Incidence Of Gray Mold Research Articles

Effect of Black Soldier Fly Larvae Frass as Organic Fertilizer on Postharvest Quality and Shelf Life of Open-field-grown Tomato (Solanum lycopersicon L.)

Open-field-grown tomatoes in Saudi Arabia are stressed by poor soil fertility because of the low organic matter content, low nutrient availability, and high pH. Thus, high chemical fertilizer inputs are crucial for commercial production; however, they cause economic loss as well as negatively affect environmental sustainability. The use of efficient organic fertilizers would be useful for developing more cost-effective, environmentally friendly, and sustainable agriculture. The current study evaluated the impact of Black soldier fly (Hermetia illucens L.) frass (BSFF) fertilizer applications as organic fertilizer on postharvest fruit quality and shelf life of open-field-grown F1 hybrid ‘Sinag Tala’ tomatoes compared with those grown under control treatment (received recommended doses of chemical fertilizers for tomato production under open field conditions). The experiment was conducted using a randomized complete block design with four replicates. The results showed that the application of BSFF fertilizer, especially at the higher rate (5 ton/ha; BSFF3), improved the overall quality of tomato fruit. The BSFF fertilizer treatments reduced weight loss, maintained higher firmness, antioxidants [vitamin C, total phenol content (TPC) and total flavinoid (TFC)], total soluble solids (TSS), and titratable acidity (TA) contents, and lowered the TSS/TA ratio of fruits during shelf life compared with those of the control. The decay incidence was only detected after 9 days of shelf life and was significantly lower in all the BSFF fertilizer treatments (range, 8.40%-12.05%) than in the control (15.9%). In addition, BSFF fertilizer treatments reduced both disease incidence and severity of gray mold following pathogen inoculation during shelf life compared with those of the control. These results might be attributable to the higher antioxidants content (vitamin C, TPC, and TFC) and higher polyphenol oxidase activity in BSFF-fertilized tomatoes. In conclusion, BSFF fertilizer could be used as a potential eco-friendly alternative to chemical fertilizers to improve tomato fruit quality during shelf life.

Association of SO2-Generating Pads before Packaging and during Cold Storage to Extend the Conservation of 'Italia' Table Grapes.

The SO2-generating pads contain different concentrations of sodium metabisulfite, which absorbs water from the grapes' transpiration, releasing SO2 gas, and there are slow-(SlowSO2) and dual (DualSO2)-releasing pads (fast release in the first 48 h and slow for up to 60 days). The ultra-fast SO2-generating pad (FieldSO2) releases the SO2 quickly for up to 6 h, and it was designed to be used soon after the harvest and until the grapes' packaging. The goal was to study the effect of FieldSO2 associated with SlowSO2 and DualSO2 pads on gray mold incidence and physicochemical and appearance characteristics of 'Italia' table grapes. Grapes were harvested from a commercial vineyard in Parana, Brazil, in 2020 and 2021, and packaged in cardboard boxes, and the treatments were as follows: control (without SO2-generating pads); FieldSO2 + SlowSO2; and FieldSO2 + DualSO2. After 30, 45, 60, 75, and 90 days of cold storage (1 ± 1 °C), the grapes were assessed for gray mold incidence, mass loss, shattered berries, stem browning, and filamentous fungi on the surface. The use of FieldSO2 associated with SO2-generating pads is effective in controlling gray mold on 'Italia' table grapes, especially the treatment FieldSO2 + DualSO2, which provides the lowest incidence of the disease up to 90 days of cold storage, while the combination with SlowSO2 results in intermediate efficacy. Treatments combining these SO2-generating pads extend the postharvest shelf life of 'Italia' grapes, with few shattered berries, low mass loss and freshness of the rachis without impairing the bunch's appearance.

