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Chitosan (CTS) and its degradation product, chitooligosaccharide (COS), promote fruit healing by activating phenylpropanoid metabolism. This study investigates their effects on sucrose metabolism in pear wounds. CTS and COS were found to activate neutral invertase, acid invertase, sucrose synthase, and sucrose phosphate synthase, increasing sucrose, glucose, and fructose levels in fruit wounds. They also enhanced sorbitol dehydrogenase activity and promoted sorbitol accumulation. In addition, CTS and COS improved the activities of hexokinase, phosphofructokinase, and pyruvate kinase, increasing phosphoenolpyruvate and ATP production. They activated glucose-6-phosphate dehydrogenase and increased erythrose-4-phosphate, NADPH, and shikimic acid levels. In conclusion, CTS and COS support the formation of the healing closing layer by supplying carbon skeletons, energy, and reducing power through the activation of sugar and respiratory metabolism during the healing process. Compared to CTS, COS was superior in activating the above metabolisms, which is expected to be widely used as a chitin product in postharvest fruit and vegetable preservation and provide new insights into preserving pear freshness., Competing Interests: Declaration of competing interest The authors declare that they have no competing interests., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Among grapevine yellows, Bois noir (BN), associated with ' Candidatus Phytoplasma solani', represents the biggest threat in the main wine-growing areas worldwide, causing significant losses in berry quality and yields. BN epidemiology involves multiple plant hosts and several insect vectors, making considerably complex the development of effective management strategies. Since application of insecticides on the grapevine canopy is not effective to manage vectors, BN management includes an integrated approach based on treatments to the canopy to make the plant more resistant to the pathogen and/or inhibit the vector feeding, and actions on reservoir plants to reduce possibilities that the vector reaches the grapevine and transmit the phytoplasma. Innovative sustainable strategies developed in the last twenty years to improve the BN management are reviewed and discussed., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Pierro, Moussa, Mori, Marcone, Quaglino and Romanazzi.)

Tuber melanosporum is an ascomycete that forms ectomycorrhizal (ECM) symbioses with a wide range of host plants, producing edible fruiting bodies with high economic value. The quality of seedlings in the early symbiotic stage is important for successful truffle cultivation. Numerous bacterial species have been reported to take part in the truffle biological cycle and influence the establishment of roots symbiosis in plant hosts and the development of the carpophore. In this work, three different bacteria formulations were co-inoculated in Quercus ilex L. seedlings two months after T. melanosporum inoculation. At four months of bacterial application, the T. melanosporum ECM root tip rate of colonization and bacterial presence were assessed using both morphological and molecular techniques. A 2.5-fold increase in ECM colonization rate was found in the presence of Pseudomonas sp. compared to the seedlings inoculated only with T. melanosporum . The same treatment caused reduced plant growth either for the aerial and root part. Meanwhile, the ECM colonization combined with Bradyrhizobium sp. and Pseudomonas sp. + Bradyrhizobium sp. reduced the relative density of fibrous roots (nutrient absorption). Our work suggests that the role of bacteria in the early symbiotic stages of ECM colonization involves both the mycorrhizal symbiosis rate and plant root development processes, both essential for improve the quality of truffle-inoculated seedlings produced in commercial nurseries.

The antibacterial effects of chitosan have been widely studied, but the underlying molecular mechanisms are not fully understood. We investigated the molecular responses of Escherichia coli MG1655 cell, a model gram-negative bacterium, upon exposure to chitosan (Cs), alkylated Cs (AlkCs), and chitosan nanoparticles (CsNPs). Nine target genes involved in relevant signaling pathways (ompF, ompC, ompA, mrcA, mrcB, mgtA, glnA, kdpA, lptA) were selected for analysis. A significant reduction in the expression of mrcA, mgtA, glnA, and lptA genes was observed in the cells treated with Cs. Those treated with Cs, AlkCs, and CsNPs revealed an increase in ompF gene expression, but the expression level was lower in the cells treated with AlkCs and CsNPs compared to Cs. This increase in porin expression suggests compromised membrane integrity and disrupted nutrient transport. In addition, the changes in the expression of mgtA, kdpA, and glnA are related to different effects on membrane permeability. The higher expression in the genes mrcA and mrcB is associated with morphological changes of cells treated with AlkCs and CsNPs. These findings contribute to our understanding of the molecular mechanisms underlying chitosan-induced stress responses and provide insights for the development of safer antimicrobial compounds in the future., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Essential oils (EOs) extracted from aromatic or medicinal plants are biodegradable, safe, and regarded as alternatives to chemical pesticides to reduce fungal species attacking different crops. In this study, thirty EOs at 0.5 mg/mL were evaluated for in vitro growth inhibition of the main postharvest fungi, which are Alternaria alternata , Botrytis cinerea , and Penicillium italicum . Cinnamomum verrum EO completely inhibited the mycelial growth of A. alternata and B. cinerea , and Syzygium aromaticum EO completely inhibited the mycelia of A. alternata . B. cinerea mycelial growth was completely inhibited by Gautheria fragrantissima , Cymbopogon nardus , Pelargonium asperum , and Cupressus sempervirens EOs. G. fragrantissima EO inhibited the mycelia growth of P. italicum by 98%. Overall, B. cinerea displayed the highest sensitivity to EOs than P. italicum and A. alternata . G. fragrantissima , C. sempervirens , C. nardus , P. asperum , Mentha piperita , Foeniculum vulgare , C. verrum , and S. aromaticum EOs showed the highest inhibition for these three pathogens. Minimum inhibitory concentrations were lower for C. verrum and S. aromaticum EOs, ranging between 0.31 and 0.45 mg/mL and 0.37 to 0.57 mg/mL, respectively, against the three pathogens. The tested EOs inhibited the in vitro growth of three of the main postharvest fungal pathogens. Further studies are needed to confirm these activities in vivo.

Gray mold and brown rot, caused respectively by Botrytis cinerea and Monilinia spp., are fungal diseases responsible for significant losses during the storage of fruit and vegetables. Nowadays, the control of postharvest diseases is shifting towards more sustainable strategies, including the use of plant secondary metabolites. In this study, the antifungal activity of Origanum vulgare , Thymus vulgaris , Thymus serpyllum , Melaleuca alternifolia , Lavandula officinalis , Lavandula hybrida , Citrus bergamia , Rosmarinus officinalis , Cinnamomum zeylanicum essential oils (EOs) in vapor phase was tested in vitro against B. cinerea, Monilinia fructicola , Monilinia fructigena , and Monilinia laxa . For the experiments, a protocol using a volatile organic compounds (VOC) chamber was designed. Results indicate a dose-dependent inhibitory activity of all the tested EOs, with O. vulgare , T. vulgaris , and T. serpyllum being the most active ones, with minimum inhibitory concentrations (MIC) of 22.73, 45.45, and 22.73 µl/L, respectively, against B. cinerea and a range between 5.64 and 22.73 µl/L against the three Monilinia spp. Overall, B. cinerea presented lower sensitivity to vapor-phase EOs than any of the Monilinia strains, except for the C. zeylanicum EO, which consistently showed higher inhibition against B. cinerea . Among the three Monilinia spp., M. fructicola was the least sensitive, while M. fructigena was the most sensitive. The use of VOC chambers proved to be a reliable protocol for the assessment of antimicrobial activities of EOs. These results suggest that the VOC emitted by the tested EOs are effective towards important decay-causing fungi, and that they could be used for the control of gray mold and brown rot in in vivo trials., Competing Interests: SÁ -G possesses a 55% share as main inventor. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The authors declare the existence of potential financial competing interests derived from the patent held by the University of León regarding the VOC Chamber. The funders had no role in the design of the study; in the collection; analyses; or interpretation of data; in the writing of the manuscript; or in the decision to publish the results. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2023 Álvarez-García, Moumni and Romanazzi.)

