engleski

Comparison of molecular epidemiology and pathosystems of grapevine yellows phytoplasmas in vineyards of Croatia and Serbia

Phytoplasmas (‘Candidatus Phytoplasma) are uncultivable, wall-less bacteria classified as members of the class Mollicutes. They affect numerous plant species causing devastating yield losses in diverse crops worldwide. They have specific lifestyle as obligate symbionts of plants and insects, and need both hosts for dispersal in nature. In Europe, the most significant aetiological agents of grapevine yellows (GY) diseases are bois noir phytoplasma (BNp: ‘Ca. P. solani’ ; 16SrXII-A subgroup) and flavescence dorée phytoplasma (FDp: 16SrV group). Although symptoms are similar, epidemiology of those two phytoplasmas differs since they are transmitted by different insect-vectors. While FDp is transmitted exclusively by monophagous vector Scaphoideus titanus Ball., BNp is transmitted by several polyphagous vectors with Hyalesthes obsoletus Sign. being the main one. Moreover, FDp is classified as a quarantine pathogen in Europe and represents a great threat to viticulture. The aim of this study was to compare variability of GY phytoplasmas and their epidemiological characteristics of pathosystems in Croatian and Serbian vineyards. Study encompassed samples of grapevine, insect-vectors and reservoir plants as integrative component of pathosystems. The sampling was performed in late summer and autumn of 2019 – 2021 on locations in selected Croatian and Serbian viticulture regions. Total nucleic acids were extracted followed by detection and identification of phytoplasma by PCR/RFLP analyses of 16S rDNA and triplex real-time PCR. Multilocus sequence typing (MLST) was performed in order to analyze isolates in more detail by amplification, sequencing and phylogenetic analysis of stamp and vmp genes (BNp) and map and sec genes (FDp).The results have confirmed the presence of BNp and FDp in grapevine samples from both countries, as well as in insect vectors S. titanus and H. obsoletus and reservoir host plants such as Urtica dioica L. and Ailanthus altissima Mill. MLST analysis has revealed significant variability and presence of different genotypes among BNp and FDp strains from Croatia and Serbia, with Croatian strains being more variable. Stamp gene proved to be the most indicative molecular marker for differentiation among strains. Even though Croatia and Serbia are neighbouring countries with the similar viticultural practices, our results have shown that GY pathosystems differ regarding phytoplasma genotypes that were prevalent in sampled vineyards.

phytoplasma ; epidemiology ; bois noir ; flavescence dorée ; grapevine yellows

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