“Candidatus Phytoplasma trifolii” related strain affecting Salix babylonica in Iran
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Over the last few years, in the northwest of Iran, symptoms of witches’ broom have been observed in Babylon willow trees (Salix babylonica). Samples from symptomatic and symptomless trees were tested using nested PCR with universal primer pair P1/P7 followed by R16F2n/R2. Phylogenetic and virtual RFLP analysis showed that the phytoplasma associated with willow proliferation is related to the16SrVI-A subgroup.
KeywordsClover proliferation Phytoplasma P1/P7 R16F2n/R2 Salix babylonica
Nested-PCR for amplification of the 16S rDNA was conducted using phytoplasma universal primer sets R16F2n/R16R2 (Gundersen and Lee 1996) in the second round. The expected amplicon of 1.2 kb was amplified in all 12 samples from symptomatic trees. Partial sequencing of the 16SrRNA region of four strains from different sampling areas was conducted with universal primer pair R16F2n/R2. The nucleotide sequences were assembled using Bioedit sequence alignment editor, version 220.127.116.11 and compared with available sequences in GenBank using blast alignment. Phylogenetic and molecular analyses were conducted by the neighbor-joining method in MEGA6 software (Tamura et al. 2013).
Several phytoplasmas were previously reported from Salix trees including ‘Ca. Phytoplasma asteris’ (16SrI-C) and ‘Ca. P. trifolii’ (16SrVI-A) in China (Wei et al. 2009; Zhang et al. 2012), clover proliferation (16SrVI) and stolbur group in Spain (Alfaro-Fernández et al. 2011; Khadhair and Hiruki 1995), ‘Ca. P. phoenicium’ (16SrIX) and Ca. P. solani’ (16SrXII) in Iran (Ghayeb Zamhari 2017; Ghayeb Zamharir and Taheri 2017). Clover proliferation phytoplasma group (16SrVI) causes diseases in numerous plant species in different geographic areas worldwide (Raj et al. 2009; Choueiri et al. 2007; Salehi et al. 2008). However, to the authors’ knowledge, there is no previous report of the 16SrVI phytoplasma group associated with Babylon willow witches’ broom from Iran.
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