Biocontrol efficacy of Botrytis cinerea on postharvest tomato fruit by the endophytic bacterium Bacillus velezensis BE1

Endophytic bacteria offer numerous advantages in the control of postharvest diseases. Bacillus velezensis has been identified as a promising biocontrol agent against postharvest pathogens in various fruits and vegetables. In this study, B. velezensis BE1 was identified by 16S rRNA sequencing and caused 76.9 % inhibition against Botrytis cinerea in dual culture assay. The cell-free culture filtrate (CFCF) of B. velezensis strongly inhibited the growth, spore germination, and germ tube elongation of B. cinerea. Moreover, 11 bioactive compounds were identified in the CFCF using gas chromatography-mass spectrometry, and phthalic acid, dioctyl ester was the predominant component by 72.92 %. Scanning and transmission electron microscopy observations revealed that the CFCF causes irreversible morphological and ultrastructural damage to the fungal hyphae and conidia, including deformed, wrinkled, lysis, collapse, and degradation of cytoplasmic organelles. The incidence and severity of gray mold were significantly suppressed after applying CFCF at 50 % in tomato fruit. The application of CFCF caused an increase in the total phenolics and flavonoids content in tomato fruit compared with the control throughout the experiment. Furthermore, the activities of enzymes associated with defense such as phenylalanine ammonia-lyase, polyphenoloxidase, and peroxidase were significantly higher in the treated tomatoes relative to the untreated group. These results indicate that B. velezensis BE1 has significant potential as an effective biocontrol agent against the pathogen B. cinerea, offering a valuable approach for controlling gray mold in postharvest fruit.

Theanine enhances resistance to Botrytis cinerea in postharvest strawberry fruit via modulating cell-wall and phenylpropanoid metabolisms

Theanine (N-ethyl-γ-glutamine), as a unique non-protein amino acid, plays vital roles in abiotic stress resistance, while its roles in biotic stress resistance are still unclear. Gray mold caused by Botrytis cinerea is a major disease in strawberries. Effects of theanine on the development of gray mold, cell-wall and phenylpropanoid metabolisms in strawberries were investigated in this study. Results showed that 5 mmol L−1 theanine treatment reduced disease incidence and severity of gray mold in strawberries with antifungal activity in vitro. Meanwhile, theanine treatment enhanced the accumulation of phenolic compounds and lignin, especially ellagic acid, cyanidin, and quercetin, which was associated with increased phenylpropanoid pathway related enzyme activities. Moreover, theanine induced callose deposition and suppressed cell- wall disassembling enzymes, accompanied by higher levels of water insoluble pectin, hemicellulose and cellulose. Therefore, theanine treatment could alleviate decay of B. cinerea-inoculated strawberries by regulating phenylpropanoid and cell-wall metabolisms, maintaining higher levels of phenolic compounds and cell-wall components, thereby contributing to disease resistance and cell-wall structure integrity.

Essential oil from orange peel in the control of Botrytis cinerea and in the postharvest conservation of ‘Benitaka’ table grape

The objective of this work was to evaluate the efficiency of essential oil from orange peel in the refrigerated conservation of the ‘Benitaka’ table grape, as well as to evaluate its in vitro effectiveness on Botrytis cinerea, the causal agent of gray mold. Grapes were harvested from a commercial field in the municipality of Cambira, Paraná, during the 2022 and 2023 seasons. The experimental design was completely randomized, with four treatments and five replications of five bunches per plot. The treatments were: a) control; b) essential oil from orange peel at 4.0 mL of the commercial product (c.p.) L-1; c) dual phase SO2-generating pads containing 1 and 4 g of the active ingredient (a.i.) in the fast and slow phases, respectively; and d) essential oil from orange peel at 4.0 mL c.p. L-1 associated with the dual phase SO2-generating pads containing 1 and 4 g of the a.i. in the fast and slow phases, respectively. A commercial product containing 61.14 g L-1 (6% w/v) of 4-isopropenyl-1-methylcyclohexane, the source of orange essential oil, was applied by spraying it directly onto the bunches. After drying, the grape bunches were stored in a refrigerated chamber at 1.0±1°C and 95% relative humidity. The following variables were assessed 30 and 45 days after the beginning of cold storage: the incidence of gray mold on berries, loss of bunch mass, stem browning, shattered berries, and bleaching. The minimum inhibitory concentration for the development of B. cinerea was determined, and fungal mycelia were observed using scanning electron microscopy to evaluate the in vitro efficacy of orange essential oil. The data were subjected to analysis of variance, and the means were compared using Fisher's difference test at 5% probability. The effectiveness of orange essential oil in suppressing the development of B. cinerea was demonstrated both in vivo and in vitro, making it a safe alternative for the postharvest conservation of 'Benitaka' table grapes.

