Monilinia Laxa Research Articles

Bacterial Allies in Agricultural Defense: Evaluating Xenorhabdus and Photorhabdus Supernatants Against Phytophthora infestans and Monilinia laxa

Fungal plant pathogens represent a significant threat to global agriculture, affecting crop productivity and food security. Phytophthora infestans and Monilinia laxa are two such pathogens causing blights and brown rot, respectively, in economically vital crops like potato and stone fruits. Developing sustainable management strategies is crucial to mitigate these threats. Xenorhabdus and Photorhabdus bacteria produce various secondary metabolites with different biological activities. This study investigates the antifungal activity of cell-free supernatants from Xenorhabdus and Photorhabdus bacteria against P. infestans and M. laxa. Results demonstrate varying degrees of antifungal efficacy among bacterial species, with X. cabanillasii and X. szentirmaii exhibiting significant suppression of fungal growth. The findings underscore the importance of exploring biocontrol agents in integrated pest management practices.

Control of Peach Brown Rot Disease Produced by Monilinia fructicola and Monilinia laxa Using Benzylidene-Cycloalkanones.

Fruit rots caused by filamentous fungi such as Monilinia fructicola and Monilinia laxa have a strong impact on crop yield and fruit commercialization, especially as they affect a wide variety of stone fruits. The antifungal efficacy of benzylidene-cycloalkanones has been previously described in in vitro assays against M. fructicola; so, this study aims to evaluate the in vivo inhibitory potential of these hybrids on fruits that have been inoculated with M. fructicola, and use molecular docking to visualize the main interactions of these molecules in the active site of the enzyme succinate dehydrogenase (SDH). The results indicate that compound C achieves the highest inhibition of both Monilinia species (15.7-31.4 µg/mL), spore germination in vitro (<10 µg/mL), and has promising results in vivo, without causing phytotoxicity in fruits. The results from molecular docking suggest that hydroxyl groups play a crucial role in enhancing the binding of compound C to SDH and contribute to the formation of hydrogen bonds with amino acid residues on the enzyme active site.

Assessment of different control means to protect grape berries from biotic injuries in postharvest

To find alternatives similar in effectiveness to conventional fungicides, two commercial disease resistance inducers, EP5-Protect (Phenom Biotech, Milan Italy; EP) and BioDea Flavor (BioDea, Arezzo, Italy; WD), and bioactive extracts (BCEs) from a strain of Streptomyces albidoflavus (CARA17), were compared to the fungicide fludioxonil in in vitro and in vivo trials to control postharvest decay on table grapes by Botrytis cinerea and Monilinia laxa. Disease severity and incidence were recorded by Mckinney index values of 0.0–5.0. On culture media, EP, BCEs, and fludioxonil significantly inhibited the growth of both pathogens by 100% for B. cinerea, and 79–100% for M. laxa, while WD inhibited both pathogens by 15–25%. Similar results were obtained from experimental trials with inoculated grape berries treated with these compounds after harvest. Fludioxonil was the most effective treatment to control both pathogens applied to uninoculated or inoculated grapes. EP was significantly but moderately effective to control both pathogens and the other saprophytic microorganisms, whereas the effectiveness of BCEs from S. albidoflavus was significantly less, and WD was the least effective treatment. Our results indicate EP and BCEs may be promising to control postharvest decay on grapes and other fresh products. They could conceivably be used to replace sulfur dioxide fumigation currently used to protect grapes after harvest, in particular when storage is not prolonged.

Comparative transcriptome profiling and co-expression network analysis uncover the key genes associated with pear petal defense responses against Monilinia laxa infection.

