Postharvest Diseases Of Apple Research Articles

Polyhydroxyalkanoates (PHAs) from Endophytic Bacterial Strains as Potential Biocontrol Agents against Postharvest Diseases of Apples.

Due to the increasing use and accumulation of petrochemical plastics in the environment and the rapid depletion of natural resources, microbial polyhydroxyalkanoates have great potential to replace them. This study provides new insights in the field of obtaining of polyhydroxyalkanoates (PHAs) from endophytic bacterial strains and applying them as potential biocontrol agents against postharvest diseases of apples. Two strains-Pseudomonas flavescens D5 and Bacillus aerophilus A2-accumulated PHAs in amounts ranging from 2.77 to 5.9 g L-1. The potential to use low-cost substrates such as beet molasses and soapstock for PHA accumulation was shown. The PHAs produced by the Ps. flavescens D5 strain had pronounced antagonistic activity against Penicillium expansum (antifungal property = 62.98-73.08%). The use of PHAs as biocontrol agents significantly reduced the severity of apple blue mold, especially in the preventive treatment option.

Management of Fungal Postharvest Diseases of Apple And Pear Using Plant Extracts

Economic losses, due to postharvest pathogens in markets and storages, are magnificent. Alternaria alternata and Penicillium expansum are considered the most important postharvest pathogens of apple and pear fruits. This work was aimed to investigate the principal pathogens on apple and pear fruits, the pathogenicity of the main pathogens, and assess of in vitro and in vivo efficacy of peel extracts of pomegranate, orange, and rutabaga against the main studied pathogens. The results of isolation designated A. alternata and P. expansum as major postharvest pathogens. The artificial inoculations of both pathogens resulted in the prominence of typical symptoms and the reisolation of the fungi proved Koch’s postulates. The results of in vitro assay revealed the highest inhibitory effect of rutabaga peel extract followed by orange peel extract while the pomegranate peel extract showed the least efficacy against both fungi. Another key fact that noticed is that both rutabaga and orange peel extract were most efficient against A. alternata than P. expansum. The results of in vivo assays have approved that pomegranate peel extract was the most effective plant extract against both pathogens of apple and pear fruits

Unreported Post-harvest Disease of Apples Caused by Plenodomus collinsoniae in Korea

Unreported Post-harvest Disease of Apples Caused by Plenodomus collinsoniae in Korea

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

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

Comparison of the occurrence of fungi causing postharvest diseases of apples grown in organic and integrated production systems in orchards in the Czech Republic.

Comparison of the occurrence of fungi causing postharvest diseases of apples grown in organic and integrated production systems in orchards in the Czech Republic.

Infection of apple fruit by Sphaeropsis pyriputrescens in the orchard in relation to Sphaeropsis rot in storage

Sphaeropsis rot, caused by Sphaeropsis pyriputrescens, is an important postharvest disease of apple in the United States. The objectives of this study were to determine the timing of apple fruit infection in the orchard in relation to development of Sphaeropsis rot in storage and to identify infection courts and mode of penetration by S. pyriputrescens on apple fruit. Fruit of apple cvs Red Delicious, Golden Delicious, and Fuji were inoculated in the orchard from 3 weeks after petal fall to 2 weeks before harvest at 5 to 6-week intervals in three consecutive seasons. All fruit were harvested and stored at 0oC to monitor decay development. Light and scanning electron microscopy were used to examine the infection courts and mode of penetration of the fungus on/in the host tissues. At harvest, the fungus was re- isolated from the stem (pedicel), sepal, anther, or fila- ment of the inoculated fruit, but decay did not develop on fruit. Sphaeropsis rot developed on inoculated fruit during cold storage beginning 1-3 months after harvest. Stem-end rot was prevalent on cv. Golden Delicious, whereas calyx-end rot was prevalent on cv. Fuji. Both stem- and calyx-end rots were common on cv. Red Delicious. Infection also occurred at lenticels on fruit skin, particularly on cv. Golden Delicious, but at low incidence. Relationships between the incidence of Sphaeropsis rot in stored apple fruit and the timing of inoculation in the orchard varied with cultivar and year. On cv. Red Delicious apples, the incidence of Sphaeropsis rot generally increased as the timing of infection approached harvest. Histological studies indi- cated that infection took place through natural openings of plant organs such as stomata on stems and sepals and lenticels on fruit skin. Fungal penetration also was ob- served at micro-cracks on the stem and sepal and at trichome sockets where mechanical damage occurred in sepals. Direct penetration was observed on the stem and sepal of fruit, but most invasions were restricted between the cuticle and the epidermis. Our results indi- cate that wounding is not required for infection of apple fruit by S. pyriputrescens, though it may facilitate infections.

