Transcriptomic Analysis of Orange Fruit Treated with Pomegranate Peel Extract (PGE)

Characterization of Alternaria and Colletotrichum Species Associated with Pomegranate (Punica granatum L.) in Maharashtra State of India

Fungal pathogens are a major constraint affecting the quality of pomegranate production around the world. Among them, Alternaria and Colletotrichum species cause leaf spot, fruit spot or heart rot (black rot), and fruit rot (anthracnose) or calyx end rot, respectively. Accurate identification of disease-causing fungal species is essential for developing suitable management practices. Therefore, characterization of Alternaria and Colletotrichum isolates representing different geographical regions, predominantly Maharashtra-the Indian hub of pomegranate production and export-was carried out. Fungal isolates could not be identified based on morphological characteristics alone, hence were subjected to multi-gene phylogeny for their accurate identification. Based on a maximum likelihood phylogenetic tree, Alternaria isolates were identified as within the A. alternata species complex and as A. burnsii, while Colletotrichum isolates showed genetic closeness to various species within the C. gloeosporioides species complex. Thus, the current study reports for the first time that, in India, the fruit rots of pomegranate are caused by multiple species and not a single species of Alternaria and Colletotrichum alone. Since different species have different epidemiology and sensitivity toward the commercially available and routinely applied fungicides, the precise knowledge of the diverse species infecting pomegranate, as provided by the current study, is the first step towards devising better management strategies.

A super absorbent polymer containing copper to control Plenodomus tracheiphilus the causative agent of mal secco disease of lemon

The aim of this study was to determine the effectiveness of a Super absorbent polymer (SAP) containing copper (SAP-Cu) in controlling mal secco disease (MSD) of lemon caused by the fungus Plenodomus tracheiphilus. Super absorbent polymer containing copper was characterized by atomic absorption spectrometry (AAS) and UV-VIS spectroscopy. In vitro tests were performed to determine the inhibitory effects of SAP-Cu against the pathogen on both potato-dextrose-agar medium and naturally infected lemon cuttings. Super absorbent polymer was able to absorb up to about 200 and 30 times its weight of ionized water and copper (II) sulfate solution (Cu²⁺ ions at the concentration 236 mM), respectively. The distribution of copper released on twigs after 24 h of contact with SAP-Cu was determined by secondary ion mass spectrometry with time-of-flight analyzer (ToF-SIMS). Super absorbent polymer containing copper significantly inhibited the viability of P. tracheiphilus in lemon twigs. Overall, the results of this study showed that the SAP could be a suitable carrier of antifungal compounds.

From Pomegranate Byproducts Waste to Worth: A Review of Extraction Techniques and Potential Applications for Their Revalorization

The food industry is quite interested in the use of (techno)-functional bioactive compounds from byproducts to develop ‘clean label’ foods in a circular economy. The aim of this review is to evaluate the state of the knowledge and scientific evidence on the use of green extraction technologies (ultrasound-, microwave-, and enzymatic-assisted) of bioactive compounds from pomegranate peel byproducts, and their potential application via the supplementation/fortification of vegetal matrixes to improve their quality, functional properties, and safety. Most studies are mainly focused on ultrasound extraction, which has been widely developed compared to microwave or enzymatic extractions, which should be studied in depth, including their combinations. After extraction, pomegranate peel byproducts (in the form of powders, liquid extracts, and/or encapsulated, among others) have been incorporated into several food matrixes, as a good tool to preserve ‘clean label’ foods without altering their composition and improving their functional properties. Future studies must clearly evaluate the energy efficiency/consumption, the cost, and the environmental impact leading to the sustainable extraction of the key bio-compounds. Moreover, predictive models are needed to optimize the phytochemical extraction and to help in decision-making along the supply chain.

Epiphytic Yeasts and Bacteria as Candidate Biocontrol Agents of Green and Blue Molds of Citrus Fruits

Overall, 180 yeasts and bacteria isolated from the peel of citrus fruits were screened for their in vitro antagonistic activity against Penicillium digitatum and P. italicum, causative agents of green and blue mold of citrus fruits, respectively. Two yeast and three bacterial isolates were selected for their inhibitory activity on mycelium growth. Based on the phylogenetic analysis of 16S rDNA and ITS rDNA sequences, the yeast isolates were identified as Candida oleophila and Debaryomyces hansenii while the bacterial isolates were identified as Bacillus amyloliquefaciens, B. pumilus and B. subtilis. All five selected isolates significantly reduced the incidence of decay incited by P. digitatum and P. italicum on ‘Valencia’ orange and ‘Eureka’ lemon fruits. Moreover, they were effective in preventing natural infections of green and blue mold of fruits stored at 4 °C. Treatments with antagonistic yeasts and bacteria did not negatively affect the quality and shelf life of fruits. The antagonistic efficacy of the five isolates depended on multiple modes of action, including the ability to form biofilms and produce antifungal lipopeptides, lytic enzymes and volatile compounds. The selected isolates are promising as biocontrol agents of postharvest green and blue molds of citrus fruits.

