Blue Mold Research Articles

Independent domestication events in the blue-cheese fungus Penicillium roqueforti.

Domestication provides an excellent framework for studying adaptive divergence. Using population genomics and phenotypic assays, we reconstructed the domestication history of the blue cheese mould Penicillium roqueforti. We showed that this fungus was domesticated twice independently. The population used in Roquefort originated from an old domestication event associated with weak bottlenecks and exhibited traits beneficial for pre‐industrial cheese production (slower growth in cheese and greater spore production on bread, the traditional multiplication medium). The other cheese population originated more recently from the selection of a single clonal lineage, was associated with all types of blue cheese worldwide except Roquefort, and displayed phenotypes more suited for industrial cheese production (high lipolytic activity, efficient cheese cavity colonization ability and salt tolerance). We detected genomic regions affected by recent positive selection and putative horizontal gene transfers. This study sheds light on the processes of rapid adaptation and raises questions about genetic resource conservation.

Blistering1 Modulates Penicillium expansum Virulence Via Vesicle-mediated Protein Secretion

The blue mold fungus, Penicillium expansum, is a postharvest apple pathogen that contributes to food waste by rotting fruit and by producing harmful mycotoxins (e.g. patulin). To identify genes controlling pathogen virulence, a random T-DNA insertional library was created from wild-type P. expansum strain R19. One transformant, T625, had reduced virulence in apples, blistered mycelial hyphae, and a T-DNA insertion that abolished transcription of the single copy locus in which it was inserted. The gene, Blistering1, encodes a protein with a DnaJ domain, but otherwise has little homology outside the Aspergillaceae, a family of fungi known for producing antibiotics, mycotoxins, and cheese. Because protein secretion is critical for these processes and for host infection, mass spectrometry was used to monitor proteins secreted into liquid media during fungal growth. T625 failed to secrete a set of enzymes that degrade plant cell walls, along with ones that synthesize the three final biosynthetic steps of patulin. Consequently, the culture broth of T625 had significantly reduced capacity to degrade apple tissue and contained 30 times less patulin. Quantitative mass spectrometry of 3,282 mycelial proteins revealed that T625 had altered cellular networks controlling protein processing in the endoplasmic reticulum, protein export, vesicle-mediated transport, and endocytosis. T625 also had reduced proteins controlling mRNA surveillance and RNA processing. Transmission electron microscopy of hyphal cross sections confirmed that T625 formed abnormally enlarged endosomes or vacuoles. These data reveal that Blistering1 affects internal and external protein processing involving vesicle-mediated transport in a family of fungi with medical, commercial, and agricultural importance.

First Report on Blue Mold Parasitism on Butterfly (Papilio polytes) Egg

The fungal (Penicillium) infection, on the eggs of butterfly Papilio polytes (Lepidoptera: Papilionidae), was reported for the first time at the urban settings, Kolkata, India. In course of rearing P. polytes, the eggs were observed to be vulnerable to the fungal attack. The eggs that oviposited on the leaves of Citrus limon were found to be infested with the fungi, identified as Penicillium sp., through further microbial culture. In all instances, the growth of Penicillium on the eggs restrained further development with the absence of larval emergence. The infestation by Penicillium on butterfly eggs caused disruption of development and eventual shrinking.

Antioxidant, Antifungal Activities of Ethnobotanical Ficus hirta Vahl. and Analysis of Main Constituents by HPLC-MS.