Biological control of postharvest diseases of apples, peaches and nectarines by Bacillus subtilis S16 isolated from halophytes rhizosphere

Penicillium expansum, Botrytis cinerea and Colletotrichum acutatum are the most common postharvest pathogens of apples, peaches and nectarines. In this study, 96 bacteria were isolated from halophytes rhizosphere and assayed for biocontrol activity under in vitro conditions. Among the 96 isolates tested, isolate S16 effectively inhibited the growth of P. expansum, B. cinerea and C. acutatum. The isolate S16 has reduced 78.33±1.53 to 82.98±2.13% of disease severity in apples, peaches and nectarines. Matrix-assisted laser desorption ionisation-time of flight mass spectrometry of the antifungal compounds revealed three lipopeptide complexes, namely surfactins, iturins and fengycins. Lipopeptides and hydrolytic enzymes produced by the isolate S16 play an important role in the antifungal activity. Polymerase chain reaction analysis using ituD, srfAD, fenD and fenE gene-specific primers showed that the isolate S16 carry sequences similar to ituD, srfAD, fenD and fenE genes. Based on the 16S rDNA sequencing, the effective isolate S16 was identified as Bacillus subtilis.

Assessment of Application Timing of Bacillus spp. to Suppress Pre- and Postharvest Diseases of Apple.

Four isolates of Bacillus spp. were tested in a 2-year field study for biological control of pre- and postharvest diseases of apple. For the preharvest test, bacteria were applied to 'Golden Delicious' and 'Rome Beauty' trees in May or May and June. Foliar apple scab severity was assessed weekly. After harvest, fruit were wounded and then either left untreated or given a postharvest application of the bacteria. Wounded fruit were then inoculated with the bitter rot pathogen and lesion size was measured over 8 days. Bacillus megaterium isolate A3-6, B. mycoides isolate A1-1, and B. cereus isolate FLS-5 applied in May or May and June significantly reduced fruit and foliar apple scab severity in both years. A postharvest application of the bacteria (alone or in combination with a preharvest application) resulted in the greatest suppression of bitter rot on both cultivars (P < 0.04). The May + June + postharvest application of isolate A3-6 resulted in the greatest suppression of bitter rot, with an average of 45 and 95% reduction in lesion size compared with nontreated controls on 'Golden Delicious' and 'Rome Beauty' fruit, respectively. Results from this study indicate that preharvest applications of the bacteria were able to reduce foliar and fruit scab and an additional postharvest application was effective in reducing bitter rot severity.

Characterization of genes associated with induced resistance against Penicillium expansum in apple fruit treated with quercetin

Penicillium expansum causes blue mould, a serious postharvest disease of apples, and is the main producer of the mycotoxin patulin. Since control by synthetic fungicides is less accepted by consumers, the demand for alternative means is pressing. In a recent study, the flavonoid quercetin, although scarcely effective in in vitro assays against P. expansum growth, significantly reduced blue mould rots on ‘Golden Delicious’ apples, suggesting an enhancement of host disease resistance. To confirm or reject this hypothesis, genes differentially expressed in quercetin-treated ‘Golden Delicious’ apples were identified by suppression subtractive hybridization (SSH). A pool of 88 unique gene transcripts was obtained. Several sequences revealed high similarities with different classes of pathogenesis-related proteins (RNase-like PR10 and PR8), or with proteins expressed under stress conditions. Other transcripts had high similarity to genes of unknown function or genes coding for proteins having a role in pathogen recognition and in signalling pathways. SSH data were validated by analysing the expression of 14 genes by quantitative real-time PCR (qPCR). Eleven genes proved to be up-regulated at a medium-high level in freshly harvested apples. Among these, 5 genes selected for temporal expression profiling revealed the existence of a combined effect, particularly at 24 or 48 h, between wounding and phenolic treatment. These results provide evidence that quercetin induces resistance to P. expansum in apples, by acting on the transcription level of genes involved in several distinct metabolic processes.

Assessment of Pichia anomala (strain K) efficacy against blue mould of apples when applied pre- or post-harvest under laboratory conditions and in orchard trials

