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.

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.

To evaluate wood colonization and interactions with Vitis spp. of Phaeomoniella chlamydospora, a fungal agent involved in Esca disease, isolate CBS 229.95 was transformed using a pCT74 construct which contained the genetic markers for synthetic green fluorescent protein (sGFP) and hygromycin B phosphotransferase. Nine stable P. chlamydospora fungal transformants (Pch-sGFP lines) were obtained using polyethylene-glycol-mediated transformation of protoplasts. These were characterized for sgfp and hygromycin B phosphotransferase (hph) genome insertions and for sGFP fluorescence emission, using quantitative polymerase chain reaction and fluorimetric systems, respectively. No correlation was observed between sgfp copy number genome insertion and sGFP fluorescence expression. Cuttings of Vitis vinifera ‘Montepulciano’, ‘Verdicchio’, ‘Sangiovese’, ‘Biancame’, and ‘Cabernet Sauvignon’; and the grapevine rootstocks ‘Kober 5BB’, ‘SO4’, ‘420A’, ‘1103P’, and V. rupestris were inoculated by immersion in a conidial suspension of the selected fungal Pch-sGFP71 line and incubated at 4 ± 1 and 25 ± 1°C. Wood colonization was estimated through epifluorescence microscopy and was affected by incubation temperature. After 6 months at 4 ± 1°C, the fungal growth was completely inhibited. At 25 ± 1°C, the highest extent of wood colonization was recorded in Montepulciano and Verdicchio, with the lowest in the rootstocks SO4 and V. rupestris. The expression of the Pch-sGFP71 transformed line was localized in the xylem area, primarily around the vessels. The use of sGFP-transformed P. chlamydospora helped to clarify different aspects associated with the location of this pathogen in grapevine tissue, before disease symptom expression.

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. 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.

Fungicides are usually applied on strawberries to manage gray mold, induced by the fungal pathogen Botrytis cinerea. In this study, four reduced-risk fungicides (formulations of pyrimethanil, PYR, 175 mL/hL; boscalid, BOS, 80 g/hL; combination fludioxonil, FLU, +cyprodinil, CYP, 110 g/hL) were applied before harvest for the management of post-harvest diseases of strawberries. The resulting fungicide residues on the strawberry fruit were also quantified. Strawberry fruits were harvested at 0, 4, 8, and 12 days following treatment (dft) and kept at 20 ± 1 °C for 4 days or cold-stored for 7 days at 0.5 ± 1 °C, followed by a 4-day shelf life at 20 ± 1 °C. All fungicides significantly reduced gray mold, according to the McKinney Index. At 0 dft and 4 days of shelf life, the FLU + CYP completely prevented post-harvest strawberry gray mold, while PYR and BOS reduced the disease by 88% and 42%, respectively, in comparison to the untreated control. For the duration of experiment, fungicide residues were always below the maximum residue levels, and FLU was the most degraded, thanks to the enzymatic pool of the strawberries. Monitoring fungicide residues in strawberries is essential to provide the consumer information on the safety of this widely consumed fruit. The present study points out the safety of strawberry fruits for consumers, even if the treatment strategy implies the use of fungicide mixtures before the consumption, with fungicide levels always being below the MRL.

‘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.