Mycelial Growth Of Pathogen Research Articles

Biological Control of Leaf Spot and Growth Promotion of Eucalyptus Plants by Trichoderma spp.

This study aimed to evaluate the potential of twelve Trichoderma isolates on eucalyptus leaf spot control induced by Cylindrocladium scoparium and determine the sporulation capacity of the isolates on two substrates (parboiled rice and millet) for selection of potential biocontrol and growth promoter agents, in eucalypt seedlings. In the in vitro experiments, volatile and non-volatile metabolites tests showed different levels of inhibition of the pathogen mycelial growth. In tests on detached leaves, it was observed suppression of disease symptoms with all Trichoderma strains in leaves inoculated with CEN494 isolate of the pathogen, whereas with isolate CEN517 did not found the same efficiency. Sporulation of Trichoderma was higher using parboiled rice as the substrate, compared to millet. In general terms, it was obtained 3.38 × 109 and 2.84 × 109 conidia/g for the two substrates, respectively. Some of these Trichoderma isolates may be used in development of biofungicides for biocontrol of leaf spot, especially CEN262, due to its suppressive effect on C. scoparium, high sporulation, growth promotion capacity and endophytic colonization in eucalyptus seedlings.

Evaluation of different fungicides and antagonists In vitro and In vivo condition against Alternaria blight of pigeonpea

Efficacy of bio agents and systemic and non-systemic fungicides @ 50, 100, 200, 250 and 500 ppm were evaluated In vitro against Alternaria tenuissima causing Alternaria blight of pigeonpea. The relative efficacy of bio agents were studied in dual culture plate method showed that Hypocrea rufa was found most effective antagonist against test pathogen followed by T. harzianum. Efficacy of six fungicides was tested in poisoned food technique. Among the six fungicides tested, mancozeb was found most effective against test pathogen followed by Chlorothalonil and Iprodione. Propineb was least effective against mycelial growth of test pathogen. Raise in concentration of fungicides was more effective in inhibiting the mycelial growth of the pathogen. Field condition studies were found out to be the effect of seed treatment, foliar spray, seed treatment+ foliar spray with six fungicides and two bio agents and their combination used as against pathogen. Artificial inoculation of mass culture of A. tenuissima was done in the inoculated seed treatment and after foliar spray on the plants sixty DAS. Amongst them twenty five treatments, combination of Mancozeb with H. rufa was found most effective in reducing the disease intensity and disease control followed by Mancozeb with T. harzianum and Mancozeb alone, respectively. While, T. harzianum alone was least effective and maximum disease intensity recorded as a compared to control followed by T. harzianum with double dose and T. harzianum and H. rufa combination treatment, respectively. In case of both seed treatment and foliar spray of Mancozeb with H. rufa was found most effective in reducing the disease intensity and disease control followed by combination of Mancozeb with T. harzianum and Mancozeb alone, respectively. Whereas, least effective and maximum disease intensity and disease control were observed T. harzianum alone as compared to control.

Antifungal activity and action mechanisms of yeasts isolates from citrus against Penicillium italicum

Penicillium italicum (Blue mold) is a major postharvest disease of citrus. An alternative to controlling the disease is through the use of yeasts. The purpose of the present study was to screen effective yeast antagonists against P. italicum, isolated from soil, leaves, flowers, and citrus fruits, to assess the action mechanisms of the yeast isolates that were demonstrated to be effective for biocontrol, and to identify the most effective yeast isolates for the biocontrol of blue mold. The in vitro assays showed that six yeast strains inhibited up to 90% of the pathogen's mycelial growth. In vivo assays, evaluating the incidence of blue mold on sweet oranges, the strains ACBL-04, ACBL-05, ACBL-10 and ACBL-11 were effective, demonstrating the potential for the blue mold control when preventively applied, whereas the ACBL-08 strain showed a high potential to preventive and curative applications. Additional studies on the modes of action of these yeast strains showed that most of the evaluated yeast strains did not produce antifungal substances, in sufficient quantities to inhibit the pathogen growth. Competition for nutrients was not a biocontrol strategy used by the yeast strains. The ‘killer’ activity might be the main action mechanism involved in P. italicum biocontrol. This study indicated that the multiple modes of action against the pathogen presented by yeasts may explain why these strains provided P. italicum control under in vitro and in vivo conditions. However, further studies in future might be able to elucidate the ‘killer’ activity and its interaction with pathogen cells and the bioproduct production using Candida stellimalicola strains for control postharvest diseases.

