Antagonistic Ability Research Articles

The endophytobiome of wild Rubiaceae as a source of antagonistic fungi against the American Leaf Spot of coffee (Mycena citricolor).

The American leaf spot, caused by Mycena citricolor, is an important disease of coffee (Coffea arabica), mostly in Central America. Currently, there are limited pathogen control alternatives that are environment friendly and economically accessible. The use of fungi isolated from the plant endomycobiota in their native habitats is on the rise because studies show their great potential for biological control. To begin to generate a green alternative to control M. citricolor, the objectives of the present study were to (i) collect, identify, screen (in vitro and in planta), and select endophytic fungi from wild Rubiaceae collected in old-growth forests of Costa Rica; (ii) confirm endophytic colonization in coffee plantlets; (iii) evaluate the effects of the endophytes on plantlet development; and (iv) corroborate the antagonistic ability in planta. Through in vitro and in planta antagonism assays, we found that out of the selected isolates (i.e. Daldinia eschscholzii GU11N, Nectria pseudotrichia GUHN1, Purpureocillium aff. lilacinum CT24, Sarocladium aff. kiliense CT25, Trichoderma rifaii CT5, T. aff. crassum G1C, T. aff. atroviride G7T, T. aff. strigosellum GU12, and Xylaria multiplex GU14T), Trichoderma spp. produced the highest growth inhibition percentages in vitro. Trichoderma isolates CT5 and G1C were then tested in planta using Coffea arabica cv. caturra plantlets. Endophytic colonization was verified, followed by in planta growth promotion and antagonism assays. Results show that Trichoderma isolates CT5 and G1C have potential for plant growth promotion and antagonism against Mycena citricolor, reducing incidence and severity, and preventing plant mortality.

Integrated Control of White Rot in Eggplant by using Pseudomonas flourescens, Penicillium Commune and Trichoderma asperellum in Iraq

The results of isolation and diagnosis of the fungus growing from Sclerotia and isolated from the infected explants showed that the pathogenic fungus Sclerotinia sclerotiorum was isolated. The results of the antagonistic ability test of the biological resistance elements against S.sclerotiorum gave a high antagonistic ability compared to the control treatment. The treatment of P.fluorescens gave the highest percentage of inhibition against the pathogenic fungus, followed by the treatment of P.commune and T.asperellum. The results showed the efficiency of biological resistance elements, including P.fluorescens, T.asperellum and P.commune, either singly or in combination with each other, in reducing the percentage of infection severity with S.sclerotiorum under plastic house conditions and in the greenhouse, where it amounted between 5.55-50 compared to the control treatment (pathogenic fungi alone), which amounted to 94.44% and under field conditions in the greenhouse, which amounted to 5.55-66.66% compared to the control treatment, which amounted to 83.33%. It provided good protection for eggplant, which was positively reflected on all plant growth parameters, in addition to an increase in the cumulative weight of eggplant fruits.

Morpho-molecular characterization of Clonostachys rosea and deciphering its biomolecules untangles the anti-fungal action against Fusarium oxysporum f.sp. lycopersici

Clonostachys rosea, a promising mycoparasite, has great biological control abilities against a variety of fungal plant diseases, insects and nematode pests. In the present study, three isolates of Clonostachys rosea were isolated from carrot, undisturbed forest and black gram rhizosphere soils respectively, out of 50 soil samples taken from different field and horticultural crops. Out of 15 onion plant samples from various locations, one isolate of C. rosea was isolated from root samples of onion. Two isolates of C. rosea from mycoparasitized sclerotia on cabbage head rot infected sample and naturally deceased whitefly in cotton was isolated respectively. They were morphologically and molecularly confirmed as C. rosea based on the fungal taxonomical keys and PCR amplification with ITS, translation elongation factor 1 alpha (TEF-1α), species specific primer sets respectively. The antagonistic ability of C. rosea against Fusarium oxysporum f.sp. lycopersici (Fol) has been shown using confrontation assay. Molecular docking of biomolecules of C. rosea using AutoDock vina module in PyRx 0.8 software reported dl-Glyceraldehyde dimer and 2(3H)-Furanone, dihydro-4-hydroxy as best hits with highest binding energy in the range of – 7.1 to −5.6 kcal/mol against target protein Global transcription regulator sge1 (SIX Gene Expression 1) of Fol. We also observed comparatively less binding energy for commercially available fungicide on docking against the target protein of Fol.

