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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Molecular Plant Pathology Laboratory » Research » Publications at this Location » Publication #312114
Title: The lilac cultivar Syringa ‘Charisma’ is a new host for ‘Candidatus Phytoplasma pruni’, the group 16SrIII, subgroup A, phytoplasma

Author
item GREEN, MARGARET - Canadian Food Inspection Agency
item Dally, Ellen
item Davis, Robert

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/27/2015
Publication Date: 6/1/2015
Citation: Green, M.J., Dally, E.L., Davis, R.E. 2015. The lilac cultivar Syringa ‘Charisma’ is a new host for ‘Candidatus Phytoplasma pruni’, the group 16SrIII, subgroup A, phytoplasma. Plant Disease. 99:886. doi.org/10.1094/PDIS-12-14-1246-PDN.

Interpretive Summary: Phytoplasmas are minute, specialized bacteria causing plant diseases that result in economic losses worldwide. They are spread by insects that feed in the food conducting tissues in veins, where phytoplasmas live and induce disease symptoms including development of witches’-broom growths. Phytoplasmas can be introduced into new geographic regions by the transportation and cultivation of vegetatively propagated, infected plant parts that serve as a source of phytoplasma for spread to crops in the new region. To reduce the spread of phytoplasmas, it is important to know whether or not a given plant is or can be infected by a phytoplasma. In this work, we investigated the lilac cultivar ‘Charisma’, which was originally derived by the propagation of a witches’ broom cutting taken from the Preston Lilac ‘Royalty’; the growth characteristics of the lilac ‘Charisma’ suggested possible infection by a phytoplasma. Molecular genetic assays of the 16S rRNA gene, and the gene encoding the SecY secretory protein, were carried out to detect possible infection by a phytoplasma. The results revealed that the ‘Charisma’ lilac was infected by a strain of ‘Candidatus Phytoplasma pruni’, the cause of Prunus X-disease. The characteristic growth form of ‘Charisma’ lilac thus may be attributable, at least in part, to phytoplasmal infection. Further work will be needed to determine whether this lilac cultivar is a dead-end host for ‘Ca. Phytoplasma pruni’ or can act as a reservoir host for spread of the phytoplasma to lilac or other woody hosts, particularly stone fruit hosts.

Technical Abstract: The lilac cultivar ‘Charisma’ (Syringa x prestoniae ‘Charisma’) was derived by the propagation of a witches’ broom cutting taken from the Preston Lilac ‘Royalty’ (Syringa x prestoniae ‘Royalty). Because lilac witches’ broom disease has previously been shown to be associated with infection by ‘Candidatus Phytoplasma fraxini’, a phytoplasma classified in ribosomal group 16SrVII, we hypothesized that the growth characteristics of the lilac ‘Charisma’ were due to infection by phytoplasma. DNA was extracted from leaf midveins and petioles sampled from the dense foliage regions of a ‘Charisma’ potted plant been maintained on-site in a screened house since 2003 and used as template in polymerase chain reactions (PCRs) designed to amplify phytoplasmal 16S rRNA and secY gene sequences. RFLP analyses and nucleotide sequencing of PCR products revealed that the lilac is infected by a strain of ‘Candidatus Phytoplasma pruni’, member of group 16SrIII, subgroup A. The 16S rRNA and secY gene sequences determined for the phytoplasma infecting lilac accession, 3184-2B,1 were deposited in the GenBank database under accession numbers KM580064 and KM580065, respectively. The findings raise the question of whether lilac cultivar ‘Charisma’ is a dead-end host for ‘Ca. Phytoplasma pruni’ or can act as a reservoir host for spread of the phytoplasma to other plants.