A new phytoplasma detected in the South Australian native perennial shrub, Allocasuarina muelleriana

Allocasuarina muelleriana shrubs growing in natural sclerophyll roadside vegetation near Willalooka in the upper south-east of South Australia have a high incidence of a yellowing disorder in either all or part of the foliage, combined in some cases with a shortening and curling of the leaf-bearing stems. Samples from symptomatic and adjacent asymptomatic plants were tested for phytoplasmas by the polymerase chain reaction (PCR) assay. All but one asymptomatic plant were negative for phytoplasmas, whereas about half of the symptomatic plants were positive. Restriction fragment polymorphism analysis of PCR products indicated that the phytoplasma was related to the buckthorn witches'-broom (BWB) and apple proliferation (AP) groups of phytoplasmas, members of which have not been previously reported in Australia. Further evidence from the sequence of the 16S rRNA gene and the use of PCR primers specific to the AP and pear decline (PD) phytoplasmas confirmed the close relationship to the BWB and AP group phytoplasmas.