Effect of Combining Wuyiencin and Pyrimethanil on Controlling Grape Gray Mold and Delaying Resistance Development in Botrytis cinerea.

By screening the compounding combination of Wuyiencin and chemical agents, this study aims to delay the emergence of chemical agent resistance, and provide a technical reference for scientific and rational fungicides technology. This study investigated the impacts of the antibiotic wuyiencin derived from Streptomyces albulus var. wuyiensis and its combination with pyrimethanil on the inhibition of Botrytis cinerea. Treatment with wuyiencin (≥80 µg mL-1) strongly inhibited the pathogenicity of B. cinerea and activated the plant defense response against B. cinerea. Application of 80-100 µg mL-1 wuyiencin effectively controlled grape gray mold (by 57.6-88.1% on leaves and 46.7-96.6% on fruits). Consequently, the application of 80-100 µg mL-1 wuyiencin effectively mitigated grape gray mold incidence, leading to a substantial reduction in disease symptoms to nearly imperceptible levels. When wuyiencin (at the median effective concentration [EC50]) was combined with pyrimethanil (EC50) at a ratio of 7:3, it exhibited the highest efficacy in inhibiting B. cinerea growth. This combination was significantly more potent (p < 0.05) than using wuyiencin or pyrimethanil alone in controlling gray mold on grape leaves and fruits. Furthermore, the combination effectively delayed resistance development in gray mold. The experimental results show that wuyiencin can delay resistance development by affecting the expression of methionine biosynthesis genes and reducing the activity of the cell wall-degrading enzyme activity.

Pseudomonas synxantha volatile organic compounds: efficacy against Cadophora luteo-olivacea and Botrytis cinerea of kiwifruit.

Volatile organic compounds (VOCs) are responsible for the antagonistic activity exerted by different biological control agents (BCAs). In this study, VOCs produced by Pseudomonas synxantha strain 117-2b were tested against two kiwifruit fungal postharvest pathogens: Cadophora luteo-olivacea and Botrytis cinerea, through in vitro and in vivo assays. In vitro results demonstrated that P. synxantha 117-2b VOCs inhibit mycelial growth of C. luteo-olivacea and B. cinerea by 56% and 42.8% after 14 and 5 days of exposition, respectively. In vivo assay demonstrated significant inhibitory effects. VOCs used as a biofumigant treatment reduced skin-pitting symptoms disease severity by 28.5% and gray mold incidence by 66.6%, with respect to the untreated control. BCA volatiles were analyzed by solid-phase microextraction coupled with gas chromatography-mass spectrometry (SPME-GC/MS), and among the detected compounds, 1-butanol, 3-methyl and 1-nonene resulted as the most produced. Their efficacy as pure synthetic compounds was assayed against mycelial growth of fungal pathogens by different concentrations (0.34, 0.56, and 1.12 µL mL-1 headspace). The effect of the application of VOCs as a biofumigant was also investigated as the expression level of seven defense-related genes of kiwifruit at different exposition times. The results indicated an enhancement of the expression of almost all the genes starting from 3h of treatment. These results described P. synxantha VOCs characteristics and their potential as a promising method to adopt for protecting kiwifruit from postharvest diseases caused by C. luteo-olivacea and B. cinerea.

