By Liz Potasek
For years, Honeycrisp didn’t know its parents. Or – more accurately – the scientists who developed Honeycrisp were uncertain of its parents. It wasn’t a situation unique to Honeycrisp, either. Sixteen of the 21 cultivars introduced by the University of Minnesota before Honeycrisp in 1991 had incorrect or incomplete pedigrees.
While consumers might be happy to bite into a Honeycrisp without knowing that it’s the cross between Keepsake and an unnamed variety (MN 1627), and a descendent of a Russian cultivar – called Duchess of Oldenburg – it’s incredibly valuable information for apple breeders.
“It’s important to us as breeders because when we know what the actual parents were and grandparents – and then sometimes great grandparents – we can actually trace back, and figure out who should be carrying genes for what traits,” says University apple breeder James Luby. “For example, we learned that a gene for resistance to apple scab that’s found in Honeycrisp traces back to an old variety called Duchess of Oldenburg. We can look at any variety that traces back to Duchess now and see whether it might also carry that gene for scab resistance, as well, and that can help guide our breeding.”
Luby, along with fellow apple breeder David Bedford, Nicholas Howard and John Tillman published these findings earlier this month in HortScience, a journal of the American Society for Horticultural Science. Their paper, “Extended Pedigrees of Apple Cultivars from the University of Minnesota Breeding Program Elucidated Using SNP Array Markers,” reveals and confirms the parentage of apples in the University breeding program using DNA markers.
Among other things, they found that Duchess of Oldenburg (also known as “Borowitsky”) is an ancestor of 27 of the 28 University of Minnesota cultivars. The apple, a Russian cultivar from the 1700s, is a parent of two University of Minnesota cultivars and grandparent to 15 cultivars (including Honeycrisp).
They also learned that Haralson, which was introduced 100 years ago and is still in production, is an offspring of Malinda and Wealthy. Another important introduction from 1943, Fireside, is the offspring of Wealthy and Northwest Greening. Wealthy – which was developed by Peter Gideon, a self-educated horticulturist with an orchard near Lake Minnetonka – was a frequent parent of older University of Minnesota cultivars.
The University’s apple breeding program has operated continuously since 1908 with open pollinated seeds collected from local orchards. Apple breeders started making controlled crosses in 1916, but the records kept were sometimes incomplete – or hard to locate, considering there were more than 100 years of handwritten records and only about 1 apple cultivar out of 10,000 crosses makes it to market, a journey that often takes decades. In the past few years, University librarians worked with Luby to digitize those records, which made it easier to confirm some of the findings of the DNA results published in the paper.
With a more complete understanding of the past, University apple breeders can make better informed breeding decisions, leading to more delicious apples in the future.