Pear brown rot and blossom blight caused by Monilinia laxa seriously affect pear production worldwide. Here, we compared the transcriptomic profiles of petals after inoculation with M. laxa using two pear cultivars with different levels of sensitivity to disease (Sissy, a relatively tolerant cultivar, and Kristalli, a highly susceptible cultivar). Physiological indexes were also monitored in the petals of both cultivars at 2 h and 48 h after infection (2 HAI and 48 HAI). RNA-seq data and weighted gene co-expression network analysis (WGCNA) allowed the identification of key genes and pathways involved in immune- and defense-related responses that were specific for each cultivar in a time-dependent manner. In particular, in the Kristalli cultivar, a significant transcriptome reprogramming occurred early at 2 HAI and was accompanied either by suppression of key differentially expressed genes (DEGs) involved in the modulation of any defense responses or by activation of DEGs acting as sensitivity factors promoting susceptibility. In contrast to the considerably high number of DEGs induced early in the Kristalli cultivar, upregulation of specific DEGs involved in pathogen perception and signal transduction, biosynthesis of secondary and primary metabolism, and other defense-related responses was delayed in the Sissy cultivar, occurring at 48 HAI. The WGCNA highlighted one module that was significantly and highly correlated to the relatively tolerant cultivar. Six hub genes were identified within this module, including three WRKY transcription factor-encoding genes: WRKY 65 (pycom05g27470), WRKY 71 (pycom10g22220), and WRKY28 (pycom17g13130), which may play a crucial role in enhancing the tolerance of pear petals to M. laxa. Our results will provide insights into the interplay of the molecular mechanisms underlying immune responses of petals at the pear-M. laxa pathosystem.

Identification of pathogens causing brown rot of stone fruit in Cuneo province (Italy) and assessment of sensitivity to azoxystrobin, cyprodinil, fenhexamid, fludioxonil, and tebuconazole

Monilinia spp. cause brown rot and blossom blight of stone fruit. This study characterized the diversity of Monilinia spp. associated with stone fruit rots in the Cuneo province, the major fruit production area in Piedmont, and assessed their sensitivity to azoxystrobin, cyprodinil, fenhexamid, fludioxonil and tebuconazole. Species diversity was determined by PCR amplification and sequencing of isolate internal transcribed spacer (ITS) regions. Sensitivity to fungicides was determined by measuring in vitro mycelium growth on fungicide-amended media. Fifty isolates were obtained from apricot, cherry, or peach fruits with typical brown rot symptoms. Thirteen isolates were identified as M. fructicola, and 37 as M. laxa. Nine isolates of Monilinia laxa and two of M. fructicola had resistance factor (RF) values greater than 10 for different fungicides. The greatest (RF) value (48.96) was measured for azoxystrobin against the M. fructicola isolate CVG 1514. Among the M. laxa isolates, isolate CVG 1547 had the greatest RF value to cyprodinil, while isolate CVG 1709 had RF values greater than 10 for cyprodinil and tebuconazole. A systematic and wider sampling should be carried out in the Piedmont region to determine the distribution of fungicide resistant Monilinia spp. in stone fruit crops. The use of site-specific fungicides remains the most effective strategy for control brown rot, and continued monitoring for fungicide resistance within Monilinia spp. populations is recommended.

In Vitro Evaluation of Chitosan Hydrochloride and COS (Chito-Oligosaccharides)-OGA (Oligo-Galacturonides) on Phytopathogenic Fungi and Escherichia coli

Use of novel alternative compounds in agriculture is being promoted to reduce synthetic pesticides. An in vitro study was conducted to evaluate antimicrobial and antioxidant activities of chitosan hydrochloride (CH) and COS (chito-oligosaccharides)-OGA (oligo-galacturonides) at concentrations of 1%, 0.5%, 0.25%, 0.1%, 0.05%, and 0.025%. COS-OGA at 1% and 0.5% concentrations completely inhibited mycelial growth of Alternaria alternata, Alternaria brassicicola, Botrytis cinerea, Monilinia laxa, Monilinia fructigena, and Monilinia fructicola. Further, complete inhibition was observed with 0.25% COS-OGA for M. fructigena and M. laxa. Inhibition for B. cinerea, M. fructicola, A. alternata, and A. brassicicola at 0.25% COS-OGA was 86.75%, 76.31%, 69.73%, and 60.45%, respectively. M. laxa and M. fructigena were completely inhibited by CH concentrations of 1–0.25% and M. fructicola by concentrations of 1–0.5%. At CH 0.25%, inhibition for M. fructicola, A. brassicicola, A. alternata, and B. cinerea was 93.99%, 80.99%, 69.73%, and 57.23%, respectively. CH showed effective antibacterial activity against foodborne Escherichia coli. COS-OGA had higher antioxidant activity than CH when assessed by DPPH and hydroxyl radical scavenging assays. Our findings offer insights into the antimicrobial efficacy and mechanisms of action of these novel compounds, which have the potential to serve as alternatives to synthetic pesticides. In vivo investigations are required to validate the prospective application of these treatments for pre- and postharvest disease management.

