Antagonistic Potential Research Articles

Decoding the Plant Growth Promotion and Antagonistic Potential of Bacterial Endophytes From Ocimum sanctum Linn. Against Root Rot Pathogen Fusarium oxysporum in Pisum sativum.

The present study demonstrates plant growth promotion and induction of systemic resistance in pea (Pisum sativum) plant against Fusarium oxysporum f.sp. pisi by two bacterial endophytes, Pseudomonas aeruginosa OS_12 and Aneurinibacillus aneurinilyticus OS_25 isolated from leaves of Ocimum sanctum Linn. The endophytes were evaluated for their antagonistic potential against three phytopathogens Rhizoctonia solani, F. oxysporum f. sp. pisi, and Pythium aphanidermatum by dual culture assay. Maximum inhibition of F. oxysporum f. sp. pisi was observed by strains OS_12 and OS_25 among all root rot pathogens. Scanning electron microscopy of dual culture indicated hyphal distortion and destruction in the case of F. oxysporum f. sp. pisi. Further, volatile organic compounds (VOCs) were identified by gas chromatography–mass spectrometry (GC-MS). The GC-MS detected eight bioactive compounds from hexane extracts for instance, Dodecanoic acid, Tetra decanoic acid, L-ascorbic acid, Trans-13-Octadecanoic acid, Octadecanoic acid. Both the endophytes exhibited multifarious plant growth promoting traits such as indole acetic production (30–33 μg IAA ml–1), phosphate solubilization, and siderophore and ammonia production. Pot trials were conducted to assess the efficacy of endophytes in field conditions. A significant reduction in disease mortality rate and enhancement of growth parameters was observed in pea plants treated with consortium of endophytes OS_12 and OS_25 challenged with F. oxysporum f.sp. pisi infection. The endophytic strains elicited induced systemic resistance (ISR) in pathogen challenged pea plants by enhancing activities of Phenylalanine ammonia lyase (PAL), peroxidase (PO), polyphenol oxidase (PPO), ascorbate oxidase (AO), catalase (CAT) and total phenolic content. The endophytes reduced the oxidative stress as revealed by decrease in malondialdehyde (MDA) content and subsequently, lipid peroxidation in host plant leaves. Robust root colonization of pea seedlings by endophytes was observed by scanning electron microscopy (SEM) and fluorescence microscopy. Thus, plant growth promoting endophytic P. aeruginosa and A. aneurinilyticus can be further exploited through bio-formulations for sustainable protection of crops against root rot diseases as bio-control agents.

Beijerinckia fluminensis BFC-33, a novel multi-stress-tolerant soil bacterium: Deciphering the stress amelioration, phytopathogenic inhibition and growth promotion in Triticum aestivum (L.)