Harvested fruit and vegetables are perishable, subject to desiccation, show increased respiration during ripening, and are colonized by postharvest fungal pathogens. Induced resistance is a strategy to control diseases by eliciting biochemical processes in fruits and vegetables. This is accomplished by modulating the progress of ripening and senescence, which maintains the produce in a state of heightened resistance to decay-causing fungi. Utilization of induced resistance to protect produce has been improved by scientific tools that better characterize physiological changes in plants. Induced resistance slows the decline of innate immunity after harvest and increases the production of defensive responses that directly inhibit plant pathogens. This increase in defense response in fruits and vegetables contributes to higher amounts of phenols and antioxidant compounds, improving both the quality and appearance of the produce. This review summarizes mechanisms and treatments that induce resistance in harvested fruits and vegetables to suppress fungal colonization. Moreover, it highlights the importance of host maturity and stage of ripening as limiting conditions for the improved expression of induced-resistance processes.

Pathogens and pests constantly challenge food security and safety worldwide. The use of plant protection products to manage them raises concerns related to human health, the environment, and economic costs. Basic substances are active, non-toxic compounds that are not predominantly used as plant protection products but hold potential in crop protection. Basic substances' attention is rising due to their safety and cost-effectiveness. However, data on their protection levels in crop protection strategies are lacking. In this review, we critically analyzed the literature concerning the field application of known and potential basic substances for managing diseases and pests, investigating their efficacy and potential integration into plant protection programs. Case studies related to grapevine, potato, and fruit protection from pre- and post-harvest diseases and pests were considered. In specific cases, basic substances and chitosan in particular, could complement or even substitute plant protection products, either chemicals or biologicals, but their efficacy varied greatly according to various factors, including the origin of the substance, the crop, the pathogen or pest, and the timing and method of application. Therefore, a careful evaluation of the field application is needed to promote the successful use of basic substances in sustainable pest management strategies in specific contexts.

Both chitosan (CTS) and chitooligosaccharide (COS) can promote fruit healing. However, whether the two chemicals regulate reactive oxygen species (ROS) homeostasis during wound healing of pear fruit remains unknown. In this study, the wounded pear fruit (Pyrus bretschneideri cv. Dongguo) was treated with a 1 g L -1 CTS and COS. We found CTS and COS treatments increased NADPH oxidase and superoxide dismutase activities, and promoted O 2 .- and H 2 O 2 production at wounds. CTS and COS also enhanced the activities of catalase, peroxidase, ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione reductase, and elevated the levels of ascorbic acid and glutathione. In addition, the two chemicals improved antioxidant capacity in vitro and maintained cell membrane integrity at fruit wounds during healing. Taken together, CTS and COS can regulate ROS homeostasis at wounds of pear fruit during healing by scavenging excessive H 2 O 2 and improving antioxidant capacity. Overall, the COS demonstrated superior performance over the CTS., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this manuscript. This work is original research, and the data presented in the manuscript has not been published elsewhere., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Xylem anatomy may change in response to environmental or biotic stresses. Vascular occlusion, an anatomical modification of mature xylem, contributes to plant resistance and susceptibility to different stresses. In woody organs, xylem occlusions have been examined as part of the senescence process, but their presence and function in leaves remain obscure. In grapevine, many stresses are associated with premature leaf senescence inducing discolorations and scorched tissue in leaves. However, we still do not know whether the leaf senescence process follows the same sequence of physiological events and whether leaf xylem anatomy is affected in similar ways. In this study, we quantified vascular occlusions in midribs from leaves with symptoms of the grapevine disease esca, magnesium deficiency and autumn senescence. We found higher amounts of vascular occlusions in leaves with esca symptoms (in 27% of xylem vessels on average), whereas the leaves with other symptoms (as well as the asymptomatic controls) had far fewer occlusions (in 3% of vessels). Therefore, we assessed the relationship between xylem occlusions and esca leaf symptoms in four different countries (California in the USA, France, Italy and Spain) and eight different cultivars. We monitored the plants over the course of the growing season, confirming that vascular occlusions do not evolve with symptom age. Finally, we investigated the hydraulic integrity of leaf xylem vessels by optical visualization of embolism propagation during dehydration. We found that the occlusions lead to hydraulic dysfunction mainly in the peripheral veins compared with the midribs in esca symptomatic leaves. These results open new perspectives on the role of vascular occlusions during the leaf senescence process, highlighting the uniqueness of esca leaf symptoms and its consequence on leaf physiology., (© The Author(s) 2022. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Strawberry is a perishable fruit with a limited shelf life after harvest due to deterioration of quality and the development of gray mold, Rhizopus rot and other minor diseases. In this study, the effectiveness of commercial compounds based on chitosan, phosphoric acid plus micronutrients, and sweet orange essential oil (EO) in reducing decay and optimizing the quality of strawberries was analyzed. The plant canopy of a greenhouse crop was sprayed once and strawberry fruit were harvested three days later. Gray mold infections were evaluated after chilled storage for seven days at 4 ± 0.5 °C followed by five days shelf life. The qualitative parameters were recorded at harvest (initial day) and after three days of storage at room temperature (RT, 20 °C) or after cold storage and shelf life (CS, 4 °C). The application of sweet orange EO increased the antioxidant and flavonoid content at harvest, while a decrease was reported following three days of storage at RT. At the same time, increased ethylene production and weight loss were observed during CS three days after harvesting. Chitosan treatment maintained the harvest fruit quality and was effective in the control of postharvest decay. Our results suggest that the investigated natural compounds could improve strawberry quality after harvest. Since chitosan performed best in terms of maintaining quality and reducing postharvest decay, it could be considered as a good substitute for chemical-synthetic fungicides for the preservation of strawberry postharvest gray mold.

Fresh fruits and vegetables contain high percentage of water and continue metabolic activity after being harvested, resulting in ripening, increased sensitivity to decay-causing fungi, and consequent loss and waste. Edible coatings are prepared from naturally occurring renewable sources and can contribute to reducing waste, respecting environment, and consumer health. Chitosan and other edible coatings form a thin layer surrounding fresh produce that acts as a protective agent, extending shelf life, and have the potential to control their ripening process and maintain nutritional properties of the coated product. This review discusses recent research on the application of chitosan and other edible coatings to prevent fungal decay, keep the quality, and reduce fresh product waste., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Background: The grape volatile fraction determines to a great extent its aroma, which is one of the most important characteristics influencing wine quality and consumer preferences. Grapevine downy mildew (GDM) is one of the most important and devastating diseases of grapevines worldwide. In this study, the impact on the volatile composition of cv. Verdicchio grapes of classical copper formulations, was compared to that of alternative products. Thus, 11 treatments were foliar applied throughout one grapevine cycle., Results: Most of the volatile compounds present in the grapes were not affected by the treatments used in order to prevent GDM. In the case of the total C 13 norisoprenoids, some differences were found between grapes untreated control and those applied with the grapefruit seed extract. Moreover, the content of alcohols was smaller in grapes from Bordeaux mixture treatment and higher in the samples from chitosan application., Conclusion: Therefore, from the qualitative point of view of the berry, treatment with tested products alternative to copper is recommended, which minimize the environmental and health problems that this heavy metal brings to the soil and in the winery, since it means that their applications did not affect the grape aroma. © 2022 Society of Chemical Industry., (© 2022 Society of Chemical Industry.)