English

Fusarium crown and root rot (FCRR) is a serious tomato disease in Tunisia which is difficult to control due to its soilborne nature and to the luck of genetic resistance. In the current study, native Solanum linnaeanum was explored as potential source of effective fungal agents for disease biocontrol. Eight fungal isolates, recovered from S. linnaeanum plants growing in the Tunisian Centre-East and shown able to colonize roots, crowns and stems of tomato (Solanum lycopersicum L.) seedlings, were tested for their ability to inhibit Fusarium oxysporum f. sp. radicis-lycopersici (FORL), the causal agent of this disease, and to promote plant growth. Tomato seedlings inoculated or not with FORL and treated using tested fungal isolates, exhibited significant increments in their growth parameters. Tested as conidial suspensions or cell-free culture filtrates, I74 and I92 isolates were the most active leading to 92.8% decrease in FCRR severity and 89.3 to 95.2% lowered vascular browning extent as compared to FORL-inoculated and untreated controls. These two isolates were microscopically and macroscopically described and identified using rDNA sequencing gene as being Penicillium crustosum I74 (MF188258) and Fusarium proliferatum I92 (MF188256). Pathogen mycelial growth was inhibited by 29.4 to 78.1% using their conidial suspensions and by 67.5 to 82% with their cell-free culture filtrates. P. crustosum I74 and F. proliferatum I92 showed chitinolytic, proteolytic and amylase activities. Only I92 isolate exhibited a lipolytic activity. Our study clearly demonstrated that I74 and I92 isolates were promising candidates for suppressing FCRR severity and promoting tomato growth. Further investigations are required for elucidating their mechanisms of action involved in disease suppression and plant growth promotion. Key words: Antifungal activity, associated fungi, Fusarium oxysporum f. sp. radicis-lycopersici, Solanum linnaeanum, tomato growth.

A preliminary investigation into Aureobasidium pullulans as a potential biocontrol agent against Phytophthora infestans of tomato

Two biological control agents (BCAs), Aureobasidium pullulans L1 and L8 strains, were evaluated for their efficacy against Phytophthora infestans, the casual agent of tomato late blight. Yeast strains were applied (108 CFU/mL) on tomato plants, grown under greenhouse conditions, 24h before or 16h after inoculation with P. infestans (1×104 sporangia/mL). The BCAs applied 24h before the pathogen inoculation were significantly more effective (43.9%) than those applied after pathogen inoculation. L8 reduced AUDPC more (60%) than L1 (37%), while both strains reduced the disease in a similar way (average 32.2%) in the post-inoculation treatment. Dynamic population assay revealed that L1 and L8 were able to survive and colonize the tomato leaf surface during the ten days of experiments. In vitro experiments showed that both strains enhanced plant defence response by increasing leaf β-1,3-glucanase activity (>30% than the control). BCAs also produced bioactive volatile and non-volatile metabolites able to inhibit pathogen colony growth and to cause morphological alterations of hyphae. Overall, volatile metabolites were more effective than non-volatiles in reducing pathogen growth. In addition, 2-phenyl, 1-butanol-3-methyl, 1-butanol-2-methyl and 1-propanol-2-methyl synthetic volatile compounds produced by both strains showed EC50 values for pathogen mycelial growth of 3.9µLL−1 on average. This study showed that L1 and L8 strains could be considered part of a control strategy against P. infestans on tomato.

