Biological Control Of Postharvest Diseases Research Articles

Endophytic Stenotrophomonas geniculata KJ-6 via producing antifungal volatile organic compounds effectively control Lanzhou lily postharvest diseases

The endophytic bacterial Stenotrophomonas geniculata KJ-6, was isolated from Arisaematis rhizoma. This strain has the ability to control three postharvest pathogenic fungi of Lanzhou lily (Trichoderma lixii F-2, Talaromyces tumuli F-3, and Fusarium annulatum F-6) by releasing volatile organic compounds (VOCs). The experiment utilized the double-layer sealed bottom plate method. The results demonstrate that KJ-6 effectively inhibits the mycelial growth of F-2, F-3, and F-6, with inhibition rates of 81.59%, 79.87%, and 84.7%, respectively. Moreover, scanning electron microscopy (SEM) revealed abnormal mycelium morphology in the test pathogenic fungi treated with KJ-6 VOCs, characterized by multiple wrinkles, cracks, and distortions. Using five common phytopathogenic fungi as controls, our results demonstrated that the VOCs from KJ-6 exhibited broad-spectrum antifungal effects. Analysis using headspace gas chromatography-ion mobility spectrometry identified three components of the VOCs produced by KJ-6, including 1-propanethiol, isoamyl acetate, and 2-methyl-1-butanol. Antifungal tests revealed that 1-propanethiol plays a crucial role in the inhibitory activity of VOCs. It exhibited inhibitory rates of 64.17%, 72.73%, and 26.71% on the mycelium growth of F-2, F-3, and F-6, respectively. In vivo experiments further confirmed that VOCs can significantly reduce the disease index and decay rate of Lanzhou lily bulbs during storage. Moreover, KJ-6 treatment led to a significant reduction in the degree of browning of lily bulbs. Additionally, it enhanced the activity of defense-related enzymes, improved disease resistance, and extended the shelf life of lily bulbs. As a result, this study offers a theoretical foundation for the biological control of postharvest diseases in Lanzhou lily.

The potentiality of Wickerhamomyces anomalus against postharvest black spot disease in cherry tomatoes and insights into the defense mechanisms involved

Our previous study revealed that Wickerhamomyces anomalus effectively inhibited Botrytis cinerea disease in cherry tomatoes. However, the potentiality of W. anomalus against black spot disease in cherry tomatoes as well as possible mechanisms related to this efficacy remain unclear. In our current study, we investigated the efficacy of W. anomalus against black spot disease in cherry tomatoes, and the molecular mechanisms related to disease-resistance response of W. anomalus treated cherry tomatoes were also investigated by transcriptome analysis. The results exhibited that W. anomalus successfully controlled postharvest black spot disease of cherry tomatoes caused by Alternaria alternata. Furthermore, W. anomalus vigorously controlled the spore germination and reduced the germ tube elongation of A. alternata. The physiological mechanisms by which W. anomalus inhibited the black spot decay in cherry tomatoes mainly through enhancing the ascorbate peroxidase (APX) and chitinase (CHI), and reducing the content of malondialdehyde (MDA). In addition, based on transcriptome technology, W. anomalus could up-regulate genes involved in several important KEGG pathways, including amino sugar and nucleotide sugar metabolism pathway, selenocompound metabolism pathway, linoleic acid metabolism pathway, and galactose metabolism pathway. These genes may help the fruit to enhance the enzyme activities and nutritional values of cherry tomatoes, synthesize the regulatory molecules in plant disease response as well as plant growth and development, increase the defense and oxidation resistance of the fruit during and after harvesting, and trigger ROS induced resistance in cherry tomatoes. Ultimately, W. anomalus has been proved as a biocontrol agent which could effectively control black spot disease in cherry tomatoes caused by A. alternata. This study can provide theoretical reference for the practical application of antagonistic yeasts in the biological control of postharvest diseases of cherry tomatoes.

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.

Cell-Free Supernatant of Bacillus subtilis Reduces Kiwifruit Rot Caused by Botryosphaeria dothidea through Inducing Oxidative Stress in the Pathogen.

