Postharvest Diseases Research Articles

Antifungal activity and mechanism of chitosan against Fusarium solani caused ginger soft rot during postharvest storage

Postharvest rot caused by Fusarium solani (F. solani) results in enormous economic loss to the global vegetables industry. Chitosan has been shown to be effective in control postharvest diseases of vegetables, but the specific mechanism of chitosan on F. solani has not been studied. In this study, we evaluated antifungal activity of chitosan against F. solani caused soft rot in vitro and in vivo. Antifungal assay results showed that chitosan significantly inhibited the mycelial growth and spore germination of F. solani. Simultaneously, chitosan showed disruptive activity on the mycelial morphology and cell membrane, which were achieved by decreasing intracellular sugars, proteins and lipids content. Furthermore, chitosan treatment significantly decreased tricarboxylic acid (TCA)-related enzymes activity, reducing the number of metabolites in the TCA cycle. UPLC-Triple-TOF/MS-based metabolomics analysis showed that chitosan interferes with fungal metabolic pathways, mainly related to energy metabolism, lipid metabolism and sugar metabolism. Exogenous α-D-glucose and linoleic acid treatment promoted mycelia growth, verifying the sugar catabolism and TCA cycle was involved in the inhibition of chitosan against F. solani. The in vivo study showed that chitosan treatment effectively reduced disease rate and severity of postharvest soft rot through activating the biochemical defense response and modulating the expression of phytopathogenic responses LysM genes. These results contribute to explore the underlying mechanisms of chitosan against F. solani.

Enhancing biological control of apple rot: Unveiling the antifungal potential and mechanism of Bacillus amyloliquefaciens HZ-12′s lipopeptide

Rot caused by fungal pathogen Aspergillus niger is an important postharvest disease of apples. To control the apple rot resulting from A. niger, five Bacillus strains with antagonism against A. niger were screened by Oxford cup diffusion method. Among them, Bacillus amyloliquefaciens HZ-12 had the most prominent antifungal activity, and its control effect reached 89.0 % on apple rot caused by A. niger. Moreover, the antifungal substances from B. amyloliquefaciens HZ-12 were analyzed, and the lipopeptide was suggested to be the key substance due to strong antifungal stability and surface activity. The lipopeptide extract was confirmed to damage the cell wall and membrane of A. niger, leading to leakage of intracellular nucleic acids and cell death. Further genetic engineering by insertion of a strong promoter significantly improved the iturin A yield by 4.2-fold, and corresponding antifungal effect of B. amyloliquefaciens was obviously increased. This study provided a new strain for biological control of apple rot disease, and also indicated the lipopeptide as antifungal and its corresponding antifungal mechanism.

Widely targeted metabolomics combined with E-tongue and E-nose reveal dynamic changes of tender coconut water in responses to the infection of Ceratocystis paradoxa

Ceratocystis paradoxa is a major cause of postharvest disease in tender coconuts worldwide. We conducted a comprehensive study using widely targeted metabolomics, electronic tongue (E-tongue), and electronic nose (E-nose) analyses to investigate the impacts of C. paradoxa invasion on the quality of tender coconut water (TCW) from fresh control (FC), uninoculated (UN), skin-inoculated (SI), and deep-inoculated (DI) nuts. DI exhibited significantly higher taste indicators associated with bitterness, saltiness, astringency aftertaste, and bitter aftertaste, as well as odor sensor values related to various compounds such as long-chain alkanes, hydrides, methane, organic sulfides, etc. Invasion of C. paradoxa into the endosperm altered the flavor characteristics of TCW mainly through the modulation of carbohydrate and secondary metabolite pathways. Furthermore, significant correlations were observed between the differentially expressed flavorful metabolites and the sensor indicators of the E-nose and E-tongue. These findings offer valuable insights into understanding the impact of C. paradoxa infection on coconuts.