Plumbagin controls fungal postharvest pathogens by affecting metabolism and inducing autophagy

Botrytis cinerea is a devastating postharvest pathogenic fungus causing severe postharvest decay in a wide range of fruit and vegetables. Controlling postharvest pathogens is essential to the postharvest industry. Plumbagin is a plant-derived naphthoquinone compound with various pharmacological activities, such as antioxidant, anti-inflammatory, and antimicrobial effects. However, its antifungal effects on B. cinerea have not been fully elucidated. In this study, we investigated the antifungal activity of plumbagin against postharvest fungal pathogens and elucidated its potential mechanism on B. cinerea through transcriptomics. Plumbagin exhibited broad-spectrum antifungal activity and completely inhibited the growth of various postharvest pathogens at a concentration of 20 mg L−1in vitro. Moreover, plumbagin effectively inhibited the incidence of gray mold in grape, sweet cherry, and strawberry fruit. The spore germination and viability of B. cinerea were also suppressed by plumbagin. Transcriptomic analysis indicated that plumbagin significantly affected the metabolic processes and induced autophagy in B. cinerea. Our results suggest that plumbagin is a promising broad-spectrum plant-derived fungicide that suppresses postharvest gray mold by affecting the metabolism of B. cinerea and inducing autophagy. These findings provide a theoretical basis for applying plumbagin to control postharvest pathogens.

Active Packaging Systems to Extend the Shelf Life of ‘Italia’ Table Grapes

Sulfur dioxide (SO2)-generating pads associated with perforated plastic liners are often used to control gray mold in table grapes during cold storage; however, SO2 may cause bleaching, shattered berries, and an unwanted taste. To overcome this difficulty, a field ultrafast SO2-generating pad was designed to be used for a few hours before packaging grape bunches as an alternative for eradicating spores of fungi from berry skin. This study aimed to assess the postharvest conservation and shelf life of ‘Italia’ table grapes packaged in plastic clamshells and perforated plastic liners using the field ultra-fast SO2-generating pads before packaging, associated with or without slow- or dual-phase SO2-generating pads during cold storage. The packaged grapes were cold stored (1.0 ± 1.0 °C; 95% relative humidity), and after 45 d, grapes were placed at room temperature (22.0 ± 1.0 °C) without plastic liners and SO2-generating pads for 3 d. Before and after the grapes had been subjected to the field ultra-fast SO2-generating pads, the quantification of filamentous fungi on the surface of the berries was assessed. The use of field ultra-fast SO2-generating pads before packaging, associated with slow- or dual-phase SO2-generating pads during cold storage, resulted in a lower incidence of gray mold after 45 d of storage, with low weight loss and shattered berries, good preservation of stem freshness, and no impairment in the color and firmness of the berries. Additionally, a significant decrease in disease incidence was observed when using only the dual-phase SO2-generating pads in cold storage, with good maintenance of bunch quality.

Application of Bacillus tequilensis for the control of gray mold caused by Botrytis cinerea in blueberry and mechanisms of action: inducing phenylpropanoid pathway metabolism.

Botrytis cinerea a blueberry gray mold, is one of the main diseases affecting postharvest storage, causing significant losses. Several studies have shown that Bacillus tequilensis can prevent the growth of plant pathogens by producing various antibacterial substances, and can induce plant resistance. However, research on the biological management of post-harvest gray mold in blueberries using B. tequilensis remains unclear. To better control the postharvest gray mold of blueberry, the effects of B. tequilensis KXF6501 fermentation solution (YY) and KXF6501 cell-free supernatant (SQ) on the induction of disease resistance in blueberry fruits were studied using biochemical and transcriptomic analyses. We found that YY controlled the conidial germination and mycelial growth of B. cinerea in vitro, followed by SQ. After 3 d of culture, the lesion diameter and incidence of gray mold in blueberry fruits inoculated with YY and SQ were smaller than those in the control group. Therefore, gray mold in blueberries was effectively controlled during the prevention period, and the control effect of YY was better than that of SQ. Transcription spectrum analysis of blueberry peel tissue showed that the YY- and SQ-induced phenylpropane metabolic pathways had more differentially expressed genes (DEGs) than other biological pathways. In addition, biochemical analyses showed that YY treatment effectively enhanced the activity of enzymes related to the phenylpropane pathway (phenylalanine ammonialyase [PAL], cinnamate 4-hydroxylase [C4H], 4-coumarate CoA ligase [4CL], and polyphenol oxidase [PPO]) and stimulated the synthesis of lignin, total phenols, and flavonoids, followed by SQ. Compared with the control, the YY and SQ treatments reduced the weight loss rate and better maintained the appearance and nutritional quality of the blueberry fruits. Our findings suggest that B. tequilensis KXF6501 is potentially useful as a suitable bio-control agent in harvested blueberries.

