This Parasite Can Hijack A Plant's Reproductive System

Researchers in the UK have unlocked the mystery behind a freaky bacterial pathogen that hijacks a plant's reproductive capacities — a nefarious process that essentially converts hosts into the living dead.

Top image: The top row shows a normal Arabidopsis plant — flowers and all. The bottom row shows a parasitized "zombie plant," one that can no longer produce petals. Credit: A. M. MacLean et al./PLOS

Nature is replete with examples of parasites controlling the lives of their hosts, including zombified bees and ants. But plants? Apparently yes.

According to researchers from the John Innes Centre in the UK, the parasitic bacterium phytoplasma is capable of hijacking the biological structure of plants for procreative purposes. It does so by injecting a protein called SAP54 into plants, transforming their flowers into leafy shoots. Once infected, their petals turn green and develop a mass called "witches brooms," which renders the plant completely sterile.

"The plant appears alive, but it's only there for the good of the pathogen," noted plant pathologist Saskia Hogenhout in a Nature News article. "In an evolutionary sense, the plant is dead and will not produce offspring."

And indeed, the point of all this is to set up the next stage in the process, one that also involves SAP54 (a remarkable example of dual-function in nature). This protein makes the plant irresistible to sap-sucking insects like leafhoppers, who tend to lay more eggs on infected plants.

As a result, leafhoppers become the vectors for these parasites. So, instead of distributing the plant's pollen, they disseminate the bacterium to other plants — thus repeating the cycle of zombie despair.

Pretty nasty, no?

Read the entire study at PLOS Biology: "Phytoplasma Effector SAP54 Hijacks Plant Reproduction by Degrading MADS-box Proteins and Promotes Insect Colonization in a RAD23-Dependent Manner."