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.

Grapevine Bois noir (BN) is associated with ' Candidatus Phytoplasma solani'. It has been recorded in vineyards throughout Europe as well as in different countries in Asia, where it now constitutes a threat to Iranian viticulture. BN is strictly dependent on ' Ca . P. solani' strains, wild host plants, and insect vectors. The molecular typing of ' Ca . P. solani', based on the nonribosomal gene tuf and the two hypervariable markers vmp 1 and stamp , is valuable for the reconstruction and clarification of the pathways of BN spread. In this study, an RFLP analysis was performed on the vmp 1 gene, and a single-nucleotide polymorphism analysis confirmed new vmp types in ' Ca . P. solani'. A stamp gene phylogenetic analysis allowed us to distinguish between the new genotype infections in the grapevines and the 'weeds' Convolvulus arvensis and Erigeron bonariensis in Iranian vineyards, highlighting the close genetic relatedness of the strains of ' Ca . P. solani' found in Iran and Azerbaijan. The most common genotype in the grapevines was tuf b/V24/ stamp III, which was associated with C . arvensis . This information contributes toward the identification of further routes of introduction of ' Ca . P. solani' in Iran to sustain the control measures for the management of BN.

Synthetic pesticides are widely used to protect crops from pathogens and pests, especially for fruits and vegetables, and this may lead to the presence of residues on fresh produce. Improving the sustainability of agriculture and, at the same time, reducing the adverse effects of synthetic pesticides on human health requires effective alternatives that improve the productivity while maintaining the food quality and safety. Moreover, retailers increasingly request fresh produce with the amounts of pesticides largely below the official maximum residue levels. Basic substances are relatively novel compounds that can be used in plant protection without neurotoxic or immune-toxic effects and are still poorly known by phytosanitary consultants (plant doctors), researchers, growers, consumers, and decision makers. The focus of this review is to provide updated information about 24 basic substances currently approved in the EU and to summarize in a single document their properties and instructions for users. Most of these substances have a fungicidal activity (calcium hydroxide, chitosan, chitosan hydrochloride, Equisetum arvense L., hydrogen peroxide, lecithins, cow milk, mustard seed powder, Salix spp., sunflower oil, sodium chloride, sodium hydrogen carbonate, Urtica spp., vinegar, and whey). Considering the increasing requests from consumers of fruits and vegetables for high quality with no or a reduced amount of pesticide residues, basic substances can complement and, at times, replace the application of synthetic pesticides with benefits for users and for consumers. Large-scale trials are important to design the best dosage and strategies for the application of basic substances against pathogens and pests in different growing environments and contexts.

Monilinia species are among the most devastating fungi worldwide as they cause brown rot and blossom blight on fruit trees. To understand the molecular bases of their pathogenic lifestyles, we compared the newly assembled genomes of single strains of Monilinia fructicola , M. fructigena and M. laxa , with those of Botrytis cinerea and Sclerotinia sclerotiorum , as the closest species within Sclerotiniaceae . Phylogenomic analysis of orthologous proteins and syntenic investigation suggest that M. laxa is closer to M. fructigena than M. fructicola , and is closest to the other investigated Sclerotiniaceae species. This indicates that M. laxa was the earliest result of the speciation process. Distinct evolutionary profiles were observed for transposable elements (TEs). M. fructicola and M. laxa showed older bursts of TE insertions, which were affected (mainly in M. fructicola ) by repeat-induced point (RIP) mutation gene silencing mechanisms. These suggested frequent occurrence of the sexual process in M. fructicola . More recent TE expansion linked with low RIP action was observed in M. fructigena , with very little in S. sclerotiorum and B. cinerea . The detection of active non-syntenic TEs is indicative of horizontal gene transfer and has resulted in alterations in specific gene functions. Analysis of candidate effectors, biosynthetic gene clusters for secondary metabolites and carbohydrate-active enzymes, indicated that Monilinia genus has multiple virulence mechanisms to infect host plants, including toxins, cell-death elicitor, putative virulence factors and cell-wall-degrading enzymes. Some species-specific pathogenic factors might explain differences in terms of host plant and organ preferences between M. fructigena and the other two Monilinia species., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 De Miccolis Angelini, Landi, Raguseo, Pollastro, Faretra and Romanazzi.)

Background: Botrytis cinerea ( B. cinerea ) is responsible for grape infection and damage to the winemaking and table grape sectors. Although anti- Botrytis chemicals are available, they are considered unsustainable for resistance phenomenon and adverse effects on the environment and human health. Research is focused on developing alternative approaches, such as exploiting biological control agents (BCAs). In this context, 19 yeasts of the genera Cryptococcus , Aureobasidium , Metschnikowia , Kluyveromyces and Wickerhamomyces were tested as antimicrobial agents against B. cinerea development., Methods: A combination of in vitro tests based on dual-culture methods, volatile organic compound production assay, laboratory tests on grape berries (punctured and sprayed with yeasts) and field experiments based on yeast treatments on grapes in vineyards allowed the selection of two potential BCAs., Results: M. pulcherrima DiSVA 269 and A. pullulans DiSVA 211 exhibited the best ability to contain the development of B. cinerea , showing the severity, the decay and the McKinney index lower than a commercial biological formulation consisting of a mixture of two different A. pullulans strains, which were used as positive controls., Conclusions: The results indicated that the selected strains were effective BCA candidates to counteract B. cinerea in the field, applying them in the partial or total replacement of conventional treatments.

Stagonosporopsis cucurbitacearum is an important seedborne pathogen of squash ( Cucurbita maxima ). The aim of our work was to develop a rapid and sensitive diagnostic tool for detection and quantification of S. cucurbitacearum in squash seed samples, to be compared with blotter analysis, that is the current official seed test. In blotter analysis, 29 of 31 seed samples were identified as infected, with contamination from 1.5 to 65.4%. A new set of primers (DB1F/R) was validated in silico and in conventional, quantitative real-time PCR (qPCR) and droplet digital (dd) PCR. The limit of detection of S. cucurbitacearum DNA for conventional PCR was ∼1.82 × 10 -2 ng, with 17 of 19 seed samples positive. The limit of detection for ddPCR was 3.6 × 10 -3 ng, which corresponded to 0.2 copies/μl. Detection carried out with artificial samples revealed no interference in the absolute quantification when the seed samples were diluted to 20 ng. All seed samples that showed S. cucurbitacearum contamination in the blotter analysis were highly correlated with the absolute quantification of S. cucurbitacearum DNA (copies/μl) in ddPCR ( R 2 = 0.986; p ≤ 0.01). Our ddPCR protocol provided rapid detection and absolute quantification of S. cucurbitacearum , offering a useful support to the standard procedure., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Murolo, Moumni, Mancini, Allagui, Landi and Romanazzi.)

