New Disease Reports
New Disease Reports (2010) 21, 11. [http://dx.doi.org/10.5197/j.2044-0588.2010.021.011]
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First report of molecular identification of 'Candidatus Phytoplasma mali' in apple trees in Belgium

T. Olivier 1*, S. Steyer 1, E. Demonty 1 and P. Laurent 2

*t.olivier@cra.wallonie.be

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Received: 05 Jan 2010; Published: 26 Mar 2010

Apple proliferation (AP) is a quarantine organism for the European Union that has been assigned to the Candidatus taxon, 'Candidatus Phytoplasma mali' (Seemüller & Schneider, 2004). Although the first case of AP was recorded in Belgium in 1981 (Maroquin et al., 1981), no molecular identification of this agent has been officially reported since then.

In September 2009, two samples out of around twenty apple trees close to each other and showing witches' broom, the most typical symptom caused by 'Ca. Phytoplasma mali', were sampled by the Federal Agency for the Safety of the Food Chain in a nursery in south-west Belgium. DNA was extracted from 0.5 g of leaf midribs using a simplified extraction method derived from the existing protocol (Ahrens & Seemüller, 1992). Samples were then tested for phytoplasma by PCR using the universal primer pair fU5/rU3 (Lorenz et al., 1995), all yielding PCR products of expected size. BLAST analysis of a sequenced amplicon (GenBank AccessionNo. FN641799) revealed 100% of identity with nine 'Ca. Phytoplasma mali' isolates (16SrX group). Infected trees as well as adjacent trees have been uprooted and burned to prevent disease spread. To our knowledge this is the first report of 'Ca. Phytoplasma mali' in orchard apple trees in Belgium, confirmed by molecular tests.

References

  1. Ahrens U, Seemüller E, 1992. Detection of DNA of plant pathogenic mycoplasmalike organisms by a polymerase chain reaction that amplifies a sequence of the 16 S rRNA Gene. Phytopathology 82, 828-832. [http://dx.doi.org/10.1094/Phyto-82-828]
  2. Lorenz K-H, Schneider B, Ahrens U, Seemüller E, 1995. Detection of the apple proliferation and pear decline phytoplasmas by PCR amplification of ribosomal and nonribosomal DNA. Phytopathology 85, 771-776. [http://dx.doi.org/10.1094/Phyto-85-771]
  3. Maroquin C, Rassel A, Legrand G, 1981. First occurrence of apple-tree proliferation disease in Belgium. Parasitica 37, 71-78.
  4. Seemüller E, Schneider B, 2004. 'Candidatus Phytoplasma mali', 'Candidatus Phytoplasma pyri' and 'Candidatus Phytoplasma prunorum', the causal agents of apple proliferation, pear decline and European stone fruit yellows, respectively. International Journal of Systematic and Evolutionary Microbiology 54, 1217-1226. [http://dx.doi.org/10.1099/ijs.0.02823-0]
To cite this report: Olivier T, Steyer S, Demonty E, Laurent P, 2010. First report of molecular identification of 'Candidatus Phytoplasma mali' in apple trees in Belgium. New Disease Reports 21, 11. [http://dx.doi.org/10.5197/j.2044-0588.2010.021.011]

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