Cinerea Growth Research Articles

Evaluation of Copper-Free Alternatives to Control Grey Mould in Organic Mediterranean Greenhouse Tomato Production

Grey mould caused by Botrytis cinerea is an endemic disease in greenhouse tomato crops in the Mediterranean Basin, where the scarcity of heating systems together with the winter weather conditions makes the use of fungicides necessary. The availability of fungicides for organic tomato production is limited, and traditionally, farmers have used copper-based formulations. In the present work, in vitro tests with twelve commercial formulations resulted in cinnamon extract and potassium hydrogen carbonate (PHC) showing high efficacy in the inhibition of B. cinerea growth. Both formulations were evaluated in on-farm greenhouse trials conducted for two seasons (2019/2020 and 2020/2021) in three greenhouses located in Almería, Spain. In terms of controlling Botrytis, PHC showed efficacy results comparable to or even better than those that have been obtained for copper oxychloride. Weather conditions outside and inside the greenhouse were conducive to the onset and development of the disease. Tomato variety selection and pruning practices (flush cuttings) were the main factors that reduced the use of copper-based formulations or any other fungicide to prevent grey mould infection. Smart and integrated management of the mentioned factors could lead to the substitution of copper to control Botrytis in the crop system studied here.

BIOCONTROL BACTERIA AGAINST BOTRYTIS GRAY MOLD AND OTHER STRAWBERRY FUNGAL PATHOGENS

Strawberries are listed among the functional foods. Beside their appreciated taste, they are rich in antioxidant compounds. Due to their sugars, fleshy pulp and thin skin, as well as dwarf habitus, they are exposed to various plant diseases, especially fungi. Botrytis gray mold is the most destroying pathogen, but there are other fungi that can cause losses in the field or after harvest. The aim of this study is to select some bacterial strains that could be easily formulated as biocontrol agents against various molds. These bacteria were isolated from winery semi-composted marc and analyzed through specific microbiologic methods. Based on their in vitro antagonistic activity, two bacterial isolates were selected. These strains revealed up to 84.2% inhibition of Botrytis cinerea growth, and high antifungal activity against various other fungi, such as Fusarium oxysporum, Macrophomina phaseolina and Sclerotinia sclerotiorum. Qualitative enzymatic tests, as well as microscopic analysis of the microbial interactions revealed fungal degradative enzymes produced by the bacterial strains. As the selected strains were determined to be spore producing bacteria, long term preservation is an advantage for their formulation as plant protection inoculants. Moreover, these bacteria revealed no phytotoxic activity against test plants.

ROS Stress and Cell Membrane Disruption are the Main Antifungal Mechanisms of 2-Phenylethanol against Botrytis cinerea.

2-Phenylethanol (2-PE), a common compound found in plants and microorganisms, exhibits broad-spectrum antifungal activity. Using Botrytis cinerea, we demonstrated that 2-PE suppressed mycelium growth in vitro and in strawberry fruit and reduced natural disease without adverse effects to fruit quality. 2-PE caused structural damage to mycelia, as shown by scanning and transmission electron microscopy. From RNA sequencing analysis we found significantly upregulated genes for enzymatic and nonenzymatic reactive oxygen species (ROS) scavenging systems including sulfur metabolism and glutathione metabolism, indicating that ROS stress was induced by 2-PE. This was consistent with results from assays demonstrating an increase ROS and hydrogen peroxide levels, antioxidant enzyme activities, and malondialdehyde content in treated cells. The upregulation of ATP-binding cassette transporter genes, the downregulation of major facilitator superfamily transporters genes, and the downregulation of ergosterol biosynthesis genes indicated a severe disruption of cell membrane structure and function. This was consistent with results from assays demonstrating compromised membrane integrity and lipid peroxidation. To summarize, 2-PE exposure suppressed B. cinerea growth through ROS stress and cell membrane disruption.

