Original scientific paper

Distribution of phytoplasma diseases in the Lombardy poplar tree population of Zagreb urban area

Martina Šeruga Musić ; University of Zagreb, Faculty of Science, Division of Biology, Maruli}ev trg 9A, HR-10000 Zagreb, Croatia
Mislav Novokmet ; Pliva Croatia Ltd., Research and Development, Prilaz baruna Filipovica 25, HR-10000 Zagreb
Ruđer Novak ; University of Zagreb, Faculty of Pharmacy and Biochemistry, Department of Biochemistry and Molecular Biology, A. Kova~i}a 1, HR-10000 Zagreb, Croatia

Abstract

Phytoplasmas are uncultivable prokaryotic wall-less pathogens belonging to the class Mollicutes that inhabit plant phloem and insects. Their identification and classification is difficult and mainly based on the polymorphism of their 16S rRNAgene sequences. Aster
yellows (AY; 'Candidatus Phytoplasma asteris') phytoplasmas (ribosomal subgroup 16SrI-P) had been previously identified in several Populus nigra L. 'Italica' (Lombardy poplar) trees from the urban area of Zagreb. The aim of this research was to examine phytoplasmosis distribution in the poplar tree population of the wider Zagreb urban area. Total nucleic acids were extracted from leaf samples of 30 symptomatic and 4 asymptomatic trees. Phytoplasma 16S rDNAwas amplified in direct and nested PCRs by using universal
and group-specific primers. The pathogens were classified on the basis of 16S rDNA amplicon RFLP analyses. Phytoplasmas belonging to the 16SrI ribosomal group (AY) were detected in 12 out of 34 trees examined. In addition, a phytoplasma putative gene for aa kinase was analyzed for positive samples. RFLP profiles from 10 samples were referable to the phytoplasma 16SrI-P ribosomal subgroup previously found only in poplars from Zagreb area. In two samples, unique restriction patterns were found, showing the presence of molecular variability within this conserved gene region. In the northern and north-western part of the area the infection was equally distributed, while in the southern part of the city phytoplasmas were not detected in sampled trees. Further research, including a search for potential insect vectors, is needed in order to indentify the ecological and epidemiological implications of these diseases and their impact on the sanitary status of ornamental trees in the city of Zagreb.

Keywords

16S rDNA; aster yellows; Candidatus; Phytoplasma asteris; phytoplasmosis; poplar tree

Hrčak ID:

28589

URI

https://hrcak.srce.hr/28589

Publication date:

20.10.2008.

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