EFFECT OF SOME PLANT LEAVES EXTRACTS ON Fusarium culmorum THAT CAUSE WHEAT DAMPING- OFF DISEASE

In vitro, study was conducted to evaluate the efficiency of leaves extracts for each of Nerium oleander , Eucalyptus camaldulensis and Myrtus communis at concentrations 0, 0.5 , 1 , 2 and 3 % on the growth and sporulation of Fusarium culmorum , the cause of wheat damping- off disease . Results revealed anoticable inhibition of a pathogen mycelial growth and its sporulation when cultured on PDA mixed with different extracts particularly with M. communis that exhibited inhibition of mycelial growth by the rate of 30.06 %, compared to 26.31 % and 14.77 % with extracts of E. camaldulensis and N. oleander , respectively. The lowest comparable sporulation of apathogen was 12.07% recorded in colonies grown on E. camaldulensis extract at 0.5 % .Wheat seedlings damping –off % was reduced significantly with increasing concentrations of examined extracts.

Pythium leak control in potato using aqueous and organic extracts from the brown alga Sargassum vulgare (C. Agardh, 1820)

The antifungal activity of the brown macroalga, Sargassum vulgare (C. Agardh, 1820), collected from different sites along Tunisian costs, was assessed against Pythium aphanidermatum causing Pythium leak disease in potato. Aqueous and organic extracts of this alga, used at different concentrations, were screened in vitro using the poisoned food technique and in vivo on potato tubers cv. Spunta for their ability to inhibit P. aphanidermatum mycelial growth and to suppress potato leak severity. All extracts tested showed antifungal activity toward the targeted pathogen depending on sampling sites, concentrations tested and organic solvent used for extraction. For aqueous extracts, the highest inhibition of pathogen radial growth, by 28%, was achieved using extracts from Tunis and Mahdia1 sites tested respectively at 40 and 50gL−1. Pythium leak severity was reduced by 34.33 and 31.67% using S. vulgare extracts from Tunis and Monastir, respectively, with these treatments being the most effective. Among S. vulgare organic extracts tested, the methanolic extract displayed the strongest antifungal potential either by inhibiting pathogen mycelial growth by almost 51%, or by reducing disease severity noted on potato tubers cv. Spunta by more than 82% over untreated controls. A total of 34 compounds were identified and quantified using HPLC-DAD chemical profiling in methanolic crude extracts of S. vulgare samples removed from Tunis and Monastir. Presence of phenolic acids and flavonoids may explain the strong antifungal activity displayed by S. vulgare against P. aphanidermatum. These results suggest that S. vulgare may be explored for the isolation of antifungal compounds for Pythium leak control.

Biological control of pathogenic and secondary (non pathogenic) fungi associated with Barley (Hordeum vulgare) seeds

Plant pathogenic fungi are a major problem in agriculture with effects on yield and quality of agricultural product. In this study, antagonistic effects of five fungi biocontrol agent Aspergillus niger, Aspergillus ostianus, Aspergillus versicolor, Penicillium sp., Trichoderma harzianum and one species of bacterium Pseudomonas aeruginosa isolated from the seeds of barley were evaluated against plant pathogenic fungi Rhizoctonia solani and secondary (non-pathogenic) fungi Aspergillus flavus. The ability of isolated microorganisms in antagonizing or inhibiting the growth of phytopathogenic fungi was tested by measuring the growth inhibition percentage over control. P. aeruginosa obtained higher inhibition with R. solani and A. flavus (88%, 76%) respectively, but A. ostianus obtained the lower inhibition with R. solani and A. flavus (59%, 53%) respectively. The results also showed that significant differences were recorded in mycelial growth of pathogens in presence of biocontrol agent when compared with control. Also, the results showed that non-significant differences were recorded between R. solani and A. flavus when treated with different antagonisms.