Control of Monilinia blossom and twig blight (Monilinia laxa) by boron, pyroligneous acid and boscalid

Control of Monilinia blossom and twig blight (Monilinia laxa) by boron, pyroligneous acid and boscalid

Biological Control of Blossom Blight and Brown Rot Caused by Monilinia laxa by Using a Bacillus subtilis Strain TV-6F

Biological Control of Blossom Blight and Brown Rot Caused by Monilinia laxa by Using a Bacillus subtilis Strain TV-6F

Antifungal activity of volatile organic compounds from essential oils against the postharvest pathogens Botrytis cinerea, Monilinia fructicola, Monilinia fructigena, and Monilinia laxa.

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.

Uncaria tomentosa-Loaded Chitosan Oligomers–Hydroxyapatite–Carbon Nitride Nanocarriers for Postharvest Fruit Protection

Given the risks associated with synthetic fungicides, it is crucial to explore safe and sustainable alternatives. One potential solution is using bioactive natural products (BNPs). However, BNPs face challenges like lability, solubility, and lack of specificity. These issues can be addressed through nanoencapsulation. This study focuses on the evaluation of novel chitosan oligomers–hydroxyapatite–carbon nitride (COS–HAp–g-C3N4) nanocarriers (NCs) for encapsulating BNPs, specifically an extract from Uncaria tomentosa bark. The NCs were characterized by transmission electron microscopy, energy-dispersive X-ray spectroscopy, and infrared spectroscopy. The NCs were monodisperse, with a mean diameter of 250 nm, and showed an encapsulation efficiency of 82%. The suitability of the loaded NCs (COS–HAp–g-C3N4–BNP, in a 2:1:0.5:1 weight ratio) for postharvest fruit protection was investigated in vitro and ex situ at a laboratory scale. Results regarding their efficacy against Botrytis cinerea on strawberries, Colletotrichum gloeosporioides on mangoes, Penicillium expansum on apples, Monilinia laxa on peaches, and Sclerotinia sclerotiorum on kiwifruit are presented. Minimum inhibitory concentrations of 250, 375, 375, 250, and 187.5 μg·mL−1 were found in vitro, respectively, while higher doses (500, 750, 750, 250, and 375 μg·mL−1, respectively) were needed to achieve effective control in postharvest tests on artificially inoculated fruit. These findings suggest that NCs containing extracts from U. tomentosa bark show promise as biorational agents and as alternatives to conventional fungicides for managing postharvest phytopathogens.

Unleashing the Potential of Bacterial Isolates from Apple Tree Rhizosphere for Biocontrol of Monilinia laxa: A Promising Approach for Combatting Brown Rot Disease.