Trichoderma asperellum GD040 upregulates defense-related genes and reduces lesion size in Coffea canephora leaves inoculated with Colletotrichum cairnsense

Coffee anthracnose is an important disease around the world, which has seriously affected the profits of coffee growers. This study firstly reported Colletotrichum cairnsense as a pathogen to cause coffee anthracnose, and screened Trichoderma asperellum GD040 with good antagonistic (inhibition rate was 88.41%) and mycoparasitism ability. Root irrigation with T. asperellum GD040 spore suspension reduces lesion size caused by C. cairnsense on coffee leaves. Transcriptomic analysis showed that the expression of 175 genes in T. asperellum GD040 treated coffee was up-regulated, including 73 disease-resistance genes involved in the plant-pathogen interaction pathway, phenylpropanes biosynthesis pathway and other pathways, respectively. Results from qRT-PCR analysis indicated that the expression levels of 16 key resistance genes (11 disease-resistance genes reported in Coffea canephora, 2 phenylalanine biosynthesis-related genes, ETR, PAL, and OPR3) and 3 growth hormone synthesis-related genes (Pin-1, SUAR, and GAs-30-O) were up-regulated remarkably in coffee leaves treated by T. asperellum GD040, and were significantly higher than those in coffee leaves inoculated with C. cairnsense. Findings of this study revealed the antagonistic mode of T. asperellum GD040 against C. cairnsense and the mechanism of inducing host resistance in coffee against anthracnose at the molecular level, which laid the foundation for the development of multifunctional Trichoderma biological agents and their application in managing coffee anthracnose.

Bacillus cereus B8W8 an effective bacterial antagonist against major postharvest fungal pathogens of fruit

The antifungal activity of Bacillus cereus (B8W8) was investigated against major post-harvest fungal pathogens affecting citrus and apples fruits namely Penicillium digitatum, Penicillium italicum, Geotrichum citri-aurantii, Penicillium expansum, Botrytis cinerea, Monilinia laxa and Monilinia fructigena. The in vitro dual culture of B8W8 and fungal pathogens showed high inhibition rates of the mycelial growth of Monilinia laxa and Penicillium digitatum (71.4% and 72.5% respectively). Subsequently, the volatile compounds (VOCs) have a high antagonistic effect against Monilinia laxa (86.4%) and Monilinia fructigena (73.4%). In addition, the bacterial-free cell filtrate of B8W8 had a significantly important effect on the inhibition of spore’s germination and mycelial growth of Penicillium expansum, Botrytis cinerea, Penicillium italicum and Geotrichum citri-aurantii. The in vivo bioassays revealed a significant impact of B8W8 on fruit decays either by reducing the disease severity of causative agents or by completely preventing their occurrence, particularly brown rot of apple caused by M. laxa and green mold of citrus caused by P. digitatum (DS = 0%). However, the severity of sour rot of citrus caused by G. citri-aurantii was only reduced by 50%. The semi-commercial trials showed a high potential of B. cereus B8W8 to reduce the incidence of gray mold of apple and green mold of citrus to very low values during at storage. In addition, the biological treatment with B8W8 was shown generally more effective than imazalil, the chemical treatment reference. Furthermore, the rapid colonization of fruit wounds by B8W8 could promote its antagonistic ability. Moreover, biochemical tests showed the ability of B8W8 to produce protease, amylase, and hydrocyanic acid (HCN). Interestingly, the molecular analysis demonstrated the ability of this bacterium to produce the fengycin. The secretion of this lipopeptide and lytic enzymes is more likely the major mechanism of action involved in the biocontrol activity of this bacterium. Results indicated that quality parameters of fruit, when challenged post-harvest pathogens and treated with B8W8, were mostly very close to those of the untreated control, suggesting that B8W8 did not affect the fruit quality. Accordingly, it was concluded that B. cereus strain B8W8 could be an effective biological agent to control the main fungal pathogens of apples and citrus fruits during post-harvest period.

