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International audience; Botrytis cinerea and Penicillium expansum are the most important pathogens of apples during the postharvest phase. In the present study, the effect of ozone (O-3) and carbon dioxide (CO2) gases combined with application of the yeast isolates Candida membranifaciens A2, Saccharomyces cerevisiae 69, Pichia guilliermondii M47 and A6, was investigated to control blue and gray molds of apples in vitro and in vivo conditions. In vitro, O-3 and CO2 treatments exerted respectively fungistatic and fungicidal activity on fungal spores. In dual culture tests, the combination of antagonistic yeasts with CO2 was the most efficient way to control the growth of both pathogens. In vitro, O-3 completely inhibited the growth of yeast isolates, whereas CO2 did not influence the yeast growth. Inoculation of apples with C. membranifaciens A2, P. guilliermondii A6 or S. cerevisiae PTCC 69 in combination with CO2 completely suppressed blue or gray mold symptoms for up to 62 days of storage, both at 20 degrees C and 4 degrees C. Yeasts combined with O-3 (10 ppm) were poorly effective in controlling disease development on fruit. However, CO2 or O-3 treatments used alone resulted in a decrease of apple quality after 62 days of storage at 4 degrees C; necrotic spots were observed for fruits treated with O-3.

The development of nanotechnology has led to the production of new valuable by-products in the food industry. In this way, we synthesized a new green fungicide using the impure montmorillonite (Mt) and extract of pomegranate fruit waste. In addition, we compared the Mt/pomegranate fruit peel extract (Mt/PFPE) with the Mt/clove leaf extract (Mt/CLE) and Mt/Gallic acid (Mt/GA) composites. The mentioned composites were prepared through the simple and low-cost intercalation technique. The antifungal activity of these composites on postharvest gray mold (Botrytis cinerea) in apple fruit were tested in vitro and in vivo. XRD pattern confirmed the highly intercalation of plant extracts between interlayers of Mt nanoparticles. HPLC analysis and FTIR spectra showed that Mt nanoparticles absorbed the phenolic compounds from extract selectively. TGA analysis indicated high loading yield up to 70%. The Mt/PFPE, Mt/CLE and Mt/GA nanocomposites had 102%, 84% and 75% higher antifungal activity than single Mt nanoparticles. These findings suggest the Mt/PFPE nanocomposite as a low-cost but valuable by-product in the pomegranate juice industry.

One of the most important orange fruit diseases is blue mold which cause by Penicillium italicum that is responsible for important economic losses. This study investigated biochemical changes in exo-mesocarp layers of orange fruits related to host- pathogen- yeast interactions. Initial result showed that among eight strains isolated, the most effective antagonist were belonged to two species of Pichia kluyveri (M45) and Rhodotorula mucilaginosa (M61). These isolates were selected for biochemical evaluation. In order to assessment of biochemical changes, the orange fruits were inoculated with 40 µl of yeast cell suspension and after 24 h, the wounds were inoculated with 20 µl of conidial suspension of P. italicum. The analysis of variance showed that all of the measured biochemical characterises were significant in both layers by treatments (yeast isolates; pathogen; yeast isolates + pathogen and control) (P ≤ 0.01), including POD, CAT and β-1, 3-glucanase activities and total phenolic compounds. Also result showed that when the yeast isolates (M45 or M54) were inoculated into wounds with the pathogen, it stimulated the orange to increase produce of total phenol and enzymes activity (POD, CAT and β-1, 3-glucanase) and these changes were related to incubation time. The result showed that understanding biochemical mechanism derived from plant-pathogen-antagonist interactions is essential for investigating the dynamics of infectious processes.

Root-knot nematodes (Meloidogyne spp.) are the most economically important group of plant parasitic nematodes on many crops worldwide. Resistance-based management is considered as one of the most sound and effective strategies against these pathogens. Plant-mediated systemic resistance against the M. javanica in tomato cv. CALJN3 was triggered using salicylic acid (SA) and Pseudomonas fluorescens CHAO as elicitors. The effect of each elicitor was assayed by (1) the calculation of nematode indices including the number of nematode galls, egg masses and eggs/egg mass; (2) the analysis of changes in the concentration of reactive oxygen species (ROS); and (3) monitoring the activities of their scavenging enzymes viz. superoxide dismutase (SOD), peroxidase (POX), and catalase (CAT). The results indicated that SA/bacterial elicitors induced the removal of high concentrations of the toxic ROS via an increase in the activity of their scavenging antioxidant enzymes, especially that of catalase. Moreover, pre- or post-treatment application of the elicitors significantly reduced the number of galls, egg masses or eggs of M. javanica in infected tomato plants as compared to the control. The results of the present study support the involvement of the elicitor-induced ROS and related scavenging enzymes for stimulating plant defense reactions in a moderately resistant tomato challenged with M. javanica.