Molecular characteristics of some Botrytis isolates and antagonistic activity of Bacillus subtilis and its bacteriocin on tomato fruit

Gray mold, caused by Botrytis cinerea, is one of the most devastating agricultural diseases during the pre and postharvest stages. This study aims to investigate the application of Bacillus subtilis as a bioagent against B. cinerea and reducing pre and postharvest disease as a replacement method to chemical pesticides. Five Botrytis isolates were molecularly confirmed and the virulent isolate BC2 was registered for the first time in the National Center of Biotechnology Information (NCBI) with accession number OP257237. The mycelial growth of B. cinerea was inhibited by up to 84% when treated with the bio agent bacterium using the double drawing method in Petri plates. Pre-harvest application of B. subtilis at a concentration of 108/ml CFU reduced postharvest -gray mold of tomato fruit during ripening stages in the greenhouse. Preharvest application of bioagent bacterium B. subtilis induced the levels of B-1, 3-glucanase and Polyphenol oxidase, indicating enhanced plant resistance to gray mold. Disease severity was decreased compared with control and extended the shelf life at 25 °C.The field application of the bio agent bacterium at the maturity of ripening in preharvest had a significant effect on increasing the level of polyphenol oxidase PPO and B-1, 3-glucanase, which are related to the enhancement of plant defenses and resistance. Additionally, it led to an increase in storage life and a reduction in post-harvest losses. The results demonstrated that preharvest application of bio agent bacterium Bacillus subtilis improved the quality of postharvest tomato fruit and significantly reduced gray mold incidence, all without the use of chemical pesticides.

Occurrence of Gray Mold in Mango Caused by Botrytis cinerea in Korea

During a disease survey conducted in April 2022, we observed severe gray mold symptoms on inflorescences of mango trees (&lt;i&gt;Mangifera indica&lt;/i&gt;) grown in a vinyl greenhouse in Jeju, Korea. The symptoms occurred on the flowers and peduncles, on which a lot of gray molds were formed. The incidence of gray mold on the inflorescences in the vinyl greenhouse ranged from 10% to 40%. Three fungal isolates were obtained from the lesions and identified as &lt;i&gt;Botrytis cinerea&lt;/i&gt; based on their morphological characteristics and phylogenetic analysis. All isolates of &lt;i&gt;B. cinerea&lt;/i&gt; were tested for their pathogenicity to inflorescences of mango trees through artificial inoculation. The pathogenicity of the isolates was confirmed on the flowers and peduncles. The symptoms induced by the isolates were similar to those on the inflorescences of mango trees observed in the disease survey. This is the first report of &lt;i&gt;B. cinerea&lt;/i&gt; causing gray mold in mango in Korea.

Volatile Organic Compounds of Scheffersomyces spartinae W9 Have Antifungal Effect against Botrytis cinerea on Strawberry Fruit.

This study aims to evaluate the antifungal effects of volatile organic compounds (VOCs) produced by a marine biocontrol yeast, Scheffersomyces spartinae W9. The results showed that the VOCs from the yeast inhibited the growth of Botrytis cinerea mycelium and spore germination by 77.8% and 58.3%, respectively. Additionally, it reduced the disease incidence and lesion diameter of gray mold on the strawberry fruit surface by 20.7% and 67.4%, respectively. Electronic micrographs showed that VOCs caused damage to the morphology and ultrastructure of the hyphae. Based on headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME/GC-MS), S. spartinae W9 emitted 18 main VOCs, and the pure substance of VOCs, such as 3-methyl-1-butanol, 2-methyl-1-butanol, 2-phenylethanol, and isoamyl acetate, showed antifungal effects against B. cinerea mycelium growth. Among them, 2-phenylethanol exhibited the strongest antifungal activity. It has been concluded that VOCs are the key antifungal mechanism of S. spartinae W9, and a promising strategy for controlling gray mold on strawberry fruit.

