Identifying resistance to myrtle rust in eucalypts

The plant pathogen, myrtle rust (Puccinia psidii) can cause dieback and death in many species in the Myrtaceae family, threatening Australian plant industries, including eucalypt forests, other native ecosystems and plant nurseries. First detected in Australia in 2010, myrtle rust is now well established along the east coast of Australia. The rust has a significant impact on several common and threatened species, affecting seedlings, saplings, mature trees as well as flower and seed production.

Forest scientists in the Department of Agriculture and Fisheries and the University of the Sunshine Coast are collaborating to determine the potential risk to Queensland’s forest industries. They are testing commercially-important tree species for their susceptibility to myrtle rust. Spotted gum (Corymbia citriodora) and Gympie messmate (Eucalyptus cloeziana) are the most important sawlog and round log species in Queensland’s 52 million hectares of native forests, and produced 159,000 m3 of sawlogs, round timbers (e.g. electric power poles) and miscellaneous hardwood products in 2014/15.

Detailed glasshouse screenings identified some rust resistance within tree families that could be harnessed in future breeding programs for spotted gum and hybrids, western white gum (E. argophloia), Gympie messmate, rose gum (E. grandis) and red mahogany (E. pellita).

The results identify the potential to select for resistance to myrtle rust at the family level within the tested populations. Estimates of the heritability of resistance suggest that efforts to enhance this trait through breeding has reasonable prospects for success.

The rust screening research was funded by the Department of Agriculture and Fisheries and the University of the Sunshine Coast. Find more information about this research:

Pegg G, Brawner J and Lee D. 2014. Screening Corymbia populations for resistance to Puccinia psidii. Plant Pathology 63(2): 425—436.

Lee D, Brawner J and Pegg G. 2015. Screening Eucalyptus cloeziana and E. argophloiapopulations for resistance to Puccinia psidii. Plant Disease 99(1): 71—79.

Butler J, Freeman J, Vaillancourt R, Potts B, Glen M, Lee D and Pegg G. 2016. Evidence for different QTL underlying the immune and hypersensitive responses of Eucalyptus globulus to the rust pathogen Puccinia psidii.Tree Genetics & Genomes 12: 39.

Myrtle rust research receives Biosecurity Impact Award