Environmental challenges like drought, salinity, heavy metals and pesticides directly/indirectly influence the environment and decreased the agricultural output. During its long developmental stages, cereal crops including wheat is exposed to a variety of abiotic/biotic stressors. Certain beneficial soil bacteria that can ameliorate environmental stresses can be exploited as crop growth promoters/enhancers under adverse situations. In this study, Beijerinckia fluminensis BFC-33 (accession no. MT672580) isolated from potato rhizosphere tolerated variousabiotic (drought, salinity, temperature, heavy metals, and fungicides) stresses. Strain BFC-33 demonstrated multifarious plant-growth-promoting (PGP) characteristics, such as the production of indole-3-acetic acid, P-solubilization, ACC deaminase, ammonia, siderophore, HCN, EPS, and extracellular enzymes. The antagonistic potential of BFC-33 against major fungal pathogens was ranked: Alternaria alternata (79.2%)>Rhizoctonia solani (69%)>Fusarium oxysporum (23.5%)>Ustilaginoidea virens (17%). Furthermore, bacterization of wheat seeds witha multi-stress-tolerant strain revealed B. fluminensis as a plant growth enhancer and biocontrol agent. For instance, increase in root length (cm) in BFC-33 inoculated wheat exposed to abiotic and biotic stresses at the seedling stage was ranked: B. fluminensis (24.2)>B. fluminensis + 100μgTBZLmL−1 (21.3) = B. fluminensis + 2%PEG (21.3)>B. fluminensis + 100 mM NaCl (19.7)>B. fluminensis + 100μgPbmL−1 (19) = B. fluminensis 100μgMNZBmL−1 (19)>B. fluminensis + A. alternata (17.4)>B. fluminensis + 100μgCdmL−1 (17)>B. fluminensis + F. oxysporum (13.4). In addition, increase in carotenoid accumulation (mg g−1FW) in the foliage of BFC-33 inoculated wheat exposed to fungal infection was ranked: BFC-33 (3.88)>BFC-33+ A. alternata (3.0)>BFC-33+ R. solani (2.78)>BFC-33+ F. oxysporum (2.44). Moreover, BFC-33 inoculation significantly (p ≤ 0.05) reduced stress-induced stressor molecules (proline and TBARS) and electrolyte leakage. Furthermore, B. fluminensis BFC-33 potentially enhanced the defense responses in wheat seedlings by increasing phenylalanine ammonia lyase (PAL), β-1,3 glucanase, and polyphenol oxidase (PPO), which play a significant role in protecting plants from phytopathogens. Even so, by successfully establishing a product with the requisite effects under field settings, selecting multi-stress-tolerant and antagonistic plant growth promoting rhizobacteria (PGPRs) would be helpful to end-users. Future use of native multi-stress-tolerant bacteria as biocontrol agents in conjunction with existing drought, salinity, heavy metal, and pesticide tolerance might contribute to global food security.

Detection of Salinity Tolerance Pseudomonas Fluorescense Isolates and their Effect on Control Fusarium Wilt Disease Caused by Fusarium Oxysporum F. Sp. Lycopersici on Tomato

This study was conducted to obtain salinity-tolerance Iraqi isolates of Pseudomonas fluorescence. Besides, test its salinity tolerance on PDA culture media and study its effect in the control of fusarium wilt disease on tomatoes caused by the fungus Fusarium oxysporum f.sp. lycopersici. Six isolates of bacteria were isolated from areas with soils showing symptoms of salinity, their potential for salinity tolerance was tested by three concentrations of NaCl (5, 10, and 15%). In addition to their antagonistic potential against the pathogenic fungus F. oxysporum f.sp. lycopersici isolate (FO3) was also tested on a PDA medium. The isolates PO1 and PO2 were selected, which showed the potential to salinity tolerate at different concentrations of salt and the most growth-inhibiting of the pathogenic fungus F. oxysporum f.sp. lycopersici. The two isolates were partially identified using the PCR technique, and the sequence was deposited in the NCBI global gene bank, they were given Accession No. (ON041212 and ON041213). The two isolates' effect in controlling fusarium wilt on tomato plants showed efficiency in reducing the rate and severity of wilt disease. Thus, the incidence reached (13.33-85.00%) and the disease severity (10.34-80.00%) respectively, compared to the control treatment (without pathogenic fungi), which showed the incidence and disease severity amounted to (90.00 - 93.33%). Moreover, the treatment of inducing resistance showed high effectiveness with significant differences among all treatments in reducing the incidence and disease severity amounted to (10.34 - 13.33%).

Potential of Native Trichoderma Strains as Antagonists for the Control of Fungal Wood Pathologies in Young Grapevine Plants

Neofusicoccum parvum and Rhizoctonia solani are fungal pathogens with an increasing incidence in young grapevine plants. In this study, the antagonistic potential of some strains of the genus Trichoderma isolated from grapevine against these pathogens was investigated at the laboratory and greenhouse levels. In-plate confrontation assays showed that the selected Trichoderma strains could inhibit the mycelial growth of both taxa, being more effective against N. parvum. In the in vivo assays, the biocontrol activity of the mentioned strains against the pathogens, when applied either simultaneously or successively, was tested on both grafted plants and seedlings germinated from seed. The effectiveness of the treatments was evaluated by comparing biomass weight and vascular rot lengths data. In seedling trials, successive treatments resulted in higher root development and a lower colonization rate of the pathogens, especially against R. solani. In grafted plants, some disparity was observed against N. parvum: simultaneous treatments resulted in higher aerial biomass, but successive treatments resulted in higher root biomass and lower necrosis. Against R. solani, simultaneous treatments were clearly more effective, with higher root and aerial length values and lower necrosis. The obtained data suggest that the use of Trichoderma spp. isolates can constitute an alternative to conventional fungicides to control certain grapevine wood diseases.