The medicinal and edible plant, Ficus hirta Vahl. (also called hairy fig), is used for the treatment of constipation, inflammation, postpartum hypogalactia, tumors, and cancer. There is an urgent need for scientific evaluation to verify the pharmacological properties of F. hirta. Therefore, in vitro assays evaluated the antioxidant and antifungal activities of various solvent extracts of hairy fig fruits (HFF). HFF extracts had abundant antioxidant components for a significant amount of total phenolic (TPC) and flavonoid contents (TFC) (TPC from 17.75 ± 0.52 to 85.25 ± 1.72 mg gallic acid/g dw and TFC from 15.80 ± 0.59 to 144.22 ± 8.46 mg rutin/g dw, respectively). The ethyl acetate extract (EAE) and acetone extract (AE) of HFF demonstrated potent antioxidant activities against 1,1-diphenyl-2-picrylhydrazyl (DPPH) (IC50 values of 2.52 and 2.02 mg/mL, respectively) and ABTS radicals (IC50 values of 3.06 and 9.26 mg/mL, respectively). Moreover, the AE with a high TFC showed a prominent in vitro and in vivo antifungal activity against Penicillium italicum, causing citrus blue mold. Eighteen metabolites were identified or putatively identified from six HFF extracts. Current findings indicated that HFF extracts had significant antioxidant and antifungal activities and could potentially be used as an alternative agent for the preservation of agricultural products.

Investigating the effect of methyl jasmonate on the biocontrol activity of Meyerozyma guilliermondii against blue mold decay of apples and the possible mechanisms involved

Apple is one of the largely grown fruits in China, and it suffers great economic losses caused by Penicillium expansum infection every year. In the present study, we ascertained the efficacy of Meyerozyma guilliermondii enhanced by 200 μmol/L methyl jasmonate (MeJA) in controlling the postharvest blue mold decay of apples and the possible mechanisms involved. The results demonstrated that the biological control ability of M. guilliermondii induced by MeJA in restraining P. expansum infection in apples. The efficacy of M. guilliermondii induced by MeJA significantly decreased the decay incidence and lesion diameter of apples. When treated with M. guilliermondii induced by MeJA, the decay incidence of apples was only 21.6%, while apples treated with M. guilliermondii was 42.4%. M. guilliermondii induced by MeJA also reduced the germ tube length, spore germination rate of P. expansum in PDB and colony diameter of P. expansum in PDA. The results also showed that antagonistic yeast induced by MeJA proliferated better in apple wounds and surface at 4 °C or 20 °C. Meanwhile, the activities of resistance-related peroxidase (POD), polyphenol oxidase (PPO), phenylalanine ammonia-lyase (PAL), Catalase (CAT), and the antibacterial substances of flavonoid contents, total phenolic content were all increased. The results manifested that M. guilliermondii induced by MeJA increased the expression levels of defense-related enzymes in apples.

The protein expression profile and transcriptome characterization of Pichia caribbica induced by ascorbic acid under the oxidative stress

Ascorbic acid (vitamin C, Vc) is a well-known antioxidant, which can eliminate reactive oxygen species (ROS) in order to protect yeasts subjected oxidative stress. In our previous research, Pichia caribbica, one of the antagonistic yeasts showed an activity against postharvest diseases of apples, and Vc enhanced the tolerance to oxidative stress of P. caribbica, and improved its biocontrol efficacy to postharvest blue mold decay of apples. However, the mechanisms, especially the molecular mechanisms of the tolerance of P. caribbica improved by Vc under oxidative stress are not sufficiently clear. The purpose of this research was to investigate the protein expression profile and transcriptome characterization of P. caribbica induced by Vc under oxidative stress. The proteomics results showed that there were 31 differentially expressed proteins (DEPs), among them 25 DEPs were up-regulated and 6 DEPs were down-regulated. These up-regulated DEPs were associated with the energy metabolism and glucose metabolism, including fructose – bisphosphate aldolase, malate dehydrogenase, peroxisomal catalase and so on. Transcriptomics analysis showed that 68 genes were differentially expressed, among them 38 genes were up-regulated and 30 genes were down-regulated. These up-regulated genes were found to be related to cell wall, energy synthesis, polysaccharides hydrolysis and antioxidant activity.

