Blue Mold Disease Research Articles

Potential application of Portuguese propolis to control blue mould disease in ‘Rocha’ pear

Potential application of Portuguese propolis to control blue mould disease in ‘Rocha’ pear

DNA analysis of a tobacco herbarium specimen reveals the presence of Peronospora tabacina in Italy in 1934

During a new cataloging of the herbaria of library “Leonardo Angeloni” at CREA-CI of Caserta (South of Italy), a dry leaf of Nicotiana tabacum (var. Burley) stored in a herbarium dated 1934, was noticed for the presence of typical symptoms of Peronospora tabacina. This plant pathogenic fungus, causal agent of blue mold disease, was unknown at that time to the cataloguers, since the first report on tobacco is dated 1958 in Europe and 1960 in Italy. The genomic DNA was extracted from the symptomatic regions of the diseased dry leaf and used as template in PCR reactions with specific primers for the internal transcribed spacers, comprising the 5.8S rDNA gene (ITS1–5.8-ITS2), of P. tabacina. Sequence analysis of PCR products confirmed the presence of the pathogen on the herbarium leaf, providing evidence on the presence of P. tabacina in Europe in 1934, 24 years before the first report. This work emphasizes the usefulness of herbarium specimens to study genetic, ecological and epidemiological aspects of fungal plant diseases through the years.

Involvement of protective enzymes and phenols in decay (Penicillium expansum) resistance in apple

Blue mold disease caused by Penicillium expansum is a major post- harvest disease of apples. In this research, the biochemical basis of apple resistance to this pathogen was studied in two relatively resistant and susceptible cultivars, Granny smith and Mashhad, respectively. The activities of catalase (CAT), peroxidase (POX), superoxide dismutase (SOD) and polyphenol oxidase (PPO) enzymes and polyphenol content were compared at different time intervals of 0 to 7 days. Based on the results, fruit polyphenol content of Granny smith was higher than that of Mashhad PPO, SOD and CAT activity was higher in Granny smith than Mashhad but CAT activity decreased three days post-treatment. No detectable difference was found in POX activities in the two cultivars. It is concluded that polyphenols contribute in apple resistance to blue mold. Activation of PPO and SOD, lack of POX activity and decrease of CAT activity, all together, could lead to a toxic environment around the blue mold fungus.

Efficacy of Non-Chemical Alternatives on Blue Mold of Apple under Controlled Cold Storage Conditions

Fruits of three apple cultivars; Golden Delicious, Granny Smith and Fuji were inoculated with blue mold, Penicillium expansum , and kept under cold storage conditions for 75 days after treatment with non-chemical alternatives and the fungicide Topsin as a standard. This aimed at providing new postharvest methods for the control of blue mold incidence and severity in apple fruits. Granny Smith showed lower sensitivity to blue mold disease than Golden Delicious but Fuji was the most sensitive to the disease in relation to fruit firmness and total soluble solid content (TSS). Dipping apple fruits in yeast ( Saccharomyces cerevisiae ) solution at a concentration of 1 g L -1 or in hot water at 50 °C for 1 or 5 min., or exposing them to microwave for 10 s resulted in an effective control of blue mold disease under controlled cold storage conditions. Calcium nitrate at 1 or 8 g L -1 did not result in an effective control of blue mold but increased the storability of apple fruits. Therefore, a combination of two or more of the alternatives may provide a long-lasting effective control of post-harvest blue mold affecting apple fruits.

