Breeding new rootstocks for the Australian citrus industry (CT23002)

What is it all about?

The project will create new and unique germplasm, providing long-term opportunities for the Australian citrus industry to increase genetic diversity using high-performing rootstock options.

Building on existing knowledge and a solid methodology, new germplasm will be created, heavily screened for disease resistance and local adaptation, and then tested under commercial conditions. A two-pronged breeding strategy will be employed based on purposeful parent selection and large-scale hybrid generation and screening. By clever breeding and incorporating diverse germplasm, the project aims to increase the genetic diversity, performance and resilience of commercial rootstocks in Australia.

This research continues the work of the levy-funded project Breeding new rootstocks for the Australian citrus industry (CT18004), which was the first in the world to demonstrate that Oceanian wild citrus species can be used as parents to produce new rootstock hybrids whose performance is comparable to current conventional options. This research has attracted international attention as a possible strategy in the fight against HLB disease. It provides industry with greatly expanded options for genetically diverse rootstocks that could be deployed if they show future disease tolerance. Many of the problems currently facing world citrus production are a consequence of genetic monocultures, and this project will demonstrate how this issue can be addressed efficiently and with rapid industry applicability.

Once breeding and screening work is completed, the successful hybrids will be included in extensive field trials located on commercial properties to determine field adaptability. Tree health, vigour, and fruit quality will be assessed at these extensive on-farm trial sites every season. This information will guide future parent selection so that there can be constant improvement in the choice of parents within the breeding program. Regularly planting large field trials will provide the breeding team with a continuous flow of new information that can be immediately captured in the hybridising program.

New information on disease resistance and segregation will be developed, and rapid molecular screening techniques will be validated and applied to Australian rootstock breeding populations. However, there is no quick way of testing field adaptability, so long-term field trials will continue to be the cornerstone of the project, giving growers the greatest confidence in any new commercial releases and reducing the risk of orchard failures. These extensive field trials will identify a subset of unique hybrids with robust performance warranting wider commercial evaluation.