Oral Presentation Science Protecting Plant Health 2017

Susceptibility of threatened Myrtaceae species in Australia (4308)

Laura Fernandez Winzer 1 2 , Katherine A. Berthon 1 , Karanjeet S. Sandhu 3 , Michelle R. Leishman 1
  1. Biological Sciences, Macquarie University, Sydney, NSW, Australia
  2. Plant Biosecurity Cooperative Research Centre, Canberra, ACT, Australia
  3. Plant Breeding Institute, The University of Sydney, Cobbity, NSW, Australia

Austropuccinia psidii (previously Puccinia psidii, commonly known as myrtle rust) is an invasive fungus native to South America that was introduced to Australia in 2010. Since its arrival it has spread throughout the east coast, with dispersion facilitated by windborne spores. It infects young growing tissues of the Myrtaceae family, including leaves, flowers and fruits, and can cause defoliation, reduced reproductive fitness and death depending on species’ susceptibility. Myrtaceae is the dominant family in Australia, with approximately 2,250 species. Susceptibility status is only known for 380 species, with 363 showing susceptibility. We chose 15 species whose distribution overlaps with myrtle rust, for susceptibility testing in order to increase our management capability of this biosecurity pest. Tested species were Triplarina nowraensis and T. imbricata (a genus that has not previously been tested), ten Eucalyptus species (E. amplifolia, E. camphora, E. castrensis, E. copulans, E. largeana, E. macarthurii, E. magnificata, E. pachycalyx (subsp. pachycalyx and waajensis), E. parvula, and E. scoparia), Callistemon megalongensis, Melaleuca irbyana, and Kardomia prominens. A first inoculation was performed and eight species showed susceptibility to myrtle rust, with different levels of disease severity (E. camphora, E. castrensis, E. copulans, E. largeana, E. macarthurii, E. parvula, E. scoparia and C. megalongensis). A second inoculation will be performed to confirm that all the plants were tested at a time when they presented potentially susceptible new growth. As these species all have an overlapping distribution with myrtle rust, it is a matter of time until they become infected in their native communities. It is necessary to assess the impacts and severity levels of these affected plants in order to guide management decisions to maximise their persistence in the wild. Monitoring of susceptible species’ populations in the wild and seed collection for seed banking would be the first steps towards their conservation.