Speed breeding top crops could protect mango and macadamia industries

Speed breeding

Dr Stephanie Kerr from the Queensland University of Technology (QUT) has been awarded funding for two research projects on speed breeding new mango and macadamia crop varieties that protect from pests, disease and climate change. 

Kerr – an expert in tree genomics from the QUT Centre for Agriculture and the Bioeconomy and the School of Biology and Environmental Science – received $22,000 from Hort Innovation to investigate genetic techniques to speed up flowering of mango and macadamia trees. She also received the $22,000 Minister for Agriculture and Northern Australia’s Award to test findings by speed breeding macadamia trees. 

Mangoes and macadamias account for half of Australia’s horticulture industry value but, unlike other commercial crops such as rice and wheat, have not undergone extensive molecular breeding programs to produce elite cultivars, Kerr said. 

“These highly valuable crops are susceptible to pests, disease, and climate change impacts, particularly as both species are induced to flower by cooler temperatures,” she said. “Mango breeders have told me they are already having lower flowering and crop yield during warmer winters. 

“Industry responses to horticultural challenges are made more difficult by the time needed to breed adaptive cultivars. Macadamia trees have a long breeding cycle. Trees cannot be induced to flower during the juvenile period, which can range from 6-10 years.” 

A potential solution is to shorten the plants’ juvenile period. Through her research, Kerr will test novel transformation technologies that influence the gene expression for flowering to help speed up development of elite mango and macadamia tree crop cultivars. 

The first technique will use nanoparticles to introduce molecules that turn off expression of genes that stop the plant from flowering. The second technique will use micro dermal needling or “micro wounding” with bacteria to deliver molecules that turn on gene expression for earlier flowering. 

“These techniques have been used successfully in other tree crops to reduce the juvenile period of 7-20 years down to several weeks or months,” Kerr said. “In apple, for example, the techniques were successfully used to breed trees resistant to fire blight through an overexpression of the FRUITFULL gene that reduced the juvenile period from more than 12 years to just a few weeks.” 

New plants will not be genetically modified because influencing gene expression using these techniques did not require changes to genetic code. 

After her initial project to investigate whether the techniques work on mango and macadamia plants, Kerr will test them in a project to speed breed macadamia trees. 

“There are currently no genetic manipulation techniques available that work with macadamia, and those in older publications for mango breeds have not been used in subsequent research,” Kerr said. “Responding to new horticultural challenges will always be an issue for macadamia, which has only been commercially bred for about 50 years. 

“So, most varieties of macadamia are very close to wild progenitors, which means they still carry many undesirable traits. Mango has been cultivated for hundreds to thousands of years. A lot more varieties have been developed, but there are still a lot of undesirable traits in many of those.” 

The aim to develop new tools for testing gene function and producing elite cultivars would help mango and macadamia industries respond quicker to challenges like pathogens and climate change. 

“I want to help keep Australia at the top of these crop markets,” Kerr said. 

Kerr was one of 12 young scientists recognised in the 2022 Science and Innovation Awards – a competitive grants program that provides funding for innovative research projects to benefit Australia’s rural industries. 

The Awards are coordinated by the Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES), the research division of the Department of Agriculture, Water and the Environment. 

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