Pantoea stewartii subsp. stewartii an inter-laboratory comparative study of molecular tests and comparative genome analysis of Italian strains

Pantoea stewartii subsp. stewartii (Pss) is a Gram-negative bacterium causing Stewart wilt, a severe disease in maize. Native to North America, it has spread globally through the maize seed trade. Resistant maize varieties and insecticides are crucial to mitigate the disease’s economic impact. Pss is a quarantine pest, requiring phytosanitary certification for the seed trade in European countries. Accurate diagnostic tests, including real-time PCR, are fundamental to detect Pss and distinguish it from other bacteria, like Pantoea stewartii subsp. indologenes (Psi), a non-quarantine bacteria associated with maize seeds. Population genetics is a valuable tool for studying adaptation, speciation, population structure, diversity, and evolution in plant bacterial pathogens. In this study, the key activities of interlaboratory comparisons are reported to assess diagnostic sensitivity (DSE), diagnostic specificity (DSP) and accuracy (ACC) for different real-time PCR able to detect Pss in seeds. The results of complete sequencing of Italian bacterial isolates are presented. This study enhances our understanding of molecular methods for diagnosing and identifying pathogens in maize seeds, improving knowledge of Pss genomes to prevent their spread and trace possible entry routes from endemic to non-endemic area

Propolis hydroalcoholic extracts: biochemical characterization and antifungal efficacy

The present study investigated the antifungal potential of hydroalcoholic extracts of propolis against the causal agent of grey mould, Botrytis cinerea, by in vitro and in vivo assays. Five different propolis from different Italian regions were subjected to hydroalcoholic extraction using different ethanol concentrations and extraction methods. The preliminary bio-assay showed significant inhibitory effects on B. cinerea mycelial growth of propolis extracts obtained using 90% ethanol and subjected to sonication. The calculation of EC50 values, based on the demonstrated efficacy of non-volatile and volatile metabolites of propolis extracts, was useful to understand the main fraction involved in the antifungal activity of the samples and to perform the in vivo assay on grape and blueberry fruits. Three of the propolis extracts showed a high amount of genistein. Conversely, the other two propolis showed a fair amount of apigenin, caffeic acid, chrysin, ferulic acid, kaempferol, luteolin, p-coumaric acid and quercetin. From the volatile analysis of propolis, the main compounds detected were α-cadinol, α-eudesmol, calamenene, cadinol, benzyl acetate, benzyl benzoate and benzyl alcohol. The results suggest that propolis extracts have potential as an effective postharvest antifungal treatment, with varying degrees of efficacy depending on the extraction method and the type of propolis metabolite

Towards the geographical traceability of the Italian walnut: a case study based on stable isotopes signatures (δ2 H, δ18O, δ13C, δ15N, δ34S) and elemental fingerprinting

Juglans regia (L.) is cultivated worldwide for its nutrient-rich nuts. Italy is among the top five importing countries of walnuts in shell due to the strong decline in the Italian walnuts production in the early seventies, combined to a constantly growing demand. The current context is therefore favourable to promote the development of a local high-quality Italian walnut production. In this respect, tools capable of tracing the origin of walnut can support the process of valorisation and promotion of this product. The main aim of this study was to investigate to what extent stable isotope data (H, O, C determined in the lipid and defatted fractions, N and S of the defatted fraction) coupled with 56-element profiles could be used to differentiate Italian walnuts on a regional and global level. A total of 122 walnut samples from six countries and two years of harvest were analysed. Multivariate data analysis (JIVE) suggested a strong effect of the geographical origin, particularly at the regional level. However, it was not possible to completely exclude the effect of the harvest year on the overall variability of the samples. A preliminary analysis focussing on a regional scale (Italian samples only) and on a few samples of international origin, confirmed that the proposed approach could be potentially applied for the discrimination of Italian walnuts. Overall, the results presented support the effectiveness of stable isotopes and multi-element analyses in walnut traceability and local origin protection

Increasing nickel concentrations in a large river network of South Tyrol, Eastern European Alps