Antifungal potential of Streptomyces rameus GgS 48 against mungbean root rot [Rhizoctonia bataticola (Taub.) Butler

Mungbean root rot caused by Rhizoctonia bataticola (Taub.) Butler is the most devastating disease inflicting yield loss up to 60%. The use of beneficial antagonist, viz., Streptomyces with diverse antifungal activity and prolific secondary metabolites production, is the ecofriendly and environmentally acceptable alternative to the existing chemical control methods. In this investigation we have identified the promising isolate of Streptomyces sp. which potentially reduced the mungbean root rot. A total of nine mungbean rhizospheric actinobacterial isolates were evaluated for their antagonistic potential against root rot pathogen and growth promoting trait of mungbean. The actinobacterial isolate GgS 48 was shown to be effective in reducing the mycelial growth of R. bataticola by 65.3% in dual culture technique and enhancing the growth of mugbean under in vitro condition. Morphological, biochemical and molecular characterization confirmed the isolate GgS 48 as Streptomyces rameus. The actinobacteria S. rameus GgS 48 exerted antifungal action against R. bataticola by hyphal coiling, which was confirmed under scanning electron microscopy (SEM), and promoted the growth through the production of IAA. It showed positive for the production of siderophore and hydrolytic enzymes, viz., chitinase and protease. The chitinase produced by the GgS 48 was purified and its molecular weight was determined as 40 kDa and it had great potential in reducing the mycelial growth of R. bataticola. The talc-based formulation of S. rameus GgS 48 was found to be promising in suppressing the root rot severity and enhancing the growth and yield attributes of mungbean both under glass house and field conditions.

Anti-phytopathogenic and plant growth promoting potential of endophytic fungi isolated from Dysoxylum gotadhora

Phytopathogens have negative impact on crop growth and production. Biological control of plant pathogens, is a safer alternative to chemical treatments, and may also provide additional advantages through plant-growth promotion activities. Recently, endophytes have received due attention to be used as biocontrol agents and plant growth promoters. The present study was designed to determine the antagonistic potential of endophytic fungi isolated from Dysoxylum gotadhora (Buch. Ham.) Mabb. against soil borne phytopathogens, Verticillium dahliae and Fusarium oxysporum, as well as to identify their plant growth promoting features. Dual culture method was used to assess the growth inhibition of phytopathogens in vitro. Results showed that Aspergillus sp. and Porostereum sp. reduced the growth of the phytopathogens with 40–70% inhibition and also produced high indole acetic acid (IAA) content with 19.237 ± 0.253 µg/mL and 18.60 ± 0.098 µg/mL, respectively. This signifies that fungal endophytes can be effectively used as biological control agents and growth promoters. Supplemental data for this article is available online at https://doi.org/10.1080/03235408.2022.2027674 .

Isolation and Identification of Indigenous Bacteria for the Control of Horse Hair Blight disease of tea

Tea plantation is covered by 434,000 hectares of land, which is further divided into two distinct regions - the North Indian tea belt and the South Indian tea belt. North-East India produces 75% of the total Indian tea. Present study is carried out to understand the various agro-climatic conditions of Barak valley like temperature, humidity, rainfall etc which are responsible for occurrence of various diseases in tea plant. Six genera of fungi were isolated and identified as Aspergillus niger, Trichoderma sp., Penicillium sp., Cladosporium sp., Helminthosporium sp. and Fusarium sp. Percentage of relative abundance of all the isolated fungi also estimated and it is found that Aspergillus niger shows high percentage of relative abundance (30%), followed by Trichoderma sp. (22%), Penicillium sp. (12%), Cladosporium sp.(18%), Helminthosporium sp. (8%) and Fusarium sp.(10%). The isolated bacterial strain (Bacillus sp) screened for their antagonistic potential against the pathogen Marasmius equicrinis by dual culture technique. The study indicated that biocontrol agents (Bacillus sp.) are very effective to control the horse hair blight disease in tea plant under in vitro conditions. Our preliminary investigations provided a key concept to use the inoculums of Bacillus sp as biocontrol equipment in the tea gardens of N.E. region to get control over horse hair blight disease of tea.

