UC Davis Researchers Uncover How Salmonella Tricks Plants to Open Gates

Discovery could lead to breeding lettuce, spinach, and other leafy greens resistant to contamination

Published on Feb. 20, 2026

Got story updates? Submit your updates here. ›

Researchers at UC Davis have discovered how the Salmonella bacteria are able to trick plants into opening their stomatal gates, allowing the bacteria to sneak inside the leaves where they cannot be removed by washing. The team, led by Professor Maeli Melotto, found that Salmonella induces the production of the plant hormone auxin, which gives a false 'all-clear' signal that causes the plant to open its gates and let the invaders in. This breakthrough could help efforts to breed lettuce, spinach, basil, and other leafy greens that are resistant to contamination by sneaky microbes.

Why it matters

Infected greens are the source of more than 9 percent of foodborne illnesses across the country, sickening an estimated 2.3 million people and costing up to $5.3 billion every year. The discovery by the UC Davis team brings researchers one step closer to developing safer crops through breeding programs.

The details

The researchers found that when plants detect bacterial flagella, they respond by closing their stomatal gates. However, some strains of Salmonella bacteria are able to reopen the stomata by inducing the production of the plant hormone auxin. It's not yet clear how the biosynthesis of auxin is triggered or whether it's the plant or the bacteria that is producing the hormone.

  • The research was featured on the cover of the PLOS Pathogens journal in February 2026.

The players

Maeli Melotto

A professor in the UC Davis Department of Plant Sciences who led the research team.

Brianna Fochs

The lead author of the study, who was a Ph.D. student in Melotto's lab and has since graduated.

Salmonella

A nasty bug that has figured out how to trick plants into opening up their safety gates so it can sneak in and live happily inside the leaves.

Arabidopsis

The model plant used for most of the research, though the mechanism is similar for lettuce, spinach, basil and other crops.

National Institute of Food and Agriculture

Part of the United States Department of Agriculture that provided funding for this research, with a priority research area on breeding food crops for greater safety.

Got photos? Submit your photos here. ›

What they’re saying

“We are now a step closer to translating this knowledge to leafy greens and start breeding for safer crops.”

— Maeli Melotto, Professor, UC Davis Department of Plant Sciences (ucdavis.edu)

What’s next

Additional research is needed to fully understand the chemical pathway involved in the plant-bacterium interaction and how to best apply this knowledge to breeding programs for leafy greens.

The takeaway

This breakthrough discovery by UC Davis researchers could help address the significant public health and economic burden of foodborne illnesses linked to contaminated leafy greens, by enabling the development of new crop varieties resistant to sneaky microbes like Salmonella.