Botrytis Cinerea Research Articles

Nanoencapsulation reduces the perception of carvacrol odor, enhances the control of Botrytis cinerea growth and preserves grape quality.

Botrytis cinerea is the causal agent of gray mold, which is one of the most widespread and destructive fungal diseases that compromises the productivity and quality of grapes produced throughout the world. This work aimed to verify, for the first time, the impact of unencapsulated carvacrol and encapsulated in Eudragit® nanocapsules (Eud-Carv NCs) and chia mucilage (Chia-Carv NCs) on mycelial growth and spore germination of B. cinerea. The impact of these three forms of carvacrol on grape quality parameters, including texture, pH, color, volatile profile and odor perception were also evaluated. All three forms of carvacrol suppress spore germination and mycelial growth of B. cinerea. When used at sublethal levels, the encapsulated forms (Eud-Carv NCs and Chia-Carv NCs) were more effective by inhibiting up to 90% of fungal growth, while unencapsulated carvacrol suppressed up to 67%. Both nanocapsules showed no effect on the physicochemical characteristics and volatile profile of the grapes. Furthermore, the odor of carvacrol was not perceived in the grapes treated with both encapsulated forms, since the levels of this monoterpene (9.0 to 11.3μg/L over 21days of grape storage) were below the odor threshold (40μg/L). Conversely, when grapes were treated with the unencapsulated form, carvacrol levels were about 10 times higher than the odor threshold, which negatively impacts the sensory perception of the grape. Therefore, the use of carvacrol encapsulated in Eudragit® and chia mucilage proved to be a promising alternative for preventing B. cinerea infections in grapes.

Sulfonated cellulose nanocrystalline- and pea protein isolate-mixture stabilizes the citral nanoemulsion to maintain its functional activity for effectively preserving fruits.

The instability of citral greatly limits its application in food field. This study aimed to develop a safe and green emulsifier-stabilized nanoemulsion (NE) to encapsulate citral for exerting its activities. A series of NEs were prepared using varying proportions (1:2 and 1:3) of sulfonated cellulose nanocrystalline- (CNC-C) and pea protein isolate- (PPI) mixture as emulsifier to encapsulate citral with different content (1%, 2%, and 3%), and their stability, antioxidant and antibacterial activities were evaluated to identify the optimal system. When CNC-C and PPI proportion was 1:3 and citral content was 2% (CC1-P3-C2), the obtained CC1-P3-C2 incorporated into pectin achieved the excellent preservation effect on kiwifruits and blueberries. It was attributed to the stability and functional activities of CC1-P3-C2. On the one hand, after storage (25 d) or at pH11 or 100mM NaCl, its size and polydispersity index were still within acceptance level (<300nm and 0.3). On the other hand, it showed good antioxidant and antibacterial activities against Escherichia coli, Staphylococcus aureus, Botrytis cinerea, and Botryosphaeria dothidea, which was due to its high encapsulation efficiency (96.78%). Therefore, CC1-P3-C2 showed a great application potential in fruit preservation, which also provided a feasible strategy to design stable citral NEs.

Combined analysis of transcriptomics and metabolomics showed that SNAC4 and SNAC9 are negative regulators of the resistance to Botrytis cinerea in tomato.

NAC (NAM, ATAF1/2 and CUC2) is a transcription factor which contributes to the response for both biotic and abiotic stresses. In this study, the regulatory effects and potential mechanisms of SNAC4/9 on resistance to Botrytis cinerea (B. cinerea) were investigated by the differences in physiological and biochemical indices as well as transcriptional and metabolic profiles between SNAC4/9 overexpressed (OE-SNAC4/9) and wild-type (WT) tomato fruit inoculated with B. cinerea. The results showed that OE-SNAC4/9 accelerated the infection to tomato fruit by B. cinerea. Specifically, OE-SNAC4/9 mediated the differential expression of genes related to defense signaling such as ROS, phytohormones (SA and JA) and MAPK cascade, and inhibited the activities of PAL, CHI and GLU. Additionally, SNAC4/9 altered the metabolic flux redirection in each branch pathway of phenylpropane metabolism by regulating the expression of 4CL, CHS1/2, FLS and F3H, with overexpression of SNAC4/9 leading to a decrease in the accumulation of rutin, quercetin, naringenin chalcone and naringenin in tomato fruit. In conclusion, SNAC4/9 may inhibit tomato fruit resistance to B. cinerea by modulating signaling, inhibiting PRs (pathogenesis related proteins) synthesis, and altering metabolic flux flow.