Antagonistic activity of resident biological agents against wilt and root rot pathogens of pea in different culture media

Antagonistic potential of rhizospheric fungal and bacterial isolates evaluated against wilt and root-rot pathogens of pea exhibited significant effect on radial growth inhibition of pathogens in comparison to control. Two isolates of Trichoderma spp., one isolate of Aspergillus niger, one isolate of Penecillium oxalicum and three isolates of Pseudomonas were isolated from rhizosphere of pea and were evaluated for their antagonistic potential against three soil borne plant pathogens viz., Fusarium oxysporum f. sp, pisi, Rhizoctonia solani and Pythium ultimum using dual culture technique in different culture media (potato carrot agar, czapek dox agar, rose bengal chloramphenicol and czapek malt agar). Antagonistic potential of fungal and bacterial isolates were found to be significantly influenced in different culture media. All fungal and bacterial isolates preferred potato carrot agar and czapek dox agar media and resulted in maximum reduction in growth of test pathogen on the culture media.

Antagonistic Potential of Bacterial Species against Fungal Plant Pathogens (FPP) and Their Role in Plant Growth Promotion (PGP): A Review

Since the 19th century to date, the fungal pathogens have been involved in causing devastating diseases in plants. All types of fungal pathogens have been observed in important agricultural crops that lead to significant pre and postharvest losses. The application of synthetic fungicide against the fungal plant pathogens (FPP) is a traditional management practice but at the same time these fungicides kill other beneficial microbes, insects, animal, and humans and are harmful to environment. The antagonistic microorganism such as bacteria are being used as an alternate strategy to control the FPP. These antagonistic species are cost-effective and eco-friendly in nature. These biocontrol bacteria have a broad mechanism against fungal pathogens present in the phyllosphere and rhizosphere of the plant. The antagonistic bacteria have different strategies against the FPP, by producing siderophore, biofilm, volatile organic compounds (VOCs), through parasitism, antibiosis, competition for limited resources and induce systemic resistance (ISR) in the host plant by activating the immune systems. The commercial bio-products synthesized by the major bacterial species Pseudomonas syringae, Burkholderia cepacia, Streptomyces griseoviridis, Pseudomonas fluorescens and Bacillus subtilis are used to control Fusarium, Pythium, Rhizoctonia, Penicillium, Alternaria, and Geotrichum. The commercial bio-formulations of bacteria act as both antifungal and plant growth regulators. The Plant growth-promoting rhizobacteria (PGPR) played a significant role in improving plant health by nitrogen-fixing, phosphorus solubilization, phytohormones production, minimizing soil metal contamination, and by ACC deaminase antifungal activities. Different articles are available on the specific antifungal activity of bacteria in plant diseases. Therefore, this review article has summarized the information on biocontrol activity of bacteria against the FPP and the role of PGPR in plant growth promotion. This review also provided a complete picture of scattered information regarding antifungal activities of bacteria and the role of PGPR.

Bacillus subtilis strain F62 against Fusarium oxysporum and promoting plant growth in the grapevine rootstock SO4

Fusarium wilt is a fungal disease that causes economic losses to viticulture, whose causal agent Fusarium sp. has been associated with the decline and death of young vines. This work had the objective of evaluating the antagonistic potential of Bacillus subtilis F62 against F. oxysporum in vitro and in vivo, as well as the growth promotion in the grapevine rootstock SO4. In the in vitro assay, the antagonism by diffusible and volatile compounds of B. subtilis F62 and the inhibition of conidial germination of four Fusarium sp. isolates were evaluated. In the in vivo assay, cuttings and micropropagated plants of SO4 were submitted to four treatments: control, Bac (B. subtilis F62 inoculation), Fus (F. oxysporum inoculation) and Bac + Fus. We observed that inhibition of mycelial growth occurred mainly by diffusible compounds. B. subtilis F62 had a positive effect on the growth promotion and in the biocontrol of F. oxysporum, reducing the frequency of pathogen re-isolation in cuttings (18.1%) and in micropropagated plants (52.4%). These results demonstrate the ability of B. subtilis F62 to upgrade plant development and assist in controlling of the Fusarium wilt in the grapevine rootstock SO4.