Towards unlocking the biocontrol potential of Pichia kudriavzevii for plant fungal diseases: in vitro and in vivo assessments with candidate secreted protein prediction

BackgroundPlant fungal pathogens cause substantial economic losses through crop yield reduction and post-harvest storage losses. The utilization of biocontrol agents presents a sustainable strategy to manage plant diseases, reducing the reliance on hazardous chemical. Recently, Pichia kudriavzevii has emerged as a promising biocontrol agent because of its capacity to inhibit fungal growth, offering a potential solution for plant disease management.ResultsTwo novel Pichia kudriavzevii strains, Pk_EgyACGEB_O1 and Pk_EgyACGEB_O2, were isolated from olive brine samples. The microscopic characterization of the strains revealed similar structures. However, there were noticeable differences in their visual morphology. Based on their internal transcribed spacer (ITS) DNA sequences, Pk_EgyACGEB_O1 and Pk_EgyACGEB_O2 strains assigned by GenBank IDs MZ507552.1 and MZ507554.1 shared high sequence similarity (~ 99.8% and 99.5%) with P. kudriavzevii, respectively. Both strains were evaluated in vitro against plant pathogenic fungi. The strains revealed the ability to consistently inhibit fungal growth, with Pk_EgyACGEB_O2 showing higher effectiveness. In addition, both P. kudriavzevii strains effectively controlled grey mold disease caused by B. cinerea in golden delicious apples, suggesting their potential as sustainable and eco-friendly biocontrol agents for post-harvest diseases. Based on a comprehensive bioinformatics pipeline, candidate-secreted proteins responsible for the potent antifungal activity of P. kudriavzevii were identified. A total of 59 proteins were identified as common among the P. kudriavzevii CBS573, SD108, and SD129 strains. Approximately 23% of the secreted proteins in the P. kudriavzevii predicted secretome are hydrolases with various activities, including proteases, lipases, glycosidases, phosphatases, esterases, carboxypeptidases, or peptidases. In addition, a set of cell-wall-related proteins was identified, which might enhance the biocontrol activity of P. kudriavzevii by preserving the structure and integrity of the cell wall. A papain inhibitor was also identified and could potentially offer a supplementary defense against plant pathogens.ConclusionOur results revealed the biocontrol capabilities of P. kudriavzevii against plant pathogenic fungi. The research focused on screening novel strains for their ability to inhibit the growth of common pathogens, both in vitro and in vivo. This study shed light on how P. kudriavzevii interacts with fungal pathogens. The findings can help develop effective strategies for managing plant diseases.

Avirulent Isolates of Penicillium chrysogenum to Control the Blue Mold of Apple Caused by P. expansum.

Blue mold is an economically significant postharvest disease of pome fruit that is primarily caused by Penicillium expansum. To manage this disease and sustain product quality, novel decay intervention strategies are needed that also maintain long-term efficacy. Biocontrol organisms and natural products are promising tools for managing postharvest diseases. Here, two Penicillium chrysogenum isolates, 404 and 413, were investigated as potential biocontrol agents against P. expansum in apple. Notably, 404 and 413 were non-pathogenic in apple, yet they grew vigorously in vitro when compared to the highly aggressive P. expansum R19 and Pe21 isolates. Whole-genome sequencing and species-specific barcoding identified both strains as P. chrysogenum. Each P. chrysogenum strain was inoculated in apple with the subsequent co-inoculation of R19 or Pe21 simultaneously, 3, or 7 days after prior inoculation with 404 or 413. The co-inoculation of these isolates showed reduced decay incidence and severity, with the most significant reduction from the longer establishment of P. chrysogenum. In vitro growth showed no antagonism between species, further suggesting competitive niche colonization as the mode of action for decay reduction. Both P. chrysogenum isolates had incomplete patulin gene clusters but tolerated patulin treatment. Finally, hygromycin resistance was observed for both P. chrysogenum isolates, yet they are not multiresistant to apple postharvest fungicides. Overall, we demonstrate the translative potential of P. chrysogenum to serve as an effective biocontrol agent against blue mold decay in apples, pending practical optimization and formulation.

