Petunias as a Late Blight Defense? Not as Crazy as It Sounds

Published online: Sep 16, 2019 Articles Katie Langford
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Source: Grand Junction Daily Sentinel

A common garden flower may contain the biological secrets needed to stop a fungus known for decimating potato and tomato crops.

Research from associate professor Margot Becktell at Colorado Mesa University suggests that a naturally occurring sticky substance on petunia leaves can kill one of two types of spores produced by late blight.

Late blight has caused widespread famine throughout history, including the Great Irish Famine in the 1840s.

Petunias are in the same plant family as potatoes and tomatoes, but the plant produces sticky sucrose esters on its leaves.

Becktell's research shows that when the sucrose esters come into contact with certain late blight spores, the late blight spores explode. She started researching this phenomenon after finding data that petunias are generally more resistant to late blight than other plants in the nightshade family.

Becktell said she still doesn't know why the blight spores explode — do the sucrose esters poke holes in them, allowing water to flow in and cause them to explode? But it's clear that when sucrose esters and late blight zoospores mix, the esters come out on top.

Becktell said she is frequently asked about whether the findings could be applied to farming.

"I wouldn't rule it out," she said. "What I don't know yet is whether or not we could produce and apply the sucrose esters in high enough levels in a field situation that it would be effective."

Also, sucrose esters are only effective against one of the late blight spores — the other is not affected.

Becktell said she's also researching wild potatoes and tomatoes, because those breeds still produce the blight-fighting sucrose esters, unlike their domesticated cousins.

Whatever her research ends up revealing, Becktell said it will likely be one part of the puzzle.

"They've been trying to breed resistant potatoes and tomatoes for a long time," she said. "It's something that could be in the toolbox, but it would not be the only thing."