Mr Brady Welsh

The Impact of Fungicides on the Phyllosphere Microbiome of Grapevines

Diseases which effect grapevines used for winemaking can cause tremendous burden on the wine industry, and as such, an array of chemical fungicides are used to prevent and treat instances of disease. Although viticulturists have used broad-spectrum fungicides for hundreds of years, the discovery of the vine’s microbiome highlights the risk of potential off-target and downstream effects caused by these disease treatments. Using both quantitative and qualitative techniques such as quantitative PCR and rRNA gene amplicon sequencing techniques, respectively, we aim to investigate how various fungicide conditions shape the grapevine microbiome over time via off-target interactions with the non-pathogenic microbial communities. With the interconnected nature of the grapevine microbiome and its role in plant health and the fermentation process, identifying these potential off-target effects is key to improving the health and yield of grapevine plants as well as ensuring the consistent production of high quality wines.

The Viable Phyllosphere Microbiome

One of the most significant limitations to current microbiome analysis techniques is the inability to differentiate between DNA that originated from viable microbial sources, and DNA from non-living sources, known as relic DNA. Relic DNA makes up all DNA from sources such as dead cells, compromised cells or the environment (eDNA) and can be amplified and sequenced alongside target DNA, leading to a potential for false positives within results.  As such results obtained using these methods at their current capacity must be regarded with suspicion as to which microorganisms were truly associated with their respective host. To combat these limitations within phyllosphere microbiome research, we are developing a sampling protocol which utilises viability selection. With this viability sampling protocol, greater characterisation of the phyllosphere microbiome can be achieved and more accurate conclusions made on factors that impact the structure of the plant microbiome.

We have also discussed how this protocol can be utilised for microbial monitoring in vineyards which focus on the production of 'wild wines', which are fermented using the inhabitants of the grapevine microbiome. For these wines to be successful, specific micro-biodiversities must be maintained to produce wines with the desired sensory characteristics. As such microbial monitoring is required to ensure the vineyards microbiome is properly maintained, and with the utilisation of viability selection, this can be done with greater accuracy and reduced risk of misleading results.