Xylella fastidiosa and olive quick decline syndrome (CoDiRO) in Salento (southern Italy): a chemometric 1H NMR-based preliminary study on Ogliarola salentina and Cellina di Nardò cultivars

Abstract

Background: Xylella fastidiosa is a Gram-negative bacterium which lives in the xylem of plants, causing its occlusion and other alterations inducing eventually the death of the infected plants. In Salento, the sub-peninsula in the south-eastern of Apulia Region (southern Italy), the infection of X. fastidiosa has been associated with the widespread presence of CoDiRO (complex of parasitic agents that constitute the so-called "olive quick decline syndrome") and currently represents a serious local emergence. The need to adopt specific agronomic measures to contrast the further disease spread has been recently raised. The extensive NMR-based metabolomic approach to study the metabolic effects of CoDiRO on local olive cultivars such as Ogliarola salentina and Cellina di Nardò was used. Results:In this study, the effects of a CE approved fertilizer containing zinc, copper, and citric acid, known as DENTAMET ® , on CoDiRO-exhibiting olive trees infected by X. fastidiosa were studied by 1 H NMR spectroscopy. The changes in the metabolomic profiles of aqueous extracts obtained from leaves of the two olive cultivars are reported. Upon the DENTAMET ® treatments, different and opposite polyphenolic and sugars patterns in the two cultivars, which showed a different incidence and severity of disease before the treatments, were detected. Conclusions:Differences in the sugars and polyphenols content of treated versus untreated trees could potentially contribute to the syndrome monitoring and might be related to the X. fastidiosa presence.

1H-NMR Metabolite Fingerprinting Analysis Reveals a Disease Biomarker and a Field Treatment Response in Xylella fastidiosa subsp. pauca-Infected Olive Trees

“…The higher predictive parameter value for treated samples revealed a stronger cultivar separation for treated with respect to untreated samples, demonstrating the treatment related metabolic response to X. fastidiosa infection. This result is in accord with our previous work [19], in which metabolic uniformity of aqueous extracts profile from X. fastidiosa infected Ogliarola salentina and Cellina di Nardò samples was observed. Once again the new findings demonstrate that effect of X. fastidiosa infection could be predominant over the cultivar metabolic profiles difference.…”

“…The two olive cultivars tested showed a similar response to the infection but a distinct response to the treatment. Both Ogliarola salentina and Cellina di Nardò untreated infected trees, irrespective of the site of sampling, showed a relative higher content of phenolic compounds and aldehydic forms of oleuropein and ligstroside when compared to the Dentamet®-treated samples in both samplings of July and September, thus confirming previous investigations [19]. As known, production and accumulation of aromatic secondary metabolites by various stresses is common in higher plants [31,32,33,34].…”

“…It is sprayed into the olive trees’ crowns once per month from March-April to September-October, at a dose of 3.9 L/ha, and can also be used in organic agriculture. In parallel, through 1 H NMR and multivariate statistical analysis, we also preliminarily assessed the metabolomic profiles of extracts obtained from the leaves of the two cultivars, and we found an opposite trend concerning the sugars and polyphenols content [19]. In this study, an 1 H NMR-based metabolomic approach was used to provide a snapshot of the X. fastidiosa -infected Ogliarola salentina and Cellina di Nardò in comparison with trees which have received some treatment with the zinc-copper-citric acid biocomplex.…”

Soil and Leaf Ionome Heterogeneity in Xylella fastidiosa Subsp. Pauca-Infected, Non-Infected and Treated Olive Groves in Apulia, Italy

“…Within this context, we observed that the supply of a zinc-copper-citric acid biocomplex to the canopy of X. fastidiosa subsp. pauca-infected olive trees during spring and summer allowed to reduce both the field symptoms (i.e., leaf and twig die-backs) and pathogen cell densities within the leaves [25] as well as a rapid re-programming of the basic metabolism of the infected tree [26,27].…”

Using Sentinel-2 Imagery to Track Changes Produced by Xylella Fastidiosa in Olive Trees

“…Detecting and monitoring spatial changes and disease outbreaks is critical to design effective surveillance strategies [5]. In addition, it is critical to accurately discriminate different stages of the development of the disease in order to map its spread [6], [7] and to monitor the damage over large areas. Spatial and temporal data provided by satellite images open new possibilities for developing monitoring methods.…”