The greatest challenge for the avocado ( Persea americana Miller) industry is to maintain the quality of the fruit to meet consumer requirements. Anthracnose is considered the most important disease in this industry, and it is caused by different species of the genus Colletotrichum , although other pathogens can be equally important. The defense mechanisms that fruit naturally uses can be triggered in response to the attack of pathogenic microorganisms and also by the application of exogenous elicitors in the form of GRAS compounds. The elicitors are recognized by receptors called PRRs, which are proteins located on the avocado fruit cell surface that have high affinity and specificity for PAMPs, MAMPs, and DAMPs. The activation of defense-signaling pathways depends on ethylene, salicylic, and jasmonic acids, and it occurs hours or days after PTI activation. These defense mechanisms aim to drive the pathogen to death. The application of essential oils, antagonists, volatile compounds, chitosan and silicon has been documented in vitro and on avocado fruit, showing some of them to have elicitor and fungicidal effects that are reflected in the postharvest quality of the fruit and a lower incidence of diseases. The main focus of these studies has been on anthracnose diseases. This review presents the most relevant advances in the use of natural compounds with antifungal and elicitor effects in plant tissues.

Anthracnose of papaya ( Carica papaya L.) caused by the fungus Colletotrichum spp. is one of the most economically important postharvest diseases. Coating with chitosan (CS) and Ruta graveolens essential oil (REO) might represent a novel eco-friendly method to prevent postharvest anthracnose infection. These compounds show both antimicrobial and eliciting activities, although the molecular mechanisms in papaya have not been investigated to date. In this study, the effectiveness of CS and REO alone and combined (CS-REO) on postharvest anthracnose of papaya fruit during storage were investigated, along with the expression of selected genes involved in plant defense mechanisms. Anthracnose incidence was reduced with CS, REO, and CS-REO emulsions after 9 days storage at 25°C, by 8, 21, and 37%, respectively, with disease severity reduced by 22, 29, and 44%, respectively. Thus, McKinney's decay index was reduced by 22, 30, and 44%, respectively. A protocol based on reverse transcription quantitative real-time PCR (RT-qPCR) was validated for 17 papaya target genes linked to signaling pathways that regulate plant defense, pathogenesis-related protein, cell wall-degrading enzymes, oxidative stress, abiotic stress, and the phenylpropanoid pathway. CS induced gene upregulation mainly at 6 h posttreatment (hpt) and 48 hpt, while REO induced the highest upregulation at 0.5 hpt, which then decreased over time. Furthermore, CS-REO treatment delayed gene upregulation by REO alone, from 0.5 to 6 hpt, and kept that longer over time. This study suggests that CS stabilizes the volatile and/or hydrophobic substances of highly reactive essential oils. The additive effects of CS and REO were able to reduce postharvest decay and affect gene expression in papaya fruit., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Landi, Peralta-Ruiz, Chaves-López and Romanazzi.)

In this work we analyzed the relationship among native arbuscular mycorrhizal fungi (AMF) and vine roots affected by esca, a serious grapevine trunk disease. The AMF symbiosis was analyzed on the roots of neighboring plants (symptomatic and asymptomatic to esca) in 14 sites of three vineyards in Marche region (central-eastern Italy). The AMF colonization intensity, identified by non-vital staining, showed higher value in all esca symptomatic plants (ranging from 24.6% to 61.3%) than neighboring asymptomatic plants (from 17.4% to 57.6%). The same trend of Glomeromycota phylum abundance was detected by analyzing fungal operational taxonomic units (OTUs) linked to the AMF community, obtained by amplicon high throughput analysis of ITS 1 region. Overall, the highest amount of OTUs was detected on roots from symptomatic plants (0.42%), compared to asymptomatic roots (0.29%). Specific primer pairs for native Rhizophagus irregularis and Funneliformis mosseae AMF species, were designed in 28S rRNA and large subunit (LSU) ribosomal RNA, respectively, and droplet digital PCR protocol for absolute quantification was set up. A higher number of DNA copies of both fungal species were detected more frequently in symptomatic than asymptomatic vines. Our study suggests a relationship between esca and native AMF in grapevine. These results underline the importance of native rhizosphere microbial communities for a better knowledge of grapevine esca disease.

Grapevine downy mildew (GDM) is one of the most serious diseases of grapevines. Limitations to the use of copper-based products in organic agriculture according to the European Union (EU) regulation EU/2002/473 and the later EU Commission implementing regulation 2018/1981 have promoted a search for alternatives. This 5-year field trial evaluated the effectiveness of several strategies against GDM using different chitosan-based formulations and application rates in comparison with other natural compounds applied individually or with copper hydroxide. Trials were performed in commercial vineyards with different environmental conditions and grapevine cultivars. For the natural compounds applied as individual treatments, a 0.5%/0.8% chitosan formulation provided the best protection against GDM; the other compounds and formulations were less effective. When copper hydroxide use was halved by combining it with the natural compounds according to three different strategies, the GDM incidence, severity, and McKinney index were reduced, particularly for copper hydroxide applied in combination with the 0.5%/0.8% chitosan formulation. The 0.5%/0.8% chitosan formulation alone and with copper hydroxide provided good protection against GDM during both high-pressure and low-pressure disease seasons. Therefore, chitosan represents a good alternative to copper formulations for the control of GDM and both organic and integrated disease management.

Subtropical fruit such as avocados ( Persea americana ), mangoes ( Mangifera indica L.), and papayas ( Carica papaya L.) are economically important in international trade and predominantly exported to European destinations. These fruits are highly consumed due to their health benefits. However, due to long-distance shipping and the time required to reach the retail department stores, postharvest losses, due to postharvest decay occurring during the supply chain, affect the fruit quality on arrival at the long-distance distribution points. Currently, the use of synthetic fungicide, Prochloraz ® , is used at the packing line to reduce postharvest decay and retain the overall quality of mangoes and avocados. Due to the ban imposed on the use of synthetic fungicides on fresh fruit, several studies have focused on the development of alternative technologies to retain the overall quality during marketing. Among the developed alternative technologies for commercial adoption is the use of edible coatings, such as chitosan biocontrol agents and essential oil vapors. The objective of this review is to summarize and analyze the recent advances and trends in the use of these alternative postharvest treatments on anthracnose decay in avocados, mangoes, and papayas., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Sivakumar, Tuna Gunes and Romanazzi.)

Although chestnut mosaic disease (ChMD) was described several decades ago, its etiology is still not clear. Using classical approaches and high-throughput sequencing (HTS) techniques, we identified a novel Badnavirus that is a strong etiological candidate for ChMD. Two disease sources from Italy and France were submitted to HTS-based viral indexing. Total RNAs were extracted, ribodepleted, and sequenced on an Illumina NextSeq500 (2 × 150 nt or 2 × 75 nt). In each source, we identified a single contig of ≈7.2 kb that corresponds to a complete circular viral genome and shares homologies with various badnaviruses. The genomes of the two isolates have an average nucleotide identity of 90.5%, with a typical badnaviral genome organization comprising three open reading frames. Phylogenetic analyses and sequence comparisons showed that this virus is a novel species; we propose the name Chestnut mosaic virus (ChMV). Using a newly developed molecular detection test, we systematically detected the virus in symptomatic graft-inoculated indicator plants (chestnut and American oak) as well in chestnut trees presenting typical ChMD symptoms in the field (100 and 87% in France and Italy surveys, respectively). Datamining of publicly available chestnut sequence read archive transcriptomic data allowed the reconstruction of two additional complete ChMV genomes from two Castanea mollissima sources from the United States as well as ChMV detection in C. dentata from the United States. Preliminary epidemiological studies performed in France and central eastern Italy showed that ChMV has a high incidence in some commercial orchards and low within-orchard genetic diversity.

