Based purely on its name, grapevine leafroll should be a relatively easy virus to detect. However, as is the norm with most plant pests and problems, the reality is somewhat different.
For a start, there are a number of different viruses (rather blandly just known as grapevine leafroll virus 1, 3, 5 etc.) with different symptoms and severity of impacts, and even coming from different families.
On top of this, the symptoms may not be linked to a virus. Tell-tale signs such as leaf rolling or puckering, or leaf reddening for red varieties, may be caused by poor nutrition or other environmental factors. Plants can also be infected with virus but show no symptoms.
And finally, there is the fact that the available diagnostics aren’t completely consistent. That’s certainly one of the concerns Dr Monica Kehoe has heard expressed by growers and agronomists in Western Australia.
‘One of the anecdotal things we get back from the field is that they feel the diagnostics are a bit hit and miss’, she said. ‘They expect one answer and get another or they get one answer at one time and a different one later.
‘What we don’t know is whether that’s to do with time of infection and time of year that sampling occurs, or because the viruses have a bit more differentiation than is accounted for in the current diagnostics, which are produced overseas.’
It’s a question Dr Kehoe hopes to find some answers to over the next 12 months. She will undertake the research project after winning the Wine Australia supported award at the 2018 Science and Innovation Awards for Young People in Agriculture, Fisheries and Forestry.
A Molecular Plant Pathologist with Western Australian Department of Primary Industries and Regional Development , Dr Kehoe will focus specifically on grapevine leafroll viruses 1 and 3, which are major virus concerns for growers across Australia and the two major viruses detected in Western Australian vineyards.
In a recent Australian study, 13 per cent of vine samples were infected with grapevine leafroll virus 1 and 14 per cent with grapevine leafroll virus 3. Both can lead to poor fruit quality and significant drops in yield.
Dr Kehoe has two aims. The first is to sequence the genome of both viruses and add them to the international GenBank database to ensure the Australian experience is accurately documented. She is rather surprised by the size of the gap to be filled.
The second is to use this knowledge to develop a portable diagnostic test that is tuned to Australian conditions and, she hopes, will be able to produce an answer in the field in just half an hour. This will allow growers to quickly identify a problem and remove infected vines before the virus spreads.
The project will begin and end in vineyards around Margaret River and Swan Valley, first talking with growers and taking samples, then trialling her test and presenting at field days. In between there will be some serious work in the laboratory, drawing on skills old and new.
Before starting a science degree and eventually specialising in plant virology, Dr Kehoe did a year of computer science, which has proved invaluable as diagnostic work evolves.
‘The new generation of sequencing and genomics involves a fair bit of computer work, so things have come full circle’, she said. ‘I’m not writing any of the programs that people are putting out there but I have the skills to be able to coax them into use. It’s been very useful.’