Fusarium core rot disease affects physicochemical and pathophysiological attributes of apple (Malus × domestica Borkh.) fruit

Core rot is becoming an important post-harvest disease in parts of North-Western Himalayan Region due to changing climate. In the present study, the causal organism of core rot was determined, and the potential effects of core rot disease on apple nutrition, vitamins and antioxidants potential were also studied. Based on morphological, molecular (TEF 1 and ITS gene) and Koch postulates studies of collected isolates, the causal fungus was identified as Fusarium fujikuroi. To the best of our knowledge, this is the first report of core rot of apple caused by Fusarium fujikuroi in India. Core rot reduced the nutritional value of apple cultivars, viz., ‘Golden Delicious’ and ‘Royal Delicious’, after 10 and 20 d of infection. The disease showed to have decay and rotting of the fruit, resulting in a loss of essential nutrients. This led to decreased levels of DPPH, carotenoid, phenols, acidity, total soluble solid, sucrose, amino acid, ascorbic acid, and anthocyanin in the affected portions of the inoculated fruit. The core rot disease was reported to influence the extent of these effects on sucrose, and TSS properties also. Total soluble sugar content was increased 1.91 and 1.21-fold in ‘Golden Delicious’ and ‘Royal Delicious’ fruit respectively after 20 d of inoculation. Additionally, the presence of F. fujikuroi triggered enzymatic reactions that further degrade antioxidants, reducing their levels in the infected areas. Our study showed that changes in the type and concentration of polyphenolic compounds were observed in infected apples compared to healthy apples. The outcome from this study will be beneficial to understand the host-pathogen interaction and for strategic management of this disease under field conditions.

Glycine Enhances Oxidative Stress Tolerance and Biocontrol Efficacy of Sporidiobolus pararoseus against Aspergillus niger Decay of Apples.

Apples are deeply loved by people because of their rich nutritional value, but they are susceptible to rotting. The use of antagonistic yeast is a promising method for controlling postharvest fruit diseases, but biocontrol efficacy of yeast will be weakened in environmental stress. In this study, the effects of glycine (Gly) on the oxidative stress tolerance and the biocontrol efficacy of Sporidiobolus pararoseus (S. pararoseus) against Aspergillus niger (A. niger) are discussed. Under the stimulation of H2O2, the yeast cells treated with Gly (1 mM) showed lower ROS content, less mitochondrial impairment and cellular oxidative damage, and the cell survival rate was significantly higher than Gly-untreated yeast. The yeast cells exposed to Gly significantly increased the activities of antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and the content of glutathione (GSH). Notably, Gly-treated yeast cells had better biocontrol efficacy against A. niger in postharvest apples. The lesion diameter and decay incidence were reduced by 17.67 mm and 79.63% compared to the control, respectively, when S. pararoseus was treated with 1 mM Gly. Moreover, Gly-treated yeast increased the antioxidant enzymes activities and their gene expression were up-regulated in apples. These results indicated that 1 mM Gly not only reduced the oxidative damage of yeast, but also induced resistance-related enzymes of apples under oxidative stress, which contributed to enhancing the biocontrol efficacy of S. pararoseus against A. niger in apples.

Biocontrol ability of marine yeasts against postharvest diseases in mangos caused by Colletotrichum gloeosporioides and Lasiodiplodia theobromae

Biocontrol ability of marine yeasts against postharvest diseases in mangos caused by Colletotrichum gloeosporioides and Lasiodiplodia theobromae

Biotechnological and Biocontrol Approaches for Mitigating Postharvest Diseases Caused by Fungal Pathogens and Their Mycotoxins in Fruits: A Review.

Postharvest diseases caused by fungal pathogens are significant contributors to the postharvest losses of fruits. Moreover, some fungal pathogens produce mycotoxins, which further compromise the safety and quality of fruits. In this review, the potential of biotechnological and biocontrol approaches for mitigating postharvest diseases and mycotoxins in fruits is explored. The review begins by discussing the impact of postharvest diseases on fruit quality and postharvest losses. Next, it provides an overview of major postharvest diseases caused by fungal pathogens. Subsequently, it delves into the role of biotechnological approaches in controlling these diseases. The review also explored the application of biocontrol agents, such as antagonistic yeasts, bacteria, and fungi, which can suppress pathogen growth. Furthermore, future trends and challenges in these two approaches are discussed in detail. Overall, this review can provide insights into promising biotechnological and biocontrol strategies for managing postharvest diseases and mycotoxins in fruits.

Sensitivity of Mucor piriformis to Natamycin and Efficacy of Natamycin Alone and with Salt and Heat Treatments Against Mucor Rot of Stored Mandarin Fruit.

