Victoria University researcher Dr David Ackerley is working to combat the PSA disease that has ravaged New Zealand’s $1 billion kiwifruit industry.
PSA was detected in New Zealand in late 2010 and as of October last year had affected 369 orchards covering 2214 hectares, with the rate of the bacterium’s spread increasing.
Dr Ackerley from Victoria’s School of Biological Sciences is working with Seeka, New Zealand’s largest kiwifruit grower, and Professor Iain Lamont and Associate Professor Russell Poulter from the University of Otago, to overcome the disease.
The research is funded by a Technology Transfer Voucher worth potentially up to $1 million over three years from the Ministry of Science and Innovation. The Ministry provides half the funding, with the other half funded by Seeka.
“PSA has been brutal for our kiwifruit industry and gold kiwifruit are particularly susceptible,” says Dr Ackerley.
“We only have to look overseas to see the potential damage. In the four seasons the PSA bacterium has been in Italy, it has essentially destroyed the gold variety in the country’s main growing area and is now affecting almost every orchard that’s growing green kiwifruit.”
His team is taking two approaches to find a solution to the disease.
“Our first strategy is to test a range of antimicrobial agents, substances that kill or inhibit the growth of microorganisms, to find compounds that may be suitable for use against PSA in the field” says Dr Ackerley. “Kiwifruit crops could potentially be sprayed or even injected with these agents to help limit the spread of the disease.”
“Another possible step is to identify and knock out key genes that make PSA particularly virulent, removing the ‘lethal’ genes that enable PSA to invade kiwifruit vines. You could then inoculate plants with a mild form of PSA that will dominate the surface of the plant and prevent the disease-causing strain from establishing a beachhead.
“This ‘biocontrol’ strategy is particularly exciting to us, and is building off the high-quality PSA genome sequence data generated by our collaborators at Otago.”
Dr Ackerley says the work to sequence the genome of PSA will have ongoing benefits. “Initially, we’re aiming to combat the spread of the bacterium; longer-term efforts may enable us to understand the precise mechanisms that make PSA such a lethal pathogen, and this could guide efforts to breed more resistant kiwifruit crops.”