Stolbur phytoplasma infection of kale crops (Brassica oleracea var. gemmifera L.) in Serbia

Kale plants (Brassica oleracea var. gemmifera L.) showing symptoms of reddening on leaf and petioles and overall stunting were found on locality Pancevo (south Banat) during inspection on vegetable crops carried out in 2010 in Serbia. The phytoplasma associated with the disease was detected through nested PCR with primer pairs P1/P7 and R16F2n/R2 followed by RFLP analysis with restriction enzyme Msel. A total of 10 symptomatic and 4 asymptomatic plants were collected and analyzed for the presence of phytoplasma. Nested PCR amplified 16S ribosomal RNA fragments of phytoplasma in all samples of kale with symptoms, while all asymptomatic plants tested negative. Digestion with Msel identified in infected kale the same pattern as a reference strain of stolbur phytoplasma belonging to 16SrXII-A group. Amplification of the elongation factor tuf gene and digestion with HpaII restriction enzyme was performed for genotype differentiation of stolbur phytoplasmas detected in kale. Digestion of tuf gene indicated presence of tuf-type b of stolbur phytoplasma in all symptomatic kale plants. This is the first report of stolbur phytoplasma infecting kale crops in Serbia