The Potential of Fungi as Bio-Control Agents in Managing Colletotrichum Kahawae In Kenya

Colletotrichum kahawae is a causative fungal agent of Coffee Berry Disease (CBD) that negatively affects coffee production. Its control relies on use of resistant varieties and chemical control. Fungicides used in control of CBD are costly and pose a risk to environment and health. The study was aimed at assessing the possible antagonistic potential of fungal isolates against Colletotrichum kahawae in in vitro conditions. Five isolates were used; one isolate was collected from berries while the rest were collected from soil. Testing for antagonism against Colletorichum kahawae was done by co-culturing the isolates on Potato Dextrose Agar. The degree of antagonism was determined by measuring and comparing the radial growth of pathogen with the bio-agent against the control. Out of the five isolates tested against C. kahawae, three isolates Fusarium proliferetum, Penicillium and Fusarium ceraneasum significantly inhibited test pathogen growth at 60%, 55% and 45.45%, respectively. The other isolates, Fumigatus aspergillus and Chaetomium perithecia showed inhibition of growth at 40% and 18.18% respectively. It was concluded that there is potential of using fungi as bio control of the coffee berry disease.

DNA cleavage of the fungal pathogen and production of antifungal compounds are the possible mechanisms of action of biocontrol agent Penicillium italicum against Macrophomina phaseolina

ABSTRACT In the present study, five Penicillium species, namely, P. italicum, P. expansum, P. simplicissimum, P. oxalicum, and P. citrinum, were identified using ITS (internal transcribed spacer) and β-tubulin markers and screened for their in vitro antagonistic potential against a soil-borne fungal pathogen, Macrophomina phaseolina, in a dual-culture plate assay. Among all the tested strains, P. italicum showed the highest antagonistic potential against M. phaseolina by reducing its growth up to 57% over control, followed by P. citrinum (42%), P. simplicissimum (21%), P. expansum (11%), and P. oxalicum (9%). In order to find out the mechanism of action of P. italicum, genomic DNA of M. phaseolina was exposed to P. italicum secondary metabolites. The findings showed that these metabolites completely degraded the fungal DNA after the 48-h incubation period. To further explore the antifungal mechanism of action of P. italicum, chloroform and ethyl acetate fractions of its metabolites were subjected to gas chromatography–mass spectrometry (GC-MS) analysis. The major compounds identified in these fractions were 9,12-octadecadienoic acid (Z,Z)- (25.19%), decane (19.72%), dodecane (18.05%), benzene, nitro- (14.62%), benzene, 1,3,5-trimethyl (14.37%), benzene, 1,4-diethyl (11.62%), 1,2-benzenedicarboxylic acid, mono(2-ethylhexyl) ester (9.02%), and 1-nonadecene (8.99%), which could be responsible for control of M. phaseolina growth.

Biological control of fungal pathogens of tomato (Lycopersicon esculentum) by chitinolytic bacterial strains

The need to increase food production and to reduce the pollution caused by synthetic chemicals has led to a search for biocontrol agents against plant pathogens. In the present study, a total of 37 chitinolytic bacteria were isolated from the rhizospheric soil of tomatoes using a chitin agar medium. In vitro bacterial isolates, that is, TD9, TD11, TD15, and TD24 showed strong antagonistic and enzymatic activities against Rhizoctonia (8%-55%), Fusarium (31%-48%), Colletotrichum (24%-49%), and Aspergillus on a dual culture plate and enzyme assay. Furthermore, these putative antagonistic bacterial isolates were identified as Pantoea agglomerans (TD9), Bacillus subtilis (TD11), Bacillus cereus (TD15 and TD24) using 16S rRNA sequence analysis. Additionally, in culture filtrate in vivo assay, the isolates TD11 and TD15 inhibited the growth of Rhizoctonia solani about 40% and Fusarium oxysporum about 80%. However,in the pot trials, these two bacterial isolates (TD11 and TD15) considerably suppressed the disease rate in tomatoes caused by Fusarium and Rhizoctonia fungal species. Moreover, it was concluded that B. subtilis (TD11) was found to be the most promising putative biocontrol agent, inhibiting the fungal diseases of tomatoes by 50% and showing versatile antagonistic potential.