Inhibitory Activity of Shrimp Waste Extracts on Fungal and Oomycete Plant Pathogens

(1) Background: This study was aimed at determining the in vitro inhibitory effect of new natural substances obtained by minimal processing from shrimp wastes on fungi and oomycetes in the genera Alternaria, Colletotrichum, Fusarium, Penicillium, Plenodomus and Phytophthora; the effectiveness of the substance with the highest in vitro activity in preventing citrus and apple fruit rot incited by P. digitatum and P. expansum, respectively, was also evaluated. (2) Methods: The four tested substances, water-extract, EtOAc-extract, MetOH-extract and nitric-extract, were analyzed by HPLC-ESI-MS-TOF; in vitro preliminary tests were carried out to determine the minimal inhibitory/fungicidal concentrations (MIC and MFC, respectively) of the raw dry powder, EtOAc-extract, MetOH-extract and nitric-extract for each pathogen. (3) Results: in the agar-diffusion-assay, nitric-extract showed an inhibitory effect on all pathogens, at all concentrations tested (100, 75, 50 and 25%); the maximum activity was on Plenodomus tracheiphilus, C. gloeosporioides and Ph. nicotianae; the diameters of inhibition halos were directly proportional to the extract concentration; values of MIC and MFC of this extract for all pathogens ranged from 2 to 3.5%; the highest concentrations (50 to 100%) tested in vivo were effective in preventing citrus and apple fruit molds. (4) Conclusions: This study contributes to the search for natural and ecofriendly substances for the control of pre- and post-harvest plant pathogens.

Novel trends in extraction and optimization methods of bioactives recovery from pomegranate fruit biowastes: Valorization purposes for industrial applications

Pomegranate biowastes present potential economic value worldwide owing to their several health benefits mediated by a complex mixture of unique bioactives. The exploitation of these bioactives has motivated the exploration of eco-friendly, efficient, and cost-effective extraction techniques to maximize their recovery. The current review aims to provide updated technical information about bioactives extraction mechanisms from pomegranate wastes (seeds and peel), their advantages and disadvantages, and factors towards optimization. A comparative overview of the modern green extraction techniques viz., supercritical fluid extraction, ultrasound-assisted extraction, microwave-assisted extraction, pressurized liquid extraction, and eutectic solvent mixture as alternatives to conventional extraction methods for seeds and peel is presented. Approaches focused on biowastes modification for properties improvement are also discussed. Such comprehensive review shall provide the best valorization practices of pomegranate biowastes and its application in food and non-food areas focusing on original methods, innovation, protocols, and development to be considered for other fruit biowastes.

Natural Biostimulants Elicit Plant Immune System in an Integrated Management Strategy of the Postharvest Green Mold of Orange Fruits Incited by Penicillium digitatum

This study was aimed at testing the integrated use of a natural biostimulant based on seaweed (Ascophyllum nodosum) and plant (alfalfa and sugarcane) extracts and reduced dosages of the conventional synthetic fungicide Imazalil (IMZ) to manage postharvest rots of orange fruits. The following aspects were investigated: (i) the effectiveness of postharvest treatment with natural biostimulant alone or in mixture with IMZ at a reduced dose against green mold caused by Penicillium digitatum; (ii) the differential expression of defense genes in orange fruits treated with the natural biostimulant both alone and in combination with a reduced dose of IMZ; (iii) the persistence of the inhibitory activity of both biostimulant and the mixture biostimulant/IMZ against green mold; and (iv) the residue level of fungicide in citrus peel when applied alone or in combination with the biostimulant. Treatments with the chemical plant resistance-inducer potassium phosphite, alone or with a reduced dose of IMZ, were included for comparison. The mixture of natural biostimulant and IMZ at a low dose consistently reduced the incidence and severity of fruit green mold and induced a significant increase of the expression level of β-1,3-glucanase-, peroxidase (PEROX)-, and phenylalanine ammonia-lyase (PAL)-encoding genes in fruit peel, suggesting that the natural biostimulant elicits a long-lasting resistance of citrus fruits to infections by P. digitatum. Interestingly, the residual concentration of IMZ in fruits treated with the biostimulant/fungicide mixture was significantly lower than that of IMZ in fruits treated only with the fungicide at the same dose and by far below the threshold values set by the European Union. This study laid the foundations for (i) conceiving a practical and more eco-friendly alternative to the conventional postharvest management of green mold of citrus fruits, based almost exclusively on the use of synthetic fungicide IMZ, alone or mixed with potassium phosphite and (ii) providing a better insight into the mechanisms of disease resistance induction by biostimulants.

