Green Mold Research Articles

Easter in Milan.

I never imagined I'd be famous. People come from all over the world to see me. Yet my beginnings were humble. My mother, a buxom Milanese, was low in the pecking order. I was expected to follow the family tradition and cater for my embryonic relative. But I didn't get the chance to pursue that calling, for I was torn from my home at an early age and assigned to decorating duty.I was to help paint a dining room wall. The traditional method involved combining pigments with water and quickly applying the mix to fresh plaster before it dried. But my supervisor had no experience with this high-throughput fresco technique. His expertise was in painting dry surfaces like wood panels. He'd mix pigments with me or oil to produce bright paints that allowed for much greater freedom to adjust and correct, suiting his meticulous ways. But these tempera- or oil-based methods hadn't been tried out on murals. He decided to risk it and do the experiment. For good measure, he threw both me and oil into the mix.That's how I found myself clinging to a dry wall, 15 ft from the ground, my supervisor perched next to me on scaffolding. Friars came and went below, for the monastery dining room was still in use despite the renovations underway. Being so close to my supervisor, I could read his thoughts. He was planning to depict thirteen males (I only became aware that his species had females much later), taking supper at a long table. I was to contribute to blue mountains in a central window that backlit the scene.My supervisor was obsessed. Not only did he ceaselessly ponder the poses and composition of his mural; his mind overflowed with inventions of war machines, flying machines, architectural designs, theories of how mountains, rivers and living beings develop and function. He didn't trust accepted ideas but always made careful observations for himself, sketching what he saw and scribbling down notes in mirror script. His mission: look at the world with fresh eyes and find better ways of understanding, representing and improving it.I was three when they removed the scaffolding. Visitors came from far and wide to witness the revolutionary composition that lit the central figure, the dazzling combinations of red, green, yellow and ultramarine robes, the extraordinary interplay of contrasts, the lifelike expressive faces, plates of food and pleated tablecloth. My supervisor had achieved lasting fame, putting to rest accusations that he never completed his works.Fortunately, he didn't witness my decay, for he died in France 22 years later. It was around then that parts of me began to flake off. By my fifties I was in such a sorry state that the friars felt justified in cutting a door into the wall beneath me, amputating the central figure's feet and further loosening paint with blows from their pickaxes. When I reached 300, Napoleon's soldiers pelted me with bricks and used the room as a stable. Four years later there was a fifteen-day flood and I became covered in green mould. At 450, an RAF bomb blew the roof off and only tarpaulin protected me from the skies. A major restoration began 34 years later. They removed the grime, overpainting, waxes, varnishes, glues, shellacs and resins that had been used to preserve me. After 22 years of painstaking work, what little colour remained was said to be 20% supervisor, 80% restorer.I'm now 529. Visitors raise hand-held devices to capture my decayed state. What if my supervisor hadn't been so experimental? What if the spirit of his age had been to stick to the tried-and-tested rather than risk failure? Maybe they'd still be able to see his creation in its full glory. But then again, I wouldn't be here, and neither would those hand-held devices.

Extracts of Ulva lactuca Induce Responses against Penicillium digitatum on Oranges

Penicillium digitatum causes severe damage to postharvest and stored citrus fruits, making it necessary to seek acceptable solutions limiting environmental and sanitary impacts. The seaweed liquid extracts (SLEs) obtained from the green macroalgae Ulva lactuca have previously shown anti-fungal activities towards postharvest green mold due to P. digitatum. Moreover, treatment with aqueous and ethanolic extracts had an influence on disease incidence and lesion severity on wounded oranges “Valentia late”. Therefore, we studied the abilities of the U. lactuca extracts and chlorophyll a (as a standard) to activate defense mechanisms in oranges. The analyses showed modifications in the protein concentrations and activities of β-1,3-glucanase and peroxidase in orange tissues, with a maximum activity level reached at 72 h after treatments. It appears that the SLEs were able to fight P. digitatum infections in the absence of direct contact with the pathogen, reflecting that the induction of host resistance is also a probable mode of action. Ulva lactuca fractions are rich in chlorophyll a, polyphenols, organic acids and ulvans, which might be the key molecules involved in the defense mechanism of oranges’ albedo. The use of these natural substances could be an alternative way to control postharvest citrus rot.

First report of green mold disease caused by Penicillium citrinum on Dictyophora rubrovalvata in China.