Biocontrol of apple blue mould by new yeast strains: Cryptococcus albidus KKUY0017 and Wickerhamomyces anomalus KKUY0051 and their mode of action

Seeking new yeast strains having the ability to protect apple fruits against blue mould for a long time under different storage conditions was the main goal of this work. Based on the in vitro test, yeast strains KKUY0017 and KKUY0051 were selected as the most effective antagonists against Penicillium expansum. Sequencing of 26S rDNA of both yeasts confirmed that the identity of KKUY0017 and KKUY0051 was Cryptococcus albidus and Wickerhamomyces anomalus, respectively. The two strains protected the apple fruits from the blue mould disease under a wide range of temperature (5–30°C); however, W. anomalus KKUY0051 was more effective. At 25°C, W. anomalus KKUY0051 involved in the reduction of disease severity and disease incidence of blue mould by 56.49% and 57.78%, respectively. When either of the two yeasts was applied in concentration of 108 or 109 cells/mL, the maximum reduction in disease severity and disease incidence was achieved. Under cold storage (5°C), both yeast strains succeeded to protect the apple fruits free from the infection up to 24 days. Electron micrograph showed a fit attachment between the cells of C. albidus KKUY0017 and the fungal hyphae leading to the degrading of the hyphae; however, W. anomalus killed the fungal hyphae without direct attachment to them. Gas chromatography–mass spectrometry analysis of the cell-free extract of W. anomalus KKUY0051 revealed the presence of toxic compounds such as the nitrophenol derivatives. The results support the assumption that the main mode of action of this yeast is by killer toxins. We conclude that application of these yeasts under cold storage condition could keep the apple fruits free from blue mould infection for a long time.

Expression of an apoplast-directed, T-phylloplanin-GFP fusion gene confers resistance against Peronospora tabacina disease in a susceptible tobacco

Phylloplanins are plant-derived, antifungal glycoproteins produced by leaf trichomes. Expression of phylloplanin-GFP fusion gene to the apoplast of a blue mold susceptible tobacco resulted in increased resistance to this pathogen. Tobaccos and certain other plants secrete phylloplanin glycoproteins to aerial surfaces where they appear to provide first-point-of-contact resistance against fungi/fungi-like pathogens. These proteins can be collected by water washing of aerial plant surfaces, and as shown for tobacco and a sunflower phylloplanins, spraying concentrated washes onto, e.g., turf grass aerial surfaces can provide resistance against various fungi/fungi-like pathogens, in the laboratory. These results suggest that natural-product, phylloplanins may be useful as broad-selectivity fungicides. An obvious question now is can a tobacco phylloplanin gene be introduced into a disease-susceptible plant to confer endogenous resistance. Here we demonstrate that introduction of a tobacco phylloplanin gene--as a fusion with the GFP gene--targeted to the apoplasm can increase resistance to blue mold disease in a susceptible host tobacco.

Use of Food Additives to Control Postharvest Citrus Blue Mold Disease

Use of Food Additives to Control Postharvest Citrus Blue Mold Disease

Effect of Metschnikowia pulcherrima and methyl jasmonate on apple blue mold disease and the possible mechanisms involved

Metschnikowia pulcherrima alone and in combination with methyl jasmonate [MeJA] was applied for control of blue mold of apple caused by Penicillium expansum. In vitro, MeJA at different concentrations had no direct effect on the pathogen. In vivo, both M. pulcherrima (1×108 cell ml-1) and MeJA, as a stand-alone treatment, significantly reduced the lesion area of blue mold decay in apple. The combination of MeJA at 100 μmol l-1 and antagonistic yeast (1×108 cell ml-1) was a more effective approach to reduce the lesion diameter of blue mold decay of apples than the application of MeJA or M. pulcherrima separately after incubation for 15 and 50 days at 20°C and 4°C, respectively. In addition, MeJA increased the population of M. pulcherrima in the wounds of the apple fruit. The activity of the defense enzyme peroxidase was enhanced by MeJA and yeast treatments, and the level of total phenolic content in MeJA and yeast-treated fruit was also higher than that in control fruit. These results suggest that MeJA was effective in reducing decay and might enhance disease resistance in apple fruit by increasing defense enzyme activity and levels of antimicrobial phenolic compounds.

