CRISPR Edit Makes Grapevines More Resistant to Downy Mildew

Scientists have used CRISPR/Cas9 gene editing in grapevine to show that a single gene, VvDMR6.1, can influence both resistance to downy mildew and the plant’s response to limited water, according to a study published in the journal Plant Stress.

The work focused on a rootstock grapevine cultivar known as Richter 110 and targeted a susceptibility gene that helps regulate salicylic acid, a hormone tied to plant immunity. By disabling VvDMR6.1, the researchers found they could reduce the vine’s vulnerability to Plasmopara viticola, the pathogen that causes downy mildew, while also changing how the plant managed water stress.

The edited vines were not fully immune to the disease, but they showed much lower infection levels than unedited plants. In leaf-disc tests, disease severity fell sharply in both edited lines compared with controls. One edited line showed infection on 0.5% of leaf area and the other on 2.1%, versus 28.1% in the control plants.

The study also found that the edited vines accumulated more salicylic acid, especially in the line that was nearly fully edited. That result fits with earlier work showing that DMR6 genes act as negative regulators of immunity by helping keep salicylic acid levels in check.

What made this study notable was the second part of the experiment. The researchers withheld water from the plants and tracked stomatal conductance, a measure of how open the pores on leaves are, along with soil moisture and hormone levels. One edited line responded differently from the control plants: it kept its stomata more open under well-watered conditions, then closed them more quickly once water became limited.

That line also showed a stronger rise in abscisic acid, or ABA, a hormone that helps plants conserve water by closing stomata. The researchers reported higher expression of ABA biosynthesis genes and antioxidant defense genes in that line during water stress. They said this pattern suggests a water-saving strategy that may help the plant react faster when moisture drops.

The findings point to a possible link between salicylic acid and ABA signaling in grapevine guard cells, where stomata open and close. The authors said the edited plants may be “primed” to respond more quickly to stress because of changes in redox balance and hormone signaling.

The results matter for viticulture because grape growers are facing more pressure from both disease and drought. Downy mildew remains one of the most costly grape diseases worldwide, while water shortages are becoming more common in many wine regions. Breeding or editing vines that can better handle both stresses at once has become a major goal for researchers.

The study adds to a growing body of work showing that DMR6 genes are promising targets in several crops. Similar edits in tomato and potato have also improved disease resistance and, in some cases, drought tolerance. In grapevine, earlier studies had already shown that knocking out DMR6 genes can reduce downy mildew susceptibility. This new work suggests VvDMR6.1 may also affect how vines manage water loss.

The researchers cautioned that their results came from controlled greenhouse and laboratory tests, not field trials under real vineyard conditions. They said more work is needed to understand how the edited vines perform across different grape backgrounds and under combined stress conditions such as drought followed by disease pressure.

Still, the study suggests that one gene may offer two benefits at once: less disease and a more responsive drought strategy.