Mucor rot caused by Mucor piriformis is an emerging postharvest disease of mandarin fruit in California. Natamycin is a newly registered biofungicide for postharvest use on citrus and some other fruits. In the study, baseline sensitivity to natamycin in 50 isolates of M. piriformis was determined in vitro. The mean EC50 (effective concentration to inhibit sporangiospore germination by 50%) and MIC (minimum inhibitory concentration to inhibit mycelial growth by 100%) values were 0.59 μg/ml and less than 1.0 μg/ml, respectively. Natamycin at the label rate of 920 μg/ml alone or in combination with 3% potassium sorbate (PS) or 3% sodium carbonate (SC) applied at 20 or 50°C was evaluated for control of Mucor rot on inoculated 'Tango' mandarin fruit. Natamycin alone reduced Mucor rot incidence on stored mandarin fruit from 100% among nontreated control fruit to approximately 30%, a reduction of more than 70% compared to the nontreated control, while 3% PS and 3% SC had no to little control. When applied at 50°C, natamycin and 3% PS reduced Mucor rot incidence by 65.0 and 31.2%, respectively; while natamycin in combination with 3% PS reduced disease incidence by 92.5% compared to the nontreated control after 2 weeks of storage at 5°C. This combined treatment remained effective even when the application of the treatment was delayed for 6 and 12 h after inoculation. However, the effectiveness of the treatments declined when storage was extended to 3 or 4 weeks. Natamycin can be an effective tool to control Mucor rot on mandarin fruit, and minimizing the period of extended storage could help maintain the control efficacy of natamycin.

Postharvest biocontrol of green mold (Penicillium digitatum) in citrus by Bacillus velezensis strain S161 and its mode of action

Green mold caused by Penicillium digitatum is a major postharvest disease of citrus that can result in significant losses during storage. Synthetic chemical fungicides typically used to control this disease have raised potential concerns regarding environmental pollution, human health, and the development of fungicide resistance. Biological control of postharvest diseases has been demonstrated to be an effective alternative to chemical control. In the present study, we investigated the postharvest biocontrol efficacy of Bacillus velezensis strain S161 against P. digitatum and its potential mechanisms of action. Results indicated that a cell-free supernatant (CFS) obtained from liquid culture of S161 strongly inhibited the mycelial growth, spore germination, and germ tube elongation of P. digitatum in vitro. The CFS effectively protected citrus fruit against P. digitatum, providing 95.6 % control. Further investigations revealed that the CFS degraded and ruptured hyphal membranes and spores and induced the excessive accumulation of reactive oxygen species (ROS) in hyphal cells resulting in oxidative damage. CFS exposure also resulted in the downregulation of genes associated with spore germination, growth, reproduction, and virulence. antiSMASH analysis of biosynthetic gene clusters (BGCs) in B. velezensis indicated that B. velezensis possesses several core clusters, encoding the synthesis of surfactin, bacillomycin D, fengycin, bacilysin, bacillibactin, macrolactin, difficidin, bacillaene, and amylocycicin. Further analysis using Liquid Chromatography Tandem Mass Spectrometry (LC-MS) revealed the presence of four of these metabolites (surfactin, iturin, fengycin, and bacillibactin) in the CFS of B. velezensis. Additional bioassays conducted in sealed plates revealed that volatile organic compounds (VOCs) produced by S161 also inhibited the growth of P. digitatum. A total of 24 VOCs were found to be produced by S161 using headspace solid-phase microextraction/gas chromatography-mass spectrometry (HS-SPME/GC-MS). The identified VOCs were mainly ketones and alcohols. Collectively, our results indicate that B. velezensis strain S161 is an effective biocontrol agent of P. digitatum on citrus and inhibits pathogen germination and growth through a range of mechanisms, including the downregulation of genes associated with spore germination and growth, induction of oxidative stress, and the antimicrobial activity of VOCs.

