The role of evolutionary interactions between intracellular endosymbiont (Wolbachia) and phytoplasma (Flavescence dorée) on fitness components and evolution of mitochondrial DNA in natural populations Dictyophara europaea

[O. M. Krstić]

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Biologija - Evoluciona biologija / Biology - Evolutionary biology

Dictyophara europaea je široko rasprostranjena i ekonomski značajna cikada koja kao alternativni vektor Flavescence dorée (FD) fitoplazme, učestvuje u prenošenju bolesti u vinogradima Evrope. Sprovedena epidemiološka istraživanja su ukazala na postojanje populacija D. europaea sa veoma visokom stopom FD-infekcije, Wolbachia-inficiranih populacija sa niskom stopom FD-infekcije (DeWo+) i odsustvo Wolbachia u populacijama sa visokom stopom FD-infekcije (DeWo-). Ispitivano je nekoliko mogućih uzroka raličite stope infekcije vektora: i) populaciono-genetičke karakteristike D. europaea i korelacija sa Wolbachia infekcijom, ii) efekat Wolbachia na komponente adaptivne vrednosti laboratorijske kolonije DeWo+, i iii) stopa inficiranosti prirodnog biljnog rezervoara FD fitoplazme i razlike u genotipovima fitoplazme u nisko- i visokoinficiranim populacijama. Genotipizacijom mitohondrijskog COI gena evidentiran je smanjen genetički diverzitet DeWo+ u poređenju sa DeWo- populacijama i različita evolucija fiksiranih haplotipova. Multilokusnom genotipizacijom Wolbachia izolata identifikovan je isti soj, wEur, u svim DeWo+ populacijama. Diverzitet FD fitoplazme nije bio u korelaciji sa različitom stopom inficiranosti vektora. Utvrđeno je da Wolbachia-infekcija nema direktnog efekta na adaptivnu vrednost D. europaea. Podaci iz prirodnih populacija D. europaea ukazuju na kompeticiju Wolbachia i FD fitoplazme: populacije koje su u niskoj stopi inficirane FD fitoplazmom su Wolbachia-inficirane i vice versa.

Dictyophara europaea is widespread planthopper of economic importance, acting as an alternative vector of the Flavescence dorée (FD) phytoplasma disease of grapevine in European vineyards. Epidemiological studies have revealed D. europaea populations that are heavily FD-infected, as well as populations with low FD-infection rates that are naturally infected with Wolbachia (DeWo+), and highly FD-infected populations in the absence of Wolbachia (DeWo-).Several possible causes of differences in vector infection rates were examined: i) population genetic characteristics of D. europaea and their correlation with Wolbachia infection, ii) Wolbachia effects on fitness components of DeWo+ laboratory colony, and iii) the rate of reservoir plant FD-infection and differences in FD genotypes harboured by low and high infected vector populations. Genotyping of mitochondrial COI loci showed lower genetic diversity level in DeWo+ than in DeWo- populations of and divergent evolution of fixed haplotypes. Multilocus genotyping of Wolbachia revealed that all DeWo+ populations were infected with the same strain (i.e. wEur). Genetically diversified FD phytoplasma had no direct influence on vector infection rates. No evidence of direct fitness effects on D. europaea was registered with regard to Wolbachia infection status. Field data and the observed negative correlation between FD-infection and Wolbachia-infection rates, indicate that Wolbachia compete with FD phytoplasma within the host insect D. europaea.

epidemiologija, ekologija, FD fitoplazma, Wolbachia, koevolutivne interakcije, komponente adaptivne vrednosti, molekularna evolucija, mitohondrijska DNK, Clematis vitalba, Dictyophara europaea

epidemiology, ecology, FD phytoplasma, Wolbachia, coevolutionary interactions, components of adaptive value, molecular evolution, mitochondrial DNA, Clematis vitalba, Dictyophara europaea

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