Monilinia laxa, a notorious fungal pathogen responsible for the devastating brown rot disease afflicting apples, wreaks havoc in both orchards and storage facilities, precipitating substantial economic losses. Currently, chemical methods represent the primary means of controlling this pathogen in warehouses. However, this study sought to explore an alternative approach by harnessing the biocontrol potential of bacterial isolates against brown rot in apple trees. A total of 72 bacterial isolates were successfully obtained from the apple tree rhizosphere and subjected to initial screening via co-cultivation with the pathogen. Notably, eight bacterial isolates demonstrated remarkable efficacy, reducing the mycelial growth of the pathogen from 68.75 to 9.25%. These isolates were subsequently characterized based on phenotypic traits, biochemical properties, and 16S rRNA gene amplification. Furthermore, we investigated these isolates' production capacity with respect to two enzymes, namely, protease and chitinase, and evaluated their efficacy in disease control. Through phenotypic, biochemical, and 16S rRNA gene-sequencing analyses, the bacterial isolates were identified as Serratia marcescens, Bacillus cereus, Bacillus sp., Staphylococcus succinus, and Pseudomonas baetica. In dual culture assays incorporating M. laxa, S. marcescens and S. succinus exhibited the most potent degree of mycelial growth inhibition, achieving 68.75 and 9.25% reductions, respectively. All the bacterial isolates displayed significant chitinase and protease activities. Quantitative assessment of chitinase activity revealed the highest levels in strains AP5 and AP13, with values of 1.47 and 1.36 U/mL, respectively. Similarly, AP13 and AP6 exhibited the highest protease activity, with maximal enzyme production levels reaching 1.3 and 1.2 U/mL, respectively. In apple disease control assays, S. marcescens and S. succinus strains exhibited disease severity values of 12.34% and 61.66% (DS), respectively, highlighting their contrasting efficacy in mitigating disease infecting apple fruits. These findings underscore the immense potential of the selected bacterial strains with regard to serving as biocontrol agents for combatting brown rot disease in apple trees, thus paving the way for sustainable and eco-friendly alternatives to chemical interventions.

MONITORING OF THE MAIN PATHOGENS FOUND IN APPLE PLANTATIONS AT SCDP IASI

The observations took place at RSFG Iasi, Development Center Falticeni in 2022, in apple plantations where a number of 9 phytosanitary treatments were applied to the warning, with the spray machine of the type Agroma. A total of 3 varieties (Jonathan, Golden delicious, Stakrimson) were studied compared to the untreated variant. The phytosanitary treatment program covered a wide range of phytopharmaceuticals, using 8 contact and systemic fungicides to prevent and combat pathogens that produce Venturia inaequalis, Erwinia amylovora,, Podosphaera leucotricha (Ell. et Ev) Salm and Monilinia laxa. Thus, in the untreated variant, the degree of attack for rapeseed on the fruit was 82.8%, and for Podosphaera leucotricha on the shoots the attack was 35% in the Jonathan variety. In the treated plot, the degree of Venturia inaequalis attack on fruit was reduced to 11.3% and 3.0% in the Starkrimson and Golden delicious varieties, and in the Jonathan variety up to 0.5%.

First Report of Brown Rot Caused by Monilinia polystroma on Sweet Cherry and Almond in Italy.