Antifungal Potential of Cell-Free Supernatant Produced by Keratinolytic Fungi against Ganoderma boninense

Keratinolytic is a microorganism ability to degrade keratin substrates. Fungi are known to produce the enzyme keratinase. This research was carried out aiming to know the keratinolytic fungi potential in inhibiting Ganoderma boninense fungi. Five isolates of keratinolytic fungi coded A 31, A 18, A 12, K 18, and A 29 have antagonistic ability against G. boninense. A 12 and A 18 had the largest inhibitory diameter of 25.23 mm and 24 mm, respectively, after 7 days of incubation. The ability of A 12 and A 18 antagonisms was observed by testing the supernatant of keratinolytic fungi incubated in a feather meal broth medium. An 18 has the largest antagonism percentage of inhibition at 84.72% against G. boninense, followed by A12 (77.78%) and combination treatment of A 12 + A 18 (73.55%) after 7 days of incubation. Keratinolytic fungi can also grow on minimum salt chitin medium (MSCM) and produced a hydrolysis zone after 3 days of incubation. G. boninense hyphae abnormalities were observed by using a 100x magnification microscope. Moreover, hyphae lysis and dwarf, curved, rolled, and curly hyphae were also observed after giving treatment on A 12, A 18, and the combination treatment of both isolates. These results showed that both keratinolytic fungi isolates and the supernatant are powerful biocontrol agents against G. boninense. There is no previous research report on endophytic fungi inhibiting the growth of Ganoderma boninense. In the future, keratinolytic fungi can be applied in agriculture technology.

The Differential Antagonistic Ability of Curcumin against Cytotoxicity and Genotoxicity Induced by Distinct Heavy Metals

Widespread heavy metal pollution has aroused severe health risks worldwide. Curcumin has been reported to play a wide-spectrum protective role for various heavy metals. However, the specificity and difference in the antagonistic ability of curcumin against distinct types of heavy metals are still largely unknown. Here, using cadmium (Cd), arsenic (As), lead (Pb), and nickel (Ni) as the typical heavy metals, we systematically compared the detoxification efficiency of curcumin on the cytotoxicity and genotoxicity elicited by different heavy metals under the same experimental conditions. Curcumin was proved to have a significant discrepant antagonistic capacity when counteracting the adverse effect of different heavy metals. Stronger protective effects of curcumin emerged when antagonizing the toxicity of Cd and As, rather than Pb and Ni. Curcumin exhibits a better detoxification ability against heavy metal-induced genotoxicity than cytotoxicity. Mechanistically, inhibiting the oxidative stress elicited by heavy metals and reducing the bioaccumulation of metal ions both contributed to the detoxification of curcumin against all the tested heavy metals. Our results illustrated that curcumin shows prominent detoxification specificity against different types of heavy metals and toxic endpoints, which provides a new clue for the better and targeted application of curcumin in heavy metal detoxification.

Antifungal bio-coating of endotracheal tube built by overexpressing the MCP1 gene of Saccharomyces boulardii and employing hydrogel as a “house” to antagonize Candida albicans

BackgroundFor some ICU patients, an artificial airway must be established with an endotracheal tube, but Candida albicans can easily adhere to the tube surface and form a biofilm, leading to potentially life threatening fungal infections. Therefore, it is urgent to prevent and reduce C. albicans infections introduced by the endotracheal tube. However, there are few antifungal drugs effective against C. albicans, and each of these drugs may have adverse effects on human cells. Saccharomyces boulardii is regarded as an alternative strategy to inhibit the adhesion of C. albicans, but it is affected by environmental stress. We hypothesized that it is feasible to strengthen the antagonistic ability of S. boulardii via encapsulating and genetically modification.MethodsIn this study, a bioactive material carrying the overexpressed MCP1 gene of Saccharomyces boulardii was constructed based on one-step photo-crosslinking. This material achieved spatial growth control of S. boulardii by encapsulating each S. boulardii cell within a hydrogel pore. The bioactive material was coated on an endotracheal tube and tested for its ability to inhibit the adhesion of C. albicans. Additionally, the material’s antagonistic activity towards C. albicans was evaluated by detecting intracellular Adenosine-triphosphate content, reactive oxygen species level and the activity of antioxidative enzymes. Tissue invasion experiment was executed to further evaluate the anti-adhesion ability of S. boulardii bio-coating.ResultsEncapsulating the overexpression of MCP1 by S. boulardii in hydrogel pores enhanced the viability of probiotics in the presence of high salt and oxidation stress. When used as the coating of an endotracheal tube, the S. boulardii bioactive material efficiently inhibited the adhesion of C. albicans by impairing the activities of superoxide dismutase and catalase and disturbing mitochondrial functions. In vivo, the S. boulardii bioactive material coating displayed good biocompatibility and reduced the host tissue invasion and virulence of C. albicans.ConclusionsThe integration of genetic modification and immobilization model breaks the bottleneck of previous application of microorganisms, and provides a new way to prevent fungal infections introduced by endotracheal tubes.Graphical