Effects of salicylic acid-grafted bamboo hemicellulose on gray mold control in blueberry fruit: The phenylpropanoid pathway and peel microbial community composition

Bamboo hemicellulose (HC) is a natural plant polysaccharide with good biocompatibility and biodegradability. But its poor antibacterial activity limits its application in fruits preservation. In this study, based on the good inducer of salicylic acid (SA) for plant diseases resistance, a novel antibacterial coating material was synthesized by grafting SA onto HC. The study aimed to investigate the synergistic effect of HC-g-SA on antibacterial ability, induces diseases resistance and microbial community composition of postharvest fruit. The graft copolymer treatment significantly reduced the incidence of gray mold caused by Botrytis cinerea in blueberries during storage (P < 0.05), and significantly stimulated the activity of key enzymes, including phenylalanine ammonia-lyase, chalcone isomerase, laccase, and polyphenol oxidase, leading to an increase in fungicidal compounds such as flavonoids, lignin, and total phenolics produced by the phenylpropanoid pathway in blueberries (P < 0.05). Moreover, the HC-g-SA coating altered bacterial and fungal community composition such that the abundance of postharvest fruit-peel pathogens was significantly reduced. After 8 days storage, the blueberry fruits treated by HC-g-SA had a weight loss rate of 12.42 ± 0.85 %. Therefore, the HC-g-SA graft copolymer had a positive impact on the control of gray mold in blueberry fruit during postharvest storage.

A site suitability analysis for castor (Ricinus communis L.) production during Brazil's second harvest incorporating disease prediction

Castor (Ricinus communis L.) is an important industrial crop with a wide range of industrial and pharmaceutical applications. Brazil is among the largest castor-producing countries. Between 2004 and 2010, castor cultivation was stimulated with an emphasis towards biodiesel production. However, this was not enough to leverage the production of castor in Brazil, mainly due to the lack of structured trade and the competition with other cheaper raw materials for the production of biodiesel. Despite this failure, the species presents itself as an excellent alternative for crop rotation in the second crop among soybean, corn, beans, and cotton cultivation areas as the oil is highly valuable for other products. Moreover, it has drawn the attention of producers and researchers in Brazil for this potential rotation as it is considered a plant tolerant of water-deficiency and is highly susceptible to gray mold, a disease favored by high humidity in the final stages of the crop. For instance, its cultivation in the second crop in Cerrado regions, where rains occur in the early stages of the crop and cease when the plants reach the final stage of production, has been successful and shows great promise. The current study aimed to evaluate the suitability of environments throughout Brazil to grow castor, incorporating variables associated with the incidence of gray mold and confirm these findings based on existing castor trial data obtained from the literature. The site suitability analysis determined that 74.99 million hectares - 8.8% of Brazilian territory - are highly suitable for castor production during second harvest, mostly located in the Northeastern and Midwestern regions. These results are surprising since Brazil currently has around 7.8% (∼66.81 million hectares) of its territory occupied with agriculture (grains, fruits, vegetables, and perennial crops). The findings of this study provide a method to perform site suitability for crops using data associated with agronomic and disease characteristics, as is the case with gray mold that often results in significant losses in castor production. Also, this analysis provides evidence for the great potential of Brazil to increase castor production and meet the world demand for its oil through utilization of second-crop cultivation.

Alternatives for the gray mold (Botrytis cinerea) control in cape gooseberry (Physalis peruviana) crop

The effect of the field applications of three bioproducts (based on Trichoderma koningiopsis, Rhodotorula mucilaginosa, and Bacillus amyloliquefaciens), the alternation of the biostimulant Kendal® and the Swinglea glutinosa extract and the rotations of two fungicides (based on Azoxystrobin-Difenoconazole and Thiram-Pyrimethanol), on the incidence of gray mold in cape gooseberry postharvest was evaluated. For this purpose, the fruit was harvested weekly in the field, arranged in wet chambers with fruits with and without calyx, and incubated for seven days at 20 °C in laboratory conditions to promote the development of B. cinerea and determine the efficacy in its control. In addition, the populations of the microbial antagonists were monitored between applications by collecting the leaflets and washing them in 0.1% Tween 80 and sowing aliquots in specific culture media. In fruits with calyx, the lowest incidence of the gray mold, with averages of 48 and 51%, occurred with the applications of the bioproducts based on T. koningiopsis and R. mucilaginosa, respectively. In contrast, the incidence did not exceed 1.4% in fruits without calyx in all treatments. Furthermore, the population of microbial antagonists in the phyllosphere remained constant between applications, with counts of 1x103 CFU g-1 for T. koningiopsis and 1x105 CFU g-1 for R. mucilaginosa and B. amyloliquefaciens.