The yeast Pichia anomala strain K was selected in Belgium from the apple surface for its antagonistic activity against post-harvest diseases of apples. The efficacy of this strain against P. expansum was evaluated in the laboratory in three scenarios designed to mimic practical conditions, with different periods of incubation between biological treatment, wounding of fruit surface, and pathogen inoculation. Higher protection levels and higher final yeast densities were obtained when the applied initial concentration was 1 × 108 cfu ml−1 than when it was only 1 × 105 cfu ml−1. The protection level correlated positively with the yeast density determined in wounds and was influenced by apple surface wetness. In orchard trials spanning two successive years, biological treatment against P. expansum, based on a powder of P. anomala strain K (1 × 107 cfu ml−1), β-1,3-glucans (YGT 2 g l−1), and CaCl2.2H20 (20 g l−1), was applied to apples pre- or post-harvest under practical conditions and its effect compared with standard chemical treatments. The first year, the highest reduction (95.2%) against blue decay was obtained by means of four successive fungicide treatments and the next-highest level (87.6%) with pre-harvest high-volume spraying of the three-component mixture 12 days before harvest. The second year, the best results were obtained with post-harvest Sumico (carbendazim 25% and diethofencarb 25%) treatment and post-harvest biological treatment, both by dipping the apples, 88.3 and 56.3% respectively. A density threshold of 1 × 104 cfu cm−2 of strain K on the apple surface seemed to be required just after harvest for high protective activity, whatever the method and time of application. In the case of pre-harvest biological treatments, variations in meteorological conditions between the 2 years may have considerably affected strain K population density and its efficacies.

Influence of storage conditions of apples on growth and patulin production by Penicillium expansum

Penicillium expansum causes blue mould rot, a serious post-harvest disease of apples, and is the main producer of the mycotoxin patulin. The present study aimed to determine the influence of storage conditions (i.e. temperature and O 2 level) on growth and patulin production by different P. expansum strains on a simulation medium and on apples. Growth was strongly influenced by the temperature, while the used atmosphere (20, 3, and 1% O 2; < 1% CO 2) had no effect. Optimal growth was observed at 25 °C for every strain tested. Patulin production was stimulated when the temperature decreased (from 20 to 10 or 4 °C), while a further decrease of the temperature to 1 °C caused a reduction in patulin production. The temperature at which the stimulation was changed into suppression was strain dependent. Similar results were observed for the O 2 level. A reduction of the O 2 level from 20 to 3% O 2 could stimulate or suppress patulin production depending on the strain, while a clear decrease of the patulin production was observed when the O 2 level was reduced from 3 to 1%. These results show that the induction of limited stress to the fungus, such as lowering the temperature or lowering the O 2 levels stimulates patulin production. However, the combination of different stress conditions (e.g. low temperature and low O 2) will result in a reduced formation of the toxin. The combination of stress conditions, at which the transition from stimulation to suppression is observed, is strain dependent. Moreover, patulin production is characterized by a high natural variability. The presented results show that the temperature and O 2 level has to be as low as possible during the storage of apples in order to suppress patulin production and to guarantee food safety.

Fosfitos aplicados em pós-colheita reduzem o mofo-azul em maçãs 'Fuji' e 'Gala'

O mofo-azul (Penicillium expansum) é uma podridão pós-colheita comum em maçãs (Malus domestica). O uso de substâncias menos ofensivas ao ambiente, como o fosfito (ácido fosforoso), é uma das alternativas de controle dessa doença. Visou-se, então, a avaliar neste estudo a eficiência de fosfito-K (40% de P2O5 e 30% de K2O) e fosfito-CaB (10,7% de P2O5, 3,89% de Ca e 0,5% de B) no controle do mofo-azul em maçãs 'Fuji' e 'Gala'. Os testes foram delineados em blocos ao acaso com seis repetições de 20 frutos cada. Os frutos foram desinfestados em hipoclorito de Na (1%) por três minutos, lavados em água esterilizada, feridos (1mm de diâmetro e de profundidade) com agulha em quatro pontos eqüidistantes, imersos nos tratamentos por 15 minutos e armazenados a 15-20ºC. Nas suspensões contaminadas com Penicillium expansum (10² conídios.mL-1), foram adicionadas as seguintes substâncias: benomil (150 mg.L-1), fosfito-K (0,5 a 1,5 mL.L-1) e fosfito-CaB (1,5 a 3,0 mL.L-1). As maçãs 'Fuji' e 'Gala' imersas em água com fosfito-CaB (1,5 mL.L-1), fosfito-K (0,5-1,5 mL.L-1) ou benomil (150 mg.L-1) foram menos afetadas pelo mofo-azul. A aplicação de fosfito-K (1,5 mL.L-1) ou benomil (150 mg.L-1) nos frutos foi mais eficiente do que os demais tratamentos no controle do mofo-azul.

