Naslov
A detective story: tracking of FD and FD-related phytoplasmas emergence and spread by MLST

Autori
Plavec, Jelena ; Križanac, Ivana ; Budinšćak, Željko ; Škorić, Dijana ; Šeruga Musić, Martina

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Abstracts of the 21st Congress of the International Organization for Mycoplasmology / Browning, Glenn - Brisbane : IOM, 2016, 62-62

Skup
21st Congress of the International Organization for Mycoplasmology

Mjesto i datum
Brisbane, Australija, 03.07.2016. - 07.07.2016

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
‘Candidatus Phytoplasma’; genotyping; epidemiology; insect vector; map gene

Sažetak
Detection, diagnosis and classification of the genus ‘Candidatus Phytoplasma’ members are still based mainly on the 16S rRNA gene analysis. Nevertheless, for the elucidation of a complex pathosystem or a distinction between closely related strains, information obtained solely on the basis of highly conserved 16S rDNA is not sufficient. Hence, the genotyping of additional less-conserved housekeeping genes together with specific variable genes permitting finer differentiation is applied. Multi-locus sequence typing (MLST) is widely used in population, evolutionary and epidemiological studies of bacterial pathogens and is recognized as a reproducible system. Yet unassigned to a species taxon within the ‘Candidatus Phytoplasma’ genus, Flavescence dorée (FD) phytoplasma encompassing ribosomal subgroups 16SrV-C and –D is one of the principal agents associated with grapevine yellows (GY) diseases in Euro-Mediterranean region. It is persistently transmitted by vector Scaphoideus titanus Ball., American grapevine leafhopper, and is considered to possess a high epidemic potential. In Croatia, the first report of FD phytoplasma infecting grapevine was given in 2009 for restricted continental areas of the country. The main objective of this study was to demonstrate tracking and tracing of FD and FD-related phytoplasmas emergence and spread by MLST approach. In the period 2012-2016, over 500 samples of grapevine, S. titanus and wild plants were taken from different viticultural regions of Croatia. Total nucleic acids were extracted and triplex real-time PCR assay amplifying map gene was performed. PCR/RFLP analyses of 16S rDNA were also performed for insect samples. Subsequently, secY, map and uvrB-degV genes were amplified and sequenced from FD positive samples and analysed phylogenetically. Real-time PCR detection revealed the continuous emergence of new locations and areas affected by FD over the years and a clear trend of the disease spread with Istrian peninsula as a new hotspot heavily affected since 2014. FD-related phytoplasmas have also been detected for the first time in in alder and invasive tree species Ailanthus altissima Mill. MLST showed the clustering of ailanthus isolate with the map-FD3, while the alder yellows (AldY) grouped with the map-FD1 cluster. Phylogenetic analyses of map gene revealed the existence of 2 clearly distinct FD clusters in grapevines and insects: map-FD2 and map-FD3, with the latter being prevalent. Different genotypes within both FD clusters could be distinguished based on additional SNPs in uvrB-degV and secY, as well as in map gene. Furthermore, MLST revealed a strong relatedness between strains detected in grapevines and insects from the same location, showing their affiliation to the same pathosystem. The finding of the presence of distinct FD clusters based on MLST suggests separate routes of the disease introduction in Croatia, a different distribution of genotypes and spread of the disease.

Izvorni jezik
Engleski

Znanstvena područja
Biologija, Poljoprivreda (agronomija)

POVEZANOST RADA