Sporminarin A, a polyketide from Sporormiella isomera as promising tomato seed coating against Botrytis cinerea

Sporminarin A, a polyketide from Sporormiella isomera as promising tomato seed coating against Botrytis cinerea

Antimicrobial Lobophorins from Endophytic Strain Streptomyces sp. R6 Obtained from Azadirachta indica

Endophytic bacteria are an important source for developing antimicrobial substances. With the aim to find eco-friendly antimicrobial agents from natural sources, Streptomyces sp. R6 was isolated from Azadirachta indica. After that, a new spirotetronate natural product, lobophorin S (compound 2), together with lobophorin H8 (compound 1) and a known macrolide compound divergolide C (compound 3) were isolated from the cultural solution of strain R6. These compounds mark the first isolation of marine-derived microbial natural products known as lobophorins (LOBs) from endophytic bacteria. The structures of these three compounds were identified by extensive NMR and HRMS analyses. The antimicrobial activities of these three compounds against eight fungal and four bacterial phytopathogens were separately evaluated. Compound 1 demonstrated better antibacterial activity against Erwinia carotovora, Pseudomonas syringae pv. tomato, and P. syringae pv. lachrymans with MIC values of 3.91, 7.81, and 15.63 μg/mL, respectively. Additionally, compounds 1–3 all showed antifungal activity against Botrytis cinerea, with the MIC values of 1.95, 7.81, and 15.63 μg/mL, respectively. Notably, the in vivo antifungal effect of 1 against B. cinerea was up to 78.51 ± 3.80% at 1.95 µg/mL, significantly surpassing polyoxin B (70.70 ± 3.81%). These results highlight the potential of lobophorins as promising lead compounds for the development of new, sustainable agents to control plant diseases.

Identification of Mycoviruses in Cytospora chrysosperma: Potential Biocontrol Agents for Walnut Canker

Walnut canker is a common disease in the Xinjiang Uygur autonomous region of China, which is caused by Cytospora chrysosperma. To date, there is no effective control measure for this disease. Infection with mycoviruses has been widely proven to reduce the virulence of plant pathogenic fungi, with some mycoviruses even serving as potential biological control agents for plant diseases. In this study, mycoviruses associated with 31 strains of C. chrysosperma from Xinjiang Uygur autonomous region were identified by metatranscriptomic sequencing. Seven new mycoviruses were identified by BLAST and RT-PCR analysis, which were Botrytis cinerea partitivirus 5 (BcPV5), Gammapartitivirus sp-XJ1 (GVsp-XJ1), Botoulivirus sp-XJ2 (BVsp-XJ2), Luoyang Fusar tick virus 2 (LfTV2), Leptosphaeria biglobosa narnavirus 17 (LbNV17), Sclerotinia sclerotiorum narnavirus 6 (SsNV6), and Cytospora ribis mitovirus (CrMV3). Among these, BcPV5, GVsp-XJ1, BVsp-XJ2, CrMV3, and LfTV2 were found to co-infect C. chrysosperma strain WS-11 and significantly reduce both the colony growth rate and virulence of the host. After co-culturing the virus-free WS-FV strain with WS-11, the colony growth rate and virulence of the derivative strain were also decreased. These results provide potential biocontrol resources for the control of walnut canker.

Advances in digital camera-based phenotyping of Botrytis disease development.

Botrytis cinerea is an important generalist fungal plant pathogen that causes great economic losses. Conventional detection methods to identify B. cinerea infections rely on visual assessments, which are error prone, subjective, labor intensive, hard to quantify, and unsuitable for artificial intelligence (AI) and machine learning (ML) applications. New, often camera-based, techniques provide objective digital data by remote and proximal sensing. We detail the B. cinerea infection process and link this with conventional and novel detection methods. We evaluate the effectiveness of current digital phenotyping methods to detect, quantify, and classify disease symptoms for disease management and breeding for resistance. Finally, we discuss the needs, prospects, and challenges of digital camera-based phenotyping.