A comparative study on the inactivation of Penicillium expansum spores on apple using light emitting diodes at 277 nm and a low-pressure mercury lamp at 253.7 nm

A comparative study was performed to assess the efficacy of UV-C light emitting diodes (UV–C LEDs) at 277 nm and a low-pressure mercury (LPM) lamp at 253.7 nm to inactivate Penicillium expansum spores on apple skin at 4 °C or 25 °C. In saline solution, the D value for the inactivation of spores using 277 nm at 25 °C was 6.62 mJ cm−2 and 7.19 mJ cm−2 at 4 °C, both of which were significantly lower than the D value at 253.7 nm (9.26 mJ cm−2). The UV-mediated inactivation of spores on the surface of apple skin followed non-linear kinetics with an initial linear phase followed by tailing. The calculated D values for spores on apple surface were significantly higher compared to within saline (14.49 and 18.80 mJ cm−2 with 277 nm at 25 °C and 4 °C, respectively, compared to 23.00 mJ cm−2 with 253.7 nm). This could be due to protective effects of apple peel constituents or the non-uniform energy distribution due to the uneven apple surface. Yet, the log reductions achieved (>2 log CFU) were equivalent to washing in hypochlorite solution (200 mg L−1 free-chlorine) which is the current industrial practice. UV-C light at 277 and 253.7 nm (500 mJ cm−2) was shown to prevent growth of blue mould and subsequent spoilage of inoculated and stored apples (28 days) if treated prior to damage. The UV-C treatments at doses corresponding to reduction of 2 log CFU of P. expansum did not impact apple physico-chemical quality parameters during 12 weeks of storage at 25 °C.

A flavonone pinocembroside inhibits Penicillium italicum growth and blue mold development in ‘Newhall’ navel oranges by targeting membrane damage mechanism

Blue mold caused by Penicillium italicum is an important postharvest disease of citrus fruit. The antifungal activity of a flavonone pinocembroside compound obtained from the fruit of Ficus hirta Vahl., was evaluated against P. italicum. Pinocembroside showed antifungal activity against in vitro mycelial growth of P. italicum, with the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of 200 and 800 mg/L, respectively. The blue mold development on ‘Newhall’ navel oranges was inhibited by pinocembroside in a dose-dependent manner. Moreover, pinocembroside might exert its antifungal activity via membrane-targeted mechanism with increasing membrane permeability, reduction of antioxidant enzyme activity and acceleration of lipid peroxidation in the pathogen. This pioneering study suggested that pinocembroside suppressed postharvest blue mold by direct inhibition of P. italicum mycelial growth via membrane-targeting mechanism, thus providing a novel mode of action against traditional fungicides for controlling blue mold of citrus fruit.

Effects of cold-storage facility characteristics on the virulence and sporulation of Penicillium expansum and the efficacy of essential oils against blue mold rot of apples

Abstract Blue mold rot, caused by Penicillium expansum, is one of the most economically important post-harvest diseases of apple worldwide. The goals of this study were threefold: to evaluate the diversity of P. expansum isolates for mycelial growth, spore production and lesion diameter on apples; to estimate the effects of cold-storage facility conditions on P. expansum population structure; and to investigate the efficacy of three essential oils against P. expansum. The results showed that storage facilities applying fungicides and storing diverse fruit species selected for P. expansum isolates with a larger lesion diameter on apples. In addition, application of fungicides and diversification in stored fruit species significantly select for P. expansum isolates with higher levels of mycelial growth and spore production, respectively. Moreover, the diversity of host species of stored fruit accounted for 38% of the variability observed between storage facilities for the measured fitness parameters in P. expansum isolates and had a stronger effect on P. expansum population structure than fungicide treatment. Essential oils from Mentha pulegium and Syzygium aromaticum significantly decreased mycelial growth and spore production of P. expansum isolates in vitro. Mentha pulegium essential oil also significantly decreased the size of lesions associated with the blue mold rot of apples. Reducing the diversity of stored host species and applying M. pulegium essential oil may be useful in counter-selecting for aggressive P. expansum isolates and reducing losses due to blue mold rot during fruit storage.