Efficiency and compatibility of Trichoderma spp. and Bacillus spp. isolates on the inhibition of Sclerotium cepivorum

Application of different biological control agents may be a strategy to be used against white rot, caused by the fungus Sclerotium cepivorum . However, isolates effectiveness and compatibility must be previously evaluated in laboratory experiments. Thus, in this study we evaluated the effect of Bacillus spp. and Trichoderma spp. isolates on the inhibition of S. cepivorum mycelial growth. In addition, we also evaluated the compatibility among the most efficient isolates. In experiments with paired cultures, eight Bacillus spp. isolates (B01, B03, B10, B120, B570, B571, B854 and B934) and five Trichoderma spp. isolates reduced pathogen mycelial growth by 42-50% and 100%, respectively. Thermostable metabolites produced by B03, B571, B570 and B120 isolates limited S. cepivorum growth when added into PDA medium, while Trichoderma cultures did not have the same effect. Twelve out of 40 combinations between bacterial and fungal isolates were incompatible. Therefore, B03, B570, B571 and B854 Bacillus spp. isolates, and SF45, SF32 and SF311 Trichoderma spp. isolates reduce mycelial growth of S. cepivorum and are mutually compatible. In addition, they can be applied together for the management of white rot.

Biocontrol of Fusarium wilt and growth promotion of tomato plants using endophytic bacteria isolated from Nicotiana glauca organs

Seven bacterial isolates, recovered from native Nicotiana glauca plants of the Tunisian Centre-East, and successfully colonizing the internal stem tissues of tomato cv. Rio Grande were screened for their ability to suppress tomato Fusarium wilt, caused by Fusaium oxysporum f. sp. lycopersici, and to enhance plant growth. S18 and S42 isolates were found to be the most effective in decreasing yellowing and wilt symptoms by 94 and 88% and the vascular browning extent by 95–97.5%, respectively, as compared to FOL-inoculated and untreated control. A significant enhancement in growth parameters of tomato plants inoculated with pathogen and treated with S18 and S42 isolates. These two bioactive isolates were characterized and identified using 16S rDNA sequencing genes as Alcaligenes faecalis S18 and Bacillus cereus S42, respectively. Pathogen mycelial growth was inhibited by 44.1 and 42.1% with S42 and S18 isolates, respectively. Using the disc diffusion method, S42 and S18 formed an inhibition zone against FOL of about 11.87–12.37mm, respectively. The isolate S42 of B. cereus showed a proteolytic and chitinolytic activity. A. faecalis S18 exhibited only chitinolytic activity in chitin-agar medium. This isolate was also able to produce the volatile metabolite hydrogen cyanide. Indole-3-acetic acid production, phosphate solubilizing, and pectinase activity were assessed for these two bioactive isolates for elucidating their plant growth promoting traits and their endophytic colonization ability. This study clearly demonstrated that N. glauca is a potential source for the isolation of potent endophytic bacteria exhibiting Fusarium wilt-suppressive and plant growth-promoting effects on tomato.

Bio-suppression of Sclerotinia Stem Rot of Tomato and Biostimulation of Plant Growth Using Tomato-associated Rhizobacteria

A collection of 25 rhizobacterial strains, recovered from rhizospheric soils around healthy tomato plants grown in Rhizoctonia-infested fields, belonging to Bacillus amyloliquefaciens, B. thuringiensis, B. megaterium, B. subtilis, Enterobacter cloacae, Chryseobacterium jejuense, and Klebsiella pneumoniae was screened for its suppressive effects of Sclerotinia Stem Rot of tomato caused by Sclerotinia sclerotiorum and plant growth-promoting ability. The inhibitory effects of diffusible and volatile metabolites from these rhizobacteria against pathogen mycelial growth depended significantly upon strains tested. Growth inhibition caused by diffusible and volatile compounds was of about 37-57% and 24-54%, respectively. All strains tested had totally suppressed myceliogenic germination of sclerotia and improved germination of bacterized tomato seeds as compared to the untreated controls. The screening of their disease-suppressive and plant growth-promoting abilities revealed 72-100% decrease in Sclerotinia Stem Rot severity and significant increments in plant height by 52-67%, roots fresh weight by about 66-88% and aerial part weight by 47-75%, compared to S. sclerotiorum-inoculated and untreated control. The most promising strains combining disease-suppressive and growth-promoting abilities were B. subtilis B10 (KT921327) and B14 (KU161090), B. thuringiensis B2 (KU158884), B. amyloliquefaciens B13 (KT951658) and B15 (KT923051), and E. cloacae B16 (KT921429).