Effect of Aloe vera gel-based edible coating on microbiological safety and quality of tomato

ABSTRACT This study investigated the effects of Aloe vera gel (AVG) based on edible coating solutions on tomatoes to maintain the postharvest quality during storage at 10°C for 30 days. The AVG coating solutions were prepared with different percentages of extracted gel ranging from 0 to 80% with addition to calcium chloride (2%), ascorbic acid (4%), carboxymethyl cellulose (3%), glycerol (2%), and oleic acid (3 mL). Results showed that coating solutions containing 60 to 80% AVG had better results than coating solutions containing 0 to 40% gel. Contents of ascorbic acid, sugar, flavonoids, carotenoids, lycopene, and pectin remained higher, and total microbial count remained lesser in fruits treated with a higher concentration of AVG over the storage time. Tomatoes coated with 60% and 80% Aloe vera gel also showed maximum antioxidant efficiency, absence of E. coli, and no signs of fungal (Botrytis cinerea) growth on tomatoes. In conclusion, applying 60–80% AVG edible coatings might be suggested to maintain the postharvest quality of tomato fruit.

Paraburkholderia phytofirmans PsJN delays Botrytis cinerea development on grapevine inflorescences.

Grapevine flowering is an important stage in the epidemiology of Botrytis cinerea, the causal agent of gray mold disease. To prevent infection and to minimize postharvest losses, the control of this necrotrophic fungus is mainly based on chemical fungicides application. However, there is a growing interest in other control alternatives. Among them, the use of beneficial microorganisms appears as an eco-friendly strategy. This study aims to investigate the effect of Paraburkholderia phytofirmans PsJN, root-inoculated or directly sprayed on fruiting cuttings inflorescences to control B. cinerea growth. For this purpose, quantification by real time PCR of Botrytis development, direct effect of PsJN on fungal spore germination and chemotaxis were assayed. Our results showed a significant protective effect of PsJN only by direct spraying on inflorescences. Moreover, we demonstrated an inhibition exerted by PsJN on Botrytis spore germination, effective when there was a direct contact between the two microorganisms. This study showed that PsJN is positively attracted by the pathogenic fungus B. cinerea and forms a biofilm around the fungal hyphae in liquid co-culture. Finally, microscopic observations on fruit cuttings revealed a co-localization of both beneficial and pathogenic microorganisms on grapevine receptacle and stigma that might be correlated with the protective effect induced by PsJN against B. cinerea via a direct antimicrobial effect. Taking together, our findings allowed us to propose PsJN as a biofungicide to control grapevine gray mold disease.

Efficiency of nanoemulsion of essential oils to control Botrytis cinerea on strawberry surface and prolong fruit shelf life

Strawberry fruit is highly susceptible to decay by fungi. The objective of this study was to determine if essential oils (EOs) or nano-emulsions (Nano-EM) of EOs from Thymus vulgaris (Th), Matricaria chamomilla (Mc), Pistacia atlantica (Pa), or Mentha longifolia (Me) could inhibit growth of strawberry spoilage fungi Botrytis cinerea and their effect, if any, on strawberry quality parameters. An In vitro study showed that Th and Me EOs had the same minimal inhibitory concentrations (MIC) of 0.021 % while the MICs for Mc and Pa EOs were 0.9 % and 1.5 %, respectively. Th and Me EOs were used for subsequent experiments. In the second experiment, the application of Th and Me EOs and their nano-EM at 0.021, 0.1, 0.5 and 1 % were studied to control B. cinerea growth on the fruit surface. Nano-EM of EOs had higher antifungal activity in the control of B. cinerea than EOs on fruit surface. Generally, antifungal activity was increased at higher concentrations of Nano-EM, but in the case of EOs, their antifungal activity was not increased by increasing concentration. Nano-EM of EOs with 0.5 % was selected for further study. Finally, the quality changes and postharvest losses of fruit treated with Nano-EM of EOs of Th and Me at 4 °C were studied. The results of third experiment showed that Nano-EM of both EOs reduced microbial load, decay index, weight loss and induced greater firmness, vitamin C, total flavonoid and antioxidant activity in strawberry during storage. NanoEM-ThEO 0.5 % was more effective than NanoEM-MeEO 0.5 % to retain strawberry firmness, vitamin C and total flavonoid.