Essential oils are gaining interest as environmentally friendly alternatives to synthetic fungicides for management of seedborne pathogens. Here, seven essential oils were initially tested in vivo for disinfection of squash seeds ( Cucurbita maxima ) naturally contaminated by Stagonosporopsis cucurbitacearum , Alternaria alternata , Fusarium fujikuro , Fusarium solani , Paramyrothecium roridum , Albifimbria verrucaria , Curvularia spicifera , and Rhizopus stolonifer . The seeds were treated with essential oils from Cymbopogon citratus , Lavandula dentata , Lavandula hybrida , Melaleuca alternifolia , Laurus nobilis , and Origanum majorana (#1 and #2). Incidence of S. cucurbitacearum was reduced, representing a range between 67.0% in L. nobilis to 84.4% in O. majorana #2. Treatments at 0.5 mg/mL essential oils did not affect seed germination, although radicles were shorter than controls, except with C. citratus and O . majorana #1 essential oils. Four days after seeding, seedling emergence was 20%, 30%, and 10% for control seeds and seeds treated with C. citratus essential oil (0.5 mg/mL) and fungicides (25 g/L difenoconazole plus 25 g/L fludioxonil). S . cucurbitacearum incidence was reduced by ~40% for plantlets from seeds treated with C. citratus essential oil. These data show the effectiveness of this essential oil to control the transmission of S. cucurbitacearum from seeds to plantlets, and thus define their potential use for seed decontamination in integrated pest management and organic agriculture.

Background: The role of fungi in cocoa crops is mainly associated with plant diseases and contamination of harvest with unwanted metabolites such as mycotoxins that can reach the final consumer. However, in recent years there has been interest in discovering other existing interactions in the environment that may be beneficial, such as antagonism, commensalism, and the production of specific enzymes, among others. Scope and approach: This review summarizes the different fungi species involved in cocoa production and the cocoa supply chain. In particular, it examines the presence of fungal species during cultivation, harvest, fermentation, drying, and storage, emphasizing the factors that possibly influence their prevalence in the different stages of production and the health risks associated with the production of mycotoxins in the light of recent literature. Key findings and conclusion: Fungi associated with the cocoa production chain have many different roles. They have evolved in a varied range of ecosystems in close association with plants and various habitats, affecting nearly all the cocoa chain steps. Reports of the isolation of 60 genera of fungi were found, of which only 19 were involved in several stages. Although endophytic fungi can help control some diseases caused by pathogenic fungi, climate change, with increased rain and temperatures, together with intensified exchanges, can favour most of these fungal infections, and the presence of highly aggressive new fungal genotypes increasing the concern of mycotoxin production. For this reason, mitigation strategies need to be determined to prevent the spread of disease-causing fungi and preserve beneficial ones.

Essential oils represent novel alternatives to application of synthetic fungicides to control against seedborne pathogens. This study investigated seven essential oils for in vitro growth inhibition of the main seedborne pathogens of cucurbits. Cymbopogon citratus essential oil completely inhibited mycelial growth of Stagonosporopsis cucurbitacearum and Alternaria alternata at 0.6 and 0.9 mg/mL, respectively. At 1 mg/mL, Lavandula dentata , Lavandula hybrida , Melaleuca alternifolia , Laurus nobilis, and two Origanum majorana essential oils inhibited mycelia growth of A. alternata by 54%, 71%, 68%, 36%, 90%, and 74%, respectively. S. cucurbitacearum mycelia growth was more sensitive to Lavandula essential oils, with inhibition of ~74% at 1 mg/mL. To determine the main compounds in these essential oils that might be responsible for this antifungal activity, they were analyzed by gas chromatography-mass spectrometry (GC-MS). C. citratus essential oil showed cirtal as its main constituent, while L. dentata and L. nobilis essential oils showed eucalyptol. The M. alternifolia and two O. majorana essential oils had terpinen-4-ol as the major constituent, while for L. hybrida essential oil, this was linalool. Thus, in vitro, these essential oils can inhibit the main seedborne fungi of cucurbits, with future in vivo studies now needed to confirm these activities.

Consumers are increasingly aware of the importance of regular consumption of fresh fruit in their diet. Since fresh fruit are highly sensitive to postharvest decay, several investigations focused on the study natural compounds alternative to synthetic fungicides, to extend their shelf life. A long list of studies reported the effectiveness of the natural biopolymer chitosan in control of postharvest diseases of fresh fruit. However, these findings remain controversial, with many mixed claims in the literature. In this work, we used random-effects meta-analysis to investigate the effects of 1% chitosan on (a) postharvest decay incidence; (b) mycelium growth of fungal pathogens Botrytis cinerea, Penicillium spp., Colletotrichum spp. and Alternaria spp.; and (c) phenylalanine ammonia-lyase, chitinase and β-1,3-glucanase activities. Chitosan significantly reduced postharvest disease incidence (mean difference [MD], -30.22; p < 0.00001) and in vitro mycelium growth (MD, -54.32; p  < 0.00001). For host defense responses, there were significantly increased activities of β-1,3-glucanase (MD, 115.06; p = 0.003) and chitinase (MD, 75.95; p < 0.0002). This systematic review contributes to confirm the multiple mechanisms of mechanisms of action of chitosan, which has unique properties in the natural compound panorama. Chitosan thus represents a model plant protection biopolymer for sustainable control of postharvest decay of fresh fruit., (© 2020 Institute of Food Technologists®.)

Grapevine trunk diseases (GTDs) are the most widespread fungal diseases, affecting grapevines in all the major growing regions of the world, and their complete eradication is still not possible. Aiming to search alternatives to avoid the spread and high incidence of these diseases, the present work intended to molecularly identify the grapevine endophytic community, the phytopathogenic fungi associated with GTDs in vineyards within the Alentejo region, and to test potential antagonist microorganisms as biological control candidates against GTDs-associated fungi. Grapevine endophytic community showed a wide variety of fungi in GTDs' asymptomatic and symptomatic plants, nine of them previously described as GTDs-associated fungi. GTDs prevalent fungi identified in symptomatic plants were Diaporthe sp., Neofusicoccum sp., and H. viticola . Almost all these fungi were also detected in asymptomatic plants, which shows the importance of investigating the interactions of fungal communities and confirms the need for early diagnosis of these diseases. Direct inhibition antagonism tests were performed among identified endophytes and GTDs phytopathogenic fungi, and all the endophyte fungi showed potential as biocontrol agents. Our findings suggest that endophytes are promising candidates for their use in biological control due to their antagonistic activity against the mycelia growth of some GTDs-associated fungi.

