PhD Student Projects
Quynh Dang
- Diseases of cinnamomi in Vietnam, identification, pathogenicity and control.
Cinnamon is known as one of the most popular plantation species in Vietnam. It has multiple purposes, for instance, as spices in the cooking worldwide and medicine as well. Although cinnamon is a hard wood species, it is also sensitive to many pests and diseases. When a tree has many diseases, forestry managers find it difficult to control it, which leads to the huge economic and environmental loss. My project aims were to investigate cinnamon diseases to find out the causal agents of some symptoms including wilting, witches’ broom, dieback, and stem canker. I will also focus on using or manipulation exiting endophytes to control these diseases.
Hoa Duong
- Shoot blight disease on Corymbia calophylla: detection, phylogeography and host resistance.
Shoot blight disease caused by the pathogenic fungi Quambalaria pitereka is one of the most serious diseases of Corymbia spp. in Australia. This species is endemic to the south-east of Australia but has been introduced to Western Australia where it is now a serious pathogen of marri (Corymbia calophyll), a keystones species in south-west Western Australia in the south. The research to date has tended to focus on the incidence and symptoms of the Quambalaria shoot blight on Corymbia calophylla flowering structures and the insect vectors and their ability to transmit Q. pitereka. No previous study has investigated the genetic variation of Q. pitereka populations and little attention has been paid to the resistance of Corymbia calophylla to this disease. My study will investigate the pathogenicity and genetic variation of this pathogen and also the resistance of host species. This will assist in the development of a disease management strategy and a tree breeding program for this species.
Suchana Rani Sarker
- Improving isolation methods of Phytophthora species
Phytophthora pathogens are responsible for different destructive diseases in agriculture, horticulture and natural ecosystems worldwide. New technologies, such as metabarcoding of using eDNA using High Throughput Sequencing (HTS), always detect a greater number and a higher diversity of species than can be isolated through direct plating or traditional baiting methods. Isolation into culture is of great importance for the study of the biology, ecology, pathology, genetics, epidemiology and management of Phytophthora species and the diseases they cause. Metabarcoding only confirms the presence of an organism in a particular habitat, it does not indicate if the organisms are viable or pathogenic. This project aims to improve the isolation methods of Phytophthora species with the objective of increasing the number of species in culture that have been detected by metabarcoding.
Former PhD Students
Rajah Bilhaj
- The introduced pathogen Phytophthora cinnamomi has had a devastating impact on the natural flora of the south-west of Western Australia. In the worst case scenarios where susceptible flora with limited distribution are endangered, the chemical phosphite can be used to control the spread and impact of P. cinnamomi. Recently, several new Phytophthora species have been described from natural ecosystems in Western Australia, however their pathogenicity, impact and ensitivity to phosphite is unknown. In my project, I have been testing the sensitivity of the new Phytophthora species to phosphite in vitro and then the ability of phosphite to stop the growth of lesion in planta using a simple lupin assay. Additionally I have conducted large scale pathogenicity testing in order to understand the host range of these new species. Finally I will test the ability of phosphite to control the different species in their hosts.
Louise Croeser
- The role of Phytophthora in the canker disease with Corymbia calophylla (marri)
Corymbia calophylla is suffering from a canker disease caused by an endemic fungal pathogen Quambalaria calophylla. It is hypothesized that Phytophthora is predisposing marri to this canker disease by infecting and killing its fine roots, thus preventing the sufficient uptake of water and nutrients. Field surveys will be done to assess the presence of Phytophora with cankered and unhealthy marri. Recovered Phytophthora spp. from the soils collected in the field will be used in pathogenicity trials, including a dual inoculation trial with both Phytophthora and Q. coyrecup.
Jamba Gyeltshen
- The life stages and survival of Phytophthora cinnamomi in soil, plant roots and organic matter
Survival studies with P. cinnamomi propagules under controlled temperature and moisture conditions seem to suggest that Mediterranean climate is unsuitable for the pathogen’s survival and yet climate has not deterred the pathogen’s spread in south-western Australia. This gives rise to one fundamental question: How does an oomycete pathogen like the P. cinnamomi that is dependent on the presence of free soil water for spread and infection survive hot and dry conditions of south-western Australia? The need for a better understanding of the mode of survival of P. cinnamomi in the Mediterranean climate and the likely spread of the pathogen in the jarrah forest ecosystem has prompted this study. Recent studies indicate that production of selfed oospores, thick-walled chlamydospores, and stromata in asymptomatic host plants may be another less understood strategy for P. cinnamomi to survive harsh natural conditions. This study will look into whether the life stages in plant roots enhance survival capability.
