Project 1: Determining the effect of Climate
Change on the impact and distribution of Phytophthora cinnamomi in Western
Australia (WA)
The researcher will get field, glasshouse and laboratory experience
in studying the epidemiology of Phytophthora cinnamomi in the
National Parks of the south-west of WA. Further the researcher will get
experience in modeling climate change scenario’s and risk assessment
methodologies.
The impact of the introduced plant pathogen, Phytophthora cinnamomi,
is recognized as one of the key threatening processes to the biodiversity
of the south-west of WA. It is unclear how the impact and distribution
of Phytophthora cinnamomi may change under the expected climate
change scenario’s to influence.
This proposed project aims to describe how the impact and distribution
of the pathogen may change under the possible climate change scenarios
proposed by CSIRO scientists. The project will require trips to National
Parks across the south-west of WA with DEC scientists. Further, the project
will involve temperature controlled glasshouse experiments that investigate
the likely epidemiology of the pathogen under various climate scenarios.
Contact for further information:
Dr Chris Dunne
Senior Research Scientist
Department of Environment & Conservation
Phone: 08 9334 0308
Mobile: 0439 093 270
Email: Chris.Dunne@dec.wa.gov.au
Fire is an integral part of the Australian landscape, but debates regarding the anthropogenic use of fire are deeply ingrained into the Australian culture. The Stirling Range Banksia woodlands are more than 60% infested with Phytophthora cinnamomi and is widespread over the eastern peaks of the range, 48% of the woody plant species are susceptible to P. cinnamomi. The Eastern Stirling Range Montane Thicket and Heath Community is one of the most threatened ecological communities in Australia. It is highly susceptible to P. cinnamomi and supports over 44 species of mature plants. Fire is considered a critical factor threatening many of the mountain ecosystems of the Stirling Range due to the much slower growth rate of regeneration at higher elevations. It has been observed that the interaction of fire and Phytophthora has seriously reduced the extent of healthy mountain thicket to a series of pockets spread across the eastern part of the range.
To investigate the biology of the dieback pathogen, Phytophthora cinnamomi we need to be able to transform the pathogen with recombinant genes. We have successfully transformed Phytophthora cinnamomi with recombinant genes for antibiotic resistance and a fluorescent protein. However the frequency of transformation is low as the procedure has not been optimised. The aim of the project is to investigate factors that affect the transformation efficiency in an attempt to improve the efficiency. The project will be to optimise the current transformation procedure; to construct new vectors for transformation by Agrobacterium; and to analyze the phenotype of the transformants.
This project will examine the biology of P. cinnamomi in different south coast soils after treatment with a range of fungicides. This project will make up part of a large project that is looking at the eradication of P. cinnamomi from the south coast.
We have a number of projects that will examine the impact of P. cinnamomi on fauna (mammals, reptiles and invertebrates). We have very little understanding of how changes in plant communities due to the pathogen can impact on the viability of fauna in the long-term. We are particularly interested in areas on the south coast. (see Fauna section below)
The chemical phosphite (phi) is a major weapon against the dieback pathogen Phytophthora cinnamomi. Application to plants can delay the spread of a disease front by 2-5 years. However the response of plant species to phi varies, some plants are protected whilst others are not. The degree of protection also depends on the time of application (summer vs winter). This variation may be related to differences in the distribution and persistence of phosphite in the plant. Accumulation in the roots may enhance protection as P cinnamomi is root infecting, whereas species that do not accumulate it in the roots may lose it through leaf fall. To investigate this we need a method to measure the concentration of Phi in small tissue samples. Current chemical methods to measure phi are cumbersome and expensive and require a lot of tissue. An alternative is to use an enzymatic method that is more sensitive, cheaper and allows analysis of many samples in parallel. This project will test the development of such a method based on a microbial enzyme that converts Phi to phosphate and produces NADH as a byproduct. By measuring the absorbance of NADH we can determine the amount of Phi in the sample. The method will be used to measure the accumulation of Phi in different plant tissues.