Grapevine Bois noir (BN) is associated with infection by " Candidatus Phytoplasma solani" (CaPsol). In this study, an array of CaPsol strains was identified from 142 symptomatic grapevines in vineyards of northern, central, and southern Italy and North Macedonia. Molecular typing of the CaPsol strains was carried out by analysis of genes encoding 16S rRNA and translation elongation factor EF-Tu, as well as eight other previously uncharacterized genomic fragments. Strains of tuf -type a and b were found to be differentially distributed in the examined geographic regions in correlation with the prevalence of nettle and bindweed. Two sequence variants were identified in each of the four genomic segments harboring hlyC , cbiQ - glyA , trxA - truB - rsuA , and rplS - tyrS - csdB , respectively. Fifteen CaPsol lineages were identified based on distinct combinations of sequence variations within these genetic loci. Each CaPsol lineage exhibited a unique collective restriction fragment length polymorphism (RFLP) pattern and differed from each other in geographic distribution, probably in relation to the diverse ecological complexity of vineyards and their surroundings. This RFLP-based typing method could be a useful tool for investigating the ecology of CaPsol and the epidemiology of its associated diseases. Phylogenetic analyses highlighted that the sequence variants of the gene hlyC , which encodes a hemolysin III-like protein, separated into two clusters consistent with the separation of two distinct lineages on the basis of tufB gene sequences. Alignments of deduced full protein sequences of elongation factor-Tu ( tufB gene) and hemolysin III-like protein ( hlyC gene) revealed the presence of critical amino acid substitutions distinguishing CaPsol strains of tuf -type a and b. Findings from the present study provide new insights into the genetic diversity and ecology of CaPsol populations in vineyards.

Bois noir is caused by ' Candidatus Phytoplasma solani', and it is one of the most important and widespread diseases in the Euro-Mediterranean region. There are complex interactions between phytoplasma and grapevines, weeds, and vectors. These ecological relationships can be tracked according to molecular epidemiology. The aims of the 2-year study (2014-2015) were to describe incidence and spatial distribution of Bois noir in a vineyard with three grapevine varieties in Sicily, and to identify the molecular types of the tuf and vmp 1 genes in these naturally infected grapevines, according to the potential reservoir plants and vectors. Disease incidence in 2015 was significantly higher in 'Chardonnay' (up to 35%) than for 'Nero d'Avola' and 'Pinot noir' (<5%). All grapevine, weed, and insect samples were infected by ' Ca. P. solani' tuf -type b. Most of the collected insects were strictly related to Vitis spp. and belonged to Neoaliturus fenestratus , Empoasca spp., and Zygina rhamni . The characterization of the vmp 1 gene revealed six different vmp types in grapevines (V1, V4, V9, V11, V12, V24), three in weeds (V4, V9, V11), and four in insects (V4, V9, V11, V24). Notably, V4, V9, appear both in hosts and vectors, with V9 predominant. Virtual restriction fragment length polymorphism (RFLP) analysis based on the nucleotide sequences supported the data of the conventional RFLP. Connections between the molecular data recorded in the vineyard ecosystems and the application of innovative tools based on the geostatistical analysis will contribute to further clarification of the specific ecological and epidemiological aspects of ' Ca. P. solani' in Sicily.

Black truffle ( Tuber melanosporum Vitt.) is a fine agro-food product known for its unique aroma and very limited shelf life (maximum of 5-7 days, room temperature). Hypobaric packaging at 30 kPa, a mix of 1% O 2 /99% N 2 , and 40% CO 2 /60% N 2 were studied to prolong the shelf life of black truffle at 4 °C in sealed polypropylene vessels, compared to normal atmosphere. Epiphytic microbial population, firmness, weight loss, CO 2 formation, and sensory properties were monitored weekly up to 35 days of storage and were related to the volatile profile. Principal components analysis revealed good correlation between the storage time and the decrease of firmness, and the increase of the microbial count and CO 2 production. Only truffles stored under hypobaric conditions showed an acceptable quality after 14 days storage. Hypobaric packaging is a cheap strategy to prevent the swelling of vessels caused by respiration and can reduce the deviation from the high-quality level of the fresh product from one to at least two weeks.

Grapevine Bois noir (BN) is caused by ' Candidatus Phytoplasma solani' (' Ca . P. solani') and is one of the most important phytoplasma diseases in the Euro-Mediterranean viticultural areas. The epidemiology of BN can include grapevine as a plant host and is usually transmitted via sap-sucking insects that inhabit herbaceous host plants. Tracking the spread of ' Ca. P. solani' strains is of great help for the identification of plant reservoirs and insect vectors involved in local BN outbreaks. The molecular epidemiology of ' Ca . P. solani' is primarily based on sequence analysis of the tuf housekeeping gene (which encodes elongation factor Tu). In this study, molecular typing of tuf , through restriction fragment length polymorphism and sequencing, was carried out on grapevine samples from Iranian vineyards. According to the molecular characterization, three molecular types- tuf b1, tuf b5 and tuf b6-were found, with tuf b1 being the most prominent. These data provide further knowledge of tuf gene diversity and question the ecological role of such "minor" tuf types in Iranian vineyards, which have been detected only in grapevines.

Bois noir (BN) is the most important phytoplasma disease of Euro-Mediterranean area and induces severe loss of production and even the death of vines. Understanding the delicate balance between disease progression and recovery of BN infected plants over space and time is crucial to set up management tools. The data collected and analysed allowed to provide insights into dispersal pattern of the disease, caused by'Candidatus Phytoplasma solani'. Point pattern analysis (PPA) was applied to assess the spatial arrangement of symptomatic plants and the spatial correlation of disease levels in four vineyards. For spatio-temporal patterns of BN, a mark-correlation function was applied. Space-time PPA over multiple years (2011-2015) provided graphical visualisation of grapevines more severely affected by BN along the borders of the vineyards, mainly in 2011 when disease incidence was high. PPA across the symptomatic plants in the four vineyards confirmed this visual trend: an overall aggregated pattern at small (<10 m) spatial scales (2013) that were more evident later at all spatial scales (0-15 m). Application of this innovative spatial approach based on point and surface pattern analyses allowed the spread and severity of BN to be monitored, to define the dispersal routes of the pathogen. Such data will contribute to better understand the distribution of symptomatic plants over space and time and to define a model for preventive strategies to reduce future infections.

Squash is one of the most important crops of tropical and temperate regions, and it can be affected by several fungal pathogens. Most of these pathogens infect the seeds, which become an efficient vehicle to disperse seedborne pathogens over long distances, with consequent severe crop losses. The main objective of this study was the identification of the principal seedborne fungi in seeds extracted from 66 samples of asymptomatic and symptomatic squash fruit ( Cucurbita maxima , Cucurbita moschata ) collected in two countries, Tunisia and Italy. The symptoms of fruit decay were identified and classified according to lesion size. Following the blotter test, 14 fungal species were detected from the seeds. Seedborne fungi were identified in all fruit samples tested, including asymptomatic fruit. The most frequent fungi from Tunisian seeds were Alternaria alternata (25.1%), followed by Stagonosporopsis cucurbitacearum (24.6%), Fusarium solani (16.6%), Rhizopus stolonifer (13.3%), F. fujikuroi (7.8%), Albifimbria verrucaria (3.3%), and Stemphylium vesicarium (2.3%). For the fruits from Italy, the most frequently identified fungal species in seed samples were Alternaria alternata (40.0%), followed by F. fujikuroi (20.8%), Stemphylium vesicarium (3.0%), and Curvularia spicifera (2.1%). Morphological identification was confirmed by molecular diagnosis using the available species-specific primers. Furthermore, specific primers were designed to identify Albifimbria verrucaria , Paramyrothecium roridum , and Stemphylium vesicarium . Application of seed-health testing methods, including such conventional and molecular diagnostic tools, will help to improve seed quality and crop yields.