Dictyophora rubrovolvata is a saprophytic mushroom widely cultivated in China, including Guizhou Province for its high nutritional, medicinal, and economical values (Chen et al. 2021). In May 2021, green mold disease was observed on the fruiting bodies of D. rubrovolvata, causing its death or preventing it from forming a sporocarp, in an indoor-production facility at Asuo village, Baiyun District Guiyang city, Guizhou Province, China (26°73'51" N, 106°72'88" E). The disease incidence was 60%-70% in the affected 1.33-ha growing area, causing a serious economic loss. To identify the causal agent, a total of 15 samples with symptomatic symptoms were collected. Small pieces (5 mm × 5 mm) were cut from the diseased tissues, surface sterilized in 0.4% NaClO for 5 min, washed three times with sterilized water, placed on potato dextrose agar (PDA) medium, and incubated at 24 °C for 7 days. Twenty-one pure cultures were obtained by single-spore isolation method. The colonies were initially white but after seven days as conidia developed they turned green. Hyphae were hyaline and guttulate. Conidiophores were verrucose stipes, triverticulate, and phialides flask shaped. Conidia were smooth and pale green, with subglobose to globose shape measuring 2.0-2.5 × 1.8-2.5 µm (n=50). Based on these morphological characteristics, the isolates matched the description of the genus Penicillium (Visagie et al. 2014). To confirm the identity, DNA of five representative isolates (QS001, QS005, QS008, QS015, QS017) was extracted according to the manufacturer's instructions (Biomiga Fungal DNA Extraction Kit; CA, USA). Afterwards, PCR was performed to amplify ITS region, calmodulin and β-tubulin genes using primer pairs ITS1/ITS4 (White et al. 1990), CMD5/CMD6 (Glass et al. 1995), and Bt2a/Bt2b (Hong et al. 2006), respectively. BLASTN analysis of these sequences showed the best matches with Penicillium citrinum CBS 139.45 (ITS region: 98.60% (493/500 bp) identity to accession MH856132.1; CMD: 99.79% (469/470 bp) identity to accession MN969245.1; β-tubulin:100% (407/407 bp) identity to accession GU944545.1). Representative sequences of the sequenced DNA regions were deposited in GenBank (ITS region: OK446552; CMD: OK492612; β-tubulin: OK482677). Furthermore, a phylogenetic tree was constructed with MEGA 7 based on the concatenated sequences. Koch's postulates were met to confirm the pathogenicity of the representative isolate (QS001) on D. rubrovolvata. Six discs (5mm×5mm) from actively growing P. citrinum QS001 colonies (5-day-old) were placed on six fruiting bodies of D. rubrovolvata (5-month-old). Mock inoculations were performed using PDA discs only without any fungus. The inoculation sites were wrapped with a sterilized 200-μm nylon mesh. All fruiting bodies were incubated at 23°C ± 2°C under a 0-h/24-h photoperiod and 80% relative humidity (RH) after inoculation. After 14 days, green mold was observed on all P. citrinum QS001 inoculated mushrooms. In contrast, no disease was observed in mock inoculated group. The disease assays were repeated three times. P. citrinum QS001 was isolated from all inoculated D. rubrovolvata and verified via the molecular analysis mentioned above. To the best of our knowledge, this is the first report that P. citrinum causes green mold on D. rubrovalvata in China and further studies should focus on managing this disease to prevent any disease outbreaks.

Evaluation of hot water and GRAS salt solutions for the control of postharvest gray and green molds of pomegranate fruit

Evaluation of hot water and GRAS salt solutions for the control of postharvest gray and green molds of pomegranate fruit

Bacillus cereus B8W8 an effective bacterial antagonist against major postharvest fungal pathogens of fruit