Biological control of postharvest diseases has been proven to be an effective alternative to chemical control. As an environmentally friendly biocontrol agent, Bacillus subtilis has been widely applied. This study explores its application in kiwifruit soft rot and reveals the corresponding mechanisms. Treatment with cell-free supernatant (CFS) of Bacillus subtilis BS-1 significantly inhibits the mycelial growth of the pathogen Botryosphaeria dothidea and attenuates the pathogenicity on kiwifruit in a concentration-dependent manner. In particular, mycelial growth diameter was only 21% of the control after 3 days of treatment with 5% CFS. CFS caused swelling and breakage of the hyphae of B. dothidea observed by scanning electron microscopy, resulting in the leakage of nucleic acid and soluble protein and the loss of ergosterol content. Further analysis demonstrated that CFS significantly induces the expression of Nox genes associated with reactive oxygen species (ROS) production by 1.9-2.7-fold, leading to a considerable accumulation of ROS in cells and causing mycelial cell death. Our findings demonstrate that the biocontrol effect of B. subtilis BS-1 CFS on B. dothidea is realized by inducing oxidative damage to the mycelia cell.

Bacillus subtilis L1-21 as a biocontrol agent for postharvest gray mold of tomato caused by Botrytis cinerea

Gray mold (Botrytis cinerea) is a serious disease causing considerable losses to harvested tomato during storage and transportation. Extensive and unjudicial use of fungicides has certain deleterious effects such as evolved resistance in pathogen and environmental pollution. The ice cold chain transportation is the most commonly used method, but the results are not satisfactory. Currently, the trend is shifting towards prevention and control measures which ensures environmental protection, therefore, the biological control of postharvest diseases has become a hot spot. In this study, Bacillus subtilis L1-21 was used to control gray mold on tomato fruits, by adopting plate confrontation and fruit acupuncture method. To evaluate the preservative effect of biocontrol agent L1-21 on tomato, the gfp-tagged L1-21 was used to study colonization potential in harvested tomatoes assay. Colonization of L1-21-gfp in postharvest tomatoes was stable at 103 cfu/g by soaking and fluorescence method. Whereas inhibition rate of B. cinerea was 39.63% ± 4.73% in plate confrontation. Culture suspension of L1-21 at a concentration of 108 cfu/ml displayed the best control effect: 86.57% ± 2.55% against tomato gray mold. In addition, different components exhibited different results such as cell pellet + saline (72.94% ± 8.49%), supernatant (41.18% ± 16.22%), sterilized culture (28.56% ± 6.54%). Further, suspension of B. cinerea and Bacillus L1-21 injected in tested tomatoes led to maximum control effect (81.40% ± 2.74%) after 4 h. Injection of L1-21 culture into tomato followed by pathogen B. cinerea spore solution resulted in 100%±0% control effect after 48 h. There was no significant difference in fruit quality between treated and untreated tomatoes. Taken together, B. subtilis L1-21 may lay theoretical foundation to be used in prevention of gray mold and other postharvest diseases during storage time.

Identification and biological control of postharvest diseases of peach

Identification and biological control of postharvest diseases of peach

Biocontrol ability and action mechanism of Bacillus halotolerans against Botrytis cinerea causing grey mould in postharvest strawberry fruit

Bacillus species are promising agent for the biological control of postharvest diseases. This study investigated the bio-control efficiency of Bacillus halotolerans KLBC XJ-5 against grey mould caused by Botrytis cinerea in postharvest strawberries, together with its underlying antagonistic mechanism. Treatment with B. halotolerans KLBC XJ-5 controlled mycelial growth as well as conidial germination of B. cinerea in vitro. The grey mould in strawberries inoculated with B. halotolerans KLBC XJ-5 was lower in comparison with that in the control fruit after 4 d of incubation. Genome sequencing and further bioinformatic analyses suggested that strain KLBC XJ-5 harboured six antimicrobial biosynthesis gene clusters, besides four glycoside hydrolase family 18 gene clusters involved in chitin degradation. In addition, it secreted the lytic enzyme chitinase (CHI). B. halotolerans KLBC XJ-5-treated strawberries exhibited significant induced enzyme activities (polyphenol oxidase, phenylalanine ammonia lyase, β-1, 3-glucanase, and chitinase) and compounds related to disease resistance (total phenols, flavonoids). Compared to the control fruit, B. halotolerans KLBC XJ-5-treated fruit did not present differences on nutritional quality (measured in ascorbic acid, titratable acidity, and total soluble solids). Thus, it can be concluded that B. halotolerans KLBC XJ-5 could be potentially useful as a suitable bio-control agent in harvested strawberries.

