Dr Xiaocheng Zhu1, Dr Karen L. Bell1, Dr Hanwen Wu1, Dr David Gopurenko1
1NSW Department of Primary Industries and Regional Development, Invasive Species Biosecurity branch, Wagga Wagga Agricultural Institute, Wagga Wagga, Australia
Biography:
Dr. Zhu is a research scientist in Invasive Species Biosecurity branch of the NSW Department of Primary Industries and Regional Development. He joined the Department in 2020 investigating the use of molecular tools for weed and pest diagnostic and detection. Before joining the Department, he worked for 10 years with the Charles Sturt University as a research fellow and completed a variety of research projects on invasive species.
Abstract:
Environmental DNA (eDNA) is a highly sensitive and non-invasive tool increasingly being used in biosecurity programs. However, DNA can persist in the environment long after the pest has left and can be released from decaying tissues from deceased pests. This complicates the interpretation of eDNA surveillance results and can lead to false alarms concerning the ongoing presence of an organism. In contrast, environmental RNA (eRNA), which is the product of functional genes and is short lived in the environment, purportedly offers an accurate means to detect only the living organisms in a local habitat. The positive detection of a pest's eRNA may serve as an indicator of its live presence, and this would be a valuable means for determining the success of local pest eradication efforts. In this study, we used a qPCR-based eRNA approach for the detection of aquatic weeds, using Amazon frogbit (Limnobium laevigatum (Humb. & Bonpl. ex Willd.)) as a model plant. We used a highly sensitive qPCR assay for eRNA detection and included a series of positive and negative controls for workflow quality assurance. Results of our experiment however indicated eRNA of the target species was only detected when the weed was present at very high abundance. Therefore, we questioned the practical use of qPCR-based eRNA in real-life scenarios, where target species are typically present at very low abundance. Future research should focus on eRNA enrichment and improving the sensitivity of research approaches for the reliable detection of living targets at low abundances in the environment.