Ramalka Kasige

Candidature

PhD Candidate

Thesis title

Build a better plant: the role of silicon and arbuscular mycorrhizal fungi to augment crop defense against Australia’s newest pest

Research Project

Australia’s distinctive location, flora, and fauna are highly susceptible to invasive pests and most recently, the fall armyworm (FAW), Spodoptera frugiperda, has been detected as a highly invasive pest in Australia. It feeds on more than 350 plant species, including Australia’s economically important crops and grasses such wheat, maize, rice, sorghum, and sugarcane, resulting in extensive defoliation and damage to plants.
Australia spends millions a year on synthetic insecticides, which are often cause environmental damage because of their impacts on non-target organisms such as bees and butterflies and even it can contaminate water and cause skin and respiratory infections to humans. This underpins the necessity for less costly and environmentally benign pest management strategies, for instance, maximising naturally occurring herbivore defences in plants.
Most grasses accumulate large amount of silicon (Si) in their tissues specially in roots and shoots. Si plays a pivotal role in alleviating the adverse impacts of abiotic (e.g., climatic) and biotic (e.g., plant enemies such as herbivores and pathogens) stresses. Moreover, nearly all grasses rely on symbiotic associations for nutrient acquisition. Recent evidence suggests that these mutualistic associations, such as those with arbuscular mycorrhizal (AM) fungi, can exert strong effects on Si uptake and prime plant defences against plant enemies. Research regarding the tripartite interaction between Si, AM fungi, and herbivory by FAW is poorly understood and has not determined the plants’ wider defensive response or underlying mechanisms.
Therefore, by using a series of glasshouse- and laboratory-based approaches, my project aims to 1) review the literature to identify the interactions between beneficial fungi and Si supply to mitigate environmental stresses, 2) determine how AM fungi support Si uptake in cultivars that are different in Si uptaking capacities, 3) investigate the combined effect of Si and AM fungi to suppress FAW in Maize, 4) Determine how different AM families enhance Si uptake in maize, and their interaction with FAW and 5) determine how temperature increase affect the Si and AM fungi synergism to reduce herbivore performance.

Research Supervisors

Professor Scott N. Johnson, Dr. Adam Frew