Metschnikowia pulcherrima alone and in combination with methyl jasmonate [MeJA] was applied for control of blue mold of apple caused by Penicillium expansum. In vitro, MeJA at different concentrations had no direct effect on the pathogen. In vivo, both M. pulcherrima (1×108 cell ml-1) and MeJA, as a stand-alone treatment, significantly reduced the lesion area of blue mold decay in apple. The combination of MeJA at 100 μmol l -1 and antagonistic yeast (1×108 cell ml-1) was a more effective approach to reduce the lesion diameter of blue mold decay of apples than the application of MeJA or M. pulcherrima separately after incubation for 15 and 50 days at 20°C and 4°C, respectively. In addition, MeJA increased the population of M. pulcherrima in the wounds of the apple fruit. The activity of the defense enzyme peroxidase was enhanced by MeJA and yeast treatments, and the level of total phenolic content in MeJA and yeast-treated fruit was also higher than that in control fruit. These results suggest that MeJA was effective in reducing decay and might enhance disease resistance in apple fruit by increasing defense enzyme activity and levels of antimicrobial phenolic compounds.

Variant somaclones of potato cultivar Russet Burbank, selected for resistance to common scab using in vitro cell selection techniques, were tested for resistance to powdery scab, another important disease of potato caused by Spongospora subterranea. This pathogen also invades roots, producing root galls. Most variants consistently showed increased resistance to powdery scab, both in field and glasshouse challenge, when compared to the parental cultivar, several significantly so. On average, the best variant reduced powdery scab incidence by 51% and severity (tuber surface coverage) by 64%. In contrast, no improvement in the extent of root infection and root galling was seen. These results suggest host interactions during root and tuber infection are distinct. Correlation analyses of disease indices amongst the selected variants showed no association between Sp. subterranea root infection and gall scores, nor between root infection and tuber disease severity. However, a weak positive association was found between root gall score and tuber disease, and a strong correlation between tuber disease incidence and severity scores. Interestingly, positive correlations were also found between the extent of powdery and common scab resistance expressed and both incidence and severity of these diseases within the variants, suggesting a common defence mechanism. The role of thaxtomin A in selecting for concurrent resistance to both diseases is discussed.

In this study, Torulaspora delbrueckii alone and in combination with silicon were evaluated for the control of apple blue mould disease caused by Penicillium expansum. In vitro, the antagonistic effects of T. delbrueckii in controlling mycelial growth of P. expansum on potato-dextrose-agar (PDA) in dual cultures, and the growth of P. expansum alone with cell-free metabolites and volatile components of T. delbrueckii were assayed. In vitro, to evaluate the direct effect of silicon on mycelial growth of pathogen, silicon at different concentrations (0.2, 0.4, 0.6, 1 and 2% (wt./vol.)) was added to PDA medium. Silicon at 0.6% (wt./vol.) and above concentrations completely inhibited the mycelial growth of P. expansum. However, it had no significant effect on population dynamics of yeast in vitro and in apple wounds. In vivo, silicon at 0.2 and 1% (wt./vol.) in combination with antagonistic yeast (1 × 108 cell/ml) was a more effective approach to reduce the lesion diameter of blue mould decay of apples than th...

In this study, antagonistic yeast Candida membranifaciens was combined with different concentrations of silicon (Si; 0, 0.1, 0.3 and 0.5% wt/vol) to evaluate the control of blue mold of apple in storage at 20°C and 5°C. Preliminary studies showed that Si at 0.6% or above inhibited mycelial growth of pathogens significantly in vitro. In vitro studies showed that Si at 0.1% had lower effect on yeast growth. In vivo studies showed that combination of different concentrations of Si with C. membranifaciens improved the efficacy of yeast in control of disease better than Si and yeast alone (P

Early blight of potato, caused by Alternaria solani, is a ubiquitous disease in many countries around the world. Our previous screening of several Iranian potato cultivars found that variation in resistance exists between two cultivars: ‘Diamond’ and ‘Granula’. Cultivar Diamond is more resistant to multiple isolates of A. solani when compared to cv. Granula. Furthermore, we have found that different pathogen isolates have varying degrees of infection. We monitored the activities of two pathogen-related (PR) glucanase proteins in Diamond and Granula in response to two isolates of A. solani with different degrees of virulence. s-1,3-glucanase and s-1,4-glucanase activities were recorded in healthy and diseased leaves of potatoes up to 10 days after inoculation. Their activities were found to be higher in diseased leaves when compared to those of uninfected leaves. Our data suggest that significantly reduced activities of theses enzymes in potato could be related to a lower degree of resistance or an increased ability of a more aggressive isolate to suppress PR protein expression.

