Research Unlocks Secrets of Heritage Apple Varieties in New Zealand

A comprehensive research project is underway to catalogue and preserve over 300 apple varieties from the Jim Dunckley Heritage Orchard in New Zealand. Led by Aaron Hewson, a master’s student in plant biotechnology, this initiative aims to ensure the future propagation of these unique heritage cultivars. Established by the Coastal Otago Branch of the New Zealand Tree Crops Association 25 years ago, the orchard houses one of the most diverse collections of apple cultivars in the country.

Hewson’s research focuses on identifying the genetic makeup of these apples, which include intriguingly named varieties like Peasgood Nonsuch, Nonnetit Bastard, and Warner’s King. The collection, originally gathered by Jim Dunckley in the 1990s, predominantly features apples sourced from locations across Otago and Southland, with many hailing from an old Plant & Food Research orchard in Clyde.

“The aim is to preserve and propagate the heritage cultivars with confident identification using genetic methods,” Hewson stated. He noted that some trees bear names that reference local landmarks, which can lead to confusion regarding their genetic identities. “For instance, we found a Plant & Food apple called Granny Smith, which is widely available in supermarkets, alongside another named Lord Lambourne. Genetically, they appear to be the same, suggesting one of the names may be incorrect.”

To accurately determine the genetic identity of these apples, samples were collected by university students and staff from the Plant Biochemistry Lab at the University of Otago. These samples were then freeze-dried and sent to a laboratory in France for analysis, thanks to collaboration with Plant & Food Research, now part of the Bioeconomy Science Institute.

Hewson acknowledged the vital support from his co-supervisor, Dr. Elena Lopez-Girona, from Plant & Food Research. “Her expertise has been incredibly beneficial throughout this process,” he said. The samples were sent along with others for genotyping using a technology known as SNP (Single Nucleotide Polymorphism) chip analysis. This method examines around 50,000 known DNA hotspots in apple leaves, generating a rapid genetic fingerprint to ascertain whether two specimens belong to the same variety.

As global biosecurity regulations restrict the import of new apple genetics, the local collection from the Jim Dunckley Heritage Orchard may play an essential role in developing disease-resistant apple varieties and enhancing genetic diversity. “Worldwide, there are approximately 10,000 different apple varieties. However, all commercial varieties, regardless of their number, trace back to just six apples, making the genetic base quite narrow,” Hewson explained.

Associate Professor Lynnette Brownfield from the University of Otago, who is also a co-supervisor for Hewson, highlighted the significance of this research. With the limited genetic base of commercial apples in New Zealand, identifying the heritage varieties could provide breeders with access to new genetic material, including traits for disease resistance.

The Coastal Otago Branch of the New Zealand Tree Crops Association, which owns the orchard, will ultimately decide how to utilise the findings from this research. Brownfield emphasized the goal of assigning unique identification numbers to all trees in the collection. This step will create a comprehensive understanding of the orchard’s contents, facilitating communication with apple breeders ranging from local growers to organisations like Plant & Food Research.

This identification will also enable the association to provide germplasm as needed, ensuring that these heritage varieties continue to thrive and contribute to the future of apple cultivation in New Zealand.