Cardamom oil-infused paper box: Enhancing rambutan fruit post-harvest disease control with reusable packaging

The research aimed to develop a paper box with 10–300 μl of cardamom oil to improve rambutan storage, reduce waste, and explore reuse possibilities. The experiment investigated the delay in mold growth caused by the post-harvest disease, Pestalotiopsis sp., both on the medium and on rambutan fruit under storage conditions of 10 ± 2 °C and approximately 80% RH. The results showed that CM at 300 μl significantly inhibited Pestalotiopsis sp. mycelium and spore germination on the medium, while a lower volume of 30 μl effectively delayed mold incidence on rambutan during the 14-day storage period. The confirmed antifungal mode of action indicated that CM disrupted Pestalotiopsis sp. ergosterol and cell membrane integrity, resulting in mycelium lysis and damaged morphology, thereby inhibiting its growth. The active fruit box can be reused for at least 2 or 3 storage cycles, effectively delaying rambutan decay and preserving its color change parameters. By using the box with 30 μl of CM, rambutan's shelf-life was extended to 14 days compared to the control's shelf-life of around 7 days. Active paper boxes offer a valuable solution for improving post-harvest fruit storage and transportation, benefiting both farmers and consumers.

Phytosynthesis of silver nanoparticles by Paulownia fortunei fruit exudates and its application against Fusarium sp. causing dry rot postharvest diseases of banana

Over the recent years, banana cultivation has increased in the South-Eastern provinces of Iran. Management of Fusarium diseases in banana poses considerable yield loss as the application of chemical and biological treatments remains challenging. At the present research, about 10 Fusarium isolates causing dry rot on banana fruits were isolated and based on the pathogenicity test, isolate MSN-7 was considered as the most pathogenic isolate. Isolate MSN-7 was identified by using the ITS (ITS1 and ITS4) genomic region. BLAST results showed that it had the highest similarity (99%) with Fusarium chalmydosporum (MN533778.1). The objective of our research was to examine different concentrations of Silver nanoparticles (SNPs) biosynthesized by Paulownia fortunei L.) Fruit Exudates as a novel antifungal agent for reduce of pathogencity of Fusarium dry rot of banana. The synthesis of SNPs was conducted utilizing Paulownia fruit extracts as an environmentally friendly biosource. The exudates derived from Paulownia fruit demonstrated the capability to generate nanoparticles with an average size of 46 nm. Analysis conducted using a transmission electron microscope (TEM) revealed that these nanoparticles possess a polyhedral structure. Furthermore, when applied at concentrations of 10, 20, 40, and 80 μg/ml, these biosynthetic nanoparticles exhibited the ability to inhibit the growth of Fusarium fungus mycelia, as well as induced the destruction of the fungal hyphae.

Mining the Penicillium expansum Genome for Virulence Genes: A Functional-Based Approach to Discover Novel Loci Mediating Blue Mold Decay of Apple Fruit.

Blue mold, a postharvest disease of pome fruits, is caused by the filamentous fungus Penicillium expansum. In addition to the economic losses caused by P. expansum, food safety can be compromised, as this pathogen is mycotoxigenic. In this study, forward and reverse genetic approaches were used to identify genes involved in blue mold infection in apple fruits. For this, we generated a random T-DNA insertional mutant library. A total of 448 transformants were generated and screened for the reduced decay phenotype on apples. Of these mutants, six (T-193, T-275, T-434, T-588, T-625, and T-711) were selected for continued studies and five unique genes were identified of interest. In addition, two deletion mutants (Δt-625 and Δt-588) and a knockdown strain (t-434KD) were generated for three loci. Data show that the ∆t-588 mutant phenocopied the T-DNA insertion mutant and had virulence penalties during apple fruit decay. We hypothesize that this locus encodes a glyoxalase due to bioinformatic predictions, thus contributing to reduced colony diameter when grown in methylglyoxal (MG). This work presents novel members of signaling networks and additional genetic factors that regulate fungal virulence in the blue mold fungus during apple fruit decay.

The effect of pulcherriminic acid produced by Metschnikowia citriensis in controlling postharvest diseases of citrus fruits