The antifungal activity of Bacillus cereus (B8W8) was investigated against major post-harvest fungal pathogens affecting citrus and apples fruits namely Penicillium digitatum, Penicillium italicum, Geotrichum citri-aurantii, Penicillium expansum, Botrytis cinerea, Monilinia laxa and Monilinia fructigena. The in vitro dual culture of B8W8 and fungal pathogens showed high inhibition rates of the mycelial growth of Monilinia laxa and Penicillium digitatum (71.4% and 72.5% respectively). Subsequently, the volatile compounds (VOCs) have a high antagonistic effect against Monilinia laxa (86.4%) and Monilinia fructigena (73.4%). In addition, the bacterial-free cell filtrate of B8W8 had a significantly important effect on the inhibition of spore’s germination and mycelial growth of Penicillium expansum, Botrytis cinerea, Penicillium italicum and Geotrichum citri-aurantii. The in vivo bioassays revealed a significant impact of B8W8 on fruit decays either by reducing the disease severity of causative agents or by completely preventing their occurrence, particularly brown rot of apple caused by M. laxa and green mold of citrus caused by P. digitatum (DS = 0%). However, the severity of sour rot of citrus caused by G. citri-aurantii was only reduced by 50%. The semi-commercial trials showed a high potential of B. cereus B8W8 to reduce the incidence of gray mold of apple and green mold of citrus to very low values during at storage. In addition, the biological treatment with B8W8 was shown generally more effective than imazalil, the chemical treatment reference. Furthermore, the rapid colonization of fruit wounds by B8W8 could promote its antagonistic ability. Moreover, biochemical tests showed the ability of B8W8 to produce protease, amylase, and hydrocyanic acid (HCN). Interestingly, the molecular analysis demonstrated the ability of this bacterium to produce the fengycin. The secretion of this lipopeptide and lytic enzymes is more likely the major mechanism of action involved in the biocontrol activity of this bacterium. Results indicated that quality parameters of fruit, when challenged post-harvest pathogens and treated with B8W8, were mostly very close to those of the untreated control, suggesting that B8W8 did not affect the fruit quality. Accordingly, it was concluded that B. cereus strain B8W8 could be an effective biological agent to control the main fungal pathogens of apples and citrus fruits during post-harvest period.

Essential oils and natural plant extracts as antifungal ingredients of pectin-based edible composite coatings to control green mold and maintain postharvest quality of ‘Valencia’ oranges

Essential oils and natural plant extracts as antifungal ingredients of pectin-based edible composite coatings to control green mold and maintain postharvest quality of ‘Valencia’ oranges

Quantitative Spectroscopic Characterization of Near-UV/visible E. coli (pYAC4), B. subtilis (PY79), and Green Bread Mold Fungus Fluorescence for Diagnostic Applications.

Ultraviolet (UV)-excited visible fluorescence is an attractive option for low-cost, low-complexity, rapid imaging of bacterial and fungal samples for imaging diagnostics in the biomedical community. While several studies have shown there is potential for identification of microbial samples, very little quantitative information is available in the literature for the purposes of diagnostic design. In this work, two non-pathogenic bacteria samples (E. coli pYAC4, and B. subtilis PY79) and a wild-cultivated green bread mold fungus sample are characterized spectroscopically for the purpose of diagnostic design. For each sample, fluorescence spectra excited with low-power near-UV continuous wave (CW) sources, and extinction and elastic scattering spectra are captured and compared. Absolute fluorescence intensity per cell excited at 340 nm is estimated from imaging measurements of aqueous samples. The results are used to estimate detection limits for a prototypical imaging experiment. It was found that fluorescence imaging is feasible for as few as 35 bacteria cells (or [Formula: see text]30 µm3 of bacteria) per pixel, and that the fluorescence intensity per unit volume is similar for the three samples tested here. A discussion and model of the mechanism of bacterial fluorescence in E. coli is provided.

Transcriptome analysis of Ganoderma lingzhi (Agaricomycetes) response to Trichoderma hengshanicum infection.

Green mold caused by Trichoderma spp. has become one of the most serious diseases which threatening the production of Ganoderma lingzhi. To understand the possible resistance mechanism of the G. lingzhi response to T. hengshanicum infection, we examined the G. lingzhi transcript accumulation at 0, 12, and 24 h after T. hengshanicum inoculation. The gene expression analysis was conducted on the interaction between G. lingzhi and T. hengshanicum using RNA-seq and digital gene expression (DGE) profiling methods. Transcriptome sequencing indicated that there were 162 differentially expressed genes (DEGs) at three infection time points, containing 15 up-regulated DEGs and 147 down-regulated DEGs. Resistance-related genes thaumatin-like proteins (TLPs) (PR-5s), phenylalanine ammonia-lyase, and Beta-1,3-glucan binding protein were significantly up-regulated. At the three time points of infection, the heat shock proteins (HSPs) genes of G. lingzhi were down-regulated. The down-regulation of HSPs genes led to the inhibition of HSP function, which may compromise the HSP-mediated defense signaling transduction pathway, leading to G. lingzhi susceptibility. Pathway enrichment analyses showed that the main enriched pathways by G. lingzhi after infection were sphingolipid metabolism, ether lipid metabolism, and valine, leucine and isoleucine degradation pathway. Overall, the results described here improve fundamental knowledge of molecular responses to G. lingzhi defense and contribute to the design of strategies against Trichoderma spp.

