Many parasites commandeer the bodies of their hosts in order to spread. Examples of this include horsehair worms that reach water by forcing their cricket hosts to drown themselves, and liver flukes that drive infected ants to climb blades of grass, where cows can eat the insects, and so the flukes. But parasites can turn plants into zombies, too — and a team of scientists from the John Innes Centre in Norwich, UK, has now discovered how they do it.
When plants are infected by parasitic bacteria called phytoplasmas, their flowers turn into leafy shoots, their petals turn green and they develop a mass of shoots called ‘witches’ brooms’. This transformation sterilizes the plant, while attracting the sap-sucking insects that carry the bacteria to new hosts. “The plant appears alive, but it’s only there for the good of the pathogen,” says plant pathologist Saskia Hogenhout from the John Innes Centre in Norwich, UK. “In an evolutionary sense, the plant is dead and will not produce offspring.” “Many might baulk at the concept of a zombie plant because the idea of plants behaving is strange,” says David Hughes, a parasitologist at Pennsylvania State University in University Park. “But they do, and since they do, why wouldn't parasites have evolved to take over their behaviour, as they do for ants and crickets?”
Via Kamoun Lab @ TSL