The biocontrol effectiveness of Metschnikowia citriensis relies on its production of pulcherriminic acid (PA), which forms insoluble and stable pulcherrimin pigments by chelating iron ions, this inhibits pathogen growth by preventing their utilization of chelated Fe3+. In this study, ΔM. citriensis, which did not produce PA, was used as a control to examine changes in its biocontrol effectiveness by adding tryptophan to the medium. Tryptophan was shown to have no discernible impact on the growth and PA production of ΔM. citriensis; moreover, the PA synthesis-related genes PULs, Snf2, and leucyl-tRNA synthesis-related genes A3136 and A3022 were all down-regulated in ΔM. citriensis. The PA-free ΔM. citriensis eventually showed a much poorer inhibition zone against the pathogens in vitro, and a noticeably decreased control efficiency against postharvest diseases in citrus fruit. Tryptophan was added to the medium, which had no appreciable impact on inhibitory zone of ΔM. citriensis against pathogens in vitro, but enhanced its ability to control citrus postharvest diseases. Additionally, the control effects of culture broth of M. citriensis and ΔM. citriensis on postharvest diseases in citrus fruit were assessed. It was found that both culture broth of M. citriensis and ΔM. citriensis exhibited remarkable control effects against citrus postharvest diseases, with culture broth of M. citriensis which containing PA being more effective in controlling the disease. Last but not least, we extracted and dissolved pulcherrimin to obtain PA extracts, which were then injected to citrus fruits to assess the biocontrol effectiveness. The findings demonstrated that postharvest diseases of citrus fruit can be effectively controlled by PA extracts. This research suggested a new biological strategy for the management of citrus postharvest diseases.

EFFECTIVENESS OF 7S GLOBULIN AGAINST BOTRYTIS CINEREA CAUSING GRAY MOLD IN STRAWBERRY

Gray mold caused by Botrytis cinerea is the most harmful postharvest disease responsible for the degradation of strawberries. The presented study targeted the preparation of 7S globulin from pea seeds to serve as an antifungal agent against B. cinerea in vitro and on the post-harvest strawberry to extend the fruits’ shelf life. The 7S globulin isolation from pea seeds and characterization employed various methods, such as SDS-PAGE, FTIR, and pH solubility curve. The molecular technique also helped confirm the identity of the causative microorganism of the gray mold disease in strawberries. Utilizing rRNA gene sequencing identified a fungal pathogen that causes gray mold as B. cinerea. The 7S globulin showed three protein bands corresponding to α/ (83 KDa), α (68 KDa), and β (60 KDa) subunits. The isoelectric point was notable at pH 5.8. The essential and non-essential amino acids occurred around 24.92% and 54.04%, respectively. The 7S globulin inhibited the mycelial growth of B. cinerea in a concentration-dependent manner. The Scanning Electron Microscope (SEM) of B. cinerea subjected to 7S globulin showed swelling of both the fungal hyphae and conidia, significantly affected by the pea 7S-globulin treatment, entirely destabilizing and deforming their shape at 0.4 g/L. The 7S-globulin exposure maintained the fruit quality and stopped the strawberry’s natural deterioration. Results further authenticated that 7S globulin (isolated from pea seeds) revealed effective antifungal action against B. cinerea mycelial development via a membrane-targeted mechanism. The 7S globulin affects hyphal morphology, compromises plasma membrane integrity, and prevents post-harvest gray mold on strawberry fruits.

Biological control of postharvest tomato fruit rots using Bacillus spp. and Pseudomonas spp.

BackgroundPostharvest diseases cause a wide loss to tomato fruits during handling and storing from harvest to consumers. Fungicides are mainly used to control postharvest diseases. Biological control is the eco-friendly substitute strategy used for postharvest diseases management as which becoming promise worldwide. Six bacterial bioagent (i.e., Bacillus subtilis, B. amyloliquefaciens, Pseudomonas resinovorans, P. alcaligenes, P. putida and P. stutzeri) were tested to suppress both Geotrichum candidum and Alternaria alternata causal agents of tomato fruit rots during storage.ResultsIn vitro, most of bioagents significantly reduced mycelial growth rate of G. candidum. Both of B. subtilis and P. stutzeri were the most superior bacterial bioagents with values 67.03 and 72.2%, respectively. In addition, B. subtilis and B. amyloliquefaciens resulted in the most superior over all antagonists against A. alternata. The lowest percent of disease incidence and severity of G. candidum were obtained by B. subtilis and P. stutzeri. The maximum reduction percent of it on tomato fruits was recorded by applying B. subtilis and P. stutzeri with values (90 and 87%) and (91, 89%) in both seasons, respectively. Also, the highest reduction of A. alternata was obtained by using B. subtilis, which resulted in 85 and 84% in both seasons, respectively. The application of bioagents against both pathogens was significantly improved fruit quality aspects (weight loss, vitamin C, TSS and acidity %) during storage period compared to infected control fruits.ConclusionThe findings revealed that both of B. subtilis and P. stutzeri could be potential biological control agents against most postharvest pathogens of tomato fruits. This might be an alternative control strategy instead of fungicides which service the sustainable and organic farming.