Monilinia laxa is the causal agent of brown rot on stone fruit, and it can cause heavy yield losses during field production and postharvest storage. This article reports the draft genome assembly of the M. laxa Mlax316 strain, obtained using a hybrid genome assembly with both Illumina short-reads and PacBio long-reads sequencing technologies. The complete draft genome consists of 49 scaffolds with total size of 42.81 Mb, and scaffold N 50 of 2,449.4 kb. Annotation of the M. laxa assembly identified 11,163 genes and 12,424 proteins which were functionally annotated. This new genome draft improves current genomic resources available for M. laxa and represents a useful tool for further research into its interactions with host plants and into evolution in the Monilinia genus.

Brown rot is a worldwide fungal disease of stone and pome fruit that is caused by several Monilinia species. Among these, Monilinia fructicola can cause severe preharvest and postharvest losses, especially for stone fruit. Here, we present a high-quality draft genome assembly of M. fructicola Mfrc123 strain obtained using both Illumina and PacBio sequencing technologies. The genome assembly comprised 20 scaffolds, including 29 telomere sequences at both ends of 10 scaffolds, and at a single end of 9 scaffolds. The total length was 44.05 Mb, with a scaffold N50 of 2,592 kb. Annotation of the M. fructicola assembly identified a total of 12,118 genes and 13,749 proteins that were functionally annotated. This newly generated reference genome is expected to significantly contribute to comparative analysis of genome biology and evolution within Monilinia species., (© The Author(s) 2019. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.)

Grapevine ( Vitis vinifera L.) is one of the most important horticultural crops in Iran, with >200,000 ha of cultivated area. Recently, outbreaks of the grapevine yellows Bois noir that is associated with phytoplasma strains related to ' Candidatus Phytoplasma solani' were recorded in several Iranian regions. This has resulted in severe economic losses. We carried out a survey in 2015, followed by collection of leaf samples from symptomatic grapevines and weeds. Because no information is available on the molecular epidemiology of ' Ca. P. solani' in Iran, multiple gene analyses were carried out here according to molecular characterization of the tuf and vmp 1 genes. From the molecular characterization, all of the samples (i.e., grapevines, weeds) were infected with tuf b type. Detailed molecular characterization of the vmp 1 gene (i.e., PCR-restriction fragment length polymorphism, sequence analysis) defined five molecular types: V1, V4, V10, V15, and V20. The abundance of Convolvulus arvensis in vineyards and detection of the same ' Ca . P. solani' molecular types in grapevines and weeds suggest that C. arvensis has a major role in Bois noir epidemiology of Iranian vineyards. Therefore, control strategies should be developed to manage these host plants to reduce inoculum sources of the phytoplasma in vineyards.

'Candidatus Phytoplasma solani' is the causal agent of Bois noir (BN) in grapevine (Vitis vinifera). It is usually detected in leaves, where typical disease symptoms are seen. However, little information is available on the presence of this phytoplasma in grapevine roots. Here, we investigated 'Ca. P. solani' in roots collected from 28 symptomatic, 27 recovered and eight asymptomatic grapevine plants. Protocols based on high-resolution melting (HRM) combined with real-time quantitative PCR (qPCR-HRM) and nested-qPCR-HRM were developed to identify 'Ca. P. solani' tuf-type variants with single nucleotide polymorphisms. In all, 21.4% of roots from symptomatic plants were positive to 'Ca. P. solani' using qPCR-HRM, and 60.7% with nested-qPCR HRM. Also, 7.4% of roots from recovered plants were positive using qPCR-HRM, which reached 44.4% using nested-qPCR HRM. These analyses identified tuf-type b1 on 88.2% of the positive samples from symptomatic grapevines, and 66.6% from recovered grapevines, with all other samples identified as tuf-type a. This study reports the presence of 'Ca. P. solani' in the roots of both symptomatic and recovered grapevines. These qPCR-HRM and nested-qPCR-HRM protocols can be applied to increase the sensitivity of detection of, and to simplify and speed up the screening for, 'Ca. P. solani' tuf-types.

Foliar application of biostimulants (including resistance inducers or elicitors) in the vineyard has become an interesting strategy to prevent plant diseases and improve grape quality on the grapevine. This also represents a partial alternative to soil fertilisation, avoiding some of the negative effects to the environment from leaching of nutrients into the groundwater. The foliar applications that most promote the synthesis of secondary metabolites in grape berries are treatments with nitrogen, elicitors, other biostimulants, and waste from the agricultural industry. However, the impact of their use in the vineyard depends on a number of conditions, including mainly the type of compound, application rate, timing and number of applications, and cultivar. This review thus summarises the influence of biostimulants as foliar applications to grapevines on grape amino acids and their phenolic and volatile concentrations, to define the most important factors in their effectiveness. © 2018 Society of Chemical Industry., (© 2018 Society of Chemical Industry.)

Chitosan is a natural biopolymer from crab shells that is known for its biocompatibility, biodegradability, and bioactivity. In human medicine, chitosan is used as a stabilizer for active ingredients in tablets, and is popular in slimming diets. Due to its low toxicity, it was the first basic substance approved by the European Union for plant protection (Reg. EU 2014/563), for both organic agriculture and integrated pest management. When applied to plants, chitosan shows triple activity: (i) elicitation of host defenses; (ii) antimicrobial activity; and (iii) film formation on the treated surface. The eliciting activity of chitosan has been studied since the 1990's, which started with monitoring of enzyme activities linked to defense mechanisms (e.g., chitinase, β-1,3 glucanase, phenylalanine ammonia-lyase) in different fruit (e.g., strawberry, other berries, citrus fruit, table grapes). This continued with investigations with qRT-PCR (Quantitative Real-Time Polymerase Chain Reaction), and more recently, with RNA-Seq. The antimicrobial activity of chitosan against a wide range of plant pathogens has been confirmed through many in-vitro and in-vivo studies. Once applied to a plant surface (e.g., dipping, spraying), chitosan forms an edible coating, the properties of which (e.g., thickness, viscosity, gas and water permeability) depend on the acid in which it is dissolved. Based on data in literature, we propose that overall, the eliciting represents 30 to 40% of the chitosan activity, its antimicrobial activity 35 to 45%, and its film-forming activity 20 to 30%, in terms of its effectiveness in the control of postharvest decay of fresh fruit. As well as being used alone, chitosan can be applied together with many other alternatives to synthetic fungicides, to boost its eliciting, antimicrobial and film-forming properties, with additive, and at times synergistic, interactions. Several commercial chitosan formulations are available as biopesticides, with their effectiveness due to the integrated combination of these three mechanisms of action of chitosan.

Objectives: Monilinia fructigena (phylum Ascomycota, family Sclerotiniaceae) is a plant pathogen that causes brown rot and blossom blight in pome fruit and stone fruit of the Rosaceae family, which can cause significant losses in the field and mainly postharvest. The aim of this study was to create a high-quality draft of the M. fructigena genome assembly and annotation that provides better understanding of the epidemiology of the pathogen and its interactions with the host(s) and will thus improve brown rot management., Data Description: We report here on the genome sequence of M. fructigena strain Mfrg269 that was collected from plum in southern Italy. This is assembled into 131 scaffolds, with a total size of 43.125 Mb, with 9960 unique protein-coding genes. The novel genomic resources allow improved genomic comparisons among the most important pathogens belonging to the Monilinia genus, with the aim being to improve the knowledge of their plant-pathogen interactions, population biology, and control.