Potential modes of action of Pseudomonas fluorescens ZX during biocontrol of blue mold decay on postharvest citrus.

The application of chemical fungicides is currently the main method for the control of postharvest decay of fruits and vegetables. However, public concern has been growing towards the effect of fungicides on food safety, human health and environmental pollution. Thus, interest in microbial biocontrol agent development has grown, such agents being considered both safe and environmentally friendly. Pseudomonas fluorescens is widely distributed in nature, and one of the most valuable biocontrol and plant growth-promoting rhizobacteria. In this study, the efficacy and the potential associated modes of action of P. fluorescens ZX against Penicillium italicum on oranges (Citrus sinensis Osbeck) were investigated. The application of P. fluorescens ZX significantly reduced blue mold lesion size and incidence in comparison to the control, where P. fluorescens ZX was effective when applied preventatively but not curatively. In dual cultures, treatment with cell-free autoclaved cultures or culture filtrate had a limited capacity to suppress P. italicum, while P. italicum was inhibited by bacterial fluid and bacterial suspension with living cells in vitro. The P. fluorescens ZX isolate displayed protease, but not chitinase, glucanase or cellulose, activity, and produced siderophores and volatile organic compounds with antifungal abilities. Competition tests showed P. fluorescens ZX could use fructose, sucrose, aspartic acid, threonine, serine, glycine, valine, lysine and proline better than P. italicum. Furthermore, an effective biofilm that peaked after a 24-hour incubation at 30 °C was formed by the P. fluorescens ZX isolate. Light microscopy and scanning electron microscopy observations indicate the P. fluorescens ZX isolate could not undergo direct parasitism or hyperparasitism. Competition for nutrients and niches, biofilm formation, inhibition of spore germination and mycelial growth, and production of inhibitory metabolites may play important roles in P. fluorescens ZX antagonism of P. italicum. © 2019 Society of Chemical Industry.

In vivo and in vitro screening for resistance against Penicillium allii in garlic accessions

Garlic blue mold disease, caused by Penicillium allii, is responsible for important economic losses produced yearly in garlic field crops and in postharvest storage. The identification of genetic resistance sources may help in the management of this disease. The present study investigated in vivo and in vitro antifungal effects of a genetically-diverse garlic collection against P. allii in two growing seasons. Cloves of garlic accessions were inoculated with P. allii conidia, and lesion area and sporulation of the fungus in the clove were estimated as a means to characterize the accessions response to the infection. Significant and continuous variation was found among the accessions (p < 0.001), suggesting a quantitative mode of resistance against P. allii in this garlic collection. ‘Castano’ and ‘Peteco’ were consistently the most resistant and susceptible genotypes, respectively. Culture media of the fungus supplemented with crude garlic extracts (CGEs) revealed significant inhibition of P. allii growth in vitro by all the garlic accessions, with fungal-growth inhibition being dose-dependent up to a concentration of 20–26% (v/v), beyond which the CGEs became fungicidal. These data indicate that garlic bulbs have antifungal compounds, which at high concentration can be fungicidal for P. allii. CGEs of ‘Castano’ and a few other accessions were consistently the more inhibitory extracts. Total phenolics and pyruvate (an estimator of the total thiosulfinates content) concentration in the garlic bulbs was not associated with P. allii resistance in vivo, but their content in the CGEs correlated significantly and negatively with the fungal growth in vitro (r = −0.38 to −0.72), suggesting that these compounds have antifungal effect, but their content is not the main factor conditioning P. allii resistance in vivo.