Preharvest and Postharvest Applications of a Pomegranate Peel Extract to Control Citrus Fruit Decay During Storage and Shelf Life

Green and blue molds are the most important postharvest diseases affecting citrus in storage. These diseases are commonly controlled with fungicides, but legislative restrictions, consumer concerns, and the development of resistant strains of the pathogens have increasingly led to the search for alternative methods of control. A pomegranate peel extract (PGE) was very effective in controlling Valencia orange and clementine postharvest rot under commercial conditions. After cold storage and 7 days of shelf life, the incidence of decay on oranges sprayed before harvest with PGE at 12, 6, and 3 g/liter was reduced by 78.9, 76.0, and 64.6%, respectively. Similarly, postharvest dipping treatments with PGE reduced rot by 90.2, 84.3, and 77.6%, respectively. Comparable levels of protection were also achieved on clementines. On both oranges and clementines, the extract provided a significantly higher level of protection compared with imazalil, a fungicide commonly used for postharvest treatments. The high level of efficacy and the consistent results on different fruit species (clementines and oranges) and with different application methods (preharvest and postharvest) were evidence of reliability and flexibility. PGE also showed a strong antimicrobial activity against fungi and bacteria, suggesting its possible use in sanitizers to reduce the microbial contamination of recirculated water in packinghouses. The results of the present study encourage the integration of conventional chemical fungicides and sanitizers with PGE to control citrus postharvest rot.

Pomegranate Peel Extracts as Safe Natural Treatments to Control Plant Diseases and Increase the Shelf-Life and Safety of Fresh Fruits and Vegetables

Although the Green Revolution was a milestone in agriculture, it was accompanied by intensive use of synthetic pesticides, which has raised serious concerns due to their impact on human and environmental health. This is increasingly stimulating the search for safer and more eco-friendly alternative means to control plant diseases and prevent food spoilage. Among the proposed alternatives, pomegranate peel extracts (PPEs) are very promising because of their high efficacy. In the present review, we discuss the complex mechanisms of action that include direct antimicrobial activity and induction of resistance in treated plant tissues and highlight the importance of PPE composition in determining their activity. The broad spectrum of activity, wide range of application and high efficiency of PPEs against bacterial, fungal and viral plant pathogens suggest a potential market not only restricted to organic production but also integrated farming systems. Considering that PPEs are non-chemical by-products of the pomegranate industry, they are perceived as safe by the public and may be integrated in circular economy strategies. This will likely encourage agro-pharmaceutical industries to develop commercial formulations and speed up the costly process of registration.

Characterization of Alternaria Species Associated with Heart Rot of Pomegranate Fruit

This study was aimed at identifying Alternaria species associated with heart rot disease of pomegranate fruit in southern Italy and characterizing their mycotoxigenic profile. A total of 42 Alternaria isolates were characterized. They were obtained from pomegranate fruits with symptoms of heart rot sampled in Apulia and Sicily and grouped into six distinct morphotypes based on macro- and microscopic features. According to multigene phylogenetic analysis, including internal transcribed spacer (ITS), translation elongation factor 1-α (EF-1α), glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and a SCAR marker (OPA10-2), 38 isolates of morphotypes 1 to 5 were identified as Alternaria alternata, while isolates of morphotype 6, all from Sicily, clustered within the Alternaria arborescens species complex. In particular, isolates of morphotype 1, the most numerous, clustered with the ex-type isolate of A. alternata, proving to belong to A. alternata. No difference in pathogenicity on pomegranate fruits was found between isolates of A. alternata and A. arborescens and among A. alternata isolates of different morphotypes. The toxigenic profile of isolates varied greatly: in vitro, all 42 isolates produced tenuazonic acid and most of them other mycotoxins, including alternariol, alternariol monomethyl ether, altenuene and tentoxin.

The Antifungal Activity of Loquat (Eriobotrya japonica Lindl.) Leaves Extract Against Penicillium digitatum

This study was performed to determine the antifungal activity of loquat (Eriobotrya japonica Lindl) leaf extract (LLE) against the citrus postharvest pathogen Penicillium digitatum (P. digitatum). The LLE exhibited an antifungal activity against P. digitatum, with a minimum inhibitory concentration (MIC) of 0.625 mg/ml and a minimum fungicidal concentration (MFC) of 1.25 mg/ml. Significant inhibitory effects of LLE on mycelial growth and spore germination of P. digitatum were seen in a dose-dependent manner. Simultaneously, to investigate possible antifungal mechanisms by LLE, we analyzed their influence on morphological changes, cell membrane permeability, cell wall and cell membrane integrity, and adenosine phosphates (ATP, ADP, and AMP) levels. Alterations, such as sunken surface and malformation, occurred in the LLE-treated P. digitatum spores. Furthermore, intracellular inclusion content decreased after LLE treatment, indicating an increase in cell membrane permeability. Besides, the LLE treatment induced a significant decline in the level of adenosine monophosphate (AMP), adenosine diphosphate (ADP), and adenosine triphosphate (ATP) with a noticeable addition of extracellular ATP, ADP, and AMP during the entire treatment period. Overall, the results manifested that the antifungal activity of LLE against P. digitatum can be attributed to the derangement of cell membrane permeability and disordered energy metabolism. This is the first report on the mechanism of antifungal activity of LLE and could be useful in the development of targeted fungicides from natural origin.

