PhD thesis - Investigating the cause of dieback in the invasive plant, Parkinsonia aculeata 2013-2017
Hawkesbury Institute for the Environment, Western Sydney University
CSIRO Health & Biosecurity (Brisbane)
Advisors: A/Prof Jeff Powell, Dr Andrew Bissett and Dr Rieks van Klinken
Healthy
Parkinsonia is a highly invasive, thorny tree, originally from South America, now found across most of northern Australia
Symptoms of Dieback
Dieback has been observed in Parkinsonia for two decades. It causes widespread death of Parkinsonia populations
Dieback
Project Aim: What is causing dieback, and can we use it as a biocontrol agent to manage Parkinsonia in Australia?
Summary
For a quick and simple explanation of my PhD project, watch my three-minute presentation for the 3MT competition.
Parkinsonia aculeata L. (Fabaceae; referred to hereafter as “parkinsonia”) is an invasive tree in northern Australia, with native populations in South and Central America and southern USA. It is a perennial thorny shrub that forms dense thickets along waterways, floodplains and throughout paddocks, seriously impacting the pastoral industry, local biodiversity, and providing shelter to other invasive species such as feral pigs. Some Australian parkinsonia populations are affected by dieback, resulting in localised control.
Despite previous and ongoing research, the cause of parkinsonia dieback remains elusive and dieback has not been observed in parkinsonia’s native range. This thesis investigates the potential cause(s) of dieback in parkinsonia to contribute towards research on determining its suitability as a biological control tool. My goals were to describe the microbial endophytes of parkinsonia, identify correlations of microbial community composition and dieback occurrence, and identify patterns and pathogens that might be involved in dieback.
Determining the cause of dieback in affected weeds may present land managers with a ‘silver bullet’ of biological control that could become a self-managed, perpetual instrument, reducing weed management costs and increasing biodiversity and land productivity. As such, future work in the use of dieback and host-specific phytopathogens for biological control of invasive plants should continue
Healthy Parkinsonia
Dieback-affected Parkinsonia
(Photos by Andrew White, CSIRO)
Publications
Raghavendra, A.K.H., Bissett, A.B., Thrall, P.H., Morin, L., Steinrucken, T.V., Galea, V.J., Goulter, K.C., van Klinken, R.D., 2017. Characterisation of above-ground endophytic and soil fungal communities associated with dieback-affected and healthy plants in five exotic invasive species. Fungal Ecology 26, 114-124. DOI: 10.1016/j.funeco.2017.01.003
Steinrucken, T.V., Bissett, A., Powell, J.R., Raghavendra, A.K.H., van Klinken, R.D., 2016. Endophyte community composition is associated with dieback occurrence in an invasive tree. Plant and Soil 405, 311-323. DOI: 10.1007/s11104-015-2529-y
Steinrucken, T.V., Aghighi, S., Hardy, G.E.J., Bissett, A., Powell, J.R., van Klinken, R.D., 2017. First report of Oomycetes associated with the invasive plant, Parkinsonia aculeata. Australasian Plant Pathology 46, 313-321. DOI: 10.1007/s13313-017-0494-z
Steinrucken, T.V., Raghavendra, A.K.H., Powell, J.R., Bissett, A., van Klinken, R.D., 2017. Triggering dieback in an invasive plant: endophyte diversity and pathogenicity. Australasian Plant Pathology 46, 157-170. DOI: 10.1007/s13313-017-0472-5
Conferences
Steinrucken, T.V., Bissett, A., Powell, J.R., Garbelotto, M., van Klinken, R.D., 2016. Age of Endophytes: invasive plants and their microbial residents. Ecological Society of Australia Conference, Fremantle, WA.
Steinrucken, T.V., Bissett, A., Powell, J.R., Raghavendra, A.K.H., van Klinken, R.D., 2015. Endophyte community composition is associated with dieback occurrence in an invasive tree. APS Annual Meeting. The American Phytopathological Society, Pasadena California, pp. 143.
Steinrucken, T.V., Bissett, A., Powell, J.R., van Klinken, R.D., Garbelotto, M., 2016. Is parkinsonia dieback due to the absence of protective fungi, or the presence of putative pathogens? , 20th Australasian Weeds Conference. The Weeds Society of WA Inc. *Weeds Society of Queensland Student Travel Award*
Steinrucken, T.V., Powell, J.R., Bissett, A., Raghavendra, A.K., Van Klinken, R., 2015. Endophytic pathogens, water stress and dieback in an invasive tree. Australian Mycological Society Conference. Australian Mycological Society, Canberra, ACT. *Prize for Best Talk*
Steinrucken, T.V., Powell, J.R., Bissett, A.B., Raghavendra, A.K.H., Klinken, R.D.v., Baker, M., van Klinken, R.D., 2014. Using genetic tools to diagnose dieback in Parkinsonia aculeata., 19th Australasian Weeds Conference, "Science, Community and Food Security: the Weed Challenge", Hobart, Tasmania, Australia, 1-4 September 2014, pp. 194-195.