Several possible biocontrol mechanisms have been suggested as being effective against post-harvest fruit spoilage. These include competition (for nutrients and space), antibiosis, parasitism, induction of resistance in the host tissue and production of volatile metabolites. Information on the mechanisms of action for most of the antagonists is still incomplete because of the lack of information on the complex interactions between the host, the pathogen, the antagonist and the other microorganisms present. However, a good understanding of the mechanism of action is essential before developing appropriate formulations and methods of application in order to obtain official approval. In this review information is provided about several mechanisms of biocontrol agents that could provide future biocontrol agents.

Bacillus pumilus (B19), B. subtilis (1J), B. crerus (B16), B. subtilis (B11) and B. cereus (B17), isolated from the rhizosphere of wheat, were tested for control of gray mold of apple caused by Botrytis mali. Dual culture, cell free metabolite and volatile tests showed that all five isolates of Bacillus spp. inhibited growth of the pathogen. Inhibition varied from 13.6 to 74% in the dual culture tests; 12.3 to 87% in the cell free metabolite tests; and 11 to 53% in the volatile tests. Five isolates of Bacillus spp. reduced B. mali lesion diameter from 7.2 to 32.2 mm compared with 41.6 to 51.4 mm in controls at 4°C. At 20°C the lesion diameters were from 7 to 24.9 mm for antagonistic treatments and from 46.2 to 46.6 mm for the control treatment after 15 days.

Bacillus licheniformis (EN74-1) was evaluated for the control of gray mold of apple caused byBotrytis mali. Dual culture, cell-free metabolite and volatile tests showed thatB. licheniformis (EN74-1) inhibited growth of the pathogen. Inhibition varied from 46.2% to 65.4% in the dual culture tests; 58.6% to 58.8% in the cell-free metabolite tests; and 28.4% to 33.8% in the volatile tests.B. licheniformis (EN74-1) appeared to be a good antagonist of gray mold on apples at 20° and 4°C. It reducedB. mali lesion diameter to 9–11 mm compared with to 32–41 mm in the control at 4°C. At 20°C the lesion diameter was reduced to 3.6–8.4 mm for the antagonistic treatment and to 25.8–38.2 mm for the control treatment after 14 days.

The aim of this study was to verify that induced resistance was another mechanism through which Bacillus pumilus 7 km can suppress Gaeumannomyces graminis (Sacc.) Von Arx and Oliver var. tritici Walker (Ggt). Also, plant growth-promotion activity of B. pumilus 7 km and its effect on disease severity of take-all were evaluated. Soil was drenched with B. pumilus 7 km and disease severity, root and shoot fresh weights and root and shoot heights were evaluated. The activities of soluble peroxidase (SPOX), ionically cell wall-bound peroxidase (CWPOX), β-1,3-glucanase, β-1,4-glucanase and the contents of total phenolic compounds were also determined. The results indicated that disease severity in the bacterized roots was significantly less than the pathogen control roots. Also this isolate promoted root height, root and shoot fresh weights, compared with the healthy control plants. Wheat plants treated with B. pumilus 7 km showed increased presence of SPOX, CWPOX, β-1,3-glucanase, β-1,4-glucanase and phenolic compounds in bacterized roots challenged with the pathogen. In this treatment, maximum SPOX, β-1,3-glucanase and β-1,4-glucanase activities on day 4 and CWPOX activity on day 8 were recorded. Also, maximum total phenolic concentration on day 6 was recorded. The results suggest that the inhibitory effect of B. pumilus 7 km on the take-all may be related to its ability to enhance defense responses in the wheat roots.