Propolis Hydroalcoholic Extracts: Biochemical Characterization and Antifungal Efficacy

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

The role of the jasmonate signalling transcription factors MYC2/3/4 in circadian clock-mediated regulation of immunity in Arabidopsis.

Plants are exposed to pathogens at specific, yet predictable times of the day-night cycle. In Arabidopsis, the circadian clock influences temporal differences in susceptibility to the necrotrophic pathogen Botrytis cinerea. The jasmonic acid (JA) pathway regulates immune responses against B. cinerea. The paralogous basic helix-loop-helix transcription factors MYC2, MYC3 and MYC4 are primary regulators of the JA pathway, but their role in regulating temporal variation in immunity is untested. This study aimed to investigate the roles of the MYC transcription factors in the temporal defence response to B. cinerea. We inoculated leaves from wild-type, myc single-, double- and triple-knockout mutants, and lines overexpressing MYC2, MYC3 or MYC4, with B. cinerea at two times of day in constant light, and compared lesion sizes. The presence of MYC2, MYC3 or MYC4 alone was sufficient to maintain temporal variation in susceptibility, but this was abolished in the myc234 triple-knockout mutant. Constitutive expression of MYC2, MYC3 or MYC4 abolished time-of-day differences in susceptibility. The data suggest that MYC2, MYC3 and MYC4 function redundantly in regulating temporal defence responses against B. cinerea and are a point of convergence between the JA pathway and the circadian clock in Arabidopsis.This article is part of the Theo Murphy meeting issue 'Circadian rhythms in infection and immunity'.

Biopesticide Compounds from an Endolichenic Fungus Xylaria sp. Isolated from the Lichen Hypogymnia tubulosa

Endolichenic fungi represent an important ecological group of microorganisms that form associations with photobionts in the lichen thallus. These endofungi that live in and coevolve with lichens are known for synthesizing secondary metabolites with novel structures and diverse chemical skeletons making them an unexplored microbial community of great interest. As part of our search for new phytoprotectants, in this work, we studied the endolichenic fungus Xylaria sp. isolated from the lichen Hypogymnia tubulosa, which grows as an epiphyte on the bark of the endemic Canarian tree Pinus canariensis. From the extract of the liquid fermentation, we isolated two unreported piliformic derivatives, (+)-9-hydroxypiliformic acid (1) and (+)-8-hydroxypiliformic acid (2), along with four previously reported compounds, (+)-piliformic acid (3), hexylaconitic acid A anhydride (4), 2-hydroxyphenylacetic acid (5), and 4-hydroxyphenylacetic acid (6). Their structures were elucidated based on NMR and HRESIMS data. The extract and the isolated compounds were tested for their insect antifeedant (Myzus persicae, Rhopalosiphum padi, and Spodoptera littoralis), antifungal (Alternaria alternata, Botrytis cinerea, and Fusarium oxysporum), nematicidal (Meloidogyne javanica), and phytotoxic effects on mono- and dicotyledonous plant models (Lolium perenne and Lactuca sativa). Compounds 4, 5, and 6 were effective antifeedants against M. persicae and 4 was also active against R. padi. Moreover, 3 and 4 showed antifungal activity against B. cinerea and 4 was the only nematicidal. The extract had a strong phytotoxic effect on L. sativa and L. perenne growth, with compounds 3, 4, and 5 identified as the phytotoxic agents, while at low concentrations compounds 3 and 4 stimulated L. sativa root growth.