Trans-2-hexenal inhibits the growth of imazalil-resistant Penicillium digitatum Pdw03 and delays green mold in postharvest citrus

This study investigated the efficacy of trans-2-hexenal in preventing green mold on postharvest citrus fruit and its mode of action against imazalil-resistant Penicillium digitatum Pdw03. Trans-2-hexenal inhibited Pdw03 at a minimum inhibitory concentration (MIC) and a minimum fungicidal concentration (MFC) of 0.25 mL L−1. Trans-2-hexenal reduced the incidence of green mold, which is a plant volatile compound with potent antifungal properties. Ultrastructural analysis revealed that trans-2-hexenal altered the mitochondrial structure of Pdw03. Trans-2-hexenal also increased the amount of reactive oxygen species, which hindered mitochondrial energy metabolism of Pdw03, resulting in mitochondrial structural damage and malfunction, and a decrease in mitochondrial membrane potential. In addition, RNA-seq analysis revealed that trans-2-hexenal altered the expression of some energy metabolism genes associated with the tricarboxylic acid (TCA) cycle, glycolysis, and oxidative phosphorylation of Pdw03. Superoxide dismutase, catalase, glutathione S-transferase, and glutathione peroxidase activities were altered, and expression of the relevant gene was also quantified by real-time fluorescence quantitative PCR. Trans-2-hexenal damaged ribosomes, primarily by downregulation of the ribosomal structural component-associated genes RPL3, RPS18, RPL12, RPL26, RPL13A, RPL9, RPL23, and RPL4, and then by reducing protein synthesis to achieve the inhibitory effect.

Enhancing bioefficacy of Bacillus amyloliquefaciens SF14 with salicylic acid for the control of the postharvest citrus green mould

Penicillium digitatum is a major post-harvest pathogen of citrus fruit causing tremendous economic losses. In this study, salicylic acid (SA) and antagonistic bacteria Bacillus amyloliquefaciens (SF14) were tested in controlling P. digitatum (green mould) infections as an alternative to chemical controls. Three concentrations of SA (0.5, 1, and 2%) were tested for their antifungal activity in both in vitro and in vivo conditions alone and in combination with SF14. Fruit quality parameters including fruit firmness, weight loss, titratable acidity, and soluble solids content were evaluated. The impact of these biological treatments was also investigated by measuring the changes in organic and mineral properties of orange fruits using Fourier transform infrared spectroscopy (FT-IR). Enzymatic activity including phenylalanine ammonia-lyase (PAL), total polyphenols and flavonoids was also tested. In vitro assays showed that SF14 combined with 0.5% SA provided the highest inhibition of green mould growth reaching 72.98%. Inhibition of spore germination was also highest in the same treatment od reaching 63.40%. FTIR of fungal biomass confirmed an alteration of fungal well wall following biological treatments. Moreover, during in vivo assays, the combination of SF14 and 0.5% SA produced the lowest disease severity (5.43%) without considerably affecting the fruit quality. Further investigation of the effect of these treatments on the mineral composition of treated oranges showed that Ca, Fe, K, Mg, and Na concentrations were significantly affected. Changes in these elements may show a defence reaction induced by the biological treatments against the pathogen, which was also confirmed with the measurement of PAL activity, total polyphenols, and flavonoids. Interestingly, FTIR of citrus peel indicated significant changes in the content of bands denoting for phenolic and aromatic rings, suggesting an induced resistance against the pathogenic fungus. Overall, our findings suggested that the combination of both bacterial antagonist SF14 and 0.5% SA can control the green mould of citrus, and as such constitutes a safer alternative to chemicals during postharvest storage.

Molecular Approaches for Detection of Trichoderma Green Mold Disease in Edible Mushroom Production.

Due to the evident aggressive nature of green mold and the consequently huge economic damage it causes for producers of edible mushrooms, there is an urgent need for prevention and infection control measures, which should be based on the early detection of various Trichoderma spp. as green mold causative agents. The most promising current diagnostic tools are based on molecular methods, although additional optimization for real-time, in-field detection is still required. In the first part of this review, we briefly discuss cultivation-based methods and continue with the secondary metabolite-based methods. Furthermore, we present an overview of the commonly used molecular methods for Trichoderma species/strain detection. Additionally, we also comment on the potential of genomic approaches for green mold detection. In the last part, we discuss fast screening molecular methods for the early detection of Trichoderma infestation with the potential for in-field, point-of-need (PON) application, focusing on isothermal amplification methods. Finally, current challenges and future perspectives in Trichoderma diagnostics are summarized in the conclusions.

