EPPO-Q-bank

A database to support plant pest diagnostic activities

Curator Phytoplasmas database

Dr. Mogens Nicolaisen
Phytosanitary and taxonomic expertise
University of Aarhus (UA)
Denmark

Curator Phytoplasmas database

Prof. Dr. Assunta Bertaccini
Taxonomic expertise and collections
University of Bologna (UB)
Italy

Curator Phytoplasmas database

Dr. Nicoletta Contaldo
Taxonomic expertise and collections
University of Bologna (UB)
Italy

EPPO-Q-bank Phytoplasmas database (in construction)

The EPPO-Q-bank Phytoplasma database contains DNA sequences (Barcodes) of more than 100 strains that are of relevance to phytoplasma phytopathology (International Phytoplasmologist Working Group). The official micropropagated collection of phytoplasma strains is maintained mainly in periwinkle at the University of Bologna (Phytoplasma Collection). The distribution as well as relevant EPPO-protocols for the phytoplasmas can be downloaded from the EPPO Global Database https://gd.eppo.int/

Phytoplasma DNA in the Q-bank collection can be ordered from Dr. Assunta Bertaccini (assunta.bertaccini@unibo.it)

Phytoplasmas are bacteria lacking cell wall that are located in the phloem of plants and in the hemolymph of insect vectors. They are infecting a high number of plant species and are associated with devastating diseases worldwide. The phytoplasma classification scheme is based on PCR/RFLP analyses of 16S rDNA: a reliable tool for the differentiation that has become the most comprehensive and widely accepted classification system. On the other hand, the 'Candidatus Phytoplasma' species description, recently under adoption, refers to 16S rRNA gene sequence with a threshold <97.5% similarity to that of any previously described 'Ca. Phytoplasma' species. However because of the highly conserved nature of the 16S rDNA some additional tools for phylogenetic analyses and finer strain differentiation of phytoplasmas such as rp, secY, tuf, groEL genes, and the 16S-23S rRNA intergenic spacer region sequences are now used as supplementary tools. Multilocus analyses is providing useful and reliable information in combination with 16SrDNA for phytoplasma strains differentiation.

Myrtle plant showing yellows and stunting associated with phytoplasma presenceGrapevine yellows symptomson a red grapevine variety 

The basic phytoplasma identification methods is based on RFLP analysis of a 1.2 kbp region of the 16S rDNA. As part of QBOL project a universal DNA barcoding based tool for phytoplasma identification was developed. Two sets of primers amplifying a fragment of the Tuf gene and a fragment of the 16S rDNA gene, respectively, were designed and the potential of these fragments as DNA barcodes was verified. Successful amplification and sequencing of phytoplasma strains, and ability to separate various phytoplasma strains to 'Candidatus species' level, 16S ribosomal group and sub-group level show that these barcode you will find here are efficient phytoplasma identification tools.

Poinsettia plants healthy (left) 
and phytoplasma infected (right)
Tomato plant infected by stolbur phytoplasmas: symptoms are present on the top part of the plant