First report of a phytoplasma associated with an oilseed rape disease in Greece

Oilseed rape (Brassica napus) is widely grown to produce vegetable oil for industrial processing and for both human and animal feed. In Greece, the winter form of B. napus has been recently introduced as a potential option for biodiesel production following European Directive 2003/30/EC. As a pilot crop, it now covers approximately1000 ha in central (Thessaly) and northern (Macedonia and Thrace) regions of Greece. During spring 2006, phytoplasma-like symptoms were observed for the first time in oilseed rape growing in an experimental site in Thessaly (39º 41′N, 22º 27′E). The diseased plants exhibited stunting, leaf reddening, and malformation of floral parts (Fig.1). Similar symptoms were observed by mid-May 2008 in an experimental site in Halastra, central Macedonia (40º 38′N, 22º 45′E).

Leaf samples from symptomatic and symptomless plants were collected from Halastra and total DNA was extracted from fresh leaf midribs and petioles using the CTAB method (Angelini et al, 2001). Initial phytoplasma identification was based on a PCR assay using R16F2/R16R2 universal primers specific to the phytoplasma 16S rRNA gene (Lee et al, 1993). PCR products of expected size (~ 1^.2 kbp) were obtained from all symptomatic (2/2) but not from the asymptomatic plant samples (0/2). The two PCR amplicons were sequenced and data deposited in EMBL-EBI database (Accession No. FM955228). BLAST comparisons of the 16S rDNA sequence showed 100% identity with that of coneflower phyllody phytoplasma (EU333394) from the group 16SrI, ‘Candidatus Phytoplasma asteris’. A 16SrI phytoplasma has been previously reported affecting winter oilseed rape in CzechRepublic (Bertaccini et al., 1998). This is the first report of the association of an oilseed rape disease with a phytoplasma in Greece, and its identification as a ‘Ca. Phytoplasma asteris’-related strain.