Root cause of poor wine from saline soils lies in the genes, finds South Australian researcher

SUBSCRIBE to our fortnightly email newsletter to receive more stories like this.

Vineyard, near Melbourne.
Developing vine rootstock better suited to Australian conditions and more resilient to salinity helps ensure the sustainability of our vineyards.
Matt Sarah, Flickr CC

Salinity is a growing challenge for Australia’s rural sector – including its expanding viticultural industry. Dr Jake Dunlevy, 32, is undertaking research to combat this problem as it affects the winemaking industry.

Dr Dunlevy’s groundbreaking research was recognised at the 2016 Science and Innovation Awards for Young People in Agriculture, Fisheries and Forestry with a win in the viticulture and oenology category.

Coming from a wine industry family, Dr Dunlevy has a PhD in wine flavour. He received the Science and Innovation award for his study of the genetics of grapevine roots, which aims at reducing vines’ damaging uptakes of sodium and chlorine ions from saline soils.

The research is part of a broader project breeding new grapevine rootstocks that are tailored for Australian conditions and resilient to climate change.

Saline soil: jeopardising wine quality and profits

Dr Dunlevy saw the damage saline soil can cause first-hand when his own parents’ winegrape crop was affected severely by salinity in 2013. Excess ion levels saw a sixth of their 17-acre harvest rejected and the rest of it downgraded in value.

“The salt primarily affects the vine’s health, which results in reduced yields, so it's bad for growers,” he says. “Then there's a secondary problem: that the berries can accumulate high levels of the sodium and chloride ions, which is detrimental to the quality of the grapes and the resulting wine.”

Dunlevy’s research has implications for exports, as some of Australia’s key wine export markets have strict limits on the amounts of sodium and chlorine they allow in wine.

A two-pronged problem: sodium and chloride

Solving the problem is complicated by the fact that movement of sodium and chloride ions within plants are controlled by independent mechanisms, governed by distinct genes.

“There’s two aspects to the salt problem – the sodium and the chloride – and their uptake and movement within the vine is controlled by different mechanisms and therefore different genes,” Dr Dunlevy explains.

“The sodium story has been pretty well characterised in other plants over the last decade, so we’ve had some key target genes that we wanted to look at, as we think they are the same genes responsible in grapevines.

“We’ve got good data to show that, and we’ve got markers now that we think we’ll be able to use for breeding, and to select between the sodium excluders and sodium accumulators. So that’s all quite clearcut and going as we predicted.

“But the chloride uptake is a bit of an enigma; no-one’s been really able to narrow down the genes in any plant,” Dr Dunlevy says.

“We think it’s probably controlled by more than one gene, which makes it harder because when you have a population, the trait doesn’t segregate into excluders and accumulators.

“There’s a gradient of differences between them, which makes it harder to tease apart. But we are making progress and we’ve got a few candidate genes that we want to look at.”

 

Vineyard near McLaren Vale, South Australia.
Vineyard near McLaren Vale, South Australia.
Keturah Stickann, Flickr CC

Accelerating the research: screening for salt tolerance and underlying genes

The key to the project is access to a ‘plant accelerator’ on The Waite Campus in Adelaide. Essentially, the accelerator is a high-tech greenhouse in which plants sit on conveyer belts, allowing them to be moved daily so their growth and other parameters, such as water usage and salt concentration, can be measured precisely.

“You get a really accurate tool for screening for salt tolerance, whereas out in the vineyard there’s a lot of variability,” Dr Dunlevy explains. “We’re the first ones to use the accelerator with grapevines.”

The Science and Innovation award win will provide Dr Dunlevy with the funding he needs to extend this work; he plans to use the bursary take a closer look at the genetics of a number of winegrape varieties held by the CSIRO, as well as measuring their salt tolerance.

Future benefits

Aside from its direct benefit to winegrape growers and winemakers across the nation, Dr Dunlevy hopes his work on the genetics of salt tolerance will assist other researchers.

“The genetic information lasts forever; it’s not going to change,” he says. “So even though we screened these plants for sodium and chloride exclusion, there’s other groups here working on phylloxera resistance or nematode resistance or potassium uptake – all sorts of things,” he says.

“Having that genetic resource, they’ll be able to utilise it for the traits they are looking at as well.

“It doesn’t just help me – it helps other groups in the future.”

The Australian Grape and Wine Authority (AGWA), which trades as Wine Australia, was the sponsor of the viticulture and oenology award. The Authority supports a prosperous Australian grape and wine community by investing in research and development (R&D), building international and domestic markets, disseminating knowledge, encouraging adoption and protecting the reputation of Australian wine.

SUBSCRIBE to our fortnightly email newsletter to receive more stories like this.

Comments