Antifungal molecular details of MNQ-derived novel carbon dots against Penicillium digitatum

It is urgent to develop high-efficiency and low-toxicity natural antifungal agents on green mold caused by Penicillium digitatum. The effect of 2-methoxy-1, 4-naphthoquinone (MNQ) inhibition of P. digitatum was not very satisfactory. MNQ-derived carbon dots (MNQ-CDs) synthesized through a solvothermal route were used as antifungal agents against P. digitatum. The antifungal activity of prepared MNQ-CDswas enhanced compared to MNQ, and the minimum inhibitory concentration was 2.8 μg/mL. A total of 441 genes and 122 metabolites have undergone significant changes. The omics data revealed that MNQ-CDs primarily modified the metabolism of aromatic amino acids and synthesis of the cell membrane in P. digitatum, thereby inhibiting its propagation. Furthermore, compared with MNQ, MNQ-CDs had a better control effect on the green mold of citrus fruits, and could more significantly inhibit the propagation of P. digitatum. This study provides a new idea for the design of new and efficient antifungal materials.

Biological control of green mould on mandarin fruit through the combined use of antagonistic yeasts

Penicillium digitatum is the primary cause of green mould in mandarins during the postharvest period, mainly controlled through synthetic fungicides. This study evaluated the biocontrol of green mould on mandarin fruit with three antagonistic yeasts (Hanseniaspora uvarum, Meyerozyma guilliermondii, and Metschnikowia aff. pulcherrima P01A016), alone or in combination, by elucidating their possible mechanisms of action. All yeast cultures alone (73.85 % − 80.64 %) and their combinations (78.40 % − 83.18 %) reduced the mycelial growth of green mold in vitro. M. aff. pulcherrima reduced the disease incidence and lesion diameters by 75.5 % and 91.3 %, respectively, demonstrating the highest biocontrolling activity alone. Meyerozyma guilliermondii showed the highest biofilm formation (OD 0.93 ± 0.01) and antifungal activity (71.13 %) through volatile organic compounds (VOCs), while H. uvarum displayed cell-wall degrading β-1,3 glucanase activity together with mycocinogenic and VOCs activity. All tested yeasts showed chitinase, protease, and leucine arylamidase activity. Among dual combinations, M. guilliermondii and M. aff. pulcherrima (M-1) were the most compatible, while M. aff. pulcherrima and H. uvarum (M-3) had the least compatibility. The combined application of these three yeasts resulted in synergistic co-operation, demonstrating the highest biocontrolling efficacy in vitro and in vivo. Integrating multiple mechanisms of action in yeasts could create a hurdle approach for inhibiting green mould in citrus as a green alternative to synthetic fungicides. Thus, our study demonstrated that combining biocontrol yeasts can result in beneficial consortia for the eco-friendly and sustainable management of P.digitatum-caused postharvest diseases of mandarins in both the wounded and intact mandarin fruits.

Experimental Study on Effect of Sand Grain Size and Heat Dissipation on the Properties of Moulding Sand

The rate of heat dissipation affects the solidification of the casting. A controlled cooling rate is necessary to produce defect-free castings. Sand qualities such as green compression strength, permeability, flow ability, mould hardness, and compactibility play a key role in controlled cooling or uniform heat flow across the casting. A research is executed in this paper to see how these properties affect the heat dissipation rate. The coarse grain and fine grain sand particle sizes are the most important influencing elements. The solidification time for casting in coarse, medium, and fine grains was noted in the results, and it was discovered that the cooling rate is better for coarse sand grains, as well as a relationship between solidification time and sand qualities was developed. During the experimental results it was observed that highest value of compactability was found to be 72% in case of medium sand, highest value of flowability was found out to be 87% in case of medium sand and highest value of permeability number was found in case of course sand particles i.e. 471.