Enhancement of biocontrol activity of Torulaspora delbrueckii with methyl jasmonate against apple blue mould disease

Torulaspora delbrueckii alone and in combination with methyl jasmonate was applied to the control of Penicillium expansum. For evaluation of direct effect of Methyl jasmonate on mycelial growth of pathogen, it was added to potato dextrose agar culture at different concentrations. Effect of methyl jasmonate on population of yeast in nutrient yeast dextrose broth media was determined after 24 and 48 h. Results showed that methyl jasmonate had no significant direct effect on pathogen and yeast. Also, evaluation of methyl jasmonate effect on the population of yeast in apple wounds indicated that methyl jasmonate at different concentrations increased population growth of yeast at 20°C, 8 and 15 days after inoculation in toward the control and it had no significant effect on population dynamics of yeast at 4°C. In vivo, the results indicated that combination of methyl jasmonate with antagonistic yeast reduced the blue mould of apples better than methyl jasmonate and yeast alone.

Control of apple blue mould disease with Torulaspora delbrueckii in combination with Silicon

In this study, Torulaspora delbrueckii alone and in combination with silicon were evaluated for the control of apple blue mould disease caused by Penicillium expansum. In vitro, the antagonistic effects of T. delbrueckii in controlling mycelial growth of P. expansum on potato-dextrose-agar (PDA) in dual cultures, and the growth of P. expansum alone with cell-free metabolites and volatile components of T. delbrueckii were assayed. In vitro, to evaluate the direct effect of silicon on mycelial growth of pathogen, silicon at different concentrations (0.2, 0.4, 0.6, 1 and 2% (wt./vol.)) was added to PDA medium. Silicon at 0.6% (wt./vol.) and above concentrations completely inhibited the mycelial growth of P. expansum. However, it had no significant effect on population dynamics of yeast in vitro and in apple wounds. In vivo, silicon at 0.2 and 1% (wt./vol.) in combination with antagonistic yeast (1 × 108 cell/ml) was a more effective approach to reduce the lesion diameter of blue mould decay of apples than the application of silicon or T. delbrueckii alone at 20 and 4°C, respectively.

Molecular Linkage Mapping and Marker-Trait Associations with NlRPT, a Downy Mildew Resistance Gene in Nicotiana langsdorffii.

Nicotiana langsdorffii is one of two species of Nicotiana known to express an incompatible interaction with the oomycete Peronospora tabacina, the causal agent of tobacco blue mold disease. We previously showed that incompatibility is due to the hypersensitive response (HR), and plants expressing the HR are resistant to P. tabacina at all stages of growth. Resistance is due to a single dominant gene in N. langsdorffii accession S-4-4 that we have named NlRPT. In further characterizing this unique host-pathogen interaction, NlRPT has been placed on a preliminary genetic map of the N. langsdorffii genome. Allelic scores for five classes of DNA markers were determined for 90 progeny of a “modified backcross” involving two N. langsdorffii inbred lines and the related species N. forgetiana. All markers had an expected segregation ratio of 1:1, and were scored in a common format. The map was constructed with JoinMap 3.0, and loci showing excessive transmission distortion were removed. The linkage map consists of 266 molecular marker loci defined by 217 amplified fragment length polymorphisms (AFLPs), 26 simple-sequence repeats (SSRs), 10 conserved orthologous sequence markers, nine inter-simple sequence repeat markers, and four target region amplification polymorphism markers arranged in 12 linkage groups with a combined length of 1062 cM. NlRPT is located on linkage group three, flanked by four AFLP markers and one SSR. Regions of skewed segregation were detected on LGs 1, 5, and 9. Markers developed for N. langsdorffii are potentially useful genetic tools for other species in Nicotiana section Alatae, as well as in N. benthamiana. We also investigated whether AFLPs could be used to infer genetic relationships within N. langsdorffii and related species from section Alatae. A phenetic analysis of the AFLP data showed that there are two main lineages within N. langsdorffii, and that both contain populations expressing dominant resistance to P. tabacina.

