Evolutionary analysis of Citrus tristeza virus outbreaks in Calabria, Italy: two rapidly spreading and independent introductions of mild and severe isolates

The evolution of citrus tristeza virus (CTV) from outbreaks occurred in Calabria, Italy, was compared with that of CTV outbreaks reported previously in another two proximal Italian regions, Sicily and Apulia. Examination of four genomic regions (genes p20, p25 and p23, and one fragment of open reading frame 1) showed two recombination events, and phylogenetic analysis disclosed two divergent CTV groups in Calabria: one formed by severe and the other by mild isolates. This analysis, together with others involving population genetic parameters, revealed a low migration rate of CTV between the three Italian regions, as well as significant differences in selective pressures, epidemiology and demography, all affecting the genetic structure of CTV populations.This research was carried out in the frame of the national project "Armonizzazione della diagnosi e valutazione del rischio di patogeni da quarantena e nocivi ai vegetali e ai prodotti vegetali (ARNADIA-ARON)", supported by the Italian Ministry of Agriculture. A. Fontana has been the recipient of a postdoctoral fellowship from "Progetto cofinanziato POR Calabria FSE 2007/2013-Obiettivo Operativo M2", and D. E. Debreczeni the recipient of a FPU predoctoral fellowship from the Spanish Ministry of Education and Science.Fontana, A.; Debreczeni, DE.; Albanese, G.; Davino, S.; Flores Pedauye, R.; Rubio, L. (2014). Evolutionary analysis of Citrus tristeza virus outbreaks in Calabria, Italy: two rapidly spreading and independent introductions of mild and severe isolates. European Journal of Plant Pathology. 140(3):607-613. doi:10.1007/s10658-014-0489-3S607613140