Efficient control of the fungal pathogens Colletotrichum gloeosporioides and Penicillium digitatum infecting citrus fruits by native soilborne Bacillus velezensis strains

Destruction of citrus fruits by fungal pathogens during preharvest and postharvest stages can result in severe losses for the citrus industry. Antagonistic microorganisms used as biological agents to control citrus pathogens are considered alternatives to synthetic fungicides. In this study, we aimed to identify fungal pathogens causing dominant diseases on citrus fruits in a specialized citrus cultivation region of Vietnam and inspect soilborne Bacillus isolates with antifungal activity against these pathogens. Two fungal pathogens were characterized as Colletotrichum gloeosporioides and Penicillium digitatum based on morphological characteristics and ribosomal DNA internal transcribed spacer sequence analyses. Reinfection assays of orange fruits confirmed that C. gloeosporioides causes stem-end rot, and P. digitatum triggers green mold disease. By the heterologous expression of the green fluorescent protein (GFP) in C. gloeosporioides using Agrobacterium tumefaciens-mediated transformation, we could observe the fungal infection process of the citrus fruit stem-end rot caused by C. gloeosporioides for the first time. Furthermore, we isolated and selected two soilborne Bacillus strains with strong antagonistic activity for preventing the decay of citrus fruits by these pathogens. Molecular analyses of 16 S rRNA and gyrB genes showed that both isolates belong to B. velezensis. Antifungal activity assays indicated that bacterial culture suspensions could strongly inhibit C. gloeosporioides and P. digitatum, and shield orange fruits from the invasion of the pathogens. Our work provides a highly effective Bacillus-based preservative solution for combating the fungal pathogens C. gloeosporioides and P. digitatum to protect citrus fruits at the postharvest stages.

A self-regulated transcription factor CsWRKY33 enhances resistance of citrus fruit to Penicillium digitatum

Green mold caused by Penicillium digitatum is a major postharvest disease in citrus fruit, but the molecular mechanism related to the induced disease resistance in citrus is still unclear. This study investigated the regulatory function of CsWRKY33 on citrus disease resistance. The results showed that CsWRKY33 was located in the nucleus, and the transient overexpression of CsWRKY33 significantly enhanced the host resistance against green mold. The DNA affinity purification sequencing and transcriptome sequencing analysis identified 485 direct target genes of CsWRKY33. KEGG pathway analysis revealed that the 250 up-regulated genes were mainly involved in the disease resistance response. And the 235 down regulated genes were mostly associated with plant growth and development. 9 up-regulated genes were selected for EMSA and DLR analysis, including CsRbohD, CsPODN1, CsPOD24, CsPOD, CsPAL, CsWRKY22, CsGSTU7, and CsHSP26A, and found CsWRKY33 activated the expression of these genes. Besides, PAL, POD, GST activities, H2O2 content and lignin content were increased when CsWRKY33 was transiently overexpressed. The results also found that CsWRKY33 could bind to its own promoter's W-box directly for positive regulation. In conclusion, CsWRKY33 plays an important regulatory role in citrus disease resistance, and the key mechanisms is the activation of disease resistance pathways such as phenylalanine metabolism and secondary metabolism.

Detection and classification of volatile compounds emitted by three fungi-infected citrus fruit using gas chromatography-mass spectrometry

Citrus fruit produced some characteristic volatile compounds when infected by fungi compared with the healthy fruit. In the present study, volatile metabolites of postharvest citrus fruit with three different diseases including stem-end rot, blue mold and green mold were detected. Multivariate analysis such as principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were employed to classify the volatile compounds between the infected and non-infected citrus fruit. The results indicated that volatile compounds of unrotten, unrotten-rotten junction, and rotten tissues were successfully classified. Importantly, eight volatile compounds as biomarkers for stem-end rot and one biomarker for green mold of citrus were screened to discriminate the infected citrus fruit. This study offers the application potential of odor profiling of volatile compounds for detecting the fungi infection in postharvest citrus fruit.

Role of Mushroom Pathogen Trichoderma harzianum Rafai in the Reduction of Growth Yield, Nutrient Quality, and Morphometric Measurements of the Fruiting Body of Pleurotus ostreatus EM-1 From Seven Oyster Mushroom Cultivation Farms in Ghana.