Antifungal mechanism of (E)-2-hexenal against Botrytis cinerea growth revealed by transcriptome analysis.

Gray mold caused by Botrytis cinerea, a necrotrophic plant pathogen, is one of the most damaging diseases of tomato, resulting in both pre- and post-harvest losses. (E)-2-Hexenal dose-dependently inhibited the mycelial growth of B. cinerea, and caused distortion of mycelia and loss of the cytoplasm content, thus altering the morphology of B. cinerea hyphae. To understand molecular processes in response to (E)-2-hexenal, transcriptome sequencing was carried out using RNA-Seq technology. RNA-Seq results revealed that a total of 3,893 genes were differentially expressed in B. cinerea samples treated with (E)-2-hexenal fumigation. Among these genes, 1,949 were upregulated and 1,944 were downregulated. Moreover, further analysis results showed 2,113 unigenes were mapped onto 259 pathways in Kyoto Encyclopedia of Genes and Genomes (KEGG). Moreover, (E)-2-hexenal stress affected the expression of genes involved in the pathways of cell wall, cell membrane, and energy metabolism. KEGG pathway analysis showed that the terpenoid backbone biosynthesis and steroid biosynthesis were the most enriched in ergosterol biosynthetic process transcriptome data. Particularly, (E)-2-hexenal fumigation had influenced ergosterol biosynthetic gene expression levels (e.g., ERG1, ERG3, ERG4, ERG7, ERG12, ERG13, ERG24, ERG25, ERG26, and ERG27), which were in good agreement with the experimental measurement results, and the ergosterol content decreased. Collectively, the results of this study increase our current understanding of (E)-2-hexenal inhibition mechanisms in B. cinerea and provide relevant information on postharvest shelf life extension and preservation of fruits and vegetables.

Antifungal properties of aqueous microalgal extracts

Microalgae are considered a promising source of eco-friendly antifungal agents that can potentially reduce the usage of synthetic fungicides. Hence, properties of aqueous extracts from Nannochloropsis sp., Phaeodactylum tricornutum, Scenedesmus obliquus, Chlorella vulgaris and Spirulina sp. were investigated in vitro regarding their antagonistic activity towards the phytopathogenic fungi Sclerotium rolfsii, Rhizoctonia solani, Botrytis cinerea and Alternaria alternata. S. obliquus showed the highest antifungal activity of all microalgal strains against Sclerotium rolfsii, inhibiting growth up to 32.01 ± 4.82%. Nannochloropsis sp. mitigated Sclerotium rolfsii by up to 13.96 ± 5.26%, while P. tricornutum suppressed the mycelial growth of Sclerotium rolfsii and Rhizoctonia solani by up to 18.35 ± 3.45%. Moreover, P. tricornutum and S. obliquus inhibited Botrytis cinerea growth by up to 11.47 ± 2.06%. The obtained results indicate that microalgae with fungicidal activity could replace chemical agents in modern and sustainable agricultural food production.

Mycofumigation of postharvest blueberries with volatile compounds from Trichoderma atroviride IC-11 is a promising tool to control rots caused by Botrytis cinerea

Botrytis cinerea, the causal agent of the gray mold, is a filamentous fungus that infects blueberries and can cause important production losses in postharvest storage. Considering that the use of synthetic fungicides is not allowed on blueberries in postharvest conditions, alternative and natural strategies are needed to control gray mold. The objective of this work was to evaluate the capability of volatile organic compounds (VOCs) produced by Trichoderma atroviride IC-11 to control B. cinerea growth in blueberries after harvest.These VOCs inhibited almost completely B. cinerea growth in vitro. The most abundant volatile compound was 6-pentyl-α-pyrone (6PP). In vitro assays with pure 6PP confirmed its antifungal activity. The incidence of gray mold was evaluated in blueberries inoculated with B. cinerea and exposed to volatiles of T. atroviride IC-11. Gray mold incidence among those stored in air at 20 °C for 14 days was 100%, while the incidence among the volatile-treated fruit was 17%. Gray mold incidence among those stored in air at 4 °C for 31 days was 82%, while the incidence among the volatile-treated fruit was 11%. T. atroviride IC-11 VOCs inhibited mycelial growth and conidia germination of B. cinerea. The binding of VOCs to the surface of hyphae caused their vacuolation and deterioration. Selective cytotoxicity of 6PP on B. cinerea was observed but not on human intestinal cells at specific concentrations that controlled gray mold.The postharvest mycofumigation of blueberries with T. atroviride IC-11 VOCs is a promising approach to protect these fruits from gray mold.

