AN INVESTIGATION by local plant scientists into the scope of indigenous and exotic viruses in orchids has revealed the presence of a symptomless virus never before found in orchids.
Researchers from Murdoch University and the Botanic Gardens and Parks Authority tested four species of donkey orchids (Diuris) for the presence of RNA viruses.
They tested two wild populations of donkey orchids and two captive populations including one at Kings Park and one in South Australia and found 11 isolates of eight distinct viruses.
Murdoch University’s WA State Agricultural Biotechnology Centre senior research fellow Steve Wylie says they are investigating the impact of viruses on different types of orchids.
“Nobody has looked seriously at Western Australian indigenous plants for the viruses that infect them or what sort of implications they might have for the plants,” he says.
“What we expect is that a number of exotic viruses—ones that have been brought into the country—might be able to spread to the native flora and also we might expect that viruses have evolved long before anybody came here.”
The team tested four orchid species with a technique called Next Generation Sequencing because of the plants’ wide distribution in wild and captive populations.
“Part of the study was to see whether these captive populations are inadvertently causing more trouble than good, because nurseries are great places for viruses to spread,” Dr Wylie says.
“We found exotic viruses that are infecting orchids—which have come from plants brought in from places around the world— infect both the captive populations and the wild populations.”
The study also found one rare orchid (diuris pendunculata) in the South Australian population was co-infected with four different viruses but was completely symptomless.
Dr Wylie says one of the four viruses (Turnip yellows virus) had never been found in orchids before and is prevalent in canola, cabbages and turnips.
“Everything we tested had at least one virus in it and that is probably the case in the wild that most things are actually infected with viruses and probably live quite happily with them.”
He says the team will now investigate whether the viruses they think are indigenous are inducing beneficial interactions between the plant and the virus.
“Conversely with the introduced viruses we want to determine if they are causing a negative effect like reducing lifespan and would it be worthwhile going to the effort of getting rid of them.”
Kings Park and Botanic Garden Authority Science Director Kingsley Dixon says viruses can impart resistance to environmental and biological stresses and more research was needed to understand the role of these viruses in the ecology of the orchids.