A notorious agricultural pest harbours a bacterium that produces a toxin which may deter its predators. Orange-grove farmers dread the Asian citrus psyllid (Diaphorina citri), a small insect that carries the bacterial disease huanglongbing, which ruins citrus crops. Atsushi Nakabachi at Toyohashi University of Technology in Japan and his colleagues sequenced the genome of a second bacterium that lives inside the insect. Tentatively dubbed 'Candidatus Profftella armatura', the microbe's genome is so tiny that it can probably exist only within its host. About 15% of the genome is dedicated to the synthesis of a polyketide compound, which might protect the insect. The authors suggest that the genes that produce the toxic polyketide may have 'jumped' into the symbiont from another bacterial species.

Curr. Biol. http://dx.doi.org/10.1016/j.cub.2013.06.027 (2013)