RA6 POSTER: A. psidii effector protein role

Elucidating the Role of an Austropuccinia psidii Effector Protein During Myrtle Rust Infection

February 2024

Sullivan J, Currie M, Eccersall S, Gilkes J, Frampton R, Panjikar S, Sethi A, Meisrimler C, Smith G, Dobson R. 2024. Elucidating the Role of an Austropuccinia psidii Effector Protein During Myrtle Rust Infection. 49th Lorne Conference on Protein Structure and Function. Lorne, Victoria, Australia. 4 - 8 Feb 2024.

ABSTRACT

Myrtle rust is caused by the invasive fungus Austropuccinia psidii and is incredibly infectious and physically devastating to Myrtaceae plants. The disease was first detected in New Zealand in 2017 and continues to spread rapidly across the country. The presence of the disease in Australia has already caused major declines in Myrtaceae populations (e.g., eucalyptus in Queensland) and now threatens Aotearoa-New Zealand natives, including taonga species such as pōhutukawa, mānuka and rātā. Localised extinctions of myrtle plants have already begun to occur in Aotearoa. Transcript experiments have identified several proteins expressed during the first 24-48 hours of infection by A. psidii on mānuka. This expression pattern is a signature of their important role in the successful infection of plant cells. In other plant pathogens these ‘effector proteins’ are known to manipulate the host plant’s cellular processes to boost pathogen fitness. Here, our aim is to elucidate the role of the A. psidii effector protein, AP1260, during infection through bioinformatic and biophysical analysis. Sequence homology and predictions of AP1260’s structure and cellular localisation were made and used to compare to later biophysical analysis. Biophysical studies sought to determine its physical characteristics in solution. These included analytical ultracentrifugation, fluorescence spectroscopy, circular dichroism, small-angle X-ray scattering, and nuclear magnetic resonance. Functional analysis of AP1260 used agrobacterium-mediated transformation of N. benthamiana and yeast-two-hybrid to determine its localisation and in planta interaction partners. The results obtained in this study represent the first studies of an A. psidii effector protein. Characterisation of AP1260 improves the knowledge of the mechanisms of A. psidii infection and may uncover methods to interfere with its function, making its characterisation critical to the biosecurity of nations with Myrtaceae populations. The outcomes of this research may lead to the development of a novel and effective method to treat and control myrtle rust.