Development of Pectin-Based Films with Encapsulated Lemon Essential Oil for Active Food Packaging: Improved Antioxidant Activity and Biodegradation

This study evaluated the physicochemical, morphological, and functional properties of pectin-based films incorporated with lemon essential oil (EO) to assess their potential as biodegradable food packaging materials. The results showed that EO incorporation significantly influenced the film’s characteristics. The control film exhibited a smooth surface, while the EO-containing film had a rougher texture with globular structures and interconnected channels, likely representing dispersed EO droplets and matrix alterations. The mechanical analysis revealed increased elongation at break (20.05 ± 0.784%) for EO-incorporated films, indicating improved flexibility, while tensile strength and Young’s modulus decreased, suggesting reduced stiffness. Film thickness increased slightly with EO (0.097 ± 0.008 mm) compared to the control (0.089 ± 0.001 mm), though the difference was not statistically significant (p &gt; 0.05). Moisture content decreased in EO-containing films (28.894%) compared to the control (35.236%), enhancing water resistance. Water solubility increased slightly (16.046 ± 0.003% vs. 15.315 ± 0.040%), while the swelling rate decreased significantly (0.189 ± 0.003 vs. 0.228 ± 0.040; p &lt; 0.05), indicating greater structural stability in aqueous environments due to the hydrophobic nature of EO. Transparency tests showed that EO slightly increased film opacity (0.350 ± 0.02 vs. 0.290 ± 0.012), aligning with trends in UV-protective materials. The EO-incorporated films also exhibited moderate antibacterial activity against Staphylococcus aureus and Escherichia coli. Antifungal tests revealed strong inhibition of Botrytis cinerea (100%) and moderate inhibition of Alternaria alternata (50%) in EO-containing films. These results demonstrate that EO incorporation improves the functional properties of pectin films, enhancing their flexibility, antimicrobial activity, and environmental stability, making them promising candidates for sustainable food packaging applications. These novel active food packaging materials exhibit strong physical properties and significant potential in maintaining food quality and prolonging shelf life.

Sunflower Head Rot Diseases: Botrytis Head Rot and Bacterial Head Rot

Sunflower is the fourth most produced vegetable oil worldwide and is ranked fifth of the 13 cultivated crops of major importance to global food security (FAO 2022; Hajjar and Hodgkin 2007; Seiler et al. 2018). Sunflower is affected by many economically-important and yield-limiting diseases, and this article is the first of an anticipated series of Plant Health Progress - Diagnostic Guides on significant heads diseases of sunflower. This follows a similar series of Plant Health Progress - Diagnostic Guides on sunflower stem diseases (Harveson et al. 2018, Ryley et al. 2021). Here we present information on Botrytis head rot and Bacterial rots, while information on Rhizopus head rot, Sclerotinia head rot, and the Phomopsis/Diaporthe head rots is anticipated in the near future. Botrytis head rot caused by Botrytis cinerea Pers. can be a common and significant disease in favorable environments while bacterial rots usually occur opportunistically and sporadically resulting in limited yield loss. In this paper, we concentrate on providing information to identify and distinguish these diseases, a comprehensive review of methods and techniques for working with the causal pathogens, and emphasizing the importance of disease cycles for identification and management.

Synthesis and antifungal activity of aldehydes-thiourea derivatives as promising antifungal agents against postharvest gray mold disease.

Gray mold disease is caused by B. cinerea, which could severely reduce the production yield and quality of tomatoes. To explore more potential fungicides with new scaffolds for controlling the gray mold disease, ten aldehydes-thiourea derivatives were designed, synthesized and assayed for inhibitory activity against three plant pathogenic fungi. The preliminary antifungal assay suggested that the some title derivatives showed moderate to good antifungal activity against Botrytis cinerea. Especially, compound 9 presented excellent in vitro antifungal activity against B. cinerea (EC50 = 0.70 mg/L), which was superior to boscalid (EC50 = 1.41 mg/L). In vivo antifungal assay indicated 9 displayed good protective effects on tomato leaves infected by B. cinerea. Preliminary mechanism study displayed that 9 could damage the surface morphology, increase the cell membrane permeability and lead to the increase of reactive oxygen species (ROS) level. Enzyme inhibition assay illustrated that 9 could be potential laccase inhibitor. The above bioassay results and mechanism investigation demonstrated that aldehydes-thiourea derivatives could be promising fungicide for further controlling postharvest gray mold disease, which would be potential candidate of fungicidal compound.

Pinnatifone A, isolated from Syringa pinnatifolia (Oleaceae), exhibits inhibitory activity against phytopathogenic fungi and can be employed to formulate a soluble concentrate agent.