Light and mycelial injury influences the volatile and non-volatile metabolites and the biocontrol properties of Trichoderma atroviride

Trichoderma spp. are common inhabitants of the rhizosphere, which produce volatile organic compounds (VOCs) and diffusible molecules such as indole-3-acetic acid (IAA) for the communication with plants. Here, we report that fungal VOCs and IAA production, as well as growth and sporulation change upon mechanical damage and compromise its biocontrol properties. Mycelium injury in combination with photoperiod conditions triggered conidiogenesis, stimulated IAA secretion, and enhanced the emission of 2-heptanone, 2-nonanone, and 1-octen-3-ol, but diminished the emission of 6-pentyl-2H-pyran-2-one (6-PP). The opposite effects were observed under darkness, where the content of 1-octen-3-ol decreased while the abundance of 6-PP increased. Arabidopsis thaliana growth promotion through fungal VOCs and diffusible compounds was sustained upon injury while in-vitro confrontation experiments showed the influence of light in the performance of the WT strain against the necrotrophic fungus Botrytis cinerea likely via 6-PP production, which inhibited B. cinerea growth. These results show that the biochemical and ecological attributes of T. atroviride are modulated by the fungal integrity and light signaling.

Evaluation of essential oils nanoemulsions formulations on Botrytis cinerea growth, pathology and grey mould incidence on cucumber fruits

BackgroundGrey mould caused by Botrytis cinerea of cucumber immature fruits is the most epidemic fungal diseases causing significantly losses of fruits during development on cucumber plant in winter season.Material and methodsCrude and nanoemulsions of clove, black seed, lemon and orange essential oils at (5000 ppm) and also different formulations of clove, black seed and lemon oils nanoemulsions as single or in combination were tested against mycelial linear growth of B. cinerea (MF996363) as well sclerotial formation and pathological activity on the development of germinated seeds of cucumber.ResultsEssential oils nanoemulsion formulation of clove + black seed (2:1) at 5000 ppm was the best formulation significantly reduced mycelia linear growth of B. cinerea by 61.0% followed by 28% formulation (1:1) and (1:2). In addition, nanoemulsions formulations of clove, black seed essential oils (2:1) were highly reduced the count of sclerotial formation of B. cinerea and completely (100%) suppress seed rot and seedling mortality of cucumber followed by nanoemulsion of clove only.ConclusionsFoliar application of nanoemulsion formulation of clove + black seeds is promising than fungicides (Topsin M-70) in controlling grey mould on cucumber fruits caused by B. cinerea in plastic greenhouse with no phytotoxicity on cucumber plants.

A dialogue-like cell communication mechanism is conserved in filamentous ascomycete fungi and mediates interspecies interactions

In many filamentous fungi, germinating spores cooperate by fusing into supracellular structures, which develop into the mycelial colony. In the model fungus Neurospora crassa, this social behavior is mediated by an intriguing mode of communication, in which two fusing cells take turns in signal sending and receiving. Here we show that this dialogue-like cell communication mechanism is highly conserved in distantly related fungal species and mediates interspecies interactions. In mixed populations, cells of N. crassa and the phytopathogenic gray mold Botrytis cinerea coordinate their behavior over a spatial distance and establish physical contact. Subsequent cell–cell fusion is, however, restricted to germlings of the same species, indicating that species specificity of germling fusion has evolved not on the level of the signal/receptor but at subsequent levels of the fusion process. In B. cinerea, fusion and infectious growth are mutually exclusive cellular programs. Remarkably, the presence of N. crassa can reprogram this behavior and induce fusion of the gray mold on plant surfaces, potentially weakening its pathogenic potential. In a third fungal species, the nematode-trapping fungus Arthrobotrys flagrans, the conserved signaling mechanism mediates vegetative fusion within mycelial colonies but has also been repurposed for the formation of nematode-catching traps. In summary, this study identified the cell dialogue mechanism as a conserved complex trait and revealed that even distantly related fungi possess a common molecular language, which promotes cellular contact formation across species borders.

