New Disease Reports (2009) 19, 61.

First report of a phytoplasma associated with Periploca aphylla witches' broom in Iran

M.M. Faghihi 1*, M. Siampour 2, M. Zaeifi 1, A.N. Bagheri 1, M. Salehi 3 and S. Samavi 1

*mm.faghihi@yahoo.com

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Accepted: 30 Jul 2009

Periploca aphylla (Asclepiadaceae), is a large erect branched shrub, grown on different altitudes, in desert or in dry, insolated grounds, on rocky and sandy slopes throughout Southwest Asia. P. aphylla is commonly used for feeding camels and goats. Its latex is applied as a poultice in tumours and swellings, while the decoction of the bark is used as a purgative or against fever (Kazimierz, 1966). In September 2008, symptoms of witches' broom, proliferation and shoot dieback were observed on P. aphylla in Hormozgan province, Iran. The affected plants developed dense clusters of highly proliferating branches with shortened internodes (Fig. 1). Total DNA was extracted separately from 0.5g of shoots of ten symptom-bearing and five symptomless plants using a modified cetyltrimethylammonium bromide (CTAB) method (Doyle & Doyle, 1990). The samples were analysed for phytoplasma DNA by both direct and nested PCR assays using phytoplasma universal 16S rDNA gene primer pairs P1/P7 and R16F2n/R16R2 that amplify fragments of 1800 bp and 1250 bp, respectively. A 1250 bp PCR product was amplified with nested PCR from all symptom-bearing, but not from symptomless, plants. Two amplicons were cloned using cloning commercial kit #K1214 (Fermentas, Lithuania), and sequenced. The partial 16S rDNA sequence (GenBank Accession No. GQ249159) of the phytoplasma associated with P. aphylla witches' broom was most closely related (98% sequence identity) to salt cedar witches' broom phytoplasma, ‘Candidatus Phytoplasma tamaricis’ (FJ432664) (Zhao et al., 2009). Moreover, P. aphylla witches' broom phytoplasma showed a 96% sequence identity with strains ofgroup 16SrX, apple proliferation, including a ‘Ca. Phytoplasma pyri’-related strain from subgroup 16SrX-C, previously associated with pear decline in Iran (Salehi et al., 2008), which has been reported in almost all pear growing areas of Fars, Isfahan, Tehran and Khorasan provinces. It is the first report of a phytoplasma associated with P. aphylla witches' broom, this being a real concern regarding its potential as a host for a 16SrX phytoplasma isolate.

Figure1+
Figure 1: Symptoms of dense clusters of highly proliferating branches with shortened internodes of P. aphylla plants affected with witches’ broom disease in Hormozgan, Iran
Figure 1: Symptoms of dense clusters of highly proliferating branches with shortened internodes of P. aphylla plants affected with witches’ broom disease in Hormozgan, Iran

References

  1. Doyle JJ, Doyle JL, 1990. Isolation of plant DNA from fresh tissue. Focus 12, 3-15.
  2. Kazimierz B, 1966. The genus Periploca L. A Monograph. Arboretum Kornichie 11, 5-104.
  3. Salehi M, Izadpanah K, Taghavi SM, Rahimian H, 2008. Characterization of a Phytoplasma Associated with Pear Decline in Iran. Journal of Phytopathology 156, 493–495.
  4. Zhao Y, Sun Q, Wei W, Davis RE, Wu W, Liu Q, 2009. 'Candidatus Phytoplasma tamaricis', a novel taxon discovered in witches'-broom diseased salt cedar (Tamarix chinensis Lour.). International Journal of Systematic and Evolutionary Microbiology (in press).

This report was formally published in Plant Pathology

©2009 The Authors