What was it all about?

Tospoviruses, which are spread by thrips, are one of the most economically important constraints to vegetable production. Species such as capsicum chlorosis virus and tomato spotted wilt virus are present in Australia, while groundnut bud necrosis virus and others are impacting crops overseas and represent a significant exotic biosecurity threat.

Since there is no treatment available for tospoviruses, efforts currently focus on virus control, including on-farm biosecurity measures, controlling insect vectors, and taking advantage of natural resistance.

However, modern biotechnology offers new hope with the potential to supercharge natural resistance – essentially using a plant’s own antiviral processes in a directed manner. The use of artificial microRNAs (amiRNAs) is a tactic that uses a small stretch of the virus’s own genome to direct the plant to attack the virus. In this project, which ran from 2015 to 2018, genomic sequence information for many tospoviruses was compiled, forming an important resource.

The team also developed a much greater understanding of tospovirus-plant interactions, including how plant defence mechanisms are activated and work against different tospovirus types.

AmiRNA constructs were designed to target all virus strains within a species, both those in Australia and exotic strains. Comprehensive testing demonstrated that amiRNA constructs can induce host resistance to a targeted tospovirus. With multiple constructs developed for tospoviruses yet to reach Australia, there is the potential for a rapid response should these biosecurity threats eventuate.

By identifying important genes and regulatory pathways involved in resistance to tospoviruses, the work is set to be highly beneficial in future horticultural breeding programs.

Full details of the project can be found in the final research report, available for download at the top of this page.