Phylloplanins Reduce the Severity of Gray Leaf Spot and Brown Patch Diseases on Turfgrasses

ABSTRACTPlant‐produced, natural‐product fungicides should be evaluated for their potential to complement or replace synthetic fungicides that are major components in the management of high maintenance turf. Tobacco (Nicotiana tabacum L.) cultivar T.I. 1068 and sunflower (Helianthus annuus L.) phylloplanins (T‐ and S‐phylloplanins), collected in leaf‐water washes (LWWs) of plants, and recombinant T‐phylloplanin inhibit Peronospora tabacina D.B. Adam (oomycete) spore germination and reduce blue mold disease on tobacco. Here, in vitro (hyphal extension) and in vivo studies were conducted to test the ability of T‐ and S‐phylloplanins to inhibit growth of the turf pathogens Pyricularia oryzae Cavara (ascomycete) and Rhizoctonia solani J.G. Kühn (basidiomycete) and to test protection of turfgrass plants from gray leaf spot and brown patch diseases. Hyphal extension assays showed that LWWs containing T‐ and S‐phylloplanins inhibited both pathogens. Spraying potted grass plants with LWWs containing T‐ and S‐phylloplanins followed by inoculation with pathogens resulted in 97 and 88% inhibition of P. oryzae disease and 94 and 82% inhibition of R. solani on annual (Lolium multiflorum Lam. cv. Linn) and perennial (Lolium perenne L. cv. Double Eagle Blend) ryegrasses, respectively, under the conditions tested. In addition, T‐ and S‐phylloplanins led to 94 and 100% symptom reduction, respectively, on creeping bentgrass (Agrostis stolonifera L. cv. L‐93), for R. solani only. Results indicate that T‐ and S‐phylloplanins have broad selectivity, inhibiting at least one member of the ascomycete and basidiomycete phyla, and may be useful as exogenously applied or endogenously expressed natural‐product antifungal agents to protect turf, crops, and other plants.

Effects of chitosan-oil coating on blue mold disease and quality attributes of jujube fruits

The effects of chitosan coating enriched with cinnamon oil on blue mold disease and quality attributes were investigated. In the in vitro experiment, the results demonstrated that the antifungal activity against P. citrinum improved with increasing concentration of chitosan or cinnamon oil. In the in vivo study, chitosan-oil treatments significantly reduced fungal decay caused by P. citrinum and all compounds with cinnamon oil at 2.0% showed complete control of the growth of P. citrinum on wound-inoculated fruits. High chitosan-oil concentrations correlated with low disease incidence regardless of storage temperature. Treatments of chitosan-oil coating also inhibited the activity of polyphenol oxidase and maintained vitamin C and phenolic compounds in wounded jujube fruits. Results suggested that the effect of chitosan coating (1.0%) enriched with cinnamon oil (0.75%) on blue mold in jujube fruits may be associated with fungitoxic properties against the pathogen and the elicitation of biochemical defense responses in fruits.

First Report of Occurrence of Pyrimethanil Resistance in Penicillium expansum from Stored Apples in Washington State.