Effect of β-glucan on the biocontrol efficacy of Cryptococcus podzolicus against postharvest decay of pears and the possible mechanisms involved

In this study, the effect of β-glucan on the biocontrol efficacy of Cryptococcus podzolicus against blue mold decay of pears as well as the physiological mechanism and related molecular mechanism through transcriptome technology was investigated. Our results revealed that β-glucan could enhance the biocontrol ability of C. podzolicus on blue mold decay of pears. Meanwhile, β-1,3-glucanase and catalase (CAT) activities of 0.5% β-glucan-induced C. podzolicus were significantly increased, though the malondialdehyde (MDA) content of 0.5% β-glucan-induced C. podzolicus was decreased. During the whole storage time, the polyphenol oxidase (PPO), peroxidase (POD) and CAT activities of pears treated with 0.5% β-glucan-induced C. podzolicus were significantly increased. In addition, the transcriptome analysis indicated that C. podzolicus induced by β-glucan was able to increase the rate of polysaccharide utilization, accelerate the synthesis of cell walls and energy, improve its antioxidant capacity, and enhance its ability to adapt to oxidative stress. The aging process of C. podzolicus cells was delayed, and could be related to the improvement of the biocontrol ability of C. podzolicus. Therefore, β-glucan treatment can be used as an effective method to improve the biocontrol ability of antagonistic yeasts on postharvest diseases of pear fruits.

Comparative Transcriptomic Analysis of the Interaction between Penicillium expansum and Apple Fruit (Malus pumila Mill.) during Early Stages of Infection.

Blue mold, caused by Penicillium expansum, is an important postharvest disease of apple, and can result in significant economic losses. The present study investigated the interaction between P. expansum and wounded apple fruit tissues during the early stages of the infection. Spores of P. expansum became activated one hour post-inoculation (hpi), exhibited swelling at 3 hpi, and the germ tubes were found entering into apple tissues at 6 hpi. RNA-seq was performed on samples of P. expansum and apple fruit tissue collected at 1, 3, and 6 hpi. The main differentially expressed genes (DEGs) that were identified in P. expansum were related to interaction, cell wall degradation enzymes, anti-oxidative stress, pH regulation, and effectors. Apple tissues responded to the presence of P. expansum by activating pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) at 1 hpi, then activated effector-triggered immunity (ETI) at 3 hpi. This research provides new information on the interaction between P. expansum and apple fruit tissue at an early stage of the infection process.

Investigating possible mechanisms of Pichia caribbica induced with ascorbic acid against postharvest blue mold of apples

The present study investigated the effect of ascorbic acid (Vitamin C, VC) at 250 μg/mL in the enhancement of biocontrol efficacy of Pichia caribbica against blue mold decay caused by Penicillium expansum on apples. Compared to the performance of the yeast without treatment, P. caribbica induced by 250 μg/mL of VC potentially enhanced biocontrol activity against P. expansum and high growth rate on the apple surface when stored at 20 °C and 4 °C. The mechanisms underlying this improvement in biocontrol efficiency were probed by investigating the protein expression profile and transcriptome characterization of P. caribbica induced by VC. From the proteomics results, 46 proteins were identified as differentially expressed proteins (DEPs), among them 18 proteins were up-regulated and 28 proteins were significantly down-regulated. These up-regulated DEPs including glyceraldehyde-3-phosphate dehydrogenase and alcohol dehydrogenase were associated with the glucose metabolism. From the transcriptomic analysis, 292 genes were found to be differentially expressed genes (DEGs), among them 137 genes were up-regulated and 155 genes were down-regulated. These up-regulated genes were involved in pyruvate metabolism, amino sugar and nucleotide sugar metabolism. These molecular studies suggest that VC treatment significantly induces the metabolic pathways of P. caribbica, thereby VC potentially enhances the biocontrol efficacy of P. caribbica to postharvest diseases of apples.