Brown rot decay is an important disease of pome and stone fruits. In Italy, the main pathogens on stone fruits are Monilinia laxa, M. fructigena, and M. fructicola (Spitaler et al. 2022a). In addition, Monilinia polystroma (G. Leeuwen) L. M. Kohn (van Leeuwen et al. 2002), was recently found in Italy on peach (Martini et al. 2014), pear (Martini et al. 2015), plum (Abate et al. 2018), apple (Rosati et al. 2021), and quince (Spitaler et al. 2022b). In South Tyrol province, sweet cherry (Prunus avium L.) and almond (Prunus dulcis Mill. D. A. Webb), plants of the Rosaceae family and belonging to stone fruits, were observed to be frequently affected by brown rot. Affected cherries as well as almonds showed brown lesions, covered by yellowish or buff-colored stroma in concentric rings. Symptomatic cherries became shriveled, while symptomatic almonds remained firm. To determine the pathogen, single spore isolates were obtained from five symptomatic fruits, each from a cherry orchard of the cultivar Kordia in July 2021 and almond trees of the variety Dulcis in August 2021. Both sample sites were situated in Vadena/Pfatten. Infestation in the cherry orchard, covered by a rain-protection foil, was determined to be about 1 %. In almond, over 50 % of the fruits of various ripening stages showed brown rot symptoms. On potato dextrose agar (PDA) at 22 °C and a photoperiod of 16 h, isolates from both fruits matched the morphological characteristics of M. polystroma (Vasić et al. 2016) within 14 days. DNA was extracted from mycelium and the rRNA encoding gene region using ITS4 and ITS6 primers as well as a genomic sequence of unknown function using the primers UniMon_Forw and UniMon_Rev (Petróczy et al. 2012), were amplified and sequenced. MegaBLAST analysis revealed 100 % identity with M. polystroma sequences of the NCBI GenBank (rRNA encoding region: NR_154198; genomic region: JN128836). Sequences were deposited in GenBank under the accession numbers OP642545/OP654171 (cherry) and OP642546/OP654172 (almond). Pathogenicity was confirmed with mature cherries cultivar Duroncino or almost mature almond fruit of the variety Dulcis, respectively: 16 samples each for both fruits were surface-sterilized by dipping in 75 % ethanol for 10 s and subsequent rinsing with sterile water for 10 s. Mycelial plugs (1 mm) were dislodged from a 7-day old colony and inserted in a 1 mm hole into the fruits. Incubation was performed in plastic boxes under the conditions described above. PDA-inoculated fruit were used as controls. All cherries and all almonds were completely covered by brown rot lesions 7 days and 15 days post inoculation, respectively. Control fruits remained symptomless. Conidia were produced in branched chains on mycelium-inoculated fruit. Conidia were one-celled, limoniform, hyaline, measuring 13.1 to 22.2 × 9.7 to 14.8 µm (cherry) and 14.1 to 20.8 × 10.7 to 15.3 µm (almond). Additionally, 16 fruits each were inoculated with 20 µL conidial suspension (5 x 10^3 spores/mL) from mycelium-inoculated fruits. All cherries as well as all almonds were completely covered by brown rot lesions 7 days and 15 days post inoculation. Control fruits remained symptomless. To confirm identity, the fungus was isolated from five spore-inoculated fruits each for cherry and almond. The isolates showed identical morphological features and sequence identity as the original isolates. To our knowledge, this is also the first report of M. polystroma on almond, while the pathogen has already been reported on sweet cherry in Poland (Poniatowska et al. 2016). These additional host plants identified in this study suggest a broad impact of M. polystroma on Italian stone fruit production. Due to the economically important cultivation of stone fruit, further knowledge about the pathogens' host range will help to assign brown rot symptoms to M. polystroma and to improve targeted control strategies.

Stone fruit phenolic and triterpenoid compounds modulate gene expression of Monilinia spp. in culture media

Phenolic and triterpenoid compounds are essential components in stone fruit skin and flesh tissues. They are thought to possess general antimicrobial activity. However, regarding brown rot disease, investigations were only confined to a limited number of phenolics, especially chlorogenic acid. The activity of triterpenoids against Monilinia spp., as an essential part of the peach cuticular wax, has not been studied before. In this work, the anti-fungal effect of some phenolics, triterpenoids, and fruit surface compound (FSC) extracts of peach fruit at two developmental stages were investigated on Monilinia fructicola and Monilinia laxa characteristics during in vitro growth. A new procedure for assaying anti-fungal activity of triterpenoids, which are notoriously difficult to assess in vitro because of their hydrophobicity, has been developed. Measurements of colony diameter, sporulation, and germination of second-generation conidia were recorded. Furthermore, the expression of twelve genes of M. fructicola associated with germination and/or appressorium formation and virulence-related genes was studied relative to the presence of the compounds. The study revealed that certain phenolics and triterpenoids showed modest anti-fungal activity while dramatically modulating gene expression in mycelium of M. fructicola on culture medium. MfRGAE1 gene was overexpressed by chlorogenic and ferulic acids and MfCUT1 by betulinic acid, at 4- and 7- days of mycelium incubation. The stage II FSC extract, corresponding to the period when the fruit is resistant to Monilinia spp., considerably up-regulated the MfLAE1 gene. These findings effectively contribute to the knowledge of biochemical compounds effects on fungi on in vitro conditions.

