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Photo: Frances Andrijich / Wine Australia

Clock ticking down for grapevine leaf-roll virus diagnostic tool

RD&E News | June 2019
Photo: Frances Andrijich / Wine Australia
07 Jun 2019
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A portable, diagnostic tool that can identify grapevine leaf-roll viruses 1 and 3 in the field within 30 minutes – and allow growers to remove infected vines before the virus spreads – is in the sights of researcher, Dr Monica Kehoe.

Dr Kehoe has been studying leaf-roll virus 1 and 3 as part of a 12-month Wine Australia supported Science and Innovation Awards for Young People in Agriculture, Fisheries and Forestry.

Grapevine leaf-roll virus (GLRV) 1 and 3 are a major problem for grapegrowers across the nation. Previous research suggests that around 13 per cent of Australian vine samples are infected with GLRV1 and 14 per cent with GLRV3.

‘These viruses result in reduced fruit quality and yield – and can even be present as a symptom-less infection, so they are a major concern for growers’, said Dr Kehoe, a Molecular Plant Pathologist with the Department of Primary Industries and Regional Development in Western Australia.

The aims of Dr Kehoe’s project were two-fold: to help fill the knowledge gap around leaf-roll viruses; and to sequence whole genomes of GLRV1 and GLRV3 and develop an in-field molecular diagnostic test for both viruses.

She was successful on both counts.

In total, Dr Kehoe collected 264 samples from vineyards across south-west Western Australia. One hundred and three of the 264 samples proved positive for GLRV1 and 123 proved positive for GLRV3. 

Dr Kehoe then sequenced 13 complete genomes of GLRV3 and 12 of GLRV1.

‘We found that particularly with GLRV3 there was a lot of diversity present in the genomes – not just compared to those collected from other places but amongst themselves too.’

The sequenced genomes will now be added to the international GenBank database, to ensure the Australian experience is accurately documented.

‘To date, there is only a single GLRV3 genome from Australia in GenBank, so this data will be a great addition to the database. It will be available for other researchers to include when they design new molecular tests as well.’

Finally, Dr Kehoe developed a LAMP-PCR (loop mediated isothermal amplification-polymerase chain reaction) assay for the viruses  – a technique that allows for the rapid amplification of DNA using a simple, hand-held device.

LAMP-PCR was used successfully for detection of leaf-roll viruses in both the laboratory and the field during the project.

Because of this, Dr Kehoe said it could prove to be a valuable surveillance tool down the track.

Dr Kehoe said fast-tracking screening for leaf-roll infection could help growers in a number of ways.

‘A quicker result means growers can get back to business quicker. Often when striking a new block, growers will send a subset of canes for testing – so the faster we can provide a result the better. We are working all the time to improve that part of the process, so growers can get on with their work.’

Looking forward, Dr Kehoe is keen to sequence more virus genomes from Western Australia and beyond.

‘A more complete picture than just south-west WA can only be beneficial in terms of ensuring that all of our molecular tests are as up to date and robust as possible. We have already seen how much diversity there is in one small region, it’s important to compare in other regions too.’

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This content is restricted to wine exporters and levy-payers. Some reports are available for purchase to non-levy payers/exporters.