In the realm of plant diseases, those caused by fungi and oomycetes are particularly challenging to manage, resulting in significant economic losses. There exist diverse active substances in natural products and developing them into fungicides holds great significance. At the initial phase of our research, we discovered that Syringa pinnatifolia extract demonstrates broad-spectrum inhibitory activity against phytopathogenic fungi. S. pinnatifolia extracts showed inhibitory activity against phytopathogenic fungi in vivo and in vitro, especially Valsa mali and Botrytis cinerea. Totals of eight compounds were isolated by bio-guided isolation (SCX-1 to SCX-8). Among these compounds, 3-methoxy-4-hydroxybenzaldehyde (SCX-2) and pinnatifone A (SCX-8) were found to have excellent antifungal activities against phytopathogenic fungi, the half maximal effective concentration (EC50) of SCX-2 against V. mali was 45.34 μg/mL, the EC50 of compound SCX-8 against B. cinerea was 9.25 μg/mL. Here a formulation of a soluble concentrate agent is presented for the prevention and control of tomato gray mold. This formulation included 45% S. pinnatifolia extract (containing 2.1% pinnatifone A), 16% benzyl alcohol, 24% absolute ethanol, 5% ethylene glycol, and 10% pesticide emulsifier No. 602. The preparation exhibited good protective and curative efficacies against tomato gray mold at a concentration of 100 μg/mL, with efficacies of 65.32% and 54.83%. Our findings provide valuable insights for the structural modification of active compounds derived from S. pinnatifolia and lay a foundation for the development of novel botanical fungicide products utilizing S. pinnatifolia as a raw material. © 2025 Society of Chemical Industry.

Botrytis cinerea PMT4 Is Involved in O-Glycosylation, Cell Wall Organization, Membrane Integrity, and Virulence.

Proteins found within the fungal cell wall usually contain both N- and O-oligosaccharides. N-glycosylation is the process where these oligosaccharides (hereinafter: glycans) are attached to asparagine residues, while in O-glycosylation the glycans are covalently bound to serine or threonine residues. The PMT family is grouped into PMT1, PMT2, and PMT4 subfamilies. Using bioinformatics analysis within the Botrytis cinerea genome database, an ortholog to Saccharomyces cerevisiae Pmt4 and other fungal species was identified. The aim of this study was to assess the relevance of the bcpmt4 gene in B. cinerea glycosylation. For this purpose, the bcpmt4 gene was disrupted by homologous recombination in the B05.10 strain using a hygromycin B resistance cassette. Expression of bcpmt4 in S. cerevisiae ΔScpmt4 or ΔScpmt3 null mutants restored glycan levels like those observed in the parental strain. The phenotypic analysis showed that Δbcpmt4 null mutants exhibited significant changes in hyphal cell wall composition, including reduced mannan levels and increased amounts of chitin and glucan. Furthermore, the loss of bcpmt4 led to decreased glycosylation of glycoproteins in the B. cinerea cell wall. The null mutant lacking PMT4 was hypersensitive to a range of cell wall perturbing agents, antifungal drugs, and high hydrostatic pressure. Thus, in addition to their role in glycosylation, the PMT4 is required to virulence, biofilm formation, and membrane integrity. This study adds to our knowledge of the role of the B. cinerea bcpmt4 gene, which is involved in glycosylation and cell biology, cell wall formation, and antifungal response.

Transcriptome, miRNA, and degradome sequencing reveal the leaf stripe (Pyrenophora graminea) resistance genes in Tibetan hulless barley