Potential of Bacillus amyloliquefaciens QY-1 as a biocontrol agent of Botrytis cinerea in postharvest blueberry

Botrytis cinerea is a prevalent disease of blueberry, causing significant postharvest losses. Bacillus amyloliquefaciens strain ‘QY-1’ is a strong antagonist of B. cinerea; therefore, it was isolated from an area severely impacted by blueberry gray mold for this study. In B. cinerea, QY-1 cell-free supernatant (CFS) treatment showed a high inhibition rate (86.93%), altered mycelial morphology, upregulated 1,3-β-glucosidase and chitinase, and downregulated ergosterol (ERG)-related gene expression, respectively. Moreover, QY-1 significantly reduced gray mold incidence in blueberries during storage without affecting fruit quality, thus highlighting its potential as an antibacterial and fresh-keeping agent for postharvest blueberries.

Aureobasidium pullulans S2 controls tomato gray mold and produces volatile organic compounds and biofilms

Gray mold emergence is detrimental to the production, transportation, and storage of tomatoes. The application of antagonistic microorganisms to control fruit diseases is a potential alternative to fungicides. This study investigated the effect of Aureobasidium pullulans S2 on controlling gray mold in tomatoes and explored the possible mechanisms. The results demonstrated that A. pullulans S2 effectively controlled the incidence of gray mold in tomatoes. The response of Botrytis cinerea to different components of the A. pullulans S2 culture showed that live yeast cells had B. cinerea inhibition ability. Environmental adaptability, host resistance induction, biofilm formation and production of volatile organic compounds (VOCs) with antimicrobial effects could also be important mechanisms of action of A. pullulans S2. The VOCs were identified, among which 2-phenylethanol, 2-heptanol and acetic acid, octyl ester could play an important role in B. cinerea inhibition. Ultimately, A. pullulans S2 may be a possible alternative to fungicides in managing tomato fruit post-harvest diseases.

Efficacy of the cyclolipopeptides fengycin and iturin A against postharvest pome fruit pathogens

Botrytis cinerea (gray mold) and Penicillium expansum (blue mold), are major pome fruit postharvest pathogens and their control relies heavily on the use of one postharvest fungicide (fludioxonil). This study aimed to evaluate the efficacy of the cyclolipopeptides (CLPs), in the form of fengycin and iturin A, in crude metabolite extracts from Bacillus amyloliquefaciens as an alternative biofungicide. The crude extract containing CLPs was applied with an edible coating (i.e., zein as a carrier) as a postharvest treatment against B. cinerea on “Packham’s Triumph” pears and P. expansum on “Cripps Pink” apples. Treatments were applied either as dips in combination with a zein edible coating at pH 2.0 or pH 8.0, or as sprays with a zein edible coating at pH 2.0 or pH 8.0. The efficacy of CLP applications was measured in comparison to the standard registered synthetic fungicide fludioxonil at a concentration of 299.0 mg/L. Treatments were applied to the fruit either preventatively (as sprays) or curatively (as dips or sprays). The lowest mean blue mold incidence (68.6%) was achieved when the edible coating containing the crude extract of B. amyloliquefaciens (CLP at pH 2.0) was applied as a curative dip treatment. B. cinerea infection was reduced by 92.6%, resulting in a 5.7% gray mold incidence for the curative application of CLPs at pH 2.0. This result was not significantly different from the inhibitory action of the fungicide fludioxonil. These results indicate that CLPs are an effective alternative biofungicide that can be used for the control of B. cinerea on pome fruit, especially if their formulation and application are improved and optimized.