Morphological characterization of Sclerotinia sclerotiorum causing fruit rot of papaya and its management using biopesticides

Papaya is an important fruit crop and susceptible to several post-harvest diseases at every stage of its life cycle. Papaya fruit rot caused by Sclerotinia sclerotiorum, is a serious postharvest disease that results in significant losses both in storage and on the market. Papaya fruit that was gathered from several Lahore fruit marketplaces was the subject of the studies. Based on physical and cultural traits, diseased papaya fruits were separated and identified. The virus developed mycelial colonies on PDA media that were sparse and creamy white. These colonies ultimately became fluffy and light brown. Sclerotia began to appear after three days of mycelial growth, and after seven days, they were fully visible in the shape of rings or distributed across the mycelial surface of the Petri plate. This allowed for the calculation of the frequency of isolated fungi. It was recorded maximum percentage of S. sclerotiorum (58%) was recorded followed by Alternaria alternata (21.5 %) and Aspergillus niger (10.0 %), while Penicillum spp. was least isolated fungi with a mean value of 5.00%. The assessment of different plant extracts including (Cascabela thevetia, Euphorbia milii, Moringa oleifera, Plumeria rubra, Quisqualis indica, Syzygium aromaticum) was done with Agar Well Diffusion Technique under CRD design. The findings showed that of the medicinal plants that were extracted using methanol and ethanol, Moringa oleifera and Syzygium aromaticum showed significant results at higher concentrations and showed maximum zone of inhibition while Cascabela thevetia was least effective against S. sclerotiorum.

New and Antifungal Diterpenoids of Sunflower against Gray Mold.

Sunflower (Helianthus annuus L.) is cultivated around the world as an oil crop, and its receptacle is the byproduct and is usually deemed to be an agro-industrial waste. Then, phytochemical constituents and antifungal bioactivity of the sunflower receptacle against phytopathogenic fungi were investigated. As a result, 17 diterpenoids including 4 new compounds were isolated, and most of them showed potential antifungal activity against Botrytis cinerea, in which compounds 1, 3, 5, and 15 exhibited better inhibitory effect with the minimum inhibitory concentration values of 0.05-0.1 mg/mL. Meanwhile, four antifungal diterpenoids destructed plasma membrane integrity, suspended the biofilm formation ability, and increased the extravasation of cellular contents of B. cinerea. Moreover, the EtOAc extract of sunflower receptacle could keep 42.9% of blueberries from the invasion of B. cinerea at 1.6 mg/mL. The finding suggested that sunflower receptacle might be a biocontrol agent for preventing fruit from postharvest diseases.

Inhibitory effects of hinokitiol on the development and pathogenicity of Colletotrichum gloeosporioides.

Postharvest anthracnose of mango fruit caused by Colletotrichum gloeosporioides is a devastating fungal disease, which causes tremendous quality deterioration and economic losses. Hinokitiol, an environmentally friendly natural compound, is effective in controlling a variety of postharvest fungal diseases. However, there is still a lack of research on the inhibitory effect of hinokitiol on C. gloeosporioides and its possible modes of action. In the present study, the activity of hinokitiol against C. gloeosporioides and its potential mechanisms involved have been investigated. We found that hinokitiol treatment could effectively inhibit the virulence of C. gloeosporioides to harvested mango fruit. After treatment with 8mg/L hinokitiol, the mycelial growth of C. gloeosporioides was completely inhibited. When the concentration of hinokitiol reached 9mg/L, the spore germination rate of C. gloeosporioides decreased to 2.43% after 9h of cultivation. The inhibitory effect is mainly due to the attenuation in cell viability, and impairment in plasma membrane followed by leakage of cytoplasmic contents such as nucleic acids, proteins, and soluble carbohydrates, which ultimately leads to the destruction of cell structure. Furthermore, hinokitiol suppressed the expression of pathogenicity-related genes, leading to reduced infection activity. Collectively, these results suggest that hinokitiol may be an excellent bio-fungicides for the management of mango anthracnose.