PSA virus may have come from China - biochemists

The Hort16A gold variety is being hit by a bacterial disease called Pseudomonas syringae pv actinidiae. Photo / APN

The PSA virus threatening New Zealand's multimillion-dollar kiwifruit industry is likely to have originated in China, says a group of biochemists who are confident they will further isolate the source of the outbreak.

Scientists from Otago University's Department of Biochemistry worked with bacterium found 16 months ago in a Te Puke orchard.

The source of the bacterium had been a key question from the outset and the biochemists had looked at three possible locations - Chile, China or Europe.

Associate Professor Russell Poulter, Professor Iain Lamont and Dr Margi Butler sourced Chinese Pseudomonas syringae pv Actinidiae (PSA) samples for sequencing and the results revealed China was the original source of both the Italian and New Zealand outbreaks.

Technology to carry out sequencing of the whole genetic code of New Zealand (PSA) arrived in New Zealand last year.

Since the outbreak in New Zealand PSA had been found in Chile and work had begum to test those strains, similar tests suggested the Chilean strain also had origins in China.

Dr Poulter said the scientists would further determine the pathway of the strains of PSA to New Zealand.

"It's unlikely to be on someone's boots or via quarantined channels. We need to know the pathway, so we can help other countries - and ourselves - avoid similar mistakes in future,' he said.

The Government committed $40 million two years ago to allow scientists to carry out advanced genomics research specific to New Zealand.

The established New Zealand Genomic Limited (NZGL) had allowed the Otago biochemists to determine the PSA genome and give the kiwifruit industry answers.

Dr Poulter said the technology and funding had allowed it to conduct sequencing tests in New Zealand instead of having to courier samples offshore.

"New Zealand is a major agricultural and horticultural producer. If something goes wrong, we need to be able to respond, prioritise and act quickly.''

The results showed the New Zealand strain was different from the Italian strain, which ruled out speculation the country was the origin of the outbreak in New Zealand.

Further research by the team at Otago would concentrate on the effective use of an antibiotic for the successful treatment of PSA in New Zealand.