Panama disease tropical race 4 (TR4) infects the roots of a banana plant and gets into its vascular system, destroying the plant. The disease, which can lie dormant in the soil for decades, was first identified in Australia on a Northern Territory plantation in 1997 and was again detected on a Queensland farm in Tully, south of Cairns, in 2015. A second Queensland farm confirmed the presence of TR4 in 2017. Professor Dale said while it had taken a long time to create a Panama disease-resistant Cavendish banana, the outcome was invaluable. “To give you some idea of the timeline, we started this project in 2012 to identify resistance genes in bananas,” he said.

“It wasn’t until we had a banana farmer who had property up in Northern Territory, where the disease was already endemic, come to us and said can you help me and we said, ‘Well, you may be able to help us as well.” The research team planted six lines of Cavendish bananas with the imported gene into the contaminated soil on the plantation and found it remained completely TR4 free for the entire three years of the trial. Three other modified lines showed robust resistance, only about 20 per cent or fewer exhibited disease symptoms at the end of the trial, Professor Dale said. “We now have a Cavendish banana that is resistant to the disease so there is a solution, Cavendish doesn’t have to be completely wiped out,” he said. “Yes they are genetically modified but the gene we have used is already in bananas and in fact, the gene is already in Cavendish bananas.

“They look exactly the same, the only difference is there is a resistance gene from a wild banana inside. “The likelihood is they will taste exactly the same as well.” RGA2-3 modified Cavendish banana in the QUT lab. Credit:QUT The research means these bananas could again grow on contaminated plantations, boosting supply and possibly reducing costs for consumers. “Some farmers will have banana plantations in Innisfail and Tully Valley and they will also have a plantation in the Northern Territory so if there is a cyclone in north Queensland then they can revert to their production in the Northern Territory,” Professor Dale said.

“That option disappeared because of this disease but once we can get resistance available to the farmers then you will have that option back on the table.” The research team have expanded their field trial on the same Northern Territory plantation to grow up to 9000 plants and quantify crops over a five-year trial, with the aim to select the best lines to take through to commercial release. The results were published in Nature Communications.