Xylella fastidiosa subsp. pauca ST53 exploits pit membranes of susceptible olive cultivars to spread systemically in the xylem. (27th September 2022)

• Record Type: Journal Article
• Authors: Montilon, Vito; De Stradis, Angelo; Saponari, Maria; Abou Kubaa, Raied; Giampetruzzi, Annalisa; D'Attoma, Giusy; Saldarelli, Pasquale
• Is Part Of: Plant pathology. Volume 72:Number 1(2023)
• Page Start: 144
• Page End: 153
• Publication Date: 2022-09-27
• Subjects: microscopy -- olive -- pit membranes -- Xylella; Agricultural pests -- Periodicals; Plant diseases -- Periodicals; 632
• DOI: 10.1111/ppa.13646
• Languages: English
• ISSNs: 0032-0862

Abstract

Abstract: Xylella fastidiosa subspecies pauca strain De Donno (XfDD) ST53 is the causal agent of olive quick decline syndrome, a severe disease first described in Apulia, Italy. Although the two local cultivars Cellina di Nardò and Ogliarola Salentina showed high susceptibility, traits of resistance to the bacterium were found in the cultivar Leccino. Previous studies in field‐grown olives suggested that vascular occlusions and anatomophysiological properties of the different cultivars played a role in the olive response to XfDD. The present investigation reports observations at the early stage of the infection on artificially inoculated olives. Electron microscope studies showed that XfDD exploits the pit membranes (PMs) of the susceptible cultivar Cellina di Nardò to spread systemically. In this cultivar, PMs were degraded upon XfDD infection, suggesting activity of bacterial cell wall‐degrading enzymes. Moreover, occluded vessels contained an amorphous electrondense matrix resembling gum. Conversely, in Leccino, occluded vessels were mainly filled by callose‐like granules that tightly entrapped XfDD cells. In addition, PMs from Leccino had a compact undegraded structure that was not permeable to XfDD. Our study suggests that exploitation of PMs is a key event in the infection process of X. fastidiosa subsp. pauca ST53 in susceptible olive cultivars. Abstract : Xylella fastidiosa subsp. pauca ST53 spreads in the xylem of the susceptible olive cultivar Cellina di Nardò by exploiting the pit membranes, while it is entrapped in an electrondense matrix in the resistant cultivar Leccino.