Determination of antagonistic potential of endophytic bacteria isolated from lettuce against lettuce white mould disease caused by Sclerotinia sclerotiorum

Determination of antagonistic potential of endophytic bacteria isolated from lettuce against lettuce white mould disease caused by Sclerotinia sclerotiorum

Influence of Trichoderma spp on Macrophoma theicola branch canker disease in South Indian tea gardens, India

Abstract Branch canker disease caused by the fungus Macrophoma theicola is a major stem disease that reduces the yield of south Indian tea plantations. Hence the present study aimed to assess the efficacy of the biocontrol agent Trichoderma spp against various isolates of Macrophoma spp. For this matter, different tea-growing regions of south India were surveyed for the isolation and characterization of Macrophoma spp. Then, fungal biocontrol strains (Trichoderma viride, Trichoderma atroviride, Trichoderma harzianum, and Gliocladium virens) were procured from microbial type culture collection Centre (MTCC) to screen their antagonistic potential on different isolates Macrophoma spp. The spores of Macrophoma spp were examined through a light microscope and identified by their peculiar morphological features such as non-septum pycnidiospores present in the sac and oval shape spore with stalk and confirmed using 18S rRNA gene sequence. The results revealed that the biocontrol G. virens followed by T. harzianum showed a higher inhibitory effect on different isolates of Macrophoma spp in the dual plate and culture filtrate studies. In the well diffusion method, the fungal biocontrol agents were found to be exhibit non-significant differences on different isolates of branch canker pathogen. The hyphal interactions studies showed that the pathogenic hyphal wall shrunk and penetrated by the interaction of G. virens.

Bioefficacy of microbial antagonists against Zymoseptoria tritici on wheat

From our previous research of bio-control agents of the wheat pathogen Zymoseptoria tritici as an alternative to chemical control, one strain of Bacillus amyloliquefaciens and one strain of Trichoderma harzianum showed high antagonistic potential in vitro and in vivo as a foliar treatment on potted plants under greenhouse. The present work aimed to evaluate the antagonistic potential of these two strains of microorganisms in seed treatment. The results obtained showed that the two antagonists can reduce the severity of the disease assessed at three growth stages of the two wheat cultivars. B. amyloliquefaciens I3 reduced the severity of septoria leaf blotch by 56% and 58% compared to the checks on Aguilal and Karim respectively at the flag leaf stage, while in the case of T. harzianum A, this rate was 54% on Aguilal and 55% on Karim. These results suggest that the antagonistic potential is due to a distant mechanism of action such as induced systemic resistance. The viability tests of the two antagonists on coated seeds stored at 4 °C showed that they were viable after twelve months of conservation and preserved their antagonistic potential against Z. tritici.

The Role of Surfactin Production by Bacillus velezensis on Colonization, Biofilm Formation on Tomato Root and Leaf Surfaces and Subsequent Protection (ISR) against Botrytis cinerea.

Many aspects regarding the role of lipopeptides (LPs) in bacterial interaction with plants are not clear yet. Of particular interest is the LP family of surfactin, immunogenic molecules involved in induced systemic resistance (ISR) and the bacterial colonization of plant surfaces. We hypothesize that the concentration of surfactin produced by a strain correlates directly with its ability to colonize and persist on different plant surfaces, which conditions its capacity to trigger ISR. We used two Bacillus velezensis strains (BBC023 and BBC047), whose antagonistic potential in vitro is practically identical, but not on plant surfaces. The surfactin production of BBC047 is 1/3 higher than that of BBC023. Population density and SEM images revealed stable biofilms of BBC047 on leaves and roots, activating ISR on both plant surfaces. Despite its lower surfactin production, strain BBC023 assembled stable biofilms on roots and activated ISR. However, on leaves only isolated, unstructured populations were observed, which could not activate ISR. Thus, the ability of a strain to effectively colonize a plant surface is not only determined through its production of surfactin. Multiple aspects, such as environmental stressors or compensation mechanisms may influence the process. Finally, the importance of surfactin lies in its impacts on biofilm formation and stable colonization, which finally enables its activity as an elicitor of ISR.

