Research Uncovers Diversity in New Zealand’s Heritage Apple Varieties

Aaron Hewson, a master of science student in plant biotechnology, is conducting significant research on over 300 apple varieties from the Jim Dunckley Heritage Orchard, located in New Zealand. This orchard, established 25 years ago by the Coastal Otago Branch of the New Zealand Tree Crops Association, is recognized as one of the most diverse collections of apple cultivars in the country. The collection includes uniquely named varieties such as Peasgood Nonsuch, Nonnetit Bastard, Warner’s King, and Albany Beauty.

Hewson’s research aims to assist in the preservation and propagation of these heritage cultivars through genetic identification. “I am doing this research for them so they can continue to preserve and propagate the heritage cultivars, with confident identification by genetic means,” he stated.

The cultivars in the orchard were primarily collected by Jim Dunckley during the 1990s, sourced from various locations across Otago and Southland, with most coming from Clyde, home to an old Plant & Food Research orchard. Hewson described the collection as a “real kind of hodgepodge mix,” emphasizing that many trees were named by local farmers based on nearby landmarks. “These names did not necessarily match the underlying genetics,” he noted.

Through his research, Hewson encountered intriguing discrepancies in apple identification. He pointed out one case involving a Plant & Food apple known as Granny Smith and another called Lord Lambourne. “These two cultivars should be really different, but the samples were saying they were genetically the same. So one of those names has to be wrong,” he explained.

To unravel these genetic mysteries, samples were meticulously collected by university students and staff from the Plant Biochemistry Lab. After being labelled and freeze-dried, the samples were sent to a laboratory in France, facilitated by Plant & Food Research, which is now part of the Bioeconomy Science Institute. Hewson acknowledged the crucial support of his co-supervisor, Dr. Elena Lopez-Girona, during this process, stating, “It has been very beneficial to have her expertise.”

The collaboration enabled the team to send their samples alongside others for genotyping using a SNP chip. This technology examines approximately 50,000 known DNA hotspots in an apple leaf, generating a genetic fingerprint that can reveal whether two trees belong to the same variety or differ significantly.

Hewson highlighted the importance of local apple genetics, particularly in light of stringent biosecurity regulations that complicate the importation of new apple varieties. “If we talk about the entire amount of apples across the world, there is something on the order of 10,000 different varieties. But all of our commercial varieties, no matter how many there are, they all come from six apples, so it is really, really narrow,” he remarked.

Associate Professor Lynnette Brownfield from the University of Otago, who serves as another co-supervisor, emphasized the potential benefits of this research. She noted that the narrow genetic base of commercial apples in New Zealand makes it essential to identify the diversity present in the heritage orchard. This information could assist breeders in discovering fresh genetic options, including traits related to disease resistance.

The orchard’s future utilization of this genetic information will be determined by the Coastal Otago Branch of the New Zealand Tree Crops Association. Professor Brownfield explained that the goal is to assign identification numbers to all trees, creating a comprehensive understanding of the collection. This will facilitate collaboration with apple breeders, ranging from local growers to larger organizations like Plant & Food Research, enabling the provision of germplasm as needed.

As Hewson continues his important work, the legacy of the Jim Dunckley Heritage Orchard stands to play a crucial role in the future of apple cultivation in New Zealand and potentially beyond.