New perspective for the upscaling of plant functional response to flooding stress in salt marshes using remote sensing.

Understanding the response of salt marshes to flooding is crucial to foresee the fate of these fragile ecosystems, requiring an upscaling approach. In this study we related plant species and community response to multispectral indices aiming at parsing the power of remote sensing to detect the environmental stress due to flooding in lagoon salt marshes. We studied the response of Salicornia fruticosa (L.) L. and associated plant community along a flooding and soil texture gradient in nine lagoon salt marshes in northern Italy. We considered community (i.e., species richness, dry biomass, plant height, dry matter content) and individual traits (i.e., annual growth, pigments, and secondary metabolites) to analyze the effect of flooding depth and its interplay with soil properties. We also carried out a drone multispectral survey, to obtain remote sensing-derived vegetation indices for the upscaling of plant responses to flooding. Plant diversity, biomass and growth all declined as inundation depth increased. The increase of soil clay content exacerbated flooding stress shaping S. fruticosa growth and physiological responses. Multispectral indices were negatively related with flooding depth. We found key species traits rather than other community traits to better explain the variance of multispectral indices. In particular stem length and pigment content (i.e., betacyanin, carotenoids) were more effective than other community traits to predict the spectral indices in an upscaling perspective of salt marsh response to flooding. We proved multispectral indices to potentially capture plant growth and plant eco-physiological responses to flooding at the large scale. These results represent a first fundamental step to establish long term spatial monitoring of marsh acclimation to sea level rise with remote sensing. We further stressed the importance to focus on key species traits as mediators of the entire ecosystem changes, in an ecological upscaling perspective.

Characterisation and functionalisation of chitosan nanoparticles as carriers for double-stranded RNA (dsRNA) molecules towards sustainable crop protection.

The need to minimise the impact of phytosanitary treatments for disease control boosted researchers to implement techniques with less environmental impact. The development of technologies using molecular mechanisms based on the modulation of metabolism by short dsRNA sequences appears promising. The intrinsic fragility of polynucleotides and the high cost of these techniques can be circumvented by nanocarriers that protect the bioactive molecule enabling high efficiency delivery to the leaf surface and extending its half-life. In this work, a specific protocol was developed aiming to assess the best methodological conditions for the synthesis of low-size chitosan nanoparticles (NPs) to be loaded with nucleotides. In particular, NPs have been functionalised with partially purified Green Fluorescent Protein dsRNAs (GFP dsRNA) and their size, surface charge and nucleotide retention capacity were analysed. Final NPs were also stained with FITC and sprayed on Nicotiana benthamiana leaves to assess, by confocal microscopy, both a distribution protocol and the fate of NPs up to 6 days after application. Finally, to confirm the ability of NPs to increase the efficacy of dsRNA interference, specific tests were performed: by means of GFP dsRNA-functionalised NPs, the nucleotide permanence during time was assessed both in vitro on detached wild-type N. benthamiana leaves and in planta; lastly, the inhibition of Botrytis cinerea on single leaves was also evaluated, using a specific fungal sequence (Bc dsRNA) as the NPs' functionalising agent. The encouraging results obtained are promising in the perspective of long-lasting application of innovative treatments based on gene silencing.

Contrasting Responses of Two Grapevine Cultivars to Drought: The Role of Non-structural Carbohydrates in Xylem Hydraulic Recovery.

Xylem embolism is one of the possible outcomes of decreasing xylem pressure when plants face drought. Recent studies have proposed a role for non-structural carbohydrates (NSCs) in osmotic pressure generation, required for refilling embolized conduits. Potted cuttings of grapevine Grenache and Barbera, selected for their adaptation to different climatic conditions, were subjected to a drought stress followed by re-irrigation. Stem embolism rate and its recovery were monitored in vivo by X-ray micro-computed tomography (micro-CT). The same plants were further analyzed for xylem conduit dimension and NSC content. Both cultivars significantly decreased Ψpd in response to drought and recovered from xylem embolism after re-irrigation. However, although the mean vessel diameter was similar between the cultivars, Barbera was more prone to embolism. Surprisingly, vessel diameter was apparently reduced during recovery in this cultivar. Hydraulic recovery was linked to sugar content in both cultivars, showing a positive relationship between soluble NSCs and the degree of xylem embolism. However, when starch and sucrose concentrations were considered separately, the relationships showed cultivar-specific and contrasting trends. We showed that the two cultivars adopted different NSC-use strategies in response to drought, suggesting two possible scenarios driving conduit refilling. In Grenache, sucrose accumulation seems to be directly linked to embolism formation and possibly sustains refilling. In Barbera, maltose/maltodextrins could be involved in a conduit recovery strategy via the formation of cell-wall hydrogels, likely responsible for the reduction of conduit lumen detected by micro-CT.