The Effectiveness Comparison Between Application of Indigenous Arbuscular Mycorrhizal Fungal Community and Stenotrophomonas maltophilia to Suppress Fusarium Wilt Incidence on Local Garlic Plant (Lumbu Hijau)

Wilt disease caused by Fusarium oxysporum is one of the most serious plant diseases in the world. There is no effective contol for. This study investigated the potential of arbuscular mycorrhizal and bacterial antagonists to control F. oxysporum through in vitro and in vivo studies. In this study, the antagonistic bacteria Stenotrophomonas maltophilia was isolated from mycorrhizal propagation media. Antagonist bacteria S. maltophilia showed antagonistic ability against F. oxysporum with an inhibition zone of 17.9 cm. Antagonistic bacteria and mycorrhizae used in this study significantly reduced the incidence of fusarium wilt in in vivo experiments. It was found that mycorrhizal and S. maltophilia inoculation showed disease incidence rates at 40% and 47.6%. While in the control treatment the incidence of disease reached 90.3%. The biocontrol agents of S. maltophilia and mycorrhizae have a promising prospective strategy to protect garlic plants. These results are expected to provide new insights for sustainable crop protection systems.

An Overview of Stress-Tolerant Promoting Endophytic Fungal Isolates from Hiyung Chilli Grown in South Kalimantan

Endophytic fungi are a unique class of microorganisms that lives in plant tissues. These fungi could spread from roots to shoots and interact with nearly all plants in a symbiotic, mutualistic, or commensal manner. Endophytic fungi are believed to exert several roles related to plant growth, including the ability to tolerate stress, especially in Hiyung chilli plants. This plant is widely cultivated in Indonesia and is a well-known host for endophytic fungi. The Hiyung chilli is a popular variety grown in the South Kalimantan Province, which receives national recognition and is geographically certified by the Indonesian government. This wetland-cultivated chilli plant has a uniquely high capsaicin content and long fruit shelf life compared to other varieties. Although endophytic fungal isolates are prevalently found on chilli plants, their potential to influence the growth of their host remains to be proven beyond a doubt. This review emphasizes the sparse reports on the potential of these antagonistic fungi in protecting chilli plants against other pathogens by producing auxin/Indole-3-Acetic Acid (IAA) and capsaicin. The study hypothesised that the antagonistic abilities of these endophytic fungi against other fungal pathogens are related to their IAA- and capsaicin production that synergistically increase the chili plants' threshold against biotic and abiotic stress.

Genome Sequence Resource of Serratia ureilytica HNU47: A Strain with Biocontrol Potential Against Bacterial Wilt Pathogen Ralstonia solanacearum.

Serratia ureilytica HNU47 was originally isolated from rhizosphere soil of stock in a continuous cropping tomato-planting field, which has excellent antagonistic ability against Ralstonia solanacearum. Here, we sequenced the genome of HNU47 to gain insights into the underlying basis of its antagonistic activity. Results of phylogenetic analysis of the whole genomic sequence demonstrated that HNU47 belongs to S. ureilytica. Through antiSMASH analysis, 10 secondary metabolite biosynthesis gene clusters were predicted. There were only two gene clusters with similarity higher than 95% with known compounds' gene clusters and the similarities of the other eight gene clusters were lower than 30%, including three gene clusters with no homology. In addition, biocontrol experiments confirmed that HNU47 could decrease the incidence of bacterial wilt caused by R. solanacearum on tomato. These findings support the potential of developing S. ureilytica HNU47 as a biocontrol agent against R. solanacearum by producing some unknown active compounds. The genome sequence reported here is also useful for revealing the modulation mechanisms underlying biosynthesis of active compounds.