Improvement in the biocontrol of postharvest diseases of apples with the use of yeast mixtures

Mixtures of yeasts were tested for theirability to control Penicillium expansum andBotrytis cinerea on Red Delicious apple fruits. The occurrence of synergistic or antagonisticinteractions between yeast strains in differentmixtures was also evaluated. Two strains ofRhodotorula (R. glutinis SL 1 and R. glutinisSL 30) and two strains of Cryptococcus (C. albidus SL 43 and C. laurentii SL 62) were selected fordeveloping yeasts mixtures.The R. glutinis SL 1–R. glutinis SL 30 mixtureexhibited a lower effectiveness than eachstrain alone, against both moulds. Othermixtures (R. glutinis SL 1–C. albidus SL 43 and R. glutinis SL 30–C. albidus SL 43) showedsynergism against P. expansum but not against B. cinerea. The R. glutinis SL 1–C. laurentii SL62 mixture was the only mixture which showedsynergism against gray mould. There was not anymixture, which showed high effectivenessagainst both moulds at the same time. Differentresults could be explained by the dynamics ofthe population of the yeasts.By using yeast mixtures, it was possible toimprove biocontrol without increasing theamount of antagonists applied. The synergismobserved could be useful in enhancingbiological control.

Interactions between Pseudomonas syringae MA-4 and cyprodinil in the control of blue mold and gray mold of apples

Blue mold [Penicillium expansum] and gray mold [Botrytis cinerea] are the principal postharvest diseases of apples in Ontario. In an attempt to develop new control measures, the efficacies of two fungicides, cyprodinil and fenhexamid, and a biocontrol agent, Pseudomonas syringae MA-4, were assessed. Surface-disinfested apples were wounded and inoculated with a 20-µL drop containing either P. expansum (1 × 104 conidia/mL) or B. cinerea (3 × 104 conidia/mL), combined with a range of concentrations of either fungicide. Cyprodinil controlled blue mold and gray mold by over 90% at 25 and 5 µg/mL, respectively. Fenhexamid controlled gray mold by 98% at 10 µg/mL but was inactive against blue mold. Cyprodinil was combined with strain MA-4 to control both diseases in separate experiments. Against blue mold, cyprodinil and strain MA-4 provided >90% control at concentrations of 20 µg/mL and 3 × 107 CFU/mL, respectively, on 'Northern Spy' apples. The addition of cyprodinil at concentrations of 2.5 to 20 µg/mL to treatments with strain MA-4 at 3 × 106 CFU/mL significantly increased blue mold control (35–91%) compared with the strain MA-4 alone treatment (11%). However, there were some antagonistic effects between strain MA-4 and cyprodinil at 2.5–10 µg/mL on 'Jonagold' apples. Against gray mold on 'Northern Spy' apples, cyprodinil gave 85% control at 2.5 µg/mL, and strain MA-4 gave 77% control at 3 × 108 CFU/mL. A combination of cyprodinil and strain MA-4 at concentrations of 2.5 µg/mL and 1 × 108 CFU/mL, respectively, controlled gray mold by 100%. Cyprodinil was not bacteriocidal and at concentrations of 5 and 20 µg/mL had no effect on strain MA-4 populations at inoculation sites.

Control of Decay of Apple and Citrus Fruits in Semicommercial Tests with Candida saitoana and 2-Deoxy-d-glucose

Abstract Efficacy of a combination of Candida saitoana and 0.2% 2-deoxy- d -glucose as a treatment for the biological control of postharvest diseases of apple and citrus fruits was determined in semicommercial tests. The combination of C. saitoana and 0.2% 2-deoxy- d -glucose was more effective in controlling decay of ‘Rome’ and ‘Empire’ apples than C. saitoana alone, and the level of control was comparable or superior to that provided by the synthetic fungicide thiabendazole, depending on the variety used. In orange (‘Washington’ navel, ‘Hamlin’, and ‘Valencia’) and ‘Eureka’ lemon trials, the combination of C. saitoana and 0.2% 2-deoxy- d -glucose was also superior to C. saitoana for controlling decay, and the control level was equal to imazalil, especially on early-season fruits. On late-season ‘Washington’ navel orange and ‘Eureka’ lemon fruits, the combination of C. saitoana and 0.2% 2-deoxy- d -glucose was superior in controlling decay than C. saitoana alone, but control was significantly less than with imazalil. These results indicate the reliability and efficacy of the combination of C. saitoana and 2-deoxy- d -glucose for the control of postharvest diseases of apple and citrus fruits. Further tests under commercial conditions are needed to confirm these results.

Control of Storage Decay of Apples withSporobolomyces roseus

The biocontrol potential of an antagonist occurring naturally on pome fruit surfaces against postharvest diseases of apple (Malus × domestica) was investigated. Pink yeast, Sporobolomyces roseus (isolate FS-43-238), isolated from pear fruit reduced blue mold (Penicillium expansum) from 100 to 0% and gray mold (Botrytis cinerea) from 78 to 0% on wounded fruit drop-inoculated with suspensions containing 7.9×10 6 and 6.3×10 5 cfu/ml yeast cells, respectively, and then challenged with the pathogen at 104 conidia per milliliter. The reduction in the percentage of infected wounds and in average lesion diameter followed a similar pattern and was effected by the antagonist and pathogen concentrations