Biocontrol of Postharvest Colletotrichum Decay in Red Chili and Tomato with Bacillus SubtilisATCC 21556

Bacillus subtilis ATCC 21556 produces the highest an antifungal of iturin A compared to the other three of B. subtilis strains ATCC 15841, ATCC 27505, and ATCC 21770. An Iturin A has a wide antifungal spectrum activity, therefore making it an ideal potential for controlling of the fungal diseases of crop not only for preharvest but also for postharvest control. This research work if very useful to overcome the problem of decreased post-harvest production of chili and tomato that caused by the fungal pathogen. Many of the fungi cause of postharvest disease in various fruits and vegetables. Biological control of postharvest diseases has emerged as an effective alternative control since the impact of chemical control of post-harvest disease cause serious consequences for human health and the environment. Twenty microliters of B. subtilis ATCC 21556 (approximately 1 x 107 cell mL-1) were injected into the fruit of red chillies and tomatoes to control its postharvest diseases caused by fungal of Colletotrichum scovillei 244830. The lesion diameter of C. scovillei 244830 significantly (p<0.005) reduced about 52-64% in chili and 39-44% in tomato. An invitro test showed that percent growth inhibition of B. subtilis ATCC 21556 against C. scovillei 244830 was about 52.38% at 14 days of the incubation time. For successful infection of the fungal pathogens into the host plants, they produce the extracellular enzymes. Qualitative test of the extracellular enzymes showed that C. scovillei 244830 produced the enzymes of amylase, laccase, lipase, pectate lyase, and protease and it did not produce polygalacturonase.

Proteomic analysis reveals the mechanisms involved in the enhanced biocontrol efficacy of Rhodotorula mucilaginosa induced by chitosan

The biocontrol efficacy of the yeast, Rhodotorula mucilaginosa against postharvest diseases of strawberries can be significantly enhanced by culturing the yeast in a medium containing chitosan. The molecular mechanisms involved in the enhanced biocontrol efficacy of R. mucilaginosa, however, have not been comprehensively explored. Results of the present study indicate that the biocontrol efficacy of the yeast against gray mold (Botrytis cinerea) of strawberry was greatest when the yeast was cultured in a medium containing 0.5% (w:v) chitosan for 24 h before use. Proteomic and bioinformatic analyses revealed that proteins involved in growth and reproduction, energy metabolism, antioxidant response, response to abiotic stress, and degradation of pathogen cell walls were all up-regulated by chitosan resulting in the enhanced antagonistic activity of R. mucilaginosa against B. cinerea. The decrease in ROS accumulation in R. mucilaginosa cultured in a medium containing chitosan was in agreement with the increased abundance of proteins related to antioxidant defense. Key differentially expressed proteins (DEPs) were identified and 12 randomly-selected DEPs were validated by parallel reaction monitoring. The present results provide a theoretical reference for further study of the molecular mechanisms involved in the improvement of biocontrol efficacy of antagonistic yeast by elicitor molecules and also provide a novel approach for improving biological control of postharvest diseases.

Identification and characterization of the Bacillus atrophaeus strain J-1 as biological agent of apple ring rot disease

Bacillus species are promising agents for the biological control of postharvest diseases. Based on the morphological, physiological and biochemical characteristics and 16S rRNA gene sequence analysis, the bacterial strain J-1 was identified as Bacillus atrophaeus. The B. atrophaeus strain J-1 showed broad spectrum antifungal activity against various plant pathogenic fungi. In assays in vitro the metabolites contained in the B. atrophaeus strain J-1 cell-free filtrate had a strong inhibitory effect on Botryosphaeria dothidea. The cell-free filtrate inhibited the growth of B. dothidea in vivo and reduced the disease incidence. Furthermore, PCR detection showed that the strain J-1 had lipopeptide antibiotic biosynthesis genes: fengycin, iturin A and surfactin. The lipopeptide crude extractions from the strain J-1 cell-free filtrate significantly suppressed the growth of B. dothidea. C14 iturin A was isolated by bioactivity-guided fractionation and identified by liquid chromatography–electronic spray ionization–tandem mass spectrometry analysis. This paper is the first to report that B. atrophaeus J-1 efficiently controls apple ring rot disease caused by B. dothidea. Using the B. atrophaeus strain J-1 may provide an alternative control method for the prevention apple ring rot disease.