First report of Botrytis cinerea causing gray mold on Prunella vulgaris in Hubei province, China.

Prunella vulgaris L. is a perennial herb plant of the Lamiaceae family, and its dried spicas have been widely used as medicine, health-promoting food or tea around the world. P. vulgaris is distributed all over the world, such as Europe, Asia, northwestern Africa and North America, as well as the Huaihe River Basin and the middle and lower Yangtze River Basin in China. In February 2022, a serious disease like gray mold occurred in planting fields of P. vulgaris in Wuhan, Hubei (N30°27'07″, E114°15'49″), causing approximately 20% of plants were diseased in the field. Early symptoms were characterized by small, round gray-brown lesions on the leaves of P. vulgaris. Later, a large number of stems and leaves are wilted or necrotic, associated with wet rot and waterlogged spots and covered with light gray or grayish white flocculent mildew layer. To determine the causal agent of disease, 10 plants with the typical symptoms were collected from fields. The stems and leaves of diseased plants were cut into pieces (2 to 3 mm×5 mm), disinfected with 75% ethanol for 3 minutes, rinsed 3 times with sterile water. Each lesion sample was isolated and purified using separate PDA petri dishes at 25°C, and ultimately all samples yielded morphologically consistent pure strain colonies. From the 10 isolates obtained, XKC-1 was chosen as a representative isolate for further study. XKC-1 colonies showed gray aerial mycelia, which were fast-growing and grew over the whole plate (9 cm) after 4 days. In addition, some black and hard sclerotia (1.88±0.94 mm, n=50) with round or irregular shape developed on the colonies after approximately 10 days of incubation at 25°C (Fig. 2A, B). XKC-1 showed branched conidiophores with enlarged apical cells and numerous conidia (Fig. 2C). Unicellular conidia were colorless or gray, ellipsoid or ovoid, smooth and 7.91-12.38 μm × 10.08-13.82 μm (n=30) in size (Fig. 2D). Based on morphological characteristics, the isolate was initially identified as Botrytis sp. (Ellis 1971). To further identify the species, the genomic DNA of XKC-1 was extracted, and the ITS, LSU and G3PDH genes were amplified with the primers ITS1/ITS4, LROR/LR5 (Zhou et al. 2022) and G3PDH-F/G3PDH-R (Jin et al. 2022), respectively. The results indicated that the ITS (ON090404), LSU (ON090417), and G3PDH (ON169893) sequences were 99.80%, 100% and 99.46% identical to the sequences of Botrytis cinerea Pers. strain (MK370693.1, MN148533.1, MN630267.1), respectively. A phylogenetic tree constructed based on a concatenated sequence (ITS, LSU, G3PDH) using the neighbor-joining method in MEGA7 (Tamura et al. 2013) revealed that XKC-1 grouped with concatenated sequences from three representative B. cinerea isolates in GenBank. Based on the morphological characteristics and molecular identification, the strain XKC-1 was identified as Botrytis cinerea. For pathogenicity tests on detached leaves, 5 mm PDA cakes prepared from XKC-1 were placed on the leaves obtained from healthy P. vulgaris after wounding with a needle (n=10), while PDA medium without mycelia were used as control (25 ± 2°C) (Li et al.2020). Mycelia began to germinate and infect plant tissues at 1 dpi. A large part of the leaves showed water soaked spots covered with mycelia on the surface at 4 dpi. For whole plant inoculations, stem bases of five P. vulgaris seedlings were pierced with sterile needle, and then inoculated with three XKC-1 mycelium PDA cakes. Five plants were inoculated with three PDA cakes without mycelia as a control. After 2-4 days, lesions appeared on the leaves and covered with a gray-white mycelial layer, similar to those observed in the field. However, controls remained symptom free. The pathogen was reisolated from the diseased tissues, the colonies, microscopic characteristics and molecular identification were consistent with those of XKC-1. To our knowledge, this is a first report of B. cinerea causing gray mold on P. vulgaris in Hubei, China. This report would provide resources and reference for controlling of the increased incidence and economic losses of gray mold on P. vulgaris.