Barley leaf stripe, a disease mainly caused by Pyrenophora graminea (P. graminea) infection, severely affects barley yield and quality and is one of the most widespread diseases in barley production. However, little is known about the underlying molecular mechanisms of leaf stripe resistance. In this study, the transcript expression profiles of normal and infected leaves of resistant Tibetan hulless barley (Hordeum vulgare L. var. nudum Hook. f.) variety Kunlun 14 and susceptible variety Z1141 were analyzed by RNA sequencing (RNA-seq). The results showed a total of 7,669 and 5,943 differentially expressed genes (DEGs) were found in resistant and susceptible Kunlun 14 and Z1141, respectively, with 8,916 DEGs found between Kunlun 14 and Z1141. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of the 8,916 DEGs identified many significantly enriched categories and pathways, of which a plant–pathogen interaction pathway, containing a total of 102 genes (100 known genes and two novel genes), was found, that was very important for the study of the leaf stripe resistance mechanism. Using RNA-seq, small RNA sequencing (miRNA-seq) combined with degradome sequencing (degradome-seq), four pairs associated with leaf-stripe miRNAs and target genes were obtained, namely Hvu-miR168-5p and Argonaute1 (HvAGO1), Hvu-novel-52 and growth-regulating factor 6 (HvGRF6), Hvu-miR6195 and chemocyanin-like protein (CLP), and Hvu-miR159b and gibberellin-dependent MYB (GAMYB). Transformation of the important target gene HvAGO1 into Arabidopsis verified that HvAGO1 could against Botrytis cinerea. Then RNA-seq and miRNA-seq of Arabidopsis transformed with overexpressed of HvAGO1 were performed. Based on the above research results, we constructed a Protein-Protein Interaction (PPI) network of barley leaf stripe resistance. This study lays the foundation for the study of the barley leaf stripe resistance mechanism and provides new targets for the genetic improvement of disease-resistant barley varieties.

Temporal dynamics of airborne fungi in Swedish forest nurseries.

In Sweden, reforestation of managed forests relies predominantly on planting nursery-produced tree seedlings. However, the intense production using containerized cultivation systems (e.g., high seedling density, irrigation from above, regular fertilization) creates favorable conditions for fungal infections. Despite the harmful role of diseases in forest nurseries, the origin and dispersal factors of fungal pathogens remain largely unknown. A better understanding of the airborne spread of pathogens could improve the prediction of fungal infection, ultimately optimizing preventative methods and decreasing the use of fungicides. This study investigated the temporal dynamics of airborne fungi in forest nurseries, with a focus on fungal pathogens. Airborne fungi were monitored in four Swedish forest nurseries over two growing seasons using spore traps and high-throughput sequencing. Fungal pathogens were identified using bioinformatics and quantified with quantitative PCR. Results showed strong temporal shifts of airborne fungal diversity and community composition following the growing seasons. The airborne spread included high abundances of important fungal pathogens (e.g., Cladosporium sp., Botrytis cinerea, Alternaria sp., Sydowia polyspora, and Melampsora populnea) with individual temporal and spatial variations. In general, the deposited spore loads of nursery pathogens correlated positively with increased temperature and negatively with higher precipitation. This was expressed the strongest for Cladosporium sp., Alternaria sp., and M. populnea, which suggests a higher availability of fungal inoculum in warm and dry periods. This study highlights the influence of seasonality on the temporal dynamics of economically important fungal pathogens in Swedish forest nurseries, which should be considered in the development of a local decision support system.IMPORTANCEFungal diseases in forest nurseries have significant environmental and economic impacts on the tree seedling production. This study highlights the role of seasonality in the airborne spread of fungal pathogens in Swedish forest nurseries. By analyzing airborne fungal spores using advanced sequencing and monitoring techniques, key fungal pathogens and their dispersal patterns over two growing seasons were identified. The findings indicate that warmer, drier periods may increase the spread of fungal pathogens, emphasizing the need for targeted preventative measures. Understanding these temporal dynamics can help optimize the use of fungicides in forest nurseries, thereby promoting more sustainable and environmentally friendly management practices. This research provides valuable insights for improving disease management in forest nurseries, ultimately supporting sustainable tree seedling production.

Effects of Preharvest Application of Acibenzolar-S-methyl and Potassium Silicate on Postharvest Diseases and Fruit Quality of Blueberries

