First report of ‘ Candidatus Liberibacter europaeus’ associated with psyllid infested Scotch broom

Abstract

In Canterbury, New Zealand, in November 2011, disease symptoms resembling those associated with 'Candidatus Liberibacter' species were observed in common or Scotch broom ( Cytisus scoparius), an invasive leguminous exotic shrub. Symptoms included stunted growth of shoots, shortened internodes, and leaf dwarfing and leaf tip chlorosis. A large population of broom psyllid, Arytainilla spartiophila, was noted on the plants. A 578-bp partial 16S rDNA fragment indicative of the presence of a 'Ca. Liberibacter' was amplified from 15 out of 19 plant samples and from five out of seven broom psyllid samples. Amplicons from seven of these samples were directly sequenced, trimmed to 510 bp, and subsequently used in a phylogenetic comparison with partial 16S rDNA sequences of 'Ca. Liberibacter' from other hosts. The resulting majority rule consensus tree clustered the partial 16S rDNA sequences from Scotch broom and broom psyllid with that of 'Ca. Liberibacter europaeus'. This is thought to be the first report of an association of 'Ca. L. europaeus' with the broom psyllid and its host plant.