NEW HOSTS OF XYLELLA FASTIDIOSA STRAIN CoDiRO IN APULIA

Abstract

In the course of surveys carried out in June 2014 in the Salento (Apulia, southern Italy) area affected by an epidemic of a strain of Xylella fastidiosa subsp. pauca (Cariddi et al., 2014) denoted CoDiRO (abbreviation from the Italian name “Complesso del Disseccamento Rapido dell’Olivo”), the following symptomatic plants were observed: (i) cherry (Prunus avium), 13 trees showing scanty vegetation and bud failure, but no leaf scorching; (ii) myrtle-leaf milkwort (Polygala myrtifolia), three shrubs showing extensive desiccation of twigs and scorched leaves; (iii) coastal rosemary (Westringia fruticosa), one shrub with extensive chlorosis and desiccation of the leaves. Samples collected from all these hosts (except for two of the 13 cherry plants) were ELISA- and PCR-positive upon testing with the protocols described by Loconsole et al. (2014). Sequencing of the amplified products from five housekeeping genes (gyrB, 16S rRNA, dnaK, tonB, RNA polymerase sigma factor) and of the PCR products obtained using the X. fastidiosa strain- specific primers 272-1int/272-2int, showed that all these amplicons, regardless of the host of origin, had 100% sequence identity with the homologous products amplified from diseased olive trees (Cariddi et al., 2014). These results provide evidence that all the analyzed positive samples contain the same X. fastidiosa strain infecting olives in the same area. With the exception of cherry, for which there is a recorded infection by X. fastidiosa subsp. fastidiosa in California (Hernandez- Martinez et al., 2007), to the best of our knowledge P. myrtifolia and W. fruticosa are hitherto unreported hosts of this bacterium.