Evolution of Plant Virus Diagnostics Used in Australian Post Entry Quarantine

Abstract

As part of a special edition for MDPI on plant virology in Australia, this review provides a brief high-level overview on the evolution of diagnostic techniques used in Australian government Post-Entry Quarantine (PEQ) facilities for testing imported plants for viruses. A comprehensive range of traditional and modern diagnostic approaches have historically been employed in PEQ facilities using bioassays, serological, and molecular techniques. Whilst these techniques have been effective, they are time consuming, resource intensive and expensive. The review highlights the importance of ensuring the best available science and diagnostic developments are constantly tested, evaluated, and implemented by regulators to ensure primary producers have rapid and safe access to new genetics to remain productive, sustainable and competitive.

Side-by-Side Comparison of Post-Entry Quarantine and High Throughput Sequencing Methods for Virus and Viroid Diagnosis

“…Traditional diagnostic tools such as serological or molecular assays (i.e., PCR, ELISA) require a priori knowledge of pathogens’ genetic blueprint to detect plant viruses and viroids. Other non-specific tests such as electron microscopy, woody indexing, or visual inspection do not require this prior knowledge [ 4 , 5 , 6 ]. However, they can result in false negatives/positives and generally provide a lower level of detection resolution that can be limited to pest features or higher-level taxonomy information (e.g., genus).…”

“…However, they can result in false negatives/positives and generally provide a lower level of detection resolution that can be limited to pest features or higher-level taxonomy information (e.g., genus). Most of these traditional tests are also unable to detect multiple pathogens in a single assay [ 4 , 5 , 6 ]. Additionally, quarantined plants often require extended periods of time in post-entry quarantine (PEQ) (up to 2 years) which can significantly increase cost and risk to importers.…”

“…Additionally, quarantined plants often require extended periods of time in post-entry quarantine (PEQ) (up to 2 years) which can significantly increase cost and risk to importers. Finally, a wide range of plant genera need to be tested at PEQ facilities, bringing an added complexity to their diagnostics testing requirements [ 6 ].…”

Implementation of GA-VirReport, a Web-Based Bioinformatics Toolkit for Post-Entry Quarantine Screening of Virus and Viroids in Plants

“…Apart from the economic impact on primary production by reducing yield and quality, plant viruses and viroids can also impair market access and cause severe ecological consequences to native biodiversity. With the ever-growing global movement of plant material and the discovery of novel viruses, improvements in the detection and surveillance of viruses and viroids have become critical to biosecurity and border protection authorities [ 2 , 3 , 4 ]. Plant quarantine is a biosecurity measure implemented to prevent the entry of economically important plant pests to an area free of those pests or where such pests are present at manageable levels and are officially controlled [ 5 ].…”

“…Moreover, biological assays require a specialist skillset that nowadays is in decline and are resource-intensive, requiring special glasshouse facilities to maintain quarantined plants over long periods (up to 2 years). These challenges add to the cost of biosecurity clearance and delay the release of new genetic material, impacting the ability of Australia’s agricultural sector to maintain its competitiveness [ 3 ]. While electron microscopy detection of viruses using particle morphology enables the discovery of infecting viruses, narrowing it down to the species taxonomic level and its low intrinsic sensitivity remain a challenge [ 7 ].…”