New Disease Reports
New Disease Reports (2009) 19, 66.
Next > < Prev

‘Candidatus Phytoplasma asteris’ identified in blackberry (Rubus fruticosus agg.) in the United Kingdom

R. Reeder 1*, P.L. Kelly 1 and Y. Arocha 1,2

*r.reeder@cabi.org

Show affiliations

Accepted: 31 Jul 2009

Blackberries (Rubus fruticosus agg.) also known as brambles are a widespread and well-known aggregate species of several hundred micro-species native throughout the temperate Northern hemisphere. Tolerating poor soils, they are early colonisers of wasteland and building sites and grow vigorously in woods, scrubland, hedgerows and roadside verges. Plants produce many soft fruits notable for their high nutritional content, making them a popular ingredient in desserts, jams and wines. Numerous cultivars have been selected for commercial cultivation. In July 2008, a small patch of R. fruticosus growing by the roadside in Egham, UK, was observed showing unusual witches’ broom symptoms (Fig. 1). Proliferations of shoots were seen at the branch nodes, midway along the stem. Symptoms on new growth presented as shortened, narrowed almost leafless branches with reduced, flower production or none at all (Fig 2.). No other plants in the near vicinity appeared affected.

Total DNA was extracted from plants with symptoms and from healthy looking blackberry plants and used as a template in a nested PCR assay with universal primers P1m (Hren et al., 2007) /P7(Gundersen & Lee, 1996) and fU5/rU3 (Lorenz et al., 1995). Amplicons of expected size (~880bp) were obtained from plants with symptoms. Nested amplicons of a representative plant were purified, cloned (pGEM-T Easy Vector, Promega, Madison, WI, USA) and sequenced in both directions using M13 sequencing primers (www.dnaseq.co.uk). The phytoplasma 16Sr rDNA sequence (GenBank Accession No. FJ008925) was compared with those held in GenBank using BLAST. The greatest similarity (99%) was with phytoplasmas of group 16SrI, ‘Candidatus Phytoplasma asteris’, including those associated with gaillardia yellows (EF583066), poa stunt (DQ640502), and festuca yellows (DQ640504). The occurrence of two phytoplasmas belonging to groups 16SrV (‘Ca. P. ulmi’) and 16SrIII (X-disease) have previously been reported in Rubus species in the UK (Davies, 2000).  As far as we know, this is the first record of a phytoplasma from 16SrI group recorded from Rubus in the UK. It is not known which insect vectors are associated with transmission.

Figure1+
Figure 1: Symptoms of witches’ broom in Rubus fruticosus agg.
Figure 1: Symptoms of witches’ broom in Rubus fruticosus agg.
Figure2+
Figure 2: Symptoms of little leaf observed on young branch of Rubus fruticosus agg. with unaffected branch on right
Figure 2: Symptoms of little leaf observed on young branch of Rubus fruticosus agg. with unaffected branch on right

References

  1. Davies DL, 2000. The occurrence of two phytoplasmas associated with stunted Rubus species in the UK. Plant Pathology 49, 86-88.
  2. GundersenDE, Lee IM, 1996. Ultrasensitive detection of phytoplasmas by nested-PCR assays using two universal primer pairs. Phytopathologia Mediterranea 35, 144-151.
  3. Hren M, Boben J, Rotter A, Kralj P, Gruden K, Ravnikar M, 2007. Real-time PCR detection systems for Flavescence dorée and Bois noir phytoplasmas in grapevine: comparison with conventional PCR detection and application in diagnostics. Plant Pathology 56, 785-796.
  4. Lorenz K-H, Schneider B, Ahrens U, Seemüller E, 1995. Detection of the Apple Proliferation and Pear Decline Phytoplasmaby PCR amplification of Ribosomal and Non-Ribosomal DNA. Phytopathology 85, 771-776.
This report was formally published in Plant Pathology

©2009 The Authors