Australian citrus could solve global disease problem

A map of the genome of a native lime species that is resistant to a devastating citrus disease could be the key to preventing that disease entering Australia.

Researchers from the University of Queensland (UQ) sequenced the genome of the Australian round lime, also known as the Gympie lime, and are looking at five other native citrus species including finger lime.

Upuli Nakandala, PhD candidate, said the work aims to identify a gene that could be incorporated into commercial citrus varieties to provide resistance to Huanglongbing (HLB), also known as ‘citrus greening’.

According to Nakandala, the Citrus australis species is recognised as HLB-resistant and the disease is currently not present in Australia. It is, however, a problem for citrus growers across a number of areas including the United States and Africa.

“People have been trying to control this disease using chemicals and other methods but there’s been no permanent solution. One option available is to develop resistant cultivars, and the first step towards that is identifying these important resistant genes in Australian citrus,” Nakandala said.

Robert Henry, UQ Professor, said mapping the genome of Australian round limes helps achieve this aim.

“Sequencing the genomes of plants, particularly these tree crops, will give us a new platform for genetic improvements and better management of their production into the future,” Henry said.

With the right technology, climate and crops to do so, Australia is in a good position to contribute to international efforts to eradicate the disease.

According to Henry, the team is also working on genomes for other tree crop species.

“We’re looking at a number of horticultural crops including macadamia, almond and mango — a wide range of species that are important in Australia and will provide the science background that we need to advance these crops,” he said.

The research was funded by Hort Innovation and The Queensland Department of Agriculture and Fisheries.

The research was published in Horticulture Research.

Image caption: Upuli Nakandala and Prof Robert Henry with a native Mount White lime. Image credit: Megan Pope