Postharvest biological control of Rhizopus rot and the mechanisms involved in induced disease resistance of peaches by Pichia membranefaciens

Abstract Biological control of postharvest diseases of fruit by antagonistic yeast has been considered to be an effective and promising strategy to reduce the postharvest loss of fruits. In this study, the biocontrol efficacy of Pichia membranefaciens against Rhizopus rot of peaches was investigated. Also, the study was aimed to explore the mechanisms involved in the induced disease resistance of peaches by investigating the activities of defense-related enzymes and transcriptome analysis. The results indicated that P. membranefaciens had significant biocontrol efficacy against Rhizopus rot of peaches. The activities of defense-related enzymes including PPO, POD, PAL and CAT were potentially induced by this yeast. The transcriptome analysis revealed that MAPK cascade signaling pathway and signal transduction pathways of ethylene (ET), jasmonate (JA) and salicylic acid (SA) were triggered in peaches by P. membranefaciens to regulate the transcription factors (TFs). Then, these TFs further mediated the expression of downstream defense-related genes including PR genes (PR1, CHI4 and major allergen Pru ar 1) and glutathione S-transferase (GST) genes (MKP11.22 and Atlg10370), the genes classified into plant-pathogen interaction pathways (CML48, MUK11.19 and ROBHA) and the genes involved in the synthesis of secondary metabolites (GGPS, PKS5, CHS1, CYP75B2, DFR, LDOX, PAL, PNC1 and ROMT) to enhance the disease resistance potential of peaches. Besides, the accumulation of some antifungal compounds including flavonoids and lignin was stimulated to enhance the antifungal ability of peaches. Consequently, the present study contributes to understand the mechanisms behind the induced disease resistance of peaches by antagonistic yeast, and would provide new disease control strategy by improving the defense responses of fruit against pathogens.

The postharvest microbiome: The other half of sustainability

Biological control of postharvest diseases has been suggested as a viable alternative to synthetic chemicals and has been the focus of considerable research worldwide for the last 30 years by many scientists and several commercial companies. Microbiome-based research has opened a whole new frontier that will greatly expand our knowledge of postharvest pathology and biology and offer new opportunities for developing novel approaches for biocontrol that are based on a deeper understanding of the complex interactions taking place between the resident microbiota and harvested produce. The postharvest microbiome is only beginning to be explored and the composition and functional effect of the microbiome on fresh produce after harvest is largely unknown. Determining if different commodities have a core microbiome that influences potential host-microbiome interactions has yet to be determined. Viewing harvested produce as a meta-organism, within the holobiont concept, and its recent iterations, may represent a useful model for the postharvest microbiome considering that harvested commodities represent dynamic systems with complex microbial community-host interactions. Understanding the functional role and impact of the endophytic and epiphytic microbiome of developing and harvested fruit would provide valuable information needed for the development of safe and effective, function-based biocontrol systems that can be used to enhance the shelf life of produce by controlling decay pathogens and perhaps even postharvest physiological disorders.

Investigating Proteome and Transcriptome Defense Response of Apples Induced by Yarrowia lipolytica

A better understanding of the mode of action of postharvest biocontrol agents on fruit surfaces is critical for the advancement of successful implementation of postharvest biocontrol products. This is due to the increasing importance of biological control of postharvest diseases over chemical and other control methods. However, most of the mechanisms involved in biological control remain unknown and need to be explored. Yarrowia lipolytica significantly inhibited blue mold decay of apples caused by Penicillium expansum. The findings also demonstrated that Y. lipolytica stimulated the activities of polyphenoloxidase, peroxidase, chitinase, l-phenylalanine ammonia lyase involved in enhancing defense responses in apple fruit tissue. Proteomic and transcriptomic analysis revealed a total of 35 proteins identified as up- and down-regulated in response to the Y. lipolytica inducement. These proteins were related to defense, biotic stimulus, and stress responses, such as pathogenesis-related proteins and dehydrin. The analysis of the transcriptome results proved that the induced resistance was mediated by a crosstalk between salicylic acid (SA) and ethylene/jasmonate (ET/JA) pathways. Y. lipolytica treatment activated the expression of isochorismate synthase gene in the SA pathway, which up-regulates the expression of PR4 in apple. The expression of 1-aminocyclopropane-1-carboxylate oxidase gene and ET-responsive transcription factors 2 and 4, which are involved in the ET pathway, were also activated. In addition, cytochrome oxidase I, which plays an important role in JA signaling for resistance acquisition, was also activated. However, not all of the genes had a positive effect on the SA and ET/JA signal pathways. As transcriptional repressors in JA signaling, TIFY3B and TIFY11B were triggered by the yeast, but the gene expression levels were relatively low. Taken together, Y. lipolytica induced the SA and ET/JA signal mediating the defense pathways by stimulating defense response genes, such as peroxidase, thaumatin-like protein, and chitinase 4-like, which are involved in defense response in apple. [Formula: see text]