Five isolates KW, 16P, 8, 11 and 7 of Pseudomonas fluorescens and fungicide thiabendazole were evaluated for control of gray mold of apple caused by Botrytis mali. Dual culture, cell free metabolite and volatile test showed that all five isolates of Pseudomonas fluorescens tested inhibited growth of the pathogen. Inhibition varied from 28.9-85.7% in dual culture, from 62-94.6% in cell free metabolite and from 45.9-87.9% in volatile test. Apples were wounded and inoculated with a 20 microL Botrytis mali (10(5) conidia mL(-1)) combined with a range of concentration of fungicide. Thiabendazole controlled gray mold by over 83% at 5 microg mL(-1). Pseudomonas fluorescens isolates prevented B. mali decay from expanding to more than 49.4% at 20 degrees C. Thiabendazole was combined with bacteria to control gray mold of apple. Mixing of thiabendazole and bacterial isolates provide more than 90.2% control at concentrations 5 microL mL(-1) and 10(7) CFU mL(-1), respectively, on Golden delicious apples. A combination of thiabendazole and Pseudomonas fluorescens isolate 11 at concentration 10 microg mL(-1) and 1 x10(7) CFU mL(-1), respectively controlled gray mold by 100%. Thiabendazole was not bactericidal and had no effect on five isloates of Pseudomonas fluorescens.

The equilibrium constants of copper and iron were determined for the copper (II)-iron (III) -LIX984-Orfom SX-1 system. The average equilibrium constants of copper (II) and iron (III) were estimated to be 15.0±4.2 and 0.00030±0.00013 respectively. The results of extraction experiments show that LIX984 is a very selective copper (II) extractant. On the other hand the extraction of iron (III) by LIX984 is very low. Results also show that higher extraction temperatures leads to higher rate of copper extraction.

Bacillus subtilis isolates B2, B6 andBacillus brevis isolate EN63-1 were evaluated for control of apple gray mould caused byBotrytis mail isolate 20JR. These isolates were evaluated alone, or in combination with sodium bicarbonate on artificially inoculated Golden Delicious apple cultivar. Treated fruit were stored at 4 and 20 °C for 30 and 14 days respectively. When applied alone, all isolates performed significantly better than the control in checking lesion diameter of gray mould. Isolate B6 was more effective than B2 and EN63-1 in this respect. A significant increase in biocontrol activity of all isolates was observed when isolates were combined with sodium bicarbonate

The rate of the crud formation was determined experimentally for a pilot plant solvent extraction settler. The results show that the rate of accumulation of crud decreases slightly with time and that the thickness of the crud in the settler increases with time. The empirical correlation between the thickness of the crud (hc) in centimeter and time (t) in hour can be expressed as hc(t) = 21.39(1-e−0.004t) It was determined that the average rate of increase of the crud thickness for the studied pilot settler is approximately 0.04 cm/h over a period of 14 days.

Biocontrol of postharvest decay on apples could provide an alternative approach for chemical control. With the effort to look for effective biocontrol agents, Bacillus pumilus (B19), B. subtilis (B11), B. cereus (B16), B. subtilis (B11), B. cereus (B17), B. brevis (EN63-1) and B. licheniformis (EN74-1) were tested for their potential activity against gray mold caused by Botrytis mali on Golden Delicious apple in Iran. Dual culture, cell free metabolite and volatile compounds tests showed that all seven isolates inhibited growth of the pathogen. All isolates prevented development of B. mali lesion diameter on apples stored at 40°C from 9 to 32.2 mm as compared to 41.6 to 51.4 mm in control. At 20°C the lesion size was from 7 to 24.9 mm for treatments with antagonistic bacteria while in control it ranged from 42.2 to 46.6.

A computerized geographic information system (GIS) was created in support of data requirements by a hydrologic model designed to predict the runoff hydrograph from ungaged basins. Some geomorphologic characteristics (i.e., channel lengths) were manually measured from topographic maps, while other parameters such as drainage area and number of channels of a specified order, land use, and soil type were digitized and manipulated through use of the GIS. The model required the generation of an integrated Soil Conservation Service (SCS) curve number for the entire basin. To this end, soil associations and land use (generated from analysis of Landsat satellite data) were merged in the GIS to acquire a map representing SCS runoff curve numbers. The volume of runoff obtained from the Watershed Hydrology Simulation (WAHS) Model using this map was compared to the volume computed by hydrograph separation and found to be accurate within 19 percent error. To quantify the effect of changing land use on basin hydrology, the GIS was used to vary percentages from the drainage area from forest to bare soil. By changing the basin runoff curve numbers, significant changes in peak discharge were noted; however, the time to peak discharge remained essentially independent of change in area of land use. The GIS capability eliminated many of the more traditional manual phases of data input arid manipulation, thereby allowing researchers to concentrate on the development and calibration of the model and the interpretation of presumably more accurate results.