Laccase enhancement and antifungal toxicity reduction: Bidirectional influences between Pomegranate peel extract and Morchella conica mycelium activity

Rich in phenolic compounds, pomegranate peel is resistant to biological degradation by fungi and bacteria. We studied the bidirectional valorization potential of pomegranate peel extract (PPE) cultured with Morchella conica mycelium for both laccase production and reduction of PPE antifungal toxicity. Wonderful PPE (WPPE) inhibited Morchella biomass accumulation after 3 days' growth on solid agar, but on day 7, inhibition was overcome and biomass accumulated at control levels. Laccase released into Morchella–WPPE culture liquid showed increased activity with increasing WPPE concentration. PPEs from two other pomegranate varieties similarly induced laccase, up to 3-fold on day 5 of incubation. LC–MS revealed a sharp reduction in 15 WPPE phenolic compounds on day 8 of culture with Morchella. Moreover, a spore-inoculation bioassay showed no inhibition of Botrytis cinerea growth by WPPE after 8-day culture with Morchella. Thus, PPE may induce laccase production, which in turn may decrease its environmental toxicity.

Responsiveness of Dichrostachys cinerea to seasonal variations in temperature and rainfall in central Namibia

Woody plants provide natural archives of climatic variation which can be investigated by applying dendroclimatological methods. Such studies are limited in Southern Africa but have great potential of improving our understanding of past climates and plant functional adaptations in the region. This study therefore investigated the responsiveness of Dichrostachys cinerea to seasonal variations in temperature and rainfall at two sites in central Namibia, Waterberg and Kuzikus. Dichrostachys cinerea is one of the encroacher species thriving well in Namibia. A moving correlation and response function analysis were used to test its responsiveness to seasonal climatic variations over time. Dichrostachys cinerea growth rings showed relationships to late summer warming, lasting up to half of the rainy season. The results also revealed that past temperatures had been fluctuating and their influence on growth rings had been intensifying over the years, but to varying extents between the two sites. Temperature was a more important determinant of ring growth at the drier site (Kuzikus), while rainfall was more important at the wetter site (Waterberg). Growth ring responsiveness to rainfall was not immediate but showed a rather lagged pattern. We conclude that D. cinerea differentially responds to variations in rainfall and temperature across short climatic gradients. This study showed that the species, due to its somewhat wide ecological amplitude, has great potential for dendroclimatological studies in tropical regions.

Double-stranded RNA targeting fungal ergosterol biosynthesis pathway controls Botrytis cinerea and postharvest grey mould.

SummaryPathogenic fungi cause major postharvest losses. During storage and ripening, fruit becomes highly susceptible to fungi that cause postharvest disease. Fungicides are effective treatments to limit disease. However, due to increased public concern for their possible side effects, there is a need to develop new strategies to control postharvest fungal pathogens. Botrytis cinerea, a common postharvest pathogen, was shown to uptake small double‐stranded RNA (dsRNA) molecules from the host plant. Such dsRNA can regulate gene expression through the RNA interference system. This work aimed to develop a synthetic dsRNA simultaneously targeting three essential transcripts active in the fungal ergosterol biosynthesis pathway (dsRNA‐ERG). Our results show initial uptake of dsRNA in the emergence zone of the germination tube that spreads throughout the fungus and results in down‐regulation of all three targeted transcripts. Application of dsRNA‐ERG decreased B. cinerea germination and growth in in vitro conditions and various fruits, leading to reduce grey‐mould decay. The inhibition of growth or decay was reversed by the addition of ergosterol. While dual treatment with dsRNA‐ERG and ergosterol‐inhibitor fungicide reduced by 100‐fold the required amount of fungicide to achieve the same protection rate. The application of dsRNA‐ERG induced systemic protection as shown by decreased decay development at inoculation points distant from the treatment point in tomato and pepper fruits. Overall, this study suggests that dsRNA‐ERG can effectively control B. cinerea growth and grey‐mould development suggesting its efficacy as a future method for postharvest control of fungal pathogens.

