Scientists aim for the ultimate macadamia

By Jessica Campion 22 July 2011
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New research into macadamias might produce an easier nut to crack and expand this lucrative Aussie industry.

IN 1882, IN WHAT is now known as the Gold Coast hinterland, a handful of nuts were plucked from a tree that was largely unknown to Europeans. They had a luxurious buttery taste, a crunchy and then creamy texture – and, crucially, they weren’t poisonous.

Some were taken to Hawaii by a Captain Robert Jordan of the US Navy – possibly an Irishman by birth – and there they were cultivated for the first time on a commercial scale. The expertise for cultivating them were then brought back to Australia at a later date.

Aboriginal tribes called the macadamia “gyndl”, “jindilli”, and “boombera”. Now it’s also known as the Queensland nut, the bush nut, the Maroochi nut, the queen of nuts, the Hawaiian nut, and the Bauple nut. Call it what you want, but the macadamia nut is big business in Australia, with the industry exporting to more than 40 countries and worth over $115 million annually.

The nut is one of Australia’s largest horticultural exports, after citrus fruit and grapes, and is the only major crop to be have been developed from a native species. And now, researchers are trying to make macadamias even better by exploring all the variety these nuts have to offer.

Macadamia nut fingerprints to sustain market

The current macadamia industry is based on only two species – Macadamia integrifolia and Macadamia tetraphylla – and it is thought to have developed from only those limited samples of macadamia seeds picked and ferried to Hawaii in the early 1880s. However, several wild species exist in Australia and scientists believe they could be untapped sources of new varieties of nut.

Researchers from the University of Queensland (UQ) are collecting DNA fingerprints of wild macadamia plants, found only between NSW’s mid-north coast and Queensland’s Fraser coast, to find new genetic characteristics that could benefit the macadamia industry. The goal is to find new genetic strains to make macadamia plants more disease- and drought-resistant and more cost-effective to farm.

Dr Craig Hardner, research fellow at UQ’s Queensland Alliance for Agriculture and Food Innovation (QAAFI), says DNA from the wild ancestors could expand the macadamia market. “Macadamias are enjoyable to eat now as we know, but it would be nice to produce a more productive and more affordable variety to reduce the price of crop farming and prices for consumers, and with this study we can get an idea of the variety that macadamias could have,” Craig says.

The demand for Australia’s macadamia nuts far outweighs its current supply, so the industry is keen to find a way to develop produce faster-growing plant varieties with as many nuts as possible. Similar research of other crops has resulted in seedless and easier-to-peel mandarins, lower-fat canola seeds, and disease- and drought-resistant legume crops. So it’s hoped that scientists can help breed macadamia varieties with disease-resistance, lower oil content, and thinner shells for hand-cracking.

And because Australia is the only place where macadamias exist in the wild, it’s only here that new genetic varieties may be found. Crops like citrus, apple and plum, have been developed over 2000 years to produce the most favourable varieties. In comparison to the centuries of breeding of other crops, the macadamia is a long way behind. UQ’s DNA studies will bring the macadamia’s development up to speed by using science to identify and breed favourable characteristics.

Long-term goals in macadamia nut ‘breeding’

The project is a long-term one. Any favourable genetic characteristics from wild plants the study identifies will take up to 30 years to commercialise. But, Lindsay Bryen, a northern NSW macadamia grower of 35 years, says any new varieties will be well worth the wait.

“People might say ’30 years, that’s a long time’, but macadamias have only had about 100 years of selection and breeding – some citrus fruits have had 400-500 years or more of selection to get to what they are today. The macadamia hasn’t been highly crossed and selected, so every step now is a big step – there are possibilities of finding new variations we’ve never found before,” Lindsay says.

Jolyon Burnett, CEO of the Australian Macadamia Society, which represents more than 650 growers Australia-wide, believes time spent investigating new variations of the nut is worthwhile. “The macadamia is one of Australia’s best ambassadors overseas. In US Subway [outlets], the macadamia cookie is the biggest-selling item and, in Japan, choc-coated macadamias are a premium gift item,” Jolyon says. “Here at home, in a Queensland Government Sesquicentenary competition for the ‘Most Iconic Queensland Things’, macadamias came in more iconic than the thong – and now, macadamias can get even better.”

The study’s collection of macadamia fingerprints will also help preserve Australia’s wild species by conserving the DNA of plants under threat from land clearing and agricultural development in areas of Queensland and NSW.