University of Western Australia PhD candidates Jaco Zandberg and Samantha Harvie have combined their complementary scientific training and passion to help Australian grain growers undertake a proof-of-concept project to develop a new frost management intervention.

To assist them in their endeavour, Mr Zandberg recently won the Young People in Agriculture, Fisheries and Forestry prize, which is supported by GRDC and part of the Federal Government’s Department of Agriculture, Water and the Environment 2022 Science and Innovation Awards.

“The money will support a one-year proof-of-concept study to develop a spray that may protect crops from enhanced frost damage caused by ice nucleating bacteria (INB),” Mr Zanberg says.

INB – Pseudomonas species – produce proteins that raise the temperature at which water freezes in the environment. It means frost damage can occur at temperatures as high as minus 2°C, rather than the minus 8°C to minus 10°C usually needed in the field.

The idea for the project came in part from Ms Harvie’s honours study on vesicles produced by root nodule bacteria. The aim of this proof-of-concept project is to develop a non-pathogenic, non-toxic, non-genetically modified, bacterial-based technology to effectively disrupt the ice nucleating activity (INA) of INB using what she has learnt about the action of vesicles.

“This technology will utilise naturally forming nanostructures called outer-membrane vesicles that can be designed to capture small interference RNA (ribonucleic acid) molecules,” Ms Harvie says.

“When applied to other bacteria, the outer-membrane vesicles are predicted to bud into the INB and release their small interference RNA payload, where it will disrupt the INA by silencing very specific ice nucleating genes, effectively suppressing the INA.

These outer-membrane vesicles can be purified and applied to field crops as a ‘spray-on’ prior to predicted frost event to suppress the ice nucleating activity of specific Pseudomonas species without disrupting the beneficial soil microbiome.

“They are nanostructures that are non-permanent and will naturally degrade soon after the frost event.”

The young scientists will work with the frost team from the Western Australian Department of Primary Industries and Regional Development to isolate Pseudomonas species from frost field trials that have suffered frost events. They will then undertake laboratory and cabinet studies to verify the scientific approach and to capture the vesicles, before more-extensive testing of a possible spray in the field to determine functional amounts required to effectively destroy bacteria.

“We are keen to build on the science knowledge base in this area of microbiology and will be looking to publish our findings as we go, together with communicating the findings to growers,” Mr Zandberg says.

The pair will be busy, as this is a side project to their PhD studies. Ms Harvie is a recipient of a GRDC Research Scholarship (GRS) and the Sir Eric Smart Scholarship to study protein pathways in wheat with Professor Harvey Millar’s team. Mr Zandberg is undertaking postgraduate studies with Professor Jaqueline Batley’s team, focusing on stress/disease interactions in canola supported by the University of Western Australia.

More information: Jaco Zandberg, jaco.zandberg@research.uwa.edu.au; Samantha Harvie, samantha.harvie@research.uwa.edu.au