Overexpression of the Bivalent Antibacterial Peptide Genes in Pichia pastoris Delays Sour Rot in Citrus Fruit and Induces Geotrichum citri-aurantii Cell Apoptosis

ABSTRACTGenetic manipulation of antagonists shows tremendous potential for improving biocontrol activity of antagonists. Here, bivalent antibacterial peptide Cecropin A/PsdI gene was transformed and expressed in methylotrophic yeast, Pichia pastoris GS115. The bivalent yeast GS115/CEC-PSD showed a great ability in delaying sour rot in citrus fruit and based on observations of restrained growth of geminated Geotrichum citri-aurantii spores relative to non-transformed strain. Although there was no remarkable discrepancy between growth rates of strain GS115 and GS115/CEC-PSD in vivo and vitro, plenty of vacuoles were observed in the cellular space of G. citri-aurantii treated with the CEC-PSD via transmission electron microscopy. Meanwhile, a gel-retardation assay exhibited that the DNA of G. citri-aurantii was degraded by CEC-PSD. Furthermore, our research revealed apoptosis genes in G. citri-aurantii were expressed at different levels with the CEC-PSD levels, among these genes, the expression level of RLM1 and RLM1was decreased remarkably, and the expression level of others changed relatively a little. These findings suggest that bivalent antimicrobial peptides can inhibit G. citri-aurantii by harming cell membrane, disrupting the cell metabolism, inducing programmed cell death and can therefore heighten the inhibition effect of the biocontrol yeast against postharvest diseases and this provides a new approach for the biological control of postharvest diseases.

Biological control of postharvest diseases by microbial antagonists: how many mechanisms of action?

The postharvest phase has been considered an environment for successful application of biological control agents (BCAs). However, the interactions between fungal pathogen, host (fruit), and antagonist are influenced by several parameters such as temperature, oxidative stresses, oxygen composition and water activity that could determine the success of biocontrol. Knowledge of the modes of action of BCAs is essential in order to enhance their viability and increase their potential in disease control. The antagonists display a wide range of modes of action: antibiosis, competition for nutrients and space, parasitism and induction of resistance are considered the main ones. Their efficacy, however, is related to the host and the pathogen; sometimes, these mechanisms could act simultaneously, and it is therefore difficult to establish which is related to a specific antifungal action. The current review presents a brief summary of the research that has led to a better understanding of the mode of action of BCAs with particular emphasis on the most recent literature.

Heat shock improves stress tolerance and biocontrol performance of Rhodotorula mucilaginosa

Biological control of postharvest diseases, utilizing wild species and strains of antagonistic yeasts, is an eco-friendly management approach that has received considerable attention over the past three decades. A few yeast-based biocontrol products are either in advanced stages of development or commercially available. Ecological fitness, stress tolerance and biocontrol performance are essential attributes for yeasts used as biocontrol agents. In the present study, a mild heat shock (HS, 40°C for 30min) pretreatment of the biocontrol yeast, Rhodotorula mucilaginosa, increased its tolerance to subsequent high temperature (48°C), oxidative stress (70mM H2O2), salt stress (3M NaCl), and low pH (pH 4). Activation of the yeast antioxidant system by HS resulted in a lower accumulation of reactive oxygen species and less oxidative damage to proteins and lipids relative to control yeast cells when both were subjected to various abiotic stresses. Additionally, HS-treated yeast exhibited increased efficacy in controlling infection of apple fruit by Penicillium expansum, and a higher growth rate in apple wounds. These results suggest that stress adaptation is a viable approach for improving the efficacy of yeast biocontrol agents under the variable environmental conditions that exist in the postharvest environment of packing houses and storage facilities.