Antagonistic potential of some phosphate solubilizing fungi against some phyto-pathogenic fungi

BackgroundLittle phosphorus availability in soil is one of the major forces for crop production. Phosphate solubilizing fungi enhance available phosphorus from soils and contribute to achieve the plants phosphorus requirement. Phosphate solubilizing fungi are important component of soil microbiota and play an essential role in the biogeochemical cycling of phosphorus in natural ecosystems.ResultsThe study tested the potential of the isolated phosphate solubilizing fungi to inhibit the growth of Alternaria alternata, Fusarium solani, Geotrichum candidum, Rhizoctonia solani and Sclerotium rolfsii. A total of 137 fungal isolates were isolated and identified from 30 soil samples. Nine isolates solubilized inorganic phosphate (tricalcium phosphate). Eight of these isolates were isolated from the rhizosphere of Alhagi graecorum Boiss., Allium cepa L., Ehrharta calycina Sm., Ludwigia stolonifera (Guill. & Perr.) Raven, Mentha longifolia L., Phragmites communis Trin.,Triticum aestivum L. and Zea mays L., respectively and one isolate was isolated from island's free soil. Purified single spore cultures of these nine isolates were identified to species level by multi loci DNA barcoding using internal transcribed spacer1and 2 (ITS1 and ITS 2) of the rRNA gene cluster, Calmodulin (CaM) and β-tubulin)BenA) gene markers.ConclusionsThe isolated phosphate solubilizing fungi belonged to two genera, Aspergillus and Penicillium. The phosphate solubilization index ranged from 1 to 1.5. Aspergillius japonicus 2 had the highest solubilization index (1.5) and also had the highest inhibition percentage (70%) against Alternaria alternata. This isolate is promising for development of biocontrol agent of Fusarium solani, Geotricum candidium and Alternaria alternata. The highest phosphate solubilization by Aspergillius japonicus 2 was obtained by using sucrose as carbon source and also ammonium chloride and tryptophan as nitrogen source. The highest solubilization percentage was 78.2% at optimum glucose concentration (5%) while the pH value that gave the highest solubilization percentage (90%) was 3. After eight days of incubation of Aspergillius japonicus 2, the solubilization percentage reached its maximum value (80.2%).

Evaluation of the Antagonistic Potential of Bacterial Strains Isolated from Moroccan Soils for the Biological Control of Sclerotium rolfsii Sacc.

Evaluation of the Antagonistic Potential of Bacterial Strains Isolated from Moroccan Soils for the Biological Control of Sclerotium rolfsii Sacc.

Inhibition of mycelial growth of Fusarium oxysporum f. sp. lycopersici by isolates of Trichoderma spp.

Tomato crops have great economic importance in Brazil and worldwide; however, its economic return is dependent on the control of several diseases, including Fusarium wilt, caused by Fusarium oxysporum f. sp. lycopersici. The control of this disease is usually based on biological products, which are commonly manufactured with antagonist isolates of Trichoderma sp. Therefore, the antagonistic potential of Trichoderma sp. should be better studied against other phytopathogens, thus expanding the biofungicide options on the market. The objective of the present work was to evaluate the antagonistic potential of different isolates of Trichoderma against the in vitro mycelial growth of F. oxysporum f. sp. lycopersici. Four isolates of Trichoderma spp. were tested, three collected in litterfall and one commercial isolate (T. asperellum). The Trichoderma spp. isolates were evaluated for antagonistic potential against F. oxysporum f. sp. lycopersici using the culture pairing technique. The variables evaluated were: mean colony size (MCS), mycelial growth inhibition percentage (MGIP), mycelial growth rate index (MGRI) of phytopathogen, and antagonism of isolates of Trichoderma spp. through a scale of grades. All isolates of Trichoderma spp. tested reduced the in vitro mycelial growth of F. oxysporum f. sp. lycopersici.