There are clear differences in conduciveness to Phytophthora cinnamomi between different soil types extending from the coast, across the Swan Coastal Plain and into the Darling Ranges. This project will examine how the different soil types influence sporangial production, zoospore release and subsequent disease development. Physical, chemical and biological factors will be examined. This information will help us to more thoroughly understand the pathogen and assist us in developing more long-lasting control strategies.
Summer rainfall seldom occurs in the south-west of Western Australia. The consequence of high summer rainfall is significant because the resulting conditions can favour an outbreak of P. cinnamomi. This project aims to determine the effect of plant water status on the ability of P. cinnamomi to colonise plant tissue.
In the past our knowledge of how P cinnamomi spreads could only be based on detection of the pathogen in samples of soil or plant material. We have developed molecular tools, which allow us to not only detect the pathogen but to differentiate between isolates with much greater precision than before. We will track the spread of individual isolates from one place to another, and to assess the effect that importation of an isolate has on the resident population. This knowledge is essential for prediction of the evolution of the pathogen, and for work on biological control.
To date, the majority of phosphite research has been conducted in plant communities in the Stirling Ranges and in the northern Jarrah forest. This project will increase the number of plant communities examined and will determine the effectiveness of phosphite against P. cinnamomi infection in field and glasshouse trials in order to optimise application of the fungicide for long-term control of the pathogen in a range of communities.
Fire is used as a management tool in the native vegetation in the south-west of Western Australia. It is important to know how these existing management practices affect the efficacy of phosphite in vegetation that has been treated prior and post fire.
Confirmation on the efficacy of existing hygiene protocols on reducing disease spread. This study will use existing mapping and 'ground-truthing' to monitor the spread of P. cinnamomi across a range of sites which have previously been given different Phytophthora status (eg dieback-free, dieback or un-interpretable). This will then allow us to determine how effective current hygiene protocols (wash-down facilities, education and training, road building, forestry and mining activities) are.
This project will test the susceptibility of taxa in DEC's comprehensive germplasm collection of rare and endangered plant taxa, particularly those under threat or extinction by Phytophthora. Knowledge of susceptibility will allow ranking of taxa according to need for protection from Phytophthora infection
There is little information on the long-term effects of phosphite on plant fitness, invertebrates, animals and microbial populations. If phosphite is to be used as a prescription for control of P. cinnamomi then we need to know if it is detrimental to biodiversity.
There is little information on the long-term effects of Phytophthora dieback in the south coast heathlands on the conservation of some of Australia's most rare animals. This project will measure the effects of this disease on guilds of vertebrate fauna, resource availability and habitat alteration. This research is essential if we are to successfully manage the devastating effects of P. cinnamomi on the particularly sensitive ecosystems of the south-coast.
Phosphite is used for chemical control of dieback disease caused by Phytophthora cinnamomi. We are interested in analyzing the mechanisms that determine the sensitivity of the pathogen to phosphite. Genes that show a transcriptional response to the application of phosphite are identified through genomic analysis. However the role of these in phosphite sensitivity has to be confirmed. This will be achieved through the mechanism of transcriptional silencing. The project will give a good training in molecular cloning techniques and bioinformatics.
It is generally thought that fire will exacerbate the activity of P. cinnamomi in native plant communities. This project will look at native plant communities which have been burnt and determine whether the pathogen is more active on recently burnt sites compared to long unburnt sites. The study will look at change in plant communities and the biology of the pathogen.
The Department of Department of Environment & Conservation has a huge culture collection dating back to the 1960’s. This project will sequence the cultures to determine whether they are all actually P. cinnamomi or not. Any new Phytophthora species will be described and pathogenicity testing will be conducted on host plants from which they were originally isolated. Sites from where the P. cinnamomi cultures were originally isolated from will be revisited and re-isolations made. We will then use molecular tools to determine how much the pathogen has changed over time.
This project will look at animals (native and feral) as vectors of P. cinnamomi. There is considerable anectodal information that animals can spread P. cinnamomi into disease-free areas. It is now time to provide scientific evidence for this.