Elmada mavi küfe neden olan Penicillium expansum’a karşı bazı bor tuzlarının antifungal etkisi

Penicillium expansum causing blue mold disease is one of the most important pathogens of pome fruit and is a necrotrophic fungus that requires wounds to infect the fruit. In the present study, the efficacy of etidot-67 and borax decahydrate against P. expansum were evaluated in both in vitro and in in vivo . In in vitro experiments, both etidot-67 and borax decahydrate strongly inhibited mycelial growth, spore germination and germ tube elongation of P. expansum . The inhibitory effects of both salts were closely correlated with their increasing concentrations. While boron salts completely inhibited the mycelial growth of P. expansum at %0.25 concentration, these salts completely inhibited spore germination and germ tube elongation of the fungus at %0.125 concentration. Additionally, it was determined that the toxicity of the salts tested were close to each other, namely EC 50 values of Etidot-67 and borax decahydrate were 0.067 and 0.071, respectively. While the minimum inhibition concentration (MIC) values of the etidot-67 and borax decahydrate were %0.25, the minimum fungicidal concentration (MFC) values of the same salts were found to be greater than 1%. In in vivo experiments, blue mold development in apple fruits treated with 3.0% concentration of etidot-67 and borax decahydrate after fungal inoculation (curative activity) was significantly reduced by %92.8 and %78.9, respectively, compared with the control treatment (P<0.05). However, at same concentration, lesion area on apple fruits treated with the salts before inoculation with the fungus (1x10 4 conidia mL -1 ) (preventive activity) reduced by %94.3 and %98.3, respectively. These results show that both boron salts can be used as a potential alternative to synthetic fungicides for the control of the postharvest disease of apple fruit caused by P. expansum .

Isolation and Identification of Fungal Pathogens Associated with Diseases of Onion Crop in District Swat, Pakistan

Onion is an important vegetable and a source of income for formers in District Swat, Pakistan. However, the crop is attacked by several pathogens i.e. fungi, bacteria, viruses, and nematodes. Therefore, a study was carried out for the estimation of fungal diseases of onion crop in district Swat. Within this study, about 50 samples of diseased onion crop were collected from 17 different regions of District Swat. The most prevalent fungal borne onion diseases were black mold (38%), onion rust (32%), Blue Mold Rot (10%) and seedling. Fungal species were consistently isolated from all infected samples. In which Aspergillus was isolated from 82% samples, Puccinia Alli was from 70%, Alternaria porri from 52%, Fusarium spp from 42% Penicillium spp from 40%, Peronospora destructor from 35%, Pyhtaium from 23% and Rhizoctonia solani from 18% of samples. These fungal species consistently isolated and cultured from diseased onion plants of different fields in Swat. Keywords: Onion crop, Fungal diseases, Aspergillus.

Electrolysed water and salt solutions can reduce green and blue molds while maintain the quality properties of ‘Valencia’ late oranges

The effect of four salt solutions; sodium metabisulfite (SM), potassium sorbate (PS), potassium carbonate (PC) and sodium chloride (SC) as electrolyte to generate alkaline (alEW) and acidic (acEW) electrolysed water was assessed in vitro and ex vivo under artificial and natural infection against Penicillium digitatum and P. italicum, the causal agents of green and blue molds, respectively. Generally, both components of the electrolysed water have exhibited decontaminating activity against the two tested Penicillium species, with clear stronger effect for the acidic component. The effect of alEW and acEW on physical and chemical properties of ‘Valencia’ sweet orange quality, including mass loss, total soluble solids (TSS), citric acid, pH, ascorbic acid and fruit color index was investigated. The results suggest that neither alEW nor acEW may have any negative impact in term of orange quality as compared to control treatments. alEW produced by PS and PC have increased citric acid content of orange fruits. The inhibitory effect of alEW and acEW against naturally occurring microbial population of filamentous fungi in the fruit washing tank was recorded. The direct effect of alEW and acEW on radial growth, conidial germination, germ tube elongation and the morphological changes of both pathogens by scanning electron microscopy (SEM) was examined. Results have shown that treatments have caused abnormal mycelia growth, irregular branching of hyphae in the apical part and loss of linearity in the tested fungal structures. Some salts, as electrolytes, have shown potential to produce robust electrolysed water that may represent valuable ecofriendly tool in controlling citrus postharvest decay.