Effect of volatile compounds produced by the cotton endophytic bacterial strain Bacillus sp. T6 against Verticillium wilt

BackgroundVerticillium wilt, caused by the fungus Verticillium dahliae, leads to significant losses in cotton yield worldwide. Biocontrol management is a promising means of suppressing verticillium wilt. The purpose of the study was to obtain and analyze endophytic bacteria with Verticillium wilt-resistant activities from the roots of Gossypium barbadense ‘Xinhai15’ and to explore the interactions between the soil and plants.ResultsAn endophytic bacterium Bacillus sp. T6 was obtained from the Verticillium wilt-resistant cotton G. barbadense ‘Xinhai15’, which showed significant antagonistic abilities against cotton Verticillium wilt. The bioassay results indicated that the strain possessed strong antagonistic abilities that inhibited V. dahliae spore germination and mycelial growth without contact, and thus it was speculated that the active factor of the bacteria might be volatile compounds. A total of 46 volatile substances were detected via headspace solid-phase microextraction and gas chromatography–mass spectrometry analysis. The pure product verification experiment confirmed that the styrene produced by the T6 strain was the main virulence factor. Transcriptome analysis showed that following styrene induction, 247 genes in V. dahliae, including four hydrolase genes, eight dehydrogenase genes, 11 reductase genes, 17 genes related to transport and transfer were upregulated. Additionally, 72 genes, including two chitinase genes, two protease genes, five transport-related genes, and 33 hypothetical protein genes, were downregulated. The quantitative real-time PCR results confirmed that the expression of the four genes VDAG_02838, VDAG_09554, VDAG_045572, and VDAG_08251 was increased by 3.18, 78.83, 2.71, and 2.92 times, respectively, compared with the uninduced control group.ConclusionsThe research provides a new reference for the development and application of the volatile compounds of endophytic bacteria as new biocontrol agents for the control of Verticillium wilt and as biological preservatives for agricultural products.

Trichoderma yunnanense and T. asperellum as potential biological agents for control of basal stem rot disease in oil palm

Basal Stem Rot (BSR) disease is a main constrain in oil palm cultivation. Ganoderma boninense is known as a causal agent of this disease. The intensity of BSR disease continues to increase in both the vegetative and generative phases of oil palm plantations and causes significant losses. Biological control is one of the BSR disease control techniques and is believed to be able to support sustainable oil palm cultivation. Trichoderma spp. is a group of fungal biological agents commonly used to control BSR disease. This study aims to obtain Trichoderma spp. isolates to be developed further as biocontrol agents for BSR disease. The research stages included isolation, morphology-based identification, antagonist potency testing, characterization, and identification with molecular technique. The results in this research obtained one isolate of Trichoderma strain TSU from oil palm plantation at Pematang Siantar Regency, and one isolate of Trichoderma strain TGLP from oil palm plantation at Musi Banyu Asin Regency, which inhibited the growth of G. boninense was 90.9 and 93.9% respectively through dual culture test. Inhibition tests by volatile compounds showed growth inhibition of G. boninense by both isolates were 55.2 and 70.6%. Both Trichoderma strains have the characteristics of producing chitinase, glucanase, and indole acetic acid. Furthermore, molecular identification showed that the Trichoderma strain TSU was similar to the Trichoderma yunnanense strain CBS121219 with an identity percentage of 99.11%, and Trichoderma TGLP as Trichoderma asperellum strain 1A4 with a percent identity of 99.65%. With their antagonistic ability and characteristics, the two Trichoderma spp. isolates have the potential to be further developed as biological agents for controlling BSR caused by G. boninense.

Utility of Trichoderma Amended Compost to Manage Soil Borne Fungal Diseases of Vegetable Crops in Kota District of Rajasthan (India)

In the present research article, Trichoderma species was isolated and multiplied on a growth medium without contamination for compost preparation. The aim of this study was detecting organic substrates of Trichoderma spp. for their antagonistic ability, for this purpose six major agricultural fields of Kota district are selected , from each field about 3-3 samples of soil are collected to detect the percentage of fungal disease incidence and tricho-compost was applied over diseased plants to minimize the fungal attack over vegetable crops. It was observed that the disease incidence is minimized by using tricho-compost mixed with soil in Gopalpura and Balita Village.

Foliar Pathogen Infection Manipulates Soil Health through Root Exudate-Modified Rhizosphere Microbiome.

