are. "These flesh types can expand options for harvest maturity and product diversification and can expand the genetic basis in flesh types in ongoing breeding pro- grams," he said. While Clark admits knowing very little about the new molecular biology, he figured younger people could master it quickly. So he recruited new graduate students, including Paul Sandefur. "I came along at just the right time," Sandefur said. "Dr. Clark was desperate to find someone to work on peaches, the fruit that was most fun to eat and had those amazing flesh types he wanted to characterize. He wanted to uncover the genetics behind textures." Sandefur was only a month into his master's program at the University of Arkansas when the first RosBREED meeting was held in San Diego, California, and Clark asked him to go. That was January 2010. They would meet annually at Michigan State University to review their progress. Over four years, the federally funded project, coordi- nated by Dr. Amy Iezzoni, the cherry breeder at Mich- igan State University, would undertake a coordinated research program with heavy emphasis on sharing new knowledge among breeders of apples, cherries, peaches, and strawberries. RosBREED published 15 newsletters and compiled a body of information that is now avail- able, to breeders and growers, on the website. Peach solidarity The peach breeders involved in RosBREED didn't take long to come together. "It's incredible how closely the public peach breeders work together," Sandefur said in an interview with Good Fruit Grower. RosBREED linked four peach breeding programs: Clark's at University of Arkansas, Dr. Ksenija Gasic's pro- gram at Clemson University in South Carolina, Dr. Tom Gradziel's program at University of California, Davis, and Dr. Dave Byrne's program at Texas A&M University. Dr. Cameron Peace at Washington State University was the Marker-Assisted Breeding Team Leader who Summer Fruit PHOTO COURTESY OF JOHN CLARK You can't know a peach by the look of its seedling, but new DNA tests can help breeders eliminate undesirable ones without waiting to taste the fruit.

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