Dynamics of specialized metabolism and physiological responses of grapevine (Vitis vinifera) infected with flavescence dorée phytoplasma

Fitoplazme (rod ‘Candidatus Phytoplasma’) su unutarstanične parazitske bakterije i patogeni širokog kruga biljaka. Fitoplazma flavescence dorée (FDp) uzročnik je velikih šteta u vinogradarskoj proizvodnji u Europi. U ovom istraživanju, sakupljeni su listovi simptomatskih i asimptomatskih listova vinove loze (Vitis vinifera L.) var. 'Pinot gris' u tri vremenske točke tijekom razvoja infekcije. FDp je detektirana korištenjem kvantitativnog PCR i genotipizirana sekvenciranjem i filogenetskom analizom map gena, što je pokazalo prisutnost dva genotipa, M38 i M54. Korištenjem spektrofotometrijskih i kromatografskih (RP-HPLC, GC-MS) metoda, analiziran je utjecaj dva FDp genotipa na fiziološke parametre i fenolni metabolizam vinove loze tijekom razvoja infekcije. Genotip M54 je slabije djelovao na fiziološke parametre, ali je održavao viši titar nego M38. Analiza korelacija pokazala je da promjene fizioloških parametara mogu biti povezane s titrom FDp. Sadržaj svih glavnih grana fenolnog metabolizma i individualnih spojeva je pokazao slične obrasce, ukazujući na pojačanje temeljnog fenolnog biosintetskog puta zbog infekcije FDp, posebno u trećoj vremenskoj točki. Analizirane promjene fiziologije vinove loze ovisne o genotipu FDp daju podatke o metama FDp u vinovoj lozi i mogu poduprijeti identifikaciju potencijalnih efektora ove fitoplazme.Phytoplasmas (genus ‘Candidatus Phytoplasma’) are intracellular parasitic bacteria and pathogens of numerous plants. Flavescence dorée phytoplasma (FDp) causes severe damage to viticultural production in Europe and is a quarantine pathogen in EU. In this study, symptomatic and asymptomatic grapevine (Vitis vinifera L.) var. ‘Pinot gris’ leaves were sampled at three time points through the development of infection. FDp was detected by using triplex real-time PCR and genotyped by sequencing and phylogenetic analysis of map gene which identified two genotypes, M38 and M54. By using spectrophotometric and chromatographic (RP-HPLC, GC-MS) analyses, impact of two FDp genotypes on grapevine physiological parameters and phenolic metabolism was evaluated through the development of infection. Genotype M54 impacted physiological parameters less severely, while maintaining higher titre than M38. Correlation analysis revealed that changes in physiological parameters could be linked to FDp titre. Content of all main branches of phenolic metabolism and most individual compounds had similar trends, pointing to the general induction of the stem phenolic biosynthetic pathway by FDp infection, particularly in the last time point. Analysed phytoplasma genotype-dependant changes to grapevine physiology provide data on certain targets of FDp in grapevine and could assist the identification of potential specific effectors of this phytoplasma