The cultivation of edible mushrooms such as Pleurotus ostreatus commonly known as oyster mushroom has been undertaken by both commercial and cottage industry entrepreneurs in Ghana with appreciable success. However, the presence of competitors and potential pathogens in the substrate militate against increased yield and quality of fruiting bodies. The most prevalent pathogen Trichoderma harzianum in the compost for cultivating P. ostreatus is responsible for the green mould disease. In this study, in vitro pathological effects of spiking Triplochiton scleroxylon sawdust substrate with T. harzianum on pinhead emergence, percentage formation of fruiting bodies, weight of fruit body, yield, Biological Efficiency as well as morphometric data of stipe length, stipe diameter, cap diameter as criteria for reduced growth performance of P. ostreatus were investigated. The effect of the pathogen on the nutritional and elemental composition of the oyster mushroom were determined with the view of assessing the quantitative changes of nutritional and elemental composition of the mushroom using standard methods. Growth substrates inoculated with T. harzianum reduced pinhead formation; number of fruiting bodies formed, percentage conversion of pinheads, weight of fruiting bodies, and reduced morphometric measurements of stipe length, stipe diameter, cap diameter with all three flushes of the mushroom. Total yield of fruiting bodies in all three flushes in the T. harzianum-inoculated bags decreased by 67.4%, 68.5% and 83.3% respectively with the concomitant reduction of total yield by 52.3% and Biological Efficiency by 52.8%. Some of the control bags (uninoculated bags) also performed poorly as a result of contamination by T. harzianum, indicative of inadequate sterilization. Fruiting bodies of P. ostreatus grown in uninoculated compost contained Ca, Cu, Fe, K, Mg, Na, P, and Zn in contrast with the absence of Na, and Zn in the infected bags. There was a reduction in fat, crude fibre, crude protein, and carbohydrates of the fruiting bodies grown in the contaminated bags. On the other hand, total ash content was doubled in the carpophore from the T. harzianum spiked contaminated bags. The pathogen therefore has adverse effect on the production and marketing quality as well as the nutritional value of the fruiting bodies

Transcription factor CsERF1B regulates postharvest citrus fruit resistance to Penicillium digitatum

Green mold, caused by Penicillium digitatum (P. digitatum), is among the most important postharvest disease of citrus fruit in terms of economic losses. Previous studies reported that AP2/ERFs in citrus pericarp positively respond to P. digitatum infection; therefore, it is presumed that AP2/ERFs could participate in the regulation of the fruit resistance response. However, limited research is available on AP2/ERF transcription factors in regulating the disease resistance of citrus fruit. In the present study, the regulatory role of CsERF1B in citrus green mold was clarified and the regulatory mechanism was initially explored. In our work, CsERF1B is a transcriptional activator with a nuclear localization signal. Transient overexpression of CsERF1B in citrus pericarp significantly enhanced fruit resistance to green mold and induced upregulated expression of pathogenesis-related genes in the pericarp. CsERF1B directly activated lignin synthesis genes, increased the activities of related enzymes, and promoted the accumulation of lignin. CsERF1B directly activated the genes related to jasmonic acid signaling and immunity, indirectly activated genes related to chitinase, and it also directly repressed salicylic acid signaling pathway genes, thus participating in the regulation of fruit disease resistance. This research provides novel insights into the mechanisms of disease resistance regulation by AP2/ERF transcription factors in citrus fruit.

Development of a real-time PCR protocol for the specific detection and quantification of Penicillium digitatum in lemons

Penicillium digitatum is the main species responsible for postharvest losses in citrus fruit and, therefore, rapid and accurate methods are needed for its early detection. For this purpose, a new procedure based on real-time quantitative PCR (qPCR) was developed to detect and quantify P. digitatum in lemons. The procedure included a rapid extraction of fungal DNA using the commercial Quick-DNA Fungal/Bacterial Miniprep Kit; the design of a specific primers pair by selecting the conserved region of the calmodulin A (cmdA) gene; and the design and evaluation of a qPCR system based on SYBR-Green dye detection chemistry. The functionality of the developed method was demonstrated by the high linear correlation of the standard curve constructed over the entire range of fungal DNA concentrations used (R2 > 0.99), indicating precision and accuracy of the qPCR. The protocol was developed aiming to evaluate the biotechnological potential of the biocontrol yeast Clavispora lusitaniae AgL21, by quantifying the fungus P. digitatum in lemon wounds. The yeast was shown to restrict the pathogen growth, reaching fungal DNA concentrations of up to 0.038 ng/wound after 4 days of incubation, compared to 173.06 ng/wound when the fungus was alone. No inhibition of qPCR due to food matrices was observed. The developed qPCR protocol could be considered as a suitable tool to detect P. digitatum in food products and can be used to specifically test the ability of new biological control microorganisms against green mold in lemons.