Negative plant-soil feedback (NPSF) due to the buildup of soilborne pathogens in soil is a major obstacle in sustainable agricultural systems. Beneficial rhizosphere microfloras are recruited by plants, and mediating this has become a strategic priority to manipulate plant health. Here, we found that foliar infection of Panax notoginseng by Alternaria panax changed plant-soil feedback from negative to positive. Foliar infection modified the rhizosphere soil microbial community and reversed the direction of the buildup of the soilborne pathogen Ilyonectria destructans and beneficial microbes, including Trichoderma, Bacillus, and Streptomyces, in rhizosphere soil. These beneficial microbes not only showed antagonistic ability against the pathogen I. destructans but also enhanced the resistance of plants to A. panax. Foliar infection enhanced the exudation of short- and long-chain organic acids, sugars, and amino acids from roots. In vitro and in vivo experiments validated that short- and long-chain organic acids and sugars play dual roles in simultaneously suppressing pathogens but enriching beneficial microbes. In summary, foliar infection could change root secretion to drive shifts in the rhizosphere microbial community to enhance soil health, providing a new strategy to alleviate belowground disease in plants through aboveground inducement. IMPORTANCE Belowground soilborne disease is the main factor limiting sustainable agricultural production and is difficult to manage due to the complexity of the soil environment. Here, we found that aboveground parts of plants infected by foliar pathogens could enhance the secretion of organic acids, sugars, and amino acids in root exudates to suppress soilborne pathogens and enrich beneficial microbes, eventually changing the plant and soil feedback from negative to positive and alleviating belowground soilborne disease. This is an exciting strategy by which to achieve belowground soilborne disease management by manipulating the aboveground state through aboveground stimulation.

Endophytic Fungi Associated with Aquilaria sinensis (Agarwood) from China Show Antagonism against Bacterial and Fungal Pathogens.

Agarwood is the most expensive non-construction wood product in the world. As a therapeutic agent, agarwood can cure some diseases, but few studies have been carried out on the antagonistic abilities of endophytic fungi associated with agarwood. Agarwood is mainly found in the genus Aquiaria. The objectives of this study are to understand the antimicrobial activities and their potential as biocontrol agents of the endophytic fungi of Aquilaria sinensis. First, fresh samples of A. sinensis were collected from Yunnan and Guangdong Provinces in 2020-2021, and the endophytic fungi were isolated and identified to genus level based on the phylogenetic analyses of the Internal Transcribed Spacer (ITS) region. In this bioassay, 47 endophytic strains were selected to check their bioactivities against three bacterial pathogens viz. Erwinia amylovora, Pseudomonas syringae, and Salmonella enterica; and three fungal pathogens viz. Alternaria alternata, Botrytis cinerea, and Penicillium digitatum. The antibiosis test was carried out by the dual culture assay (10 days), and among the 47 strains selected, 40 strains belong to 18 genera viz. Alternaria, Annulohypoxylon, Aspergillus, Botryosphaeria, Colletotrichum, Corynespora, Curvularia, Daldinia, Diaporthe, Fusarium, Lasiodiplodia, Neofusicoccum, Neopestalotiopsis, Nigrospora, Paracamarosporium, Pseudopithomyces, Trichoderma, Trichosporon and one strain belongs to Xylariaceae had antimicrobial activities. In particular, Lasiodiplodia sp. (YNA-D3) showed the inhibition of all the bacterial and fungal pathogens with a significant inhibition rate. In addition, the strains viz; Curvularia sp. (GDA-3A9), Diaporthe sp. (GDA-2A1), Lasiodiplodia sp. (YNA-D3), Neofusicoccum sp. (YNA-1C3), Nigrospora sp. (GDA-4C1), and Trichoderma sp. (YNA-1C1) showed significant antimicrobial activities and are considered worthy of further studies to identify individual fungal species and their bioactive compounds. This study enriches the diversity of endophytic fungi associated with agarwood, and their potential antagonistic effects against bacterial and fungal pathogens.

