New research could reshape fight against gray mold in produce crops

A pair of newly published studies from the University of California-Davis may fundamentally change how researchers and growers approach one of the produce industry’s most persistent postharvest threats: gray mold.

Known scientifically as Botrytis cinerea, the fungus affects hundreds of food crops and ornamental plants, including blueberries, strawberries, tomatoes, grapes, lettuce and cut flowers. UC Davis says the pathogen itself is responsible for an estimated 5% to 10% crop loss globally.

Now, researchers at UC Davis say decades of resistance breeding efforts may have been limited by a flawed assumption about how plants and pathogens interact.

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The studies, published in the Proceedings of the National Academy of Sciences and led by Dan Kliebenstein, professor in the UC Davis Department of Plant Sciences, found that plants do not respond to gray mold in a uniform way — and that the fungus itself appears to tailor its attack depending on the host crop.

“For years, scientists assumed plants mounted broadly similar defenses against fungal pathogens,” Kliebenstein said. “What we found is that each plant species responds in fundamentally different ways.”

According to the research team, that variability helps explain why resistance traits identified in one crop often fail to translate effectively to another.

The second study focused on the pathogen itself and revealed that Botrytis cinerea may actively detect which crop it is infecting and adjust its infection strategy accordingly.

“The pathogen is almost acting like it can ‘taste’ the plant,” Kliebenstein said. “If it’s attacking a strawberry, it behaves differently than if it’s attacking a tomato.”

The findings suggest future disease-control strategies may need to shift away from breeding plant-by-plant resistance and instead target the mechanisms the fungus uses to recognize its host.

Researchers believe disrupting the pathogen’s ability to identify crops could weaken infections and allow plants’ natural defenses to respond more effectively.

“If we can understand how the fungus knows what it’s attacking, we may be able to confuse it chemically or genetically,” Kliebenstein said.

The approach could potentially offer broader protection across multiple commodities rather than requiring separate resistance strategies for each crop.

Other authors on the studies include Ritu Singh, Anna Jo Muhich, Cloe Tom, Celine Caseys, Jack McMillan, Karishma Srinivas and Lucca Faieta of UC Davis.

The research was funded by the National Science Foundation.