Chestnut blight is caused by the fungus Cryphonectria parasitica. As one of the most ecologically important diseases of Castanea spp., C. parasitica can rapidly kill trees. In Europe, mitigation of disease severity took place spontaneously through colonization of C. parasitica by mycoviruses, which reduced the virulence of the fungus. In the framework of a survey, 138 C. parasitica isolates were identified, and virulent/hypovirulent phenotypes were determined through morphological properties and pathogenicity tests. For a pool of four hypovirulent isolates, dsRNA was extracted, cDNA synthesized, and a library subjected to next-generation sequencing. The bioinformatics analysis allowed detecting and reconstructing the complete genome of Cryphonectria hypovirus 1 (CHV-1), denoted as CHV-1 Marche. When compared with the available genomes of other hypoviruses that affected the virulence of C. parasitica, available in databases, CHV-1 Marche showed some nucleotide diversity. The approach used in this study was effective to explore the virome inside a pool of hypovirulent C. parasitica isolates. Next-generation sequencing allowed us to exclude the presence of any other ssRNA and dsRNA viruses infecting the fungus and determine CHV-1 as the only responsible of hypovirulence of C. parasitica in the analyzed samples.

The effectiveness of Wickerhamomyces anomalus, Metschnikowia pulcherrima and Saccharomyces cerevisiae as biocontrol agents on postharvest decay of strawberry (Fragaria x ananassa, cv. 'Alba') fruit, and their inhibitory activities on some decay-causing fungi were evaluated. Volatile organic compounds from these yeasts decreased mycelial growth of Botrytis cinerea by 69%, and by less for Monilinia fructicola, Alternaria alternata, Aspergillus carbonarius, Penicillium digitatum, Cladosporium spp., and Colletotrichum spp. Strawberry fruit exposed to 6-day-old liquid cultures of W. anomalus, M. pulcherrima and S. cerevisiae for 48h showed 89%, 40%, and 32% reductions, respectively, in gray mold McKinney Index. Vapours of ethyl acetate, the main volatile organic compound of these yeasts, completely inhibited B. cinerea growth at 8.97mg/cm 3 , and suppressed gray mold on strawberry fruit at 0.718mg/cm 3 . The biocontrol activities of these yeasts can be ascribed to ethyl acetate, which can be used for control of postharvest gray mold of strawberry fruit., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The use of resistance inducers is a novel strategy to elicit defense responses in strawberry fruit to protect against preharvest and postharvest decay. However, the mechanisms behind the specific resistance inducers are not completely understood. Here, global transcriptional changes in strawberry fruit were investigated using RNA-Seq technology. Preharvest, benzothiadiazole (BTH) and chitosan were applied to the plant canopy, and the fruit were harvested at 6, 12, and 24 h post-treatment. Overall, 5,062 and 5,210 differentially expressed genes (fold change ≥ 2) were identified in these fruits under the BTH and chitosan treatments, respectively, as compared to the control expression. About 80% of these genes were differentially expressed by both elicitors. Comprehensive functional enrichment analysis highlighted different gene modulation over time for transcripts associated with photosynthesis and heat-shock proteins, according to elicitor. Up-regulation of genes associated with reprogramming of protein metabolism was observed in fruit treated with both elicitors, which led to increased storage proteins. Several genes associated with the plant immune system, hormone metabolism, systemic acquired resistance, and biotic and abiotic stresses were differentially expressed in treated versus untreated plants. The RNA-Seq output was confirmed using RT-qPCR for 12 selected genes. This study demonstrates that these two elicitors affect cell networks associated with plant defenses in different ways, and suggests a role for chloroplasts as the primary target in this modulation of the plant defense responses, which actively communicate these signals through changes in redox status. The genes identified in this study represent markers to better elucidate plant/pathogen/resistance-inducer interactions, and to plan novel sustainable disease management strategies.

Among alternatives that are currently under investigation to replace the use of synthetic fungicides to control postharvest diseases in fresh produce and to extend their shelf life, chitosan application has shown promising disease control, at both preharvest and postharvest stages. Chitosan shows a dual mode of action, on the pathogen and on the plant, as it reduces the growth of decay-causing fungi and foodborne pathogens and induces resistance responses in the host tissues. Chitosan coating forms a semipermeable film on the surface of fruit and vegetables, thereby delaying the rate of respiration, decreasing weight loss, maintaining the overall quality, and prolonging the shelf life. Moreover, the coating can provide a substrate for incorporation of other functional food additives, such as minerals, vitamins, or other drugs or nutraceutical compounds that can be used to enhance the beneficial properties of fresh commodities, or in some cases the antimicrobial activity of chitosan. Chitosan coating has been approved as GRAS substance by USFDA, and its application is safe for the consumer and the environment. This review summarizes the most relevant and recent knowledge in the application of chitosan in postharvest disease control and maintenance of overall fruit and vegetable quality during postharvest storage.

Grapevine downy mildew (GDM) is one of the most serious diseases of grapevines. With limitations in the use of copper-based products imposed for organic agriculture by the European Union, research for alternatives is encouraged. The aim of this research was to follow a 2-year trial to evaluate the control of GDM using some alternative compounds, and to determine their effects on shoot growth, plant photosynthesis, and grape quality and quantity. Under low disease pressure, Bordeaux mixture, copper hydroxide, laminarin combined with low copper, and 0.5 and 0.8% chitosan had the lowest GDM incidence, reduced on leaves by 96, 95, 75, 56, and 81%, respectively, compared with the untreated control in the last survey. With high disease pressure, Bordeaux mixture, laminarin combined with Saccharomyces extracts, and 0.5 and 0.8% chitosan had the lowest GDM incidence, reduced on grape by 86, 37, 66, and 75%, respectively, compared with the untreated control in the survey of mid-July. Chitosan at 0.8% lowered net photosynthesis, due to reduced stomatal conductance, leaf area, and dry weight, with no negative effects observed on the quantity of the grape berries and the quality parameters of their juice. Among the alternatives to copper, chitosan provided the best GDM protection and reduced the vigor of the vegetation, inducing physiological changes without negative effects on grape production.

The effectiveness of the control of postharvest decay of strawberry (Fragaria × ananassa, 'Alba' and 'Romina' cvs.) fruit following field applications of chitosan, laminarin, extracts of Abies spp., Polygonum spp., and Saccharomyces spp., an organic acids and calcium combination, and benzothiadiazole, were compared with a fungicide strategy. These compounds were sprayed every 5 days on the strawberry canopy, from flowering to ripening, in 2012 and 2013. The treatments with alternative compounds provided ∼ 30% reduction in postharvest decay of strawberry compared to the water-treated controls, mainly against gray mold and Rhizopus rot, and without negatively affecting fruit color and firmness. Chitosan and benzothiadiazole were the most effective alternative treatments. Preharvest spraying with these alternative treatments can complement the use of conventional fungicides in the control of postharvest decay of strawberry fruit, especially when disease pressure is low., (Copyright © 2015 Elsevier Ltd. All rights reserved.)