Blueberries are highly perishable and susceptible to storage spoilage, especially fruit rot diseases caused by fungal pathogens. Alternaria rot caused by Alternaria alternata and gray mold caused by Botrytis cinerea are the primary postharvest diseases of blueberries grown in California. We conducted a three-year field experiment to evaluate the effects of preharvest application of Acibenzolar-S-methyl (ASM) and potassium silicate (PSi) on Alternaria rot and gray mold in blueberry fruit inoculated with these pathogens after harvest, as well as naturally occurring fruit rots, fruit-to-fruit spread of gray mold during cold storage, and fruit quality. After four weeks of cold storage, all inoculated fruit developed rots regardless of the treatments applied in the field. In non-inoculated fruit, ASM significantly reduced the percentage of naturally occurring decayed fruit compared to the non-treated control in 2023 but not in 2021 and 2022. PSi significantly reduced the percentage of decayed fruit compared to the non-treated control in 2021 and 2023, but not in 2022. A significant increase in soluble solids and reduction in titratable acidity were observed in the fruit treated with ASM and PSi for the second and third years of the experiment, indicating that both treatments may have enhanced fruit maturity. Our results suggested that preharvest use of ASM and PSi had limited efficacy in postharvest disease control, but may have potential as tools for adjusting fruit maturity of blueberries.

Inhibitory and Curative Effects and Mode of Action of Hydroxychloroquine on Botrytis cinerea of Tomato.

Gray mold is an important disease of crops and is widespread, harmful, difficult to control, and prone to developing fungicide resistance. Screening new fungicides is an important step in controlling this disease. Hydroxychloroquine is an anti-inflammatory and anti-malarial agent, which has shown marked inhibitory activity against many fungi in medicine. This study evaluated the inhibitory activity of hydroxychloroquine against several phytopathogenic fungi, finding a half-maximal effective concentration of 113.82 μg/ml against the hyphal growth of Botrytis cinerea, with significant in-vivo curative effects of 92.37% or 78.37% for gray mold on detached tomato leaves or fruits at 10.0 or 200.0 mg/ml, respectively. Ultrastructural studies indicated that hydroxychloroquine induced collapse of hyphae, with a wrinkled surface, unclear organelle boundaries, and organelle disintegration. Transcriptomic assays revealed that hydroxychloroquine could affect the expression of metabolism-related genes. Molecular docking and molecular dynamics analyses indicated that hydroxychloroquine bound to glucose-methanol-choline oxidoreductase, with low free energy value of -11.4 kcal/mol. Cell membrane permeability assays and hyphal staining confirmed that hydroxychloroquine damaged the cell membrane, causing leakage of hyphal contents and disturbing cell function. Biochemical assays indicated that hydroxychloroquine reduced the concentration of soluble proteins and reducing sugars in the hyphae. In total, hydroxychloroquine disturbed amino acid metabolism, therefore inhibiting the production of biomacromolecules, damaging the cell membrane, and restraining the growth of hyphae, and hence inhibiting gray mold on tomato. This study will explore the use of medicine in the development of agricultural fungicides and their application in managing crop diseases, providing valuable background information.

Spray-Induced Gene Silencing (SIGS): Nanocarrier-Mediated dsRNA Delivery Improves RNAi Efficiency in the Management of Lettuce Gray Mold Caused by Botrytis cinerea

The plant pathogenic fungus Botrytis cinerea causes significant losses in agricultural production and it is rather difficult to control due to its broad host range and environmental persistence. The management of gray mold disease is still mainly based on the use of chemicals, which could have harmful effects not only due to impacts on the environment and human health, but also because they favor the development of fungicide-resistant strains. In this scenario, the strategy of RNA interference (RNAi) is being widely considered, and Spray-Induced Gene Silencing (SIGS) is gaining interest as a versatile, sustainable, effective, and environmentally friendly alternative to the use of chemicals in the protection of crops. The SIGS approach was evaluated to control B. cinerea infection on lettuce plants. In vitro-synthesized dsRNA molecules (BcBmp1-, BcBmp3-, and BcPls1-dsRNAs) were used naked, or complexed to small layered double hydroxide (sLDH) clay nanosheets. Therefore, treatments were applied by pressure spraying whole lettuce plants lately inoculated with B. cinerea. All sprayed dsRNAs proved effective in reducing disease symptoms with a notable reduction compared to controls. The effectiveness of SIGS in reducing disease caused by B. cinerea was high overall and increased significantly with the use of sLDH clay nanosheets. The sLDH clay nanosheet–dsRNA complexes showed better plant protection over time compared to the use of naked dsRNA and this was particularly evident at 27 days post-inoculation. RNAi-based biocontrol could be an excellent alternative to chemical fungicides, and several RNAi-based products are expected to be approved soon, although they will face several challenges before reaching the market.