Characterization of endophytic Bacillus strains from tomato plants (Lycopersicon esculentum) displaying antifungal activity against Botrytis cinerea Pers.

Eighty endophytic bacteria were isolated from healthy tissues of roots, stems, leaves and fruits of tomato plants (Lycopersicon esculentum). Four strains, named BL1, BT5, BR8 and BF11 were selected for their antagonism against Botrytis cinerea, a phytopathogenic fungus responsible of gray mold in several important crops, with growth inhibitory activity ranging from 27 to 53%. Morphological, biochemical, and molecular parameters as 16S rDNA sequencing demonstrated that the selected bacterial strains were related to Bacillus species which are known to produce and secrete a lot of lipopeptides with strong inhibitory effect against pathogen mycelial growth. Electrospray mass spectrometry analysis showed that these strains produced heterogeneous mixture of antibiotics belonging to fengycin and surfactin for BL1 and BT5, to iturin and surfactin for BR8, to bacillomycin D, fengycin and surfactin for BF11. Furthermore, these bacteria exhibited biocontrol potential by reducing the disease severity when tested on detached leaflets. Based on their antifungal activity against Botrytis cinerea, these strains could be used for biological control of plant diseases.

In vitro antimicrobial activity of aqueous extracts from Lentinula edodes isolates against Colletotrichum sublineolum and Xanthomonas axonopodis pv. Passiflorae

The aim of this study was to evaluate the antimicrobial activity of aqueous extracts from fruiting bodies of different isolates of Lentinula edodeson the pathogens Colletotrichum sublineolum, the causal agent of anthracnose in sorghum, and Xanthomonas axonopodispv. passiflorae, the causal agent of bacterial spot in passion fruit. Results showed that the aqueous extracts from isolates LE JAB-K and LE 95/01 significantly reduced C. sublineolumspore germination,while the isolate LE 96/22 was the only one to inhibit the pathogen mycelial growth. However, all L. edodesisolates showed inhibitory effect on C. sublineolumappressorium formation. Regarding X. axonopodispv. passiflorae, the aqueous extracts from all L. edodesisolates significantly reduced the in vitromultiplication of the bacterium. However, antimicrobial activity was lost when the extracts were autoclaved, demonstrating their thermolabile property. The aqueous extract from isolate LE 96/22 was also partially purified by anion exchange chromatography and fraction V exhibited high inhibitory activity on the in vitromycelial growth of C. sublineolum, while the multiplication of X. axonopodispv. passifloraewas inhibited by fractions IV, V and VII. Thus, L. edodesisolates were shown to produce compounds exhibiting antifungal and antibacterial activities against phytopathogens, which are mainly concentrated in fraction V.

Control of lettuce bottom rot by isolates of Trichoderma spp

Bottom rot, caused by Rhizoctonia solani AG 1-IB, is an important disease affecting lettuce in Brazil, where its biological control with Trichoderma was not developed yet. The present study was carried out with the aim of selecting Trichoderma isolates to be used in the control of lettuce bottom rot. Forty-six Trichoderma isolates, obtained with baits containing mycelia of the pathogen, were evaluated in experiments carried out in vitro and in vivo in a greenhouse in two steps. In the laboratory, the isolates were evaluated for their capabilities of parasitizing and producing toxic metabolic substances that could inhibit the pathogen mycelial growth. In the first step of the in vivo experiments, the number and the dry weight of lettuce seedlings of the cultivar White Boston were evaluated. In the second step, 12 isolates that were efficient in the first step and showed rapid growth and abundant sporulation in the laboratory were tested for their capability of controlling bottom rot in two repeated experiments, and had their species identified. The majority of the isolates of Trichoderma spp. (76%) showed high capacity for parasitism and 50% of them produced toxic metabolites capable of inhibiting 60-100% of R. solani AG1-IB mycelial growth. Twenty-four isolates increased the number and 23 isolates increased the dry weight of lettuce seedlings inoculated with the pathogen in the first step of the in vivo experiments.In both experiments of the second step, two isolates of T. virens, IBLF 04 and IBLF 50, reduced the severity of bottom rot and increased the number and the dry weight of lettuce seedlings inoculated with R. solani AG1-IB. These isolates had shown a high capacity for parasitism and production of toxic metabolic substances, indicating that the in vitro and in vivo steps employed in the present study were efficient in selecting antagonists to be used for the control of lettuce bottom rot.