Spatial distribution of flavor components and antioxidants in the flesh of ‘Conference’ pears and its relationship with postharvest pathogens susceptibility

The spatial distribution of dry matter, ethylene production, respiration rate, organic acids, sugars, antioxidants, volatiles and fungal (Penicillium expansum and Rhizopus stolonifer) growth was evaluated analyzing four different slices of ‘Conference’ pear flesh taken along an equatorial radius. A common spatial distribution trend was found for ethylene emission, CO2 production, antioxidant capacity and total phenolic compounds with a minimum in the slice under the skin and a maximum in the slice near the core. Fructose, which was the dominant sugar followed by sucrose and glucose, showed a quasi-linear decreasing profile from the outer slice towards the core. Malic and ascorbic acid had the highest content in the outer slice while citric remained practically constant over the different slices. Twenty-nine volatile organic compounds (VOCs) were identified using solid-phase microextraction (SPME), yet only six of them showed significant differences between flesh slices. The content in VOCs was further related to the tissue susceptibility to the above-mentioned postharvest pathogens using a multivariate approach. Fruit flesh from inner sections was more prone to P. expansum whereas flesh from the slice under the skin presented the highest incidence of R. stolonifer. A Partial Least Square (PLS) model showed that P. expansum growth was negatively correlated with malic acid, dry matter content, 2-ethyl-hexanal and butyl hexanoate concentrations and R. stolonifer was negatively correlated to sucrose and some volatiles such as hexanal and 1-butanol. Based on the results from the PLS, selected volatiles naturally present in the pear flesh were tested in vitro, at different concentrations, in order to investigate their effectiveness to control blue mold caused by P. expansum and soft rot caused by R. stolonifer. A completely control of P. expansum was found with 2-ethyl-hexanal application and hexanal while 1-butanol showed a total fungicide effect against R. stolonifer. This study is a step towards a better understanding of how biochemical compounds are spatially distributed among different slices of ‘Conference’ pears as well as in the development of natural compounds to fight major postharvest pathogens in pear fruit.

Efficacy of Yarrowia lipolytica in the biocontrol of green mold and blue mold in Citrus reticulata and the mechanisms involved

Green mold and blue mold caused by Penicillium digitatum and P. italicum respectively, are two main fungal diseases in Citrus reticulata (mandarin oranges) worldwide. They are difficult to prevent for the lack of effective antagonists. This study investigated the efficacy of Yarrowia lipolytica against these diseases in mandarins and the relative defense mechanisms. The results indicated that Y. lipolytica has a great potential to inhibit the infections by P. digitatum and P. italicum in mandarins, while both the decay incidence and lesion diameter decreased in Y. lipolytica treated mandarins, in a dose-dependent manner. Furthermore, Y. lipolytica treatment had no side effects on quality paraments of mandarins. In vitro tests demonstrated that, spore germination and germ tube length of P. digitatum and P. italicum were both inhibited by Y. lipolytica. In addition, Y. lipolytica had a better ability to adapt to the environment, occupy space and utilize nutrients than pathogens, which provided a favorable condition for Y. lipolytica to colonize wounds and surfaces of mandarins. This research also showed that, Y. lipolytica induced higher activities of polyphenol oxidase (PPO), peroxidase (POD), catalase (CAT), phenylalanine ammonia lyase (PAL), and increased the contents of flavonoid compounds and total phenols, which activated the defense mechanisms of mandarins. These results suggested that Y. lipolytica is a promising antagonistic yeast to control green mold and blue mold in mandarins.

Moringa oleifera Extraction as Alternative Option for Controlling Citrus Post-harvest Green and Blue Molds In vetro

The post-harvest green and blue molds caused by Penicillium digitatum and Penicillium italicum, respectively are considered universal diseases that lead to the spoilage of almost all kinds of mature citrus fruits, and cause significant losses in citrus fruits during storage and in the markets greater than what people believes.