First report of Spartium witches' broom disease in Spain

Symptoms of witches' brooms and decline were observed on Spanish broom (Spartium junceum L.) in Catalonia, Spain (Fig. 1). The appearance of witches' brooms which developed from axillary buds on this woody perennial shrub was followed by a drying of foliage. Affected plants eventually withered and died within a few years. A similar disease of S. junceum described in Italy was attributed to a phytoplasma etiology (Marcone et al., 1996).

Samples from both affected and symptomless plants were analysed for phytoplasma infection by a nested polymerase chain reaction (PCR) assay employing rRNA primer pairs P1/P7 (Smart et al., 1996) followed by U5/U3 (Lorenz et al., 1995) or R16F2/R2 (Lee et al., 1995). An rDNA product of expected size (1.2 kb) was amplified by nested R16F2/R2-primed PCR from all nine symptomatic plant sample DNAs whereas no product was amplified from four symptomless plant samples. No products were obtained from either symptomatic or symptomless plants by nested U5/U3-primed PCR. R16F2/R2 products from two S. junceum plants (T-500 and T-701) were analysed further by reamplification of products by PCRs using nested 16S rRNA primer pair R16(V)F1/R1 or R16(X)F1R1 (Lee et al., 1995). An rDNA product (1.1 kb) was obtained from both plants with the latter apple proliferation phytoplasma (16SrX) group-specific primer pair only.

Identification and classification of S. junceum-infecting phytoplasmas as strains belonging to 16SrX group, subgroup D was determined by restriction fragment length polymorphism analysis of R16F2/R2-primed rDNA products using six endonuclease enzymes. Phylogenetic analysis of 16S rDNA sequences also delineated phytoplasma strain T-701 (EMBL accession no. AJ430067) as a 16SrX group strain most closely related to the phytoplasma associated with Spartium witches' broom in Italy (Fig. 2). This is the first report of a phytoplasma disease of S. junceum in Spain.