Antimicrobial Activity of Pomegranate Peel and Its Applications on Food Preservation

Pomegranate (Punica granatum L.) fruit is being cultivated since the civilization is known, and its production and consumption have been increased since the last century due to the scientific confirmation of its health benefits. Pomegranate fruits, fruit juice, its seeds, and peels are known to have higher contents of bioactive compounds, viz., phenolic acids, flavonoids, and hydrolysable tannins. The peels of pomegranate fruits are the major by-products produced during food processing of pomegranate enriched in antioxidants and broad-spectrum antimicrobial agents and can prevent food deterioration even. This health potential of pomegranate is known to vary significantly upon the varieties, growing conditions, cultivation practices, stages of the development, and the extraction methods. Herein, the biochemical composition of the pomegranate peel extract (PPE), its efficacy in food preservation, and antimicrobial activities are discussed to provide a comprehensive guide for farmers, food processing, and storage sectors and academia.

The Effect of Polyphenols on Pomegranate Fruit Susceptibility to Pilidiella granati Provides Insights into Disease Tolerance Mechanisms

Pilidiella granati, also known as Coniella granati, is the etiological agent of pomegranate fruit dry rot. This fungal pathogen is also well-known as responsible for both plant collar rot and leaf spot. Because of its aggressiveness and the worldwide diffusion of pomegranate crops, the selection of cultivars less susceptible to this pathogen might represent an interesting preventive control measure. In the present investigation, the role of polyphenols in the susceptibility to P. granati of the two royalties-free pomegranate cultivars Wonderful and Mollar de Elche was compared. Pomegranate fruit were artificially inoculated and lesion diameters were monitored. Furthermore, pathogen DNA was quantified at 12-72 h post-inoculation within fruit rind by a real time PCR assay setup herein, and host total RNA was used in expression assays of genes involved in host-pathogen interaction. Similarly, protein extracts were employed to assess the specific activity of enzymes implicated in defense mechanisms. Pomegranate phenolic compounds were evaluated by HPLC-ESI-MS and MS2. All these data highlighted 'Wonderful' as less susceptible to P. granati than 'Mollar de Elche'. In the first cultivar, the fungal growth seemed controlled by the activation of the phenylpropanoid pathway, the production of ROS, and the alteration of fungal cell wall. Furthermore, antifungal compounds seemed to accumulate in 'Wonderful' fruit following inoculation. These data suggest that pomegranate polyphenols have a protective effect against P. granati infection and their content might represent a relevant parameter in the selection of the most suitable cultivars to reduce the economic losses caused by this pathogen.

Antioxidant, Antifungal Activities of Ethnobotanical Ficus hirta Vahl. and Analysis of Main Constituents by HPLC-MS

The medicinal and edible plant, Ficus hirta Vahl. (also called hairy fig), is used for the treatment of constipation, inflammation, postpartum hypogalactia, tumors, and cancer. There is an urgent need for scientific evaluation to verify the pharmacological properties of F. hirta. Therefore, in vitro assays evaluated the antioxidant and antifungal activities of various solvent extracts of hairy fig fruits (HFF). HFF extracts had abundant antioxidant components for a significant amount of total phenolic (TPC) and flavonoid contents (TFC) (TPC from 17.75 ± 0.52 to 85.25 ± 1.72 mg gallic acid/g dw and TFC from 15.80 ± 0.59 to 144.22 ± 8.46 mg rutin/g dw, respectively). The ethyl acetate extract (EAE) and acetone extract (AE) of HFF demonstrated potent antioxidant activities against 1,1-diphenyl-2-picrylhydrazyl (DPPH) (IC₅₀ values of 2.52 and 2.02 mg/mL, respectively) and ABTS radicals (IC₅₀ values of 3.06 and 9.26 mg/mL, respectively). Moreover, the AE with a high TFC showed a prominent in vitro and in vivo antifungal activity against Penicillium italicum, causing citrus blue mold. Eighteen metabolites were identified or putatively identified from six HFF extracts. Current findings indicated that HFF extracts had significant antioxidant and antifungal activities and could potentially be used as an alternative agent for the preservation of agricultural products.