Paternity test implicates Napoleon
Scientists used genetic markers to identify Bing's parents.
Genetic testing has revealed that the blush cherry Napoleon Bigarreau (Napoleon for short) is the father of the Bing cherry. Black Republican, a red cherry, was known to be the mother variety, but the other parent (the source of the pollen) was unknown until now.
Dr. Amy Iezzoni, cherry breeder at Michigan State University, and Dr. Umesh Rosyara, RosBREED statistician, used genetic data generated by the RosBREED project to discover Bing’s paternity. They have been studying the genomes of cherry varieties to help them identify potential parents for new crosses and develop genetic markers to improve the chances of developing new and better varieties.
The Bing paternity test was just another use of the RosBREED-generated genetic information, Iezzoni said. Though the entire Bing genome has not been sequenced, Rosyara was able to identify its ancestry using 60 genomewide markers that covered all eight chromosomes. “You don’t need a lot of markers, but you need them not to be clustered,” Iezzoni explained.
Napoleon is a paternal grandparent of Stella, a variety developed by Agriculture and AgriFood Canada’s breeding program at Summerland in British Columbia. Because of its self-fertility, Stella has been widely used as a parent in the development of new cherry varieties. Its offspring include Lapins, Selah, Tieton, Benton, and Chelan. Sweetheart came from a cross of Van and Newstar, and Newstar is a cross of Van and Stella.
That means that Bing is related to the new varieties coming out of the Stella lineage, Iezzoni points out. Until now, they were not known to be genetically connected.
“So, if you’re going to have a family reunion for Stella, you would have to invite Bing, because they have a common ancestor,” she said. “In the case of Bing, Napoleon is a direct parent. In the case of Stella, it’s a grandparent.”
Rainier would also be at the reunion because it is a cross of Bing and Van.
“What this means is there’s DNA in Selah, Sweetheart, and Lapins, for example, that has the exact same ancestry as DNA in Bing and Rainier, and it gives us more power to figure out which of those Napoleon-derived DNA segments are making Bing so good,” Iezzoni said. “For example, what does Bing have that was not bred into Chelan?”
Iezzoni said cherry breeders need to be concerned about inbreeding, which sometimes results in albino varieties. However, those are quickly identified and never make it as far as field tests.
“We don’t have a good handle on how negative inbreeding really is,” she said. “It’s something we need to watch.”
Dr. Cheryl Hampson, cherry breeder at Summerland, wonders if the difficulty of getting cherry seeds to germinate has something to do with inbreeding.
That Napoleon is Bing’s father did not come as a total surprise, Iezzoni said. “I suspected it was Napoleon for some time, because sweet cherry is not native to the United States and there are not that many possibilities. Also since Bing is a parent of Rainier, Bing had to be heterozygous for the blush-type cherry. ”
Hampson said the discovery stands to reason. Bing originated in Oregon, so the missing parent would have to be one of a small number of cherry varieties that were brought West before that time.
According to a brief history of the Bing cherry, published in the May 15, 2011, issue of Good Fruit Grower, nursery pioneer Henderson Luelling migrated from Iowa to Oregon’s Willamette Valley in 1847, bringing 700 fruit tree seedlings in earth-filled boxes to start a nursery. One of the trees he brought from Iowa was Napoleon, which he called Royal Ann. His younger brother Seth is credited for discovering the original Black Republican tree grown from a seed of a Black Eagle cherry. In 1875, he found a promising seedling in a Black Republican planting that he named Bing, after Ah Bing, his Chinese foreman, who cared for the trees that produced the variety.