Dr Smith completing his PhD in genetics and gained research experience in cell, molecular and plant developmental biology in the US. In 2012, he moved to Adelaide to lead the Rootstock Breeding Team at the Commonwealth Scientific and Industrial Research Organisation (CSIRO), with a focus on developing climate resilient rootstocks with long term resistance to grape phylloxera and root knot nematode for Australian conditions. ‘We’re at a point where innovation in rootstock breeding is no longer a luxury – it’s a necessity for the future of viticulture in a changing climate,’ he said.
The importance of maintaining resistance
Most of the rootstocks currently used in vineyards were created over a century ago in Europe and do not possess the genetics to maintain immunity to soil pests over a long period of time due to resistance controlled by a single trait.
For example, in California, vineyards established with rootstocks, such as Freedom and Harmony, which harbour a single root knot nematode resistance gene, initially provided immunity to this soil pest. Unfortunately, over time, some of the endogenous root knot nematode populations living in the soil were able to evolve and break the resistance controlled by a single trait.
‘The challenge is that pests, such as root knot nematodes and phylloxera, can evolve and adapt to feeding on material that contains a single resistance gene, making it imperative that we work on developing rootstocks that can maintain resistance over a long period of time,’ Dr Smith explained, emphasising the urgency of his work.
Additionally, climate change is also creating another layer of complexity for vineyard management. Periods of drought limit water availability to vineyards. Under drought conditions, water often becomes saline, leading to a decline in water quality. Further, an increase in soil temperatures can also break root knot nematode resistance and reduce salinity tolerance in some rootstocks. ‘Climate change is not just a series of current and future risks; it’s continually changing and impacting vineyard performance on the daily,’ said Dr Smith.
Creating ‘genetically diverse rootstocks’
To safeguard vineyards from pests, Harley’s team is utilising a breeding approach to stack and combine phylloxera and root knot nematode resistance traits into a suite of genetically diverse rootstocks. Harley’s team has identified several phylloxera and root knot nematode traits from genetically diverse parental breeding lines and are using DNA-markers linked to these traits to combine them into future rootstocks. ‘Our goal is to develop genetically diverse rootstocks with longterm resistance to phylloxera and root knot nematodes for Australian vineyard production,’ Dr. Smith explained.
To reduce the impacts of climate events on vineyard production due to poor water quality, Harley’s team has also identified salinity tolerant genes and are using DNA-markers to stack these genes along with the resistance traits. In addition, the team has also developed in-vitro and glasshouse screening systems to select for rootstocks that maintain root knot nematode resistance and salinity tolerance at higher soil temperatures. In addition, water deficit field trials will be utilised to select for rootstocks that perform well with reduced irrigation.
Interestingly, rootstocks can also influence grape and wine quality. ‘Different rootstocks can alter flavour profiles and even more so, influence the colour of red wines, which adds another layer of complexity for selecting new rootstocks,’ said Dr Smith. This aspect highlights the importance of evaluating rootstocks in field trials to not only assess yield-associated traits but also to evaluate the impact on grape and wine quality attributes.
After the selection and evaluation of these rootstocks, Harley’s team expects that these new rootstocks may be available by 2032. Given this research project is funded by Wine Australia, as well as CSIRO, Harley and his team are working with these industries to develop an adoption pathway(s) to ensure that the Australian wine grape growers will have access to the new rootstock offering upon release.
A sustainable strategy for the future
The work of Dr Smith and his team at CSIRO represents a significant step forward in the future of viticulture, particularly in the face of climate change and evolving pest threats. The innovative approach to rootstock breeding, focusing on stacking multiple resistance traits and addressing climate-related challenges offers a sustainable strategy to maintain wine grape production in Australian viticulture.
By not only enhancing pest resistance but also improving grape and wine quality, these new rootstocks will allow growers to adapt grape cultivation in this evolving climate. As the industry eagerly anticipates the release of these rootstocks by 2032, it’s clear that Dr Smith’s efforts are poised to secure a more resilient and sustainable future for wine production.