Antifungal activity of chili pepper extract with potential for the control of some major pathogens in grapevine.

BACKGROUND: In recent years, biofungicides have drawn increasing interest in vineyards for a more sustainable integrated and copper-limited pest management. Among alternatives, botanicals could represent valuable tools, being rich sources of biologically active compounds. Conversely to the well-known antioxidant and biological properties in relation to health benefits, investigation on bioactivity of hot pungent Capsicum sp. products against fungal phytopathogens in vineyards is still scarce. Therefore, the present study aimed at exploring the biologically active compounds profile of a chili pepper (Capsicum chinense Jacq.) pod extract and its antimicrobial properties against some of the major fungal and Oomycetes pathogens of grapevine, including Botrytis cinerea Pers., Guignardia bidwellii (Ellis) Viala & Ravaz and Plasmopara viticola (Berk. & M.A. Curtis) Berl. & De Toni. RESULTS: The ethyl acetate-extracted oleoresin from the most pungent varieties was rich in capsaicinoids and polyphenols (371.09 and 268.5 µg mg-1 dry weight, respectively). Capsaicin and dihydrocapsaicin, hydroxycinnamic and hydroxybenzoic acids and quercetin derivatives were the most abundant, while carotenoids represented only a minor fraction. The oleoresin was efficient to inhibit all three pathogenic fungi and ED50 values were determined, evidencing that G. bidwellii was the more sensitive (0.233 ± 0.034 mg mL-1 ). CONCLUSION: The results suggested a potentiality of chili pepper extract for the control of some important grapevine pathogens, their possible application being helpful for the recommended limitation in extensive use of copper in vineyard. The complex mixture of high amounts of capsaicinoids, associated to specific phenolic acids and other minor bioactive components might contribute to the observed antimicrobial action of chili pepper extract. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Calcium Phosphate Particles Coated with Humic Substances: A Potential Plant Biostimulant from Circular Economy.

Nowadays, the use of biostimulants to reduce agrochemical input is a major trend in agriculture. In this work, we report on calcium phosphate particles (CaP) recovered from the circular economy, combined with natural humic substances (HSs), to produce a plant biostimulant. CaPs were obtained by the thermal treatment of Salmo salar bones and were subsequently functionalized with HSs by soaking in a HS water solution. The obtained materials were characterized, showing that the functionalization with HS did not sort any effect on the bulk physicochemical properties of CaP, with the exception of the surface charge that was found to get more negative. Finally, the effect of the materials on nutrient uptake and translocation in the early stages of development (up to 20 days) of two model species of interest for horticulture, Valerianella locusta and Diplotaxis tenuifolia, was assessed. Both species exhibited a similar tendency to accumulate Ca and P in hypogeal tissues, but showed different reactions to the treatments in terms of translocation to the leaves. CaP and CaP-HS treatments lead to an increase of P accumulation in the leaves of D. tenuifolia, while the treatment with HS was found to increase only the concentration of Ca in V. locusta leaves. A low biostimulating effect on both plants' growth was observed, and was mainly scribed to the low concentration of HS in the tested materials. In the end, the obtained material showed promising results in virtue of its potential to elicit phosphorous uptake and foliar translocation by plants.

Analysis of Non-Structural Carbohydrates and Xylem Anatomy of Leaf Petioles Offers New Insights in the Drought Response of Two Grapevine Cultivars.

In grapevine, the anatomy of xylem conduits and the non-structural carbohydrates (NSCs) content of the associated living parenchyma are expected to influence water transport under water limitation. In fact, both NSC and xylem features play a role in plant recovery from drought stress. We evaluated these traits in petioles of Cabernet Sauvignon (CS) and Syrah (SY) cultivars during water stress (WS) and recovery. In CS, the stress response was associated to NSC consumption, supporting the hypothesis that starch mobilization is related to an increased supply of maltose and sucrose, putatively involved in drought stress responses at the xylem level. In contrast, in SY, the WS-induced increase in the latter soluble NSCs was maintained even 2 days after re-watering, suggesting a different pattern of utilization of NSC resources. Interestingly, the anatomical analysis revealed that conduits are constitutively wider in SY in well-watered (WW) plants, and that water stress led to the production of narrower conduits only in this cultivar.