Biological control of blue mold rot in apple by Kluyveromyces marxianus XZ1 and the possible mechanisms of action

The yeast Kluyveromyces marxianus was permitted for direct addition to food and shown antagonistic ability against some pathogens. However, the effect and detailed mechanism of K. marxianus on control blue mold disease and patulin accumulation in apple remain unknown. In our study, K. marxianus XZ1 reduced the disease incidence and patulin content in apple caused by Penicillium expansum at 3 d after incubation compared with the control, which is decreased by 51% and 52%, respectively. Studies on the potential mechanisms of action revealed that (1) K. marxianus XZ1 adhered well to the apple wound to gain a competitive advantage; (2) antibacterial substances produced by K. marxianus XZ1 under the stimulation of P. expansum to inhibit the growth of this fungus; (3) activity of catalase, peroxidase, polyphenoloxidase, chitinase, and phenylalanine ammonialyase was activated to participate in the defense of fruit against P. expansum; (4) the expression levels of some genes involved in plant hormone signal transduction, including salicylic acid, jasmonate acid and ethylene signaling pathway, were upregulated to strengthen the fruit's defense against mold. Taken together, our results indicated that K. marxianus XZ1 may serve as a potential biological agent against postharvest decay and patulin contamination caused by P. expansum in apple fruit, mainly attributed to its ability of competition for space and nutrients, secretion of antifungal components, parasitism and activation of plant hormone signal transduction.

Assessing the Various Antagonistic Mechanisms of Trichoderma Strains against the Brown Root Rot Pathogen Pyrrhoderma noxium Infecting Heritage Fig Trees

A wide range of phytopathogenic fungi exist causing various plant diseases, which can lead to devastating economic, environmental, and social impacts on a global scale. One such fungus is Pyrrhoderma noxium, causing brown root rot disease in over 200 plant species of a variety of life forms mostly in the tropical and subtropical regions of the globe. The aim of this study was to discover the antagonistic abilities of two Trichoderma strains (#5001 and #5029) found to be closely related to Trichoderma reesei against P. noxium. The mycoparasitic mechanism of these Trichoderma strains against P. noxium involved coiling around the hyphae of the pathogen and producing appressorium like structures. Furthermore, a gene expression study identified an induced expression of the biological control activity associated genes in Trichoderma strains during the interaction with the pathogen. In addition, volatile and diffusible antifungal compounds produced by the Trichoderma strains were also effective in inhibiting the growth of the pathogen. The ability to produce Indole-3-acetic acid (IAA), siderophores and the volatile compounds related to plant growth promotion were also identified as added benefits to the performance of these Trichoderma strains as biological control agents. Overall, these results show promise for the possibility of using the Trichoderma strains as potential biological control agents to protect P. noxium infected trees as well as preventing new infections.

Solation and selection of Streptomyces sp. species and Trichoderma sp. species against coffee berry disease by Colletotrichum sp. CC1.5 in Dak Nong province

Anthracnose is one of the serious diseases on coffee trees. Prevention of coffee berry disease on coffee trees by biological measures is an alternative solution to the use of chemical pesticides. The study aims to select strains of Streptomycesand Trichoderma with strong antagonistic ability against Colletotrichum sp. CC1.5 fungus causing coffee berry disease. Results revealed that an actinomycete strain DR92S showed a high ability to antagonize Colletotrichum sp. CC1.5 after 8 days by direct antagonism and diffusion through agar holes, with the antagonism efficiency and inhibition zone of 71.85% and 28.63 mm, respectively. A strain of Trichoderma DR10T8 showed 100% inhibitory effects against Colletotrichum sp. CC1.5 after 5 days of treatment. The gene sequence analyses exhibited that the closest genetic relationships of the actinomycete strain DR9S2 and the fungal strain DR10T8 were Streptomyces hiroshimensis and Trichoderma viride, respectively.

Trichoderma asperellum T10 - Apotential microbial strain against the Neoscytalidium dimidiatum causes white spot disease on dragon fruitin Binh Thuan province

The Trichoderma asperellum T10 isolated from soil for dragon fruit growth in Binh Thuan province, has a strong antagonistic ability against the Neoscytalidium dimidiatum, causing the white spot disease on dragon fruit. The results showed that T. asperellum T10 had a high antagonistic effect against fungal pathogens of 100%, and the inhibitory zone diameterreached 28.00 mm in laboratory conditions. T. asperellum T10 has been influential in the prevention and treatment of white spot disease in greenhouse conditions and reducing disease rates by 28-40% and disease index by 23-33% compared to the control. T. asperellum T10 is proposed as a potential strain of a microbial product for the prevention and treatment of white spot disease on dragon fruit.