Efficacy assessment of Pantoea jilinensis D25 fermentation broth against Botrytis cinerea

Tomato gray mold, caused by Botrytis cinerea, is one of the most devastating diseases affecting tomato plants. In this study, Pantoea jilinensis D25 fermentation broth (PJFB) was used to inhibit B. cinerea growth. The optimum fermentation time was 7 days. PJFB antifungal activity decreased when PJFB was heated to ≥60°C, whereas it was the strongest at pH 8. Moreover, ultraviolet treatment for a long time reduced its antifungal effect. PJFB, applied at 10 % (v/v), could inhibit B. cinerea growth by inhibiting its mycelial diameter, conidial production, and mycelial dry weight with the inhibition rates of 57.3 %, 51.2 %, and 78.6 %, respectively. PJFB could also increase conductivity and malondialdehyde (MDA) content in B. cinerea. Furthermore, PJFB inhibited B. cinerea on not only the leaf tissues but also the seedlings of tomato. The secondary metabolites in PJFB were determined through gas chromatography–mass spectrometry. Through laboratory toxicity analysis, we found that the major compounds in PJFB were 1,2-benzenedicarboxylic acid bis(2-methylpropyl) ester (14.3098 %), 2,4-di-tert-butylphenol (3.8036 %), 2,6,10,14-tetramethyl pentadecane (2.9947 %), and 1,3-dimethyl naphthalene (1.8586 %).

Efficacy of pterostilbene suppression of postharvest gray mold in table grapes and potential mechanisms

Botrytis cinerea is an economically devastating necrotrophic fungus that is responsible for gray mold infection of table grapes. Fungicides application remains the most common approach in its control. However, in consideration of food and environmental safety, safe and eco-friendly alternatives are desirable to manage gray mold. Pterostilbene is a natural antimicrobial metabolite that inhibits growth of several phytopathogenic fungi. Moreover, pterostilbene has been widely used as a food additive on the basis of its safety and oxidation properties. However, the specific inhibitory effects of pterostilbene for pathogen control of postharvest fruit and its precise mechanism of action remain to be defined. Here, 0.25 g L−1 pterostilbene could suppress the development of gray mold in table grapes. Fluorescent staining indicated that pterostilbene-mediated disease suppression is mediated through loss of plasma membrane integrity. Electron microscopy revealed that pterostilbene inhibits B. cinerea by altering the morphology of the hyphae and conidiophores, with destruction of the plasma membrane and organelles. Furthermore, quantitative real-time PCR highlighted pterostilbene-mediated gene modulation and overexpression of genes associated with laccase production and cellular damage on B. cinerea, together with increased laccase activity. These data better define the mechanisms through which pterostilbene inhibits B. cinerea growth, thus making pterostilbene an attractive candidate in postharvest fruit disease management strategies.

Role of a corona field application in the physicochemical properties of stored strawberries

Grey mould disease caused by the fungus Botrytis cinerea Pers is widely distributed on strawberries as the dominant postharvest disease. Therefore, fruits have been treated using a pin-to-plate corona electrical field at a high voltage electric field (HVEF) intensity of 3.61, 4.56, and 5.13 kV·cm<sup>–1</sup> for 60 minutes. The result revealed that the corona discharge demolished the B. cinerea growth using 20 kV·cm<sup>–1</sup> for 10 min in the Petri dishes. In addition, the treated strawberries at 4.56 kV·cm<sup>–1</sup> had an average infection rate of 23.33% compared with non-treated samples rate of 45.33%. The HVEF-treated samples showed significantly lower mass losses. The analysis of variance showed that the HVEF did not significantly affect the total soluble solids content, pH, titratable acidity, and softness; however, the lower acidity affected the Botrytis cinerea growth. No significant differences were observed among the mean values in the colour change parameters and colour difference for 4.56 kV·cm<sup>–1</sup> compared with the control, while the lightness was significantly higher. The result show that the corona electrical field was able to demolish the B. cinerea growth, and an electric field intensity at 4.56 kV·cm<sup>–1</sup> was found to extend the strawberries' cold storage and to lead to a lower mass loss.