Molecular characterization of Aureobasidium spp. strains isolated during the cold season. A preliminary efficacy evaluation as novel potential biocontrol agents against postharvest pathogens

Several Aureobasidium spp. strains isolated from wild environments during winter 2022 were characterized by sequence analysis of the internal transcribed spacer (ITS), the translation elongation factor EF-1α gene (EF1), and part of the elongase gene (ELO). The variability in the EF1 and ELO loci are higher than in the ITS. All strains but one (UC14), were identified as A. pullulans. To assess the effectiveness of the characterized strains as biocontrol agents (BCAs) of diseases occurring during postharvest storage, a selection of the strains was evaluated by in vitro and in vivo assays. On average, the reduction of Monilinia spp. colony growth was more marked for non-volatile metabolites than for volatile (VOCs). Strain UC14 provided the strongest mycelial growth reduction of Monilinia fructicola by VOCs (66%). According to the in vivo results, all strains were effective in controlling brown rot during cold storage and remarkably in restricting the growth of Monilinia polystroma. In particular, VB23 was the most effective in controlling brown rot incidence, by 80%, 60%, 100%, and severity, by 79.5%, 72.7% and 100%, for Monilinia laxa, M. fructicola, and M. polystroma, respectively.

Genome-Wide Discovery of Structural Variants Reveals Distinct Variant Dynamics for Two Closely Related Monilinia Species.

Structural variants (SVs) are variants with sizes bigger than 50 bp and capable of changing the size, copy number, location, orientation, and sequence content of genomic DNA. Although these variants have been proven to be extensive and involved in many evolutionary processes along the tree of life, there is still insufficient information on many fungal plant pathogens. In this study, the extent of SVs, as well as single-nucleotide polymorphisms (SNPs), has been determined for two prominent species of the Monilinia genus (the causal agents of brown rot disease in pome and stone fruits): Monilinia fructicola and Monilinia laxa for the first time. The genomes of M. fructicola were found to be more variant-rich in contrast to M. laxa based on the reference-based variant calling (with a total number of 266.618 and 190.599 SNPs and 1,540 and 918 SVs, respectively). The extent, as well as distribution of SVs, presented high conservation within the species and high diversity between the species. Investigation of potential functional effects of characterized variants revealed high potential relevance of SVs. Moreover, the detailed characterization of copy number variations (CNVs) for each isolate revealed that around 0.67% of M. fructicola genomes and 2.06% of M. laxa genomes are copy number variables. The variant catalog as well as distinct variant dynamics within and between the species presented in this study opens doors for many further research questions.

Antifungal activities of aqueous extracts of moroccan medicinal plants against Monilinia spp. agent of brown rot disease

Apple fruit is one of the worldwide most industrially valuable horticulture crops. However, the fruit is vulnerable to post-harvest brown rot degradation caused by Monilinia laxa and Monilinia fructigena, which is a prominent pre-and post-harvest disease of tree fruit. Numerous non-chemical post-harvest treatments have been investigated so far to control these pathogens to provide an alternative option to the synthetic fungicides that are commonly used and may have negative effects on human health and the environment. Therefore, this study aimed to assess the in vitro and in vivo efficacy at different concentrations of nine plants' aqueous extracts from Mentha pulegium, Citrus aurantium, Thymus vulgaris, Origanum compactum, Lavandula angustifolia, Syzygium aromaticum, Rosmarinus officinalis, Citrus sinensis and Eucalyptus radiate against the development of brown rot. The results demonstrated significant antifungal activities of all tested aqueous extracts on both fungi compared to the thiophanate-methyl fungicide (1 ppm) (100% inhibition). At the concentration of 1.5 mg/ml, S. aromaticum and O. compactum extracts were the most effective, showing significant inhibition values against M. laxa (91.06%) and against M. fructigena (90.02%). Interestingly, at higher concentration, spore germination of both Monilinia strains was significantly reduced with inhibition rate of 98.64% for M. laxa and 93.04% for M. fructigena. Also, high flavonoids and polyphenols contents were shown. Aqueous extracts of O. compactum, S. aromaticum, and T. vulgaris reduced the brown rot severity and incidence in vivo. The application of these plants' aqueous extracts on fruits seems to have a significant effect on fruit quality persistence, as indicated by weight loss, fruit firmness, total soluble solids, titrable acidity, and maturity index during 15 days of storage at 4 °C. The spectra analyzed from all tested plants revealed typical peaks and a large variety of functional groups such as C–H bonds, O–H groups, and C–C stretching. The plant’s aqueous extracts studied can be used as bio-fungicides against brown rot diseases.

