A natural infection of Hebe is associated with an isolate of Candidatus Phytoplasma asteris causing a yellowing and little leaf disease in the UK

Hebe (Veronica scutellata) is a herbaceous perennial widely grown throughout the UK and elsewhere. In 2005 symptoms of yellowing and little leaf were observed on a bush, that was more than 20 years old, growing on the Rothamsted estate in Hertfordshire. The symptoms, which were prevalent on shoots produced by branches which had rooted from the main bush, had shortened internodes, little leaves and yellowing of the foliage (Fig. 1).

Samples of apparently healthy shoots and those affected by the little leaf symptoms were collected and the DNA extracted. This was used as a template for nested PCR analysis using primers P1/P7 and R16F2/R16R2 (Arocha et al., 2005). Bands of expected size (1.25kb) were produced in all samples with little leaf disease but none of the healthy ones. These amplicons were sequenced by The Sequencing Service, School of Life Sciences, University of Dundee, Scotland (www.dnaseq.co.uk), using Applied Biosystems Big-Dye Ver 3.1 chemistry on an Applied Biosystems model 3730 automated capillary DNA sequencer. The sequences were aligned, subject to BLAST analysis and deposited in GenBank (Accession number DQ387053). The highest similarity (99.7%) was with the barley deformation phytoplasma (AY734453) from Lithuania; an isolate of Candidatus Phytoplasma asteris (aster yellows) (IRPCM Phytoplasma/Spiroplasma Working Team - Phytoplasma taxonomy group, 2004). We believe this is both the first record of a phytoplasma infecting hebe and the first definitive record of Candidatus Phytoplasma asteris in the UK.