Bacteria Turns Plants Into Zombies

witches' broom

Witches’ broom are indications of parasites

We all know how to turn people into zombies: just give them boring, 9-5 jobs (or worse, 8-6, 7-7, etc) that don’t require them to use their brains at all and thus turn them into the shuffling, vacant-eyed folks that appear in Shaun of the Dead even before the undead start snacking on them. Animals can become zombies too, when under the control of bodysnatching parasites. Now, scientists have learned that bacteria can work their zombie mojo on plants, too.

A team of scientists from Norwich, UK’s John Innes Centre published research in PLOS Biology that describes how phytoplasmas, parasitic bacteria that wreak havoc on the likes of sugarcane and coconut, take over plants and make them do all sorts of things they otherwise wouldn’t. Flowers become shoots, petals change color, and the plant sends up the telltale “witches’ broom” shoots. As the parasite takes hold, the host becomes incapable of reproducing. Insects descend on these new shoots, transmitting the bacteria to make new zombies. They don’t even have to bite anything. The report points out that for all intents and purposes, the plant is dead, living on bacterial life support.

The bacteria’s secret weapon is the SAP54 protein, which interacts with the plant’s proteins that send certain molecules to be disposed of by the cell. The invader specifically targets flower-making molecules. The interaction between the two proteins controls both the behavior of the plant, as well as the behavior of the insects that feed on it and live on it, such as leafhoppers. The research indicates that plants with this bacteria attracted more egg-laying leafhoppers than others, even blooming ones. Just the SAP54 by itself attracts insects.

The scientists are particularly surprised at the connection between plants’ development and their immune systems. It’s unlikely that this connection is unique to a certain type of plants or to plants in general, and thus it opens up new fields of research. For example, this could lead to strategies to improve crop yields while simultaneously staving off pests.

Puccinia monoica

Puccinia monoica

It turns out that this is only one way that plants can be zombified. Fungi, such as Puccinia monoica, can do it too, causing drastic transformations, like sprouting fake flowers full of cells that insects will spread to other plants. Scientists don’t yet understand how this works, but regardless of the explanation, we can all admire nature for its resourcefulness, warts and all.

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