Evaluation of Fruit Rot Resistance in Cucurbita Germplasm Resistant to Phytophthora capsici Crown Rot

Phytophthora blight is a destructive disease of cucurbits affecting the fruit, leaves, crown, and/or roots. Ten cucurbit PIs with known partial resistance to Phytophthora capsici root and crown rot were evaluated for resistance to Phytophthora fruit rot. Unwounded fruit from field-grown plants of Cucurbita moschata and C. pepo were inoculated in a controlled environment at 7 to 10 or 21 to 24 days post-pollination (dpp) with virulent P. capsici isolates to examine the effect of fruit age on disease development. Inoculated fruit were rated for lesion area and pathogen mycelial growth 7 days post-inoculation (dpi); fruit length, diameter, and pericarp thickness were also rated. Two C. pepo accessions (PI 169417 and PI 181761) had significant resistance to Phytophthora fruit rot at both 7 to 10 dpp and 21 to 24 dpp. All accessions evaluated displayed reduced disease susceptibility as the fruit aged.

Avaliação de fungicidas, óleos essenciais e agentes biológicos no controle de Amphobotrys ricini em mamoneira (Ricinus communis L.)

A mamoneira (Ricinus communis L.) é uma espécie oleaginosa tropical, sendo o óleo extraído de suas sementes um dos mais versáteis da natureza e com inúmeras aplicações industriais. Embora ainda seja uma espécie rústica, ela está sujeita a diversas doenças, dentre elas o mofo-cinzento, causada pelo fungo Amphobotrys ricini. O melhoramento genético seria a melhor alternativa para o controle da doença, mas demanda tempo para se obter cultivares resistentes. Dessa maneira, o uso de métodos de controle baseado em métodos químicos, alternativos ou biológicos mostra-se viável no curto prazo. O objetivo do trabalho foi estudar a eficiência do controle do mofo-cinzento, na cultura da mamoneira, utilizando-se de métodos químico, alternativo e biológico. Assim, procurou-se avaliar, tanto in vitro, quanto in vivo a eficiência de controle do patógenos utilizando-se de fungicidas, óleos essenciais e agentes de controle biológico. Quanto a inibição do crescimento micelial do patógeno in vitro os melhores tratamentos com os óleos essenciais foram os com a base de Cymbopogon martini e Cynnamomum zeylanicum, nas cinco concentrações testadas. Em ambos os óleos, o diâmetro médio das colônias ficou em 0,7 cm contra a média de 4,79 cm da testemunha. Com os fungicidas, nas quatro concentrações testadas, os mais eficientes foram os ingredientes ativos tiofanato metílico, carbendazim, tebuconazole e iprodione. O ED50 destes fungicidas ficou < 1uL/L, atestando 100% de inibição do crescimento micelial em todas as concentrações. Quanto à inibição da germinação dos conídios de A. ricini, os fungicidas tebuconazole e clorotalonil foram os melhores em todas as concentrações testadas, sendo a média dos conídios germinados destes fungicidas de 0,0 e 0,15%, respectivamente, contra 100% da testemunha. No campo, o tratamento com o fungicida iprodione foi o melhor quanto ao controle da doença quando comparados com os tratamentos biológico e alternativo. Em condições de campo, a severidade média da doença com o tratamento com iprodione foi de 15,76% contra 95,81% na testemunha inoculada.