Climate change and cryosphere degradation may enhance the concentrations of heavy metals in high-mountain rivers. However, the downstream export of these contaminants to lower elevations is still overlooked. In this study, we investigated the spatial and temporal patterns of dissolved and bioavailable nickel concentrations in the upper Etsch/Adige river basin (1590 km2; 54 sites) during the period of 2005−2023. Furthermore, we investigated the same concentrations seasonally (2022−2023) along a tributary (Schnals/Senales River), from the glacier origin down to the confluence with the Etsch River (13 sites). Concentrations of both nickel forms increased during the past decade by up to 4 times, yet only in river reaches draining the acidic metamorphic Ötztal Unit. Sulfide oxidation, more intense at sites featuring larger glaciers, rock glaciers, and permafrost extent in their catchment, enhanced nickel concentrations. Along the Schnals River, values were elevated in the proglacial waters (dissolved fraction up to 112 μg L−1), gradually decreased moving to lower elevations, and dropped (from 20 to 30 to 2−5 μg L−1) downstream of a large reservoir. Currently, bioavailable nickel concentrations exceed the EU environmental quality standards at 40% of the investigateinvestigated sites, demonstrating sharp environmental implications that may be extended to other similar geological and cryospheric settings

Placement matters: implications of trail- versus random-based camera-trap deployment for monitoring mammal communities

Optimizing protocols to assess and monitor mammal communities is essential to meet the current biodiversity targets of halting species loss. Camera-traps are the most effective tool for multispecies monitoring, yet their deployment strategy is debated, with two main strategies adopted: trail- and random-based camera deployment. To date, few studies have compared these two strategies and reached contrasting recommendations. Here, by simultaneously deploying 60 camera-traps for each placement strategy in a National Park in central Italy, we aimed to assess differences in species richness and composition, photographic rate, detection/occupancy probabilities, also in responses to environmental and anthropogenic variables, and temporal activity. Site species richness was greater on than off-trails, with elusive carnivores mainly detected on trails. Community composition was different, with a smaller proportion of ungulates on trails, and lower detections of carnivores off-trails. Photographic rate, detection, and occupancy probabilities were higher on trails for almost all mammals. Occupancy responses to environmental variables did not match, possibly due to the different behavioral strategy adopted by mammals (trails for movement, off-trails for resting and foraging). Thus, a mixed approach with cameras located both on- and off-trails is recommended when studying habitat use. We also found a consistent negative response of occupancy and site-use intensity to human frequentation, with mammals avoiding both highly frequented trails and adjacent random sites. Temporal activity curves were similar between designs, suggesting that the choice of the sampling strategy would not bias the inference. However, nocturnal behavior was higher on trails for some species, indicating varying degrees of temporal avoidance of humans. With faster data accumulation, easier accessibility of sampling sites, and the ability to record human activity, on-trail cameras are more efficient than off-trail cameras for monitoring mammal communities

Study of the dynamic of cultural microbiome of kiwifruit along postharvest storage for the selection of beneficial microorganisms

The aim is to investigate the evolution of the microbial community of kiwifruit during postharvest storage and the impact of eight different bacterial strains, possessing specific metabolic activity, on the fruit of A. chinensis var. chinensis quality parameters. Additionally, the fate and growth of bacterial strains were assessed when inoculated on kiwifruit and subjected to cold storage conditions. Fruits were sampled in a commercial orchard in Italy (Latina, LT, Italy) and analyzed at harvest for the cultural population of fungi and bacteria. Approximately 250 fungal, yeast, and 500 bacterial strains were identified. Fungal strains were dissected for their potential pathogenic activity on fruit. Bacterial strains were also characterized for their potential beneficial functions (e.g., IAA, production, acetoin, siderophore) and their ability to grow at low temperatures. Sampling was performed during the first two months of storage with the aim of identifying the fungal and bacterial species specifically selected by cold storage. Eight bacterial species were selected for postharvest treatments on fruit to assess their potential ability to prolong storage, reduce losses, or increase fruit quality. Different strains showed the potential to inhibit Botrytis cinerea growth. Furthermore, six strains were able to increase sugar content in fruit; however, the effect was related to an increase in softening, suggesting that these strains were inducing an earlier ripening. Interestingly, the inoculation generally increases storage breakdown, a chilling-related disorder, suggesting a possible microbial component of this physiological disorde