Influence of Fruit Wounding on Subsequent Monilinia laxa Infection of Nectarines

Despite the fact that brown rot is the most economically important disease in stone fruits, the relationship between mechanical stress and infection has never been explored. Thus, to explore this connection, we carried out four experiments linking nectarine wounding and M. laxa infection. First, we evaluated a possible systemic reaction of the fruit to wounding that could impact the M. laxa infection. Afterward, we study the impact of the fruit in the environment on M. laxa colonies grown in vitro. Subsequently, we tested the disease susceptibility of fruits inoculated with M. laxa placed in the same environment as wounded fruits. Finally, in the fourth experiment, the effect of wounding on the subsequent fruit infections was evaluated at three fruit stages. As a result, we observed that there was no evidence of a fruit systemic reaction to wounding and M. laxa infection. In the study related to the impact of the fruit in the environment of M. laxa, the findings suggest that M. laxa “perceived” the fruit’s presence, resulting in accelerated in vitro growth. Moreover, the presence of wounded fruits in the box increased the susceptibility to brown rot. Inoculated fruits showed a delayed and reduced infection 7 h after being wounded, during the second stage of fruit development (15–19 weeks after full bloom). Moreover, a red reaction associated with inoculation was detected immediately after the fruits were wounded. Nine phenolic compounds exclusively related to the red areas were extracted, while six other compounds were present in higher proportions. These compounds may be actively involved in plant–pathogen interactions and the activation of metabolic pathways involved in nectarine susceptibility/resistance to M. laxa.

Preventive and Curative Effects of Salicylic and Methyl Salicylic Acid Having Antifungal Potential against Monilinia laxa and the Development of Phenolic Response in Apple Peel.

The effects of salicylic acid (SA) and one of its better-known derivatives-methyl salicylic acid (MeSA)-on the infection of apple fruits with the fungus Monilinia laxa, which causes brown rot, were investigated. Since research to date has focused on preventive effects, we also focused on the curative use of SA and MeSA. Curative use of SA and MeSA slowed the progression of the infection. In contrast, preventive use was generally unsuccessful. HPLC-MS was used to analyze the content of phenolic compounds in apple peels in healthy and boundary peel tissues around lesions. The boundary tissue around the lesions of untreated infected apple peel had up to 2.2-times higher content of total analyzed phenolics (TAPs) than that in the control. Flavanols, hydroxycinnamic acids and dihydrochalcones were also higher in the boundary tissue. During the curative treatment with salicylates, the ratio of TAP content between healthy and boundary tissue was lower (SA up to 1.2-times higher and MeSA up to 1.3-times higher content of TAPs in boundary compared to those in healthy tissue) at the expense of also increasing the content in healthy tissues. The results confirm that salicylates and infection with the fungus M. laxa cause an increased content of phenolic compounds. Curative use of salicylates has a greater potential than preventive use in infection control.

Vermikompost ekstraktlarının bazı havai fungal bitki patojenleri baskılama etkinliğinin belirlenmesi

The use of vermicompost in agriculture has become increasingly common, especially in organic agriculture. In this research, the suppression efficiency of horse and cattle vermicompost extracts against some aerial fungal plant pathogens (Monilinia laxa, Cytospora leucostoma, Botryosphaeria obtusa, Phomopsis viticola, Alternaria mali, and Botrytis cinerea) that damage fruit trees and are common in fruit production areas, was studied for the first time in our country. 25%, 50%, 75%, and 100% concentrations of horse and cattle extracts were tested against fungal plant isolates. The results were evaluated by two-way ANOVA testing the suppression rates of vermicompost extracts in petri plates. While the best results were found in M. laxa (90.6%), P. viticola (80.2%), A. mali (65.1%) at 100% concentration for horse and cattle vermicomposts respectively, the suppression of B. obtusa (44.7%), C. leucostoma (38.1%), and B. cinerea (35.5%) was found to be lower.