Antagonistic Bacillus species as a biological control of ginseng root rot caused by Fusarium cf. incarnatum

BackgroundThis study aimed to develop a biocontrol system for ginseng root rot caused by Fusarium cf. incarnatum. MethodsIn total, 392 bacteria isolated from ginseng roots and various soils were screened for their antifungal activity against the fungal pathogen, and a bacterial isolate (B2-5) was selected as a promising candidate for the biocontrol because of the strong antagonistic activity of the bacterial cell suspension and culture filtrate against pathogen. ResultsThe bacterial isolate B2-5 displayed an enhanced inhibitory activity against the pathogen mycelial growth with a temperature increase to 25°C, produced no pectinase (related to root rotting) and no critical rot symptoms at low [106 colony-forming units (CFU)/mL] and high (108 CFU/mL) inoculum concentrations. In pot experiments, pretreatment with the bacterial isolate in the presumed optimal time for disease control reduced disease severity significantly with a higher control efficacy at an inoculum concentration of 106 CFU/mL than at 108 CFU/mL. The establishment and colonization ability of the bacterial isolates on the ginseng rhizosphere appeared to be higher when both the bacterial isolate and the pathogen were coinoculated than when the bacterial isolate was inoculated alone, suggesting its target-oriented biocontrol activity against the pathogen. Scanning electron microscopy showed that the pathogen hyphae were twisted and shriveled by the bacterial treatment, which may be a symptom of direct damage by antifungal substances. ConclusionAll of these results suggest that the bacterial isolate has good potential as a microbial agent for the biocontrol of the ginseng root rot caused by F. cf. incarnatum.

Phytochemical Analysis and Antifungal Activity of Fruit Leaves Extracts on the Mycelial Growth of Fungal Plant Pathogens

Methanolic extracts of leaves of thompson seedless grape, flame seedless grape, zizyphus, pomegranate and fig were screened for their phytochemical constituents and also investigated for their antifungal activity in vitro against phytopathogenic fungi, Alternaria solani, Botrytis cinerea, Botrytis fabae, Fusarium oxysporum and Fusarium solani. Phytochemical screening of crude methanolic extracts revealed the presence of terpenes, tannins, flavonoids, alkaloids, carbohydrate or glycosides, phenolic glycosides and resins in all extracts, while saponins were not detected from any extracts except zizyphus and fig. Zizyphus leaves had the highest concentration of total polyphenols and total flavonoids content which were 147.47 mgGAE/g and 16.35 mgQE/g, respectively. HPLC analysis identified twelve polyphenolic compounds; pyrogallic acid, gallic acid, protocatechuic, catechin, p-hydroxy benzoic acid, p-coumaric acid, phenol, o-coumaric acid, salicylic acid, coumarin, quercetin and cinnamic acid. All extracts contained protocatechuic, catechin, p-hydroxy benzoic acid, p-coumaric acid, o-coumaric acid and coumarin with different concentrations. The methanolic extract of zizyphus leaves had the greatest inhibitory effect on mycelial growth of B. fabae by 95.56% at 4 mg/ml. Also, extract of pomegranate caused remarkable reduction on the fungal growth (94.44%) of B. fabae at 4 mg/ml, while fig extract caused 91.11% inhibition against the same fungus at the same concentration. F. oxysporum and F. solani were the most resistant fungi against all methanolic extracts tested.

Enhancement of biocontrol activity of Torulaspora delbrueckii with methyl jasmonate against apple blue mould disease

Torulaspora delbrueckii alone and in combination with methyl jasmonate was applied to the control of Penicillium expansum. For evaluation of direct effect of Methyl jasmonate on mycelial growth of pathogen, it was added to potato dextrose agar culture at different concentrations. Effect of methyl jasmonate on population of yeast in nutrient yeast dextrose broth media was determined after 24 and 48 h. Results showed that methyl jasmonate had no significant direct effect on pathogen and yeast. Also, evaluation of methyl jasmonate effect on the population of yeast in apple wounds indicated that methyl jasmonate at different concentrations increased population growth of yeast at 20°C, 8 and 15 days after inoculation in toward the control and it had no significant effect on population dynamics of yeast at 4°C. In vivo, the results indicated that combination of methyl jasmonate with antagonistic yeast reduced the blue mould of apples better than methyl jasmonate and yeast alone.

Control of apple blue mould disease with Torulaspora delbrueckii in combination with Silicon

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 the application of silicon or T. delbrueckii alone at 20 and 4°C, respectively.