Blue mold caused by Penicillium expansum is a major postharvest fruit rot disease of apples (Malus domestica) worldwide. Pyrimethanil was registered in late 2004 in the United States for postharvest use on apples. Since then, pyrimethanil has been increasingly used in Washington State as a postharvest drench treatment for control of blue mold and other postharvest diseases in apples. Baseline sensitivity to pyrimethanil in P. expansum populations from apples in Washington State has been established and all isolates in the baseline population were sensitive to pyrimethanil (1). To monitor resistance to pyrimethanil in P. expansum populations, blue mold-like decayed apple fruit were sampled from May to August 2009 from the fruit that had been drenched with pyrimethanil prior to storage from fruit packinghouses. Isolation of Penicillium species from decayed fruit was attempted. Isolates of Penicillium species were identified to species according to the descriptions by Pitt (2). In total, 186 P. expansum isolates were collected and tested for resistance to pyrimethanil in a conidial germination assay on an agar medium amended with pyrimethanil at the discriminatory concentration of 0.5 μg ml-1 (1). Isolates that were able to germinate were considered resistant to pyrimethanil. Of the 186 isolates tested, one was resistant to pyrimethanil. EC50 (the effective concentration that inhibits fungal growth by 50% relative to the control) of pyrimethanil for the resistant isolate was determined according to a method described previously (1) and the test was done twice. EC50 values of pyrimethanil on mycelial growth and conidial germination for the resistant isolate were 9.9 and 3.1 μg/ml, respectively, which were 7.4-fold and 16.5-fold higher than the means of the baseline population (1). To evaluate whether pyrimethanil at label rate is still able to control this resistant isolate, 'Fuji' apples were wounded, inoculated with conidial suspensions (1 × 104 conidia ml-1) of either the resistant isolate or a pyrimethanil-sensitive isolate, treated with either pyrimethanil or sterile water as controls, and stored at 20°C for 10 days following a method described previously (1). There were four 20-fruit replicates for each treatment. The experiment was performed twice. All inoculated fruit in the nontreated controls were decayed. Pyrimethanil applied at label rate completely controlled blue mold incited by a pyrimethanil-sensitive isolate, but 75% of the fruit that were inoculated with the resistant isolate and treated with pyrimethanil developed blue mold. To our knowledge, this is the first report of pyrimethanil resistance in P. expansum from decayed apple fruit collected from commercial packing houses. The pyrimethanil-resistant isolate was obtained from a packing house in which pyrimethanil had been used as a postharvest drench treatment in each of four consecutive years, suggesting that pyrimethanil-resistant individuals are emerging in P. expansum populations in Washington State after repeated use of pyrimethanil. Our results also indicate that pyrimethanil resistance in P. expansum reported in this study can result in failure of blue mold control in apples with pyrimethanil.

Inhibition of Penicillium digitatum and Penicillium italicum in vitro and in planta with Panomycocin, a novel exo-β-1,3-glucanase isolated from Pichia anomala NCYC 434

Panomycocin, a novel exo-beta 1,3 glucanase, was tested as an antifungal agent against green and blue mold diseases, the most important causes of post harvest decay in citrus fruits. All tested isolates of Penicillium digitatum and Penicillium italicum were susceptible to panomycocin in vitro. Effective panomycocin concentrations for 50% growth inhibition (MIC-2) for P. digitatum and P. italicum were 2 and 1 microg ml(-1), respectively. Complete (MIC-0) growth inhibition of all isolates observed at a panomycocin concentration of 16 microg ml(-1). Treatment of spores with panomycocin at values lower than the MIC-0 led to slower germ tube elongation and mycelium growth. In tests on fruit, panomycocin at concentrations equal to in vitro MIC-0 value protected lemon fruit from decay.

Aureobasidium pullulans as a biocontrol agent of postharvest pathogens of apples in Uruguay

Aureobasidium pullulans was the microorganism most frequently recovered from the surface of apple fruit (cv. Red Delicious) stored in commercial cold chambers for 6 months. In the present work, 10 isolates of Aureobasidium pullulans were assayed to determine if they could control blue and grey mold disease of apple during cold storage. Although nine of 10 isolates, significantly reduced the percentage of decayed wounds when compared to the control, one of them, designated isolate ApB, showed the highest levels of protection. ApB was able to grow in a wide range of temperatures lower than 35°C, which is an important human health safety factor. ApB was resistant to thiabendazole, iprodione and imazalil, the most commonly commercially applied fungicides in postharvest treatment of apples in Uruguay. Regarding the mechanisms of action of the selected biocontrol agent, lytic enzymes did not seem to play a central role. ApB depleted iron from nutrient media, which may be an important aspect of its ability to inhibit Botrytis cinerea. Further experiments are needed, however, to determine if the depletion of iron is caused by the production of siderophores, by the immobilization of iron in an insoluble pigment, or a combination of both.

