Isolation and pathogenicity of Xylella fastidiosa associated to the olive quick decline syndrome in southern Italy

Abstract

In autumn 2013, the presence of Xylella fastidiosa, a xylem-limited Gram-negative bacterium, was detected in olive stands of an area of the Ionian coast of the Salento peninsula (Apulia, southern Italy), that were severely affected by a disease denoted olive quick decline syndrome (OQDS). Studies were carried out for determining the involvement of this bacterium in the genesis of OQDS and of the leaf scorching shown by a number of naturally infected plants other than olive. Isolation in axenic culture was attempted and assays were carried out for determining its pathogenicity to olive, oleander and myrtle-leaf milkwort. The bacterium was readily detected by quantitative polymerase chain reaction (qPCR) in all diseased olive trees sampled in different and geographically separated infection foci, and culturing of 51 isolates, each from a distinct OQDS focus, was accomplished. Needle-inoculation experiments under different environmental conditions proved that the Salentinian isolate De Donno belonging to the subspecies pauca is able to multiply and systemically invade artificially inoculated hosts, reproducing symptoms observed in the field. Bacterial colonization occurred in prick-inoculated olives of all tested cultivars. However, the severity of and timing of symptoms appearance differed with the cultivar, confirming their differential reaction.

Update of the Xylella spp. host plant database

“…The publication of Saponari et al. () that describes the isolation and pathogenicity of X. fastidiosa ‐associated with the olive quick decline syndrome in southern Italy was published in December 2017 and it is the most recent publication retrieved through the literature search.…”

PM 7/24 (4) Xylella fastidiosa

“…More recently a new olive disorder, consisting of olive plants showing leaf scorching and desiccated branches (including partial defoliation and shoot death) and associated with the presence of X. fastidiosa , has been reported in southern Italy (Saponari et al ., ; Giampetruzzi et al ., ), Argentina (Haelterman et al ., ) and Brazil (Coletta‐Filho et al ., ). The X. fastidiosa strains in all these cases have been assigned to the subspecies pauca (Saponari et al ., ).…”

PM 7/24 (3) Xylella fastidiosa

“…The X. fastidiosa strains in all these cases have been assigned to subsp. pauca (Saponari et al ., ).…”