Ishan Khaliq
- Phytophthora cinnamomi dieback on the move
Phytophthora cinnamomi one of the most devastating plant pathogens worldwide. Recently, P. cinnamomi has been detected in highly diverse and fragile sub-alpine ecosystems previously considered pathogen free. Either environmental conditions at higher elevations have changed and are no longer unfavourable for survival of Phytophthora cinnamomi, or Phytophthora cinnamomi has changed and can now survive under colder conditions at higher elevations This proposal seeks to explorethe potential implications of this discovery for the integrity of these critically important environments by (1) Determining the extent of invasion of Australian mountain ecosystems by Phytophthora species, in particular P. cinnamomi (2) Examining the adaptive capability of P. cinnamomi and its ability to survive and cause disease in sub-alpine regions (3) developing of species distribution model that explains the current distribution and impacts of P. cinnamomi, and predict changes in distribution associated with changes in environmental conditions
Daniel Kollehn
- Genetic analysis of phosphite sensitivity in Arabidopsis thaliana
Phosphite is widely used to protect crops and native plant ecosystems from the devastating economic and environmental effects of plant diseases caused by Phytophthora species. The treatment of phosphite has also been shown to enhance and accelerate the plants general defence response including pathogen specific mechanisms. Although the physiological responses to phosphite have been observed in a wide variety of plant species, details on how plants detect the biologically inert phosphite or differentiate it from the essential and growth limiting phosphate are not known. To fully understand the mechanism(s) of how phosphite affects plant metabolism, identification of the genes or their products that differentiate between phosphate and phosphite is required. This project investigates host plant phosphite sensitivity by identifying genes responding differentially to phosphite and phosphate. Natural genetic variation as well as a mutant screen in Arabidopsis thaliana will be performed to analyse differences in response to phosphite treatment.
Manisha Kunadiya
- New tools for the detection of Phytophthora cinnamomi in environmental samples following eradication treatments
Phytophthora root rot is a plant disease caused by the soil born plant pathogen Phytophthora cinnamomi. P. cinnamomi affects many native plants and ecosystems, crops and horticultural plants in Australia and throughout the world. Currently, there are no proven methods to eradicate P. cinnamomi from a site or to prevent autonomous spread of the pathogen. The traditional baiting methods are time consuming and not sufficient enough to detect this pathogen. In addition, there are a large proportion of false negatives when using molecular genetic detection methods. This PhD project aims to develop new robust molecular tools using Real time PCR and Digital PCR to detect P. cinnamomi from infested sites and to confirm whether the eradication treatments have been effective. This project will develop an RNA assay to ensure that any P. cinnamomi detected is living and not dead. This will provide definitive proof whether the eradication treatments have been effective or not.
Sarah Sapsford
- Biotic and abiotic factors predisposing marri (Corymbia calophylla) to canker disease caused by Quambalaria coyrecup in the southwest of Western Australia
The decline of Corymbia calophylla (marri) has been increasing over recent years. A canker caused by the fungus Quambalaria coyrecup, believed to be endemic to Western Australia, has devastated many marri stands in the southwest of WA. Incidence of the fungus is higher in remnant stands of trees that border cleared land such as road edges and farmland where there is greater anthropogenic disturbance, such as fertilizer, pesticide and herbicide use. The progression of the decline strongly suggests a breakdown in the ability of the trees to maintain nutrient balance and it is believed that mycorrhizal fungi play a role in this process. Mycorrhizal fungi are known to be more important for the uptake of vital nutrients on low fertility sites and are essential for below-ground carbon storage; thus, any change in the mycorrhizal community would result in critical changes in nutrient uptake and tree health as evidenced by declining crown vigour. It is possible that the use of pesticides and herbicides are causing a decline in the diversity of mycorrhizal fungi in disturbed sites, and thus predisposing marri to canker. Therefore, the aim of this project is to examine the mycorrhizal species associated with marri and how these communities differ between intact forest and anthropogenically disturbed sites.
Christopher Shaw
- The impact of Phytophthora species on the survival of seed and seedlings in native and disturbed Southwest Australian kwongan plant communities.
Phytophthora species are known damping-off pathogens. Recently, a number of Phytophthora species have been isolated north of Perth, Western Australia in diverse kwongan plant communities. Rehabilitation of kwongan plant communities after mining has been hindered in the past by poor seed germination and damping-off pathogens may be responsible. However, in natural species rich ecosystems native plant pathogens have been shown to have a positive influence on the diversity as they can promote coexistence. The impact of Phytophthora spp., found in kwongan plant communities, on the germination and survival of seed and seedlings has yet to be studied. The project aims to identify the role of Phytophthora species in natural and rehabilitated kwongan ecosystems.
Agnes Simamora
- A new nursery Phytophthora pathogen from Western Australia: taxonomy, pathogenicity, epidemiology and origin.
My project has concentrated on a newly emerged Phytophthora pathogen in WA nurseries. The species is rarely encountered outside nurseries and it could be a new invasive species. The casual agent has been identified as a new species closely related to Phytophthora alticola. Extensive sampling and glasshouse trials have been conducted to determine the epidemiology of this pathogen.
Mohammed Yaseen
- Detection, assessment and management of Phtyophthora in the urban forest
An urban forest is a collection of trees and woody vegetation that grow within a city providing many social, environmental and climatic services. These forests are exposed to many stresses, especially drought and are particularly vulnerable to pests and diseases. More Phytophthora species have been recovered from urban landscapes than from natural forests in Western Australia. This study will use traditional and molecular techniques to determine Phytophthora diversity and distribution in Perth, Western Australia. The pathogenicity of major species will be determined and examine new methods for disease monitoring and control examined.
