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Movement of viruses between native plants and introduced crops is being investigated in a new research project focusing on WA’s South West Australian Floristic Region (SWAFR).

According to Professor Mike Jones, Director, WA State Agricultural Biotechnology Centre (SABC), Murdoch University, the SWAFR represents a unique interface between an ancient ecosystem and modern agriculture.

“It is one of 34 international ‘hot spots’ of global diversity and endemic plant species.

“Unlike Eurasia where agriculture has occurred for thousands of years, agriculture has only existed in WA for 150 years,” Professor Jones said.

“This provides the opportunity to investigate encounters where plant viruses present in native plants can move into crop plants and vice versa.”

SABC Senior Postdoctoral Fellow, Dr Stephen Wylie and colleagues at the SABC and Department of Agriculture and Food WA (DAFWA) discovered the first new virus identified from an indigenous plant in this region, naming it Hardenbergia mosaic virus.

“This virus infects the native wisteria, Hardenbergia comptonia, causing mottling and distortion of the leaf and may affect its ability to persist in the wild,” he said.

“Viruses are usually transported via a vector from one plant to another and the vector can be an insect, pollen, soil fungus or the mechanical action of animals.

“We know from glasshouse experiments that this new virus can readily infect lupins.”

Professor Mike Jones, Director, WA State Agricultural Biotechnology Centre.

According to Dr Wylie, native wisteria often grows around the margins of lupin crops and Hardenbergia mosaic virus therefore has the potential to infect lupin, an important rotation crop in WA, which is the world’s largest lupin producer.

Another concern is that commercial nurseries which propagate plants or re-vegetate degraded natural areas could inadvertently spread viruses within the nursery, which could then be transferred back into the natural environment.
“Monoculture conditions in the nursery provide a perfect ’green bridge’ that may make it easy for vectors to survive and pass on viruses,” Dr Wylie said.

“So far, we’ve only found one indigenous virus that has evolved in WA’s south west, but with more than 12,000 endemic plant species in WA it undoubtedly represents the tip of the iceberg.

“Because of the region’s isolation over millions of years, it’s probable that there are many undescribed families of viruses yet to be discovered.”

Dr Wylie emphasised the importance of considering how climate change might affect the ranges of indigenous and introduced plants and insects, creating new conditions for the transfer of disease.

“It’s also possible that ecosystem stress could cause viruses of introduced plants to move into native plant communities and we have evidence that this is already happening.

“Similarly, native viruses could emerge from the flora and be transmitted into crop species, creating epidemics.

“We know this has already occurred with deforestation in Brazil and Africa, where insect vectors have caused outbreaks of previously unknown gemini viruses to move from forest plants into tomatoes and maize and seriously impact crop production,” he said.

The research is now funded by an Australian Research Council Linkage Project, supported by the SABC, Saturn Biotech, Worsley Alumina, ALCOA, Kings Park and Botanic Gardens and DAFWA.

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