Occurrence of copper‐resistant <i>Pseudomonas syringae</i> pv. <i>actinidiae</i> strains in kiwifruit orchards of Central Italy

Cesari, Erica; Marocchi, Fabio; L'Aurora, Alessia; Pucci, Nicoletta; Scala, Valeria; Loreti, Stefania; Scortichini, Marco

doi:10.1111/jph.13219

Cited by 4 publications

(3 citation statements)

References 38 publications

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“…However, P. actinidiae exhibited distinctions, as kiwifruit plants displayed symptoms during summer under high-temperature and high-humidity conditions, without the formation of leaf spots typically associated with P. syringae pv. actinidiae (Cesari et al, 2023;Visnovsky et al, 2017).…”

Section: P Carotovorum Was Identified In Dieffenbachia Plants In the ...mentioning

confidence: 99%

Isolation, identification, and characterization of Pectobacterium actinidiae isolated from infected sugar beet leaves

Öztürk

2024

Journal of Phytopathology

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During the sugar beet growing seasons of 2019 and 2020, symptomatic leaf samples displaying necrotic spots were collected for the isolation of pectinolytic bacteria. Seven bacterial isolates were obtained from these infected leaves on crystal violet pectate (CVP) medium. Two of these isolates exhibited the ability to macerate potato tuber slices and induced disease symptoms on petioles of sugar beet plants. Initially, their identity was determined to be Pectobacterium spp. through a polymerase chain reaction (PCR) that produced a 434 bp amplicon using Y1/Y2 primers. Subsequently, they generated a 550 bp PCR product with the EXPCCF/EXPCCR primers, classifying them as P. carotovorum. Further analysis of both strains involved the examination of the dnaX and mdh genes to confirm their taxonomic status. BLASTn analysis revealed the highest sequence similarity with P. actinidiae strains in GenBank for dnaX (99.39%–100%) and mdh (100%) genes. Phylogenetic analysis, based on sequences from dnaX, mdh, and a concatenation of both genes, conducted alongside 21 species of Pectobacterium spp., unequivocally confirmed that strains Pact1 and Pact2 belong to P. actinidiae. This study marks the first‐ever report of the presence of P. actinidiae in sugar beet worldwide.

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Section: P Carotovorum Was Identified In Dieffenbachia Plants In the ...mentioning

confidence: 99%

Isolation, identification, and characterization of Pectobacterium actinidiae isolated from infected sugar beet leaves

Öztürk

2024

Journal of Phytopathology

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“…Moreover, there is growing concern over the development of resistance to copper-based treatments, highlighted by findings indicating resistance among populations of P. syringae pv. actinidiae in kiwi orchards in Italy, Japan, and Korea, for example [5,6].…”

Section: Introductionmentioning

confidence: 99%

Varietal Susceptibility of Olive to Pseudomonas savastanoi pv. savastanoi and the Antibacterial Potential of Plant-Based Agents

Košćak,

Lamovšek,

Lukić

et al. 2024

Microorganisms

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Olive knot disease, caused by the bacterium Pseudomonas savastanoi pv. savastanoi, causes great damage in olive orchards. While control measures of P. savastanoi pv. savastanoi in olive orchards primarily rely on pruning and copper-based treatments, the use of antibiotics as bactericidal preparations in agriculture is limited and highly restricted. However, plants are naturally endowed with protective molecules, such as phenolic compounds, which defend them against herbivores, insects, and microorganisms. This research aimed to test the virulence of five strains of P. savastanoi pv. savastanoi isolated from different growing regions and olive varieties, and to examine whether there is a difference in plant susceptibility based on the variety. An additional goal was to test the antimicrobial activity of olive mill wastewater, known for its high content of phenolic compounds, and aqueous garlic hydrolysate, as well as to compare them with a commercial copper-based product, pure hydroxytyrosol, and a standard antibiotic as references. Analysis of knot characteristics showed variations in the virulence of the P. savastanoi pv. savastanoi strains, with the highest virulence being observed for the strain I7L and the lowest virulence for the strain B45C-PR. The olive cultivar Rosinjola displayed higher susceptibility compared to Frantoio, Buža, and Leccino, while cv. Istarska bjelica exhibited the least susceptibility compared to the other investigated olive cultivars. In an attempt to explore alternative solutions for disease control, in vitro tests revealed that the phenol HTyr, GE, and the wastewater with the highest total phenolic content (cv. Istarska bjelica) possess the highest antibacterial activity. This supports the role of polyphenols in host defense, aligning with previous field observations of lower susceptibility of cv. Istarska bjelica to olive knot disease. These findings highlight the complex nature of olive knot interactions with bacterial strains and olive cultivars, simultaneously accentuating and underscoring the importance of considering the host’s defenses as well as bacterial virulence in disease management strategies.

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“…Still, the standard copper-based preparations can be effective when used correctly; improper use can lead to phytotoxicity and long-term environmental contamination. Moreover, the emergence of bacterial resistance to various antimicrobials through horizontal gene transfer or mutations is an additional growing concern [5,6].…”

Section: Introductionmentioning

confidence: 99%

The Antibacterial Effect of Selected Essential Oils and Their Bioactive Constituents on Pseudomonas savastanoi pv. savastanoi: Phytotoxic Properties and Potential for Future Olive Disease Control

Košćak,

Lamovšek,

Đermić

et al. 2023

Microorganisms

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Plant pathogenic bacteria pose a significant threat to olive cultivation, leading to substantial economic losses and reduced yield. The efficacy of antimicrobial agents against these pathogens is of great interest for sustainable disease management strategies. As such, the management of olive knot disease is one of the major challenges in olive protection. In the presented study, through a series of in vitro assays, we investigated the antimicrobial effect of six essential oils (EOs) and their most concentrated constituents against causative agent of olive knot disease—Pseudomonas savastanoi pv. savastanoi, highlighting the high potential of Origanum compactum EO and its constituent carvacrol. Carvacrol exhibited the highest potential for practical application, demonstrating membrane disruption as its mechanism of action even at the lowest concentration. The bactericidal effect of antimicrobials was confirmed in a time–kill assay, where concentrations of MIC, 2× MIC, and 4× MIC were evaluated. Some of the applied treatments resulted in inhibition equal or higher than copper-based treatment. Additionally, we assessed the phytotoxicity of carvacrol by foliar application on olive cv. Leccino. The appearance of phytotoxic injuries majorly occurred on the young leaves of olive plants, with the highest proportion of damaged canopy observed when the 2× MIC concentration was applied. Due to its great efficiency against P. savastanoi pv. savastanoi in vitro, these findings highlight the potential of carvacrol as a molecule of interest for the development of environmentally friendly biopesticides. This study also contributes to the advancement of disease management practices in olive cultivation, leading to enhanced crop protection.

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Occurrence of copper‐resistant Pseudomonas syringae pv. actinidiae strains in kiwifruit orchards of Central Italy

Cited by 4 publications

References 38 publications

Isolation, identification, and characterization of Pectobacterium actinidiae isolated from infected sugar beet leaves

Isolation, identification, and characterization of Pectobacterium actinidiae isolated from infected sugar beet leaves

Varietal Susceptibility of Olive to Pseudomonas savastanoi pv. savastanoi and the Antibacterial Potential of Plant-Based Agents

The Antibacterial Effect of Selected Essential Oils and Their Bioactive Constituents on Pseudomonas savastanoi pv. savastanoi: Phytotoxic Properties and Potential for Future Olive Disease Control

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