Control of blue mold disease and natural decay of postharvest peaches by hot water treatment

Control of blue mold disease and natural decay of postharvest peaches by hot water treatment

Genetic Resistance to Peronospora tabacina in Nicotiana langsdorffii, a South American Wild Tobacco

Several accessions of Nicotiana langsdorffii, a wild tobacco relative native to South America, express an incompatible interaction in response to infection by Peronospora tabacina, an oömycete that causes blue mold disease of tobacco (N. tabacum) and many other species of Nicotiana. In resistant accessions of N. langsdorffii, such as S-4-4, incompatibility takes the form of necrotic lesions that appear 48 h after pathogen inoculation, restricting pathogen growth, and suppressing subsequent asexual sporulation. Significantly elevated levels of salicylic acid and expression of a defense-related gene (HSR203J) were observed in S-4-4 leaves following blue mold infection. Genetic segregation analysis in F(2) and modified backcross populations showed that blue mold resistance is determined by a single dominant gene (NlRPT) present in S-4-4. Further characterization of this unique host-pathogen interaction has revealed that (i) necrotic lesion resistance is due to the hypersensitive response (HR), (ii) HR-mediated resistance is present in 7 of 10 N. langsdorffii accessions examined, but not in closely related species, (iii) in some accessions of N. langsdorffii, resistance is expressed in cotyledon tissue and seedling leaves as well as in adult plants, and (iv) several resistant accessions including S-4-4 express an unregulated ("runaway") HR in response to P. tabacina infection.

Suppression of postharvest blue mould of apple fruit by Cryptococcus laurentii and N6‐benzyladenine

AbstractBACKGROUND: Cryptococcus laurentii is a well‐known postharvest yeast antagonist. N6‐benzyladenine (6‐BA), a cytokinin plant hormone, has a role in retarding ripening and senescence of harvested produce. This study was conducted to evaluate the efficacy of C. laurentii and 6‐BA in reducing the blue mould disease of apple fruit.RESULTS: The combination of C. laurentii with 6‐BA (20 µg mL−1) was more effective in suppressing the Penicillium expansum infection in apple fruit wounds than C. laurentii alone, although 6‐BA (20 µg mL−1) alone neither affected the growth of C. laurentii nor reduced the incidence of the blue mould disease in vivo. Moreover, treatment of apple fruit with C. laurentii and 6‐BA (20 µg mL−1) resulted in stimulation of superoxide dismutase activity but in inhibition of the increase in peroxidase activity.CONCLUSION: 6‐BA (20 µg mL−1) could enhance the efficacy of C. laurentii in reducing the postharvest blue mould disease of apple fruit, which offered great potential in minimizing the postharvest decay of apple fruit in an integrated pest management strategy. Copyright © 2008 Society of Chemical Industry

SIMPEROTA 1/3 – a decision support system for blue mould disease of tobacco*

Blue mould (Peronospora tabacina) is the most serious threat to German tobacco crops. In order to efficiently control the disease whilst minimizing the risk of nontolerable fungicide residue levels on tobacco leaves, a decision support system has been developed which optimizes the timing of fungicide treatments. The DSS consists of two models, SIMPEROTA 1, which forecasts the dates of blue mould first appearance and SIMPEROTA 3 which forecasts the dates of fungicide applications. Crucial biological processes are included in the models (infection, mycelium growth, sporulation and spore release). Input parameters are temperature, relative humidity and leaf wetness recorded on an hourly basis. Validation with data from 2003 and 2006 showed that SIMPEROTA 1 gave satisfying results. The model is suitable for practical use and can be employed for steering monitoring efforts of extension services and for the timing of the first fungicide treatment. SIMPEROTA 3 gives advice on follow‐up treatments and the length of spraying intervals, but this model needs to be validated before being introduced into practice.