Regulation of Botrytis cinerea Infection and Gene Expression in Cut Roses by Using Nano Silver and Salicylic Acid.

Botrytis cinerea (B. cinerea) is one of the necrotrophic pathogens resulting in the heaviest commercial losses in cut rose flowers, and the severity of gray mold disease partly depends on the presence of ethylene during the storage and transport. The effectiveness of nano silver (NS) and salicylic acid (SA) was assessed as a novel control agent in protecting the cut rose flowers against B. cinerea infection and ethylene damages. The efficacy of NS and SA was compared with an inoculated control (CON). A non-treated control (NT) was also used to evaluate the natural infection process. The results indicated that pretreatment with 20 mg L−1 NS significantly reduced B. cinerea growth in rose petals during vase periods. NS effectively suppressed the mRNA levels of ethylene biosynthesis genes (RhACS2, RhACS4, and RhACO1) and the reduction in expression levels of ethylene receptor genes (RhETR1, RhETR2, and RhETR5) and the downstream regulator RhCTR2 in rose petals after B. cinerea inoculation. NS application also decreased the expression of the B. cinerea snod-prot-like 1 (Bcspl1) gene which acts as the virulence factor in cut roses. In NS flowers, the maximum quantum yield of PSII (Fv/Fm) value was higher and the leaf temperature was lower on day 1, suggesting that these factors can be used for detecting B. cinerea infection and water stress in cut rose flowers. Furthermore, NS improved water relations and extended the vase life of cut rose flowers by 3.3 d, compared with that of NT flowers. In contrast, SA had no inhibitive effects on both B. cinerea growth and ethylene response in cut roses. The findings from the present study highlight NS as a promising new candidate for preventing B. cinerea infection and ethylene damages and for improving the postharvest quality of cut roses exported overseas.

Metarhizium anisopliae reduces conidial germination and mycelium growth of the apple gray mold Botrytis cinerea

Fresh apple market is affected every year by losses caused by fungi invasion and spoilage, with Botrytis cinerea one of the main responsible pathogens. The objective of this study was the characterization of the in vitro antagonistic activity of Metarhizium anisopliae Ma70 against Botrytis cinerea and its trial on apple fruit. The antagonism was tested by dual cultures, cellophane membrane assay and the effect of M. anisopliae crude extract over conidia germination and mycelium growth of B. cinerea. The trials on apple fruit evaluated crude and semi purified extracts activity against apple gray mold. Antifungal volatile organic compounds produced during the process were determined using GC–MS. We observed that M. anisopliae (Ma70), reduced the B. cinerea growth by 60–63% (P < 0.01). Pathogen’s mycelium is degraded, even without physical contact. Cellophane tests showed that growth inhibition by antibiosis reach a 88%. The Ma70 extracts affects conidia germination (92%) and mycelial growth (50–80%) of B. cinerea. The phytopathogen suffers membrane lipoperoxidation by the effect of antagonist extracts, the malondialdehyde production was increased by a factor of two, in mycelium and in the culture medium. We observed that crude (CE) and semi-purified (SPE) MA70 extracts reduced the damage caused by B. cinerea in apple. The B. cinerea growth inhibition by the VOCs produced by Ma70 was different depending on the culture media, with the highest inhibition effect (75%) seen in sabouraud dextrose agar plus yeast extract. Twenty-eight volatile organic compounds (VOCs) were identified in CE (mainly oxalic acid) and 13 in SPE (mainly octane,1-methoxy). Only 1-Octanol appears in both CE and SPE. M. anisopliae Ma70 can be an effective treatment for biocontrol of the apple gray mold disease, producing compounds that inhibited conidia germination and mycelium growth of B. cinerea.