Isolation and characterization of Bacillus amyloliquefaciens PG12 for the biological control of apple ring rot

Bacillus spp. are promising candidates for biological control of postharvest diseases. Bacillus amyloliquefaciens PG12 was isolated from apple fruit and exhibited broad-spectrum antifungal activity. Botryosphaeria dothidea was significantly suppressed by PG12 in in vitro and in vivo. Lumpy appearance and abnormal structure of the mycelia from the edge of inhibition zone were observed using scanning electron microscopy (SEM) in in vitro assays. Furthermore, the lipopeptide crude extracts from cell-free supernatant of PG12 had remarkable antifungal activity against B. dothidea, indicating that lipopeptides played a major role in the biological control ability of PG12. PCR detection revealed that PG12 harbored the gene clusters required for the biosynthesis of the two main families of lipopeptide, including iturin and fengycin. One iturin-like compound (Rf 0.4) showed inhibitory activity against B. dothidea using thin layer chromatography (TLC)-bioautography analysis and were further fractionated by semipreparative high performance liquid chromatography (HPLC). The fraction with a molecular weight of 1043.55 m/z was identified as iturin A by electrospray ionization quadrupole-time-of-flight mass spectrometry/mass spectrometry (ESI-Q-TOF MS). Taken together, B. amyloliquefaciens PG12 was an effective biocontrol agent against apple ring rot caused by B. dothidea and iturin A was an important factor in its activity.

Stress tolerance and biocontrol performance of the yeast antagonist, Candida diversa, change with morphology transition.

As an eco-friendly management method, biological control of postharvest diseases, utilizing antagonistic yeasts, is a research topic receiving considerable attention. Detailed knowledge on the biology of yeast antagonists is crucial when considering their potential application and development as biocontrol products. Changes in the growth form, such as single-cell to pseudohyphae, have been associated with the mode of action in postharvest biocontrol yeasts. In this study, the antagonistic yeast, Candida diversa, reversibly shifted from a single-cell morphology on yeast peptone dextrose (YPD) medium with 2 % agar to a pseudohyphal morphology on YPD with 0.3 % agar. The tolerance of the pseudohyphal form to heat and oxidative stresses, as well as the biocontrol efficacy against Botrytis cinerea on apple and kiwifruit stored at 25 and 4 °C, was significantly higher as compared to the single-cell form. This study provides new information on the ability of C. diversa to change its morphology and the impact of the morphology shift on stress tolerance and biocontrol performance.

Utilização de compostos bioativos de plantas medicinais na pós-colheita de tomate

Various methods are been used to control post-harvest diseases of tomato fruits . With the increasing restrictions on the use of fungicides, due the food safety and environmental impacts, the use of alternative methods and biological control of postharvest diseases have been stimulated . The aim of this work was to investigate the effect of alternative products in post-harvest treatment of tomato “Delta” and “ Debora” produced under two cropping systems: intermediate (IS ) and conventional system (CS) . The components evaluated were the reduction of fresh mass, pH, soluble solids ( SS), titratable acidity (TA ) and the pathogens incidence after being treated by immersion with acibenzolar -S-methyl ( ASM), Azadirachta indica crude extract, citric biomass extract and fumigation with essential oils (EO) of Syzygium aromaticum and Citrus aurantium ssp. bergamia . The products did not affect the parameters analyzed in the fruits from the CS , regardless of cultivar . In the fruits produced in IS was observed influence of the treatments . F or weight reduction , were observed the lowest values in fruits of “Debora” treated with EO and ASM . Were observed also, the highest values of SS and TA in fruits “Debora” treated with S. aromaticum EO and ASM . The fruits “Delta” had the highest pH when treated with S . aromaticum EO.

A Preliminary Preparation of Endophytic Bacteria CE3 Wettable Powder for Biological Control of Postharvest Diseases

A Preliminary Preparation of Endophytic Bacteria CE3 Wettable Powder for Biological Control of Postharvest Diseases