Bioactive Polyphenols Modulate Enzymes Involved in Grapevine Pathogenesis and Chitinase Activity at Increasing Complexity Levels.

The reduction of synthetic chemistry use in modern viticulture relies on either the biological control of microorganisms or the induction of pathogenesis-related proteins. In the present study, the effects of hydro-alcoholic plant extracts (PEs) (i.e., by-products of Vitis vinifera L., leaves of Olea europaea L. and Ailanthus altissima (Mill.) Swingle) were tested on purified enzymes activity involved in plant-pathogen interactions. The polyphenolic composition was assayed and analyzed to characterize the extract profiles. In addition, suspension cell cultures of grapevine were treated with PEs to study their modulation of chitinase activity. Application of grape marc's PE enhanced chitinase activity at 4 g L-1. Additionally, foliar treatment of grape marc's PE at two doses (4 g L-1 and 800 g L-1) on grapevine cuttings induced a concentration-dependent stimulation of chitinase activity. The obtained results showed that the application of bioactive compounds based on PEs, rich in phenolic compounds, was effective both at in vitro and ex/in vivo level. The overall effects of PEs on plant-pathogen interaction were further discussed by applying a multi-criteria decision analysis, showing that grape marc was the most effective extract.

Carbapenem-resistant Enterobacteriaceae Infections in Children: An Italian Retrospective Multicenter Study.

BACKGROUND: The spread of carbapenem-resistant Enterobacteriaceae (CRE) is a health problem of major concern. CRE-related infections have significant morbidity and mortality, but data on CRE infection in pediatric population are limited. The aim of this study was to analyze epidemiologic and clinical characteristics, risk factors, therapeutic options and outcome of CRE infections in children in Italy. METHODS: We performed a retrospective, multicenter, observational study of children with confirmed CRE infection or colonization admitted between January 1, 2011, and March 1, 2014, to 7 Italian pediatric centers. RESULTS: Sixty-nine patients presenting 74 CRE infections and/or colonization were included. The most frequently isolated strain was Klebsiella pneumoniae carbapenemase-producing K. pneumoniae. Children with CRE infections had longer length of stay in hospital (P < 0.001), duration of disease (P = 0.001) and antimicrobial treatment (P < 0.001) than colonized children. Oncologic/immunosuppressive conditions are one of the factors significantly associated with a fatal outcome among children with CRE infections. CONCLUSIONS: Our study confirms that CRE infections affect mostly children with oncologic diseases and immunosuppression. Controlled studies in large cohorts are needed to evaluate the best therapeutic options and to assess further risk factors influencing outcomes and the survival of pediatric patients with infections caused by CRE.

Low birth weight for gestational age associates with reduced glucose concentrations at birth, infancy and childhood.

BACKGROUND/AIMS: Our aim was to investigate glucose homeostasis, insulin sensitivity and insulin-like growth factor (IGF) system status in children born small for gestational age (SGA). METHODS: A case-control study was carried out at birth, infancy and childhood, comparing SGA with children appropriate for gestational age strictly matched for age, gender, pubertal status and body mass index. Ninety newborns, 52 infants, and 68 children were studied. Fasting insulin (I(F)), fasting glucose (G(F)) to I(F) ratio (G(F)/I(F)), the homeostasis model assessment of insulin sensitivity, the quantitative insulin sensitivity check index, insulinogenic index and the triglyceride/high-density lipoprotein-cholesterol ratio were measured. IGF-I, IGF-binding protein-3 and the IGF-I/IGF-binding protein-3 molar ratio were assessed. RESULTS: Glucose concentrations were lower in SGA newborns (p < 0.0001), infants (p = 0.01), and children (p = 0.001). Birth weight correlated with glucose levels at birth (r = 0.59, p < 0.0001), 12 months (r = 0.29, p = 0.04) and childhood (r = 0.44, p < 0.0001). CONCLUSION: Our results provide evidence for a developmental adaptation of glucose metabolism in SGA children leading to reduced glucose concentrations.