scholarly journals Improvement of the Fungal Biocontrol Agent Trichoderma atroviride To Enhance both Antagonism and Induction of Plant Systemic Disease Resistance

2005 ◽  
Vol 71 (7) ◽  
pp. 3959-3965 ◽  
Author(s):  
Kurt Brunner ◽  
Susanne Zeilinger ◽  
Rosalia Ciliento ◽  
Sheridian L. Woo ◽  
Matteo Lorito ◽  
...  
Keyword(s):  
Glucose Oxidase ◽  
Biocontrol Agent ◽  
Systemic Disease ◽  
Pythium Ultimum ◽  
Biocontrol Agents ◽  
Systemic Resistance ◽  
Infested Soil ◽  
Trichoderma Atroviride ◽  
Transgenic Strain ◽  
Wild Type

ABSTRACT Biocontrol agents generally do not perform well enough under field conditions to compete with chemical fungicides. We determined whether transgenic strain SJ3-4 of Trichoderma atroviride, which expresses the Aspergillus niger glucose oxidase-encoding gene, goxA, under a homologous chitinase (nag1) promoter had increased capabilities as a fungal biocontrol agent. The transgenic strain differed only slightly from the wild-type in sporulation or the growth rate. goxA expression occurred immediately after contact with the plant pathogen, and the glucose oxidase formed was secreted. SJ3-4 had significantly less N-acetylglucosaminidase and endochitinase activities than its nontransformed parent. Glucose oxidase-containing culture filtrates exhibited threefold-greater inhibition of germination of spores of Botrytis cinerea. The transgenic strain also more quickly overgrew and lysed the plant pathogens Rhizoctonia solani and Pythium ultimum. In planta, SJ3-4 had no detectable improved effect against low inoculum levels of these pathogens. Beans planted in heavily infested soil and treated with conidia of the transgenic Trichoderma strain germinated, but beans treated with wild-type spores did not germinate. SJ3-4 also was more effective in inducing systemic resistance in plants. Beans with SJ3-4 root protection were highly resistant to leaf lesions caused by the foliar pathogen B. cinerea. This work demonstrates that heterologous genes driven by pathogen-inducible promoters can increase the biocontrol and systemic resistance-inducing properties of fungal biocontrol agents, such as Trichoderma spp., and that these microbes can be used as vectors to provide plants with useful molecules (e.g., glucose oxidase) that can increase their resistance to pathogens.

scholarly journals Seed Treatment Using Pre-infiltration and Biocontrol Agents to Reduce Damping-off of Corn Caused by Species of Pythium and Fusarium

Plant Disease ◽  
1998 ◽  
Vol 82 (3) ◽  
pp. 294-299 ◽  
Author(s):  
W. Mao ◽  
R. D. Lumsden ◽  
J. A. Lewis ◽  
P. K. Hebbar
Keyword(s):  
Disease Control ◽  
Plant Height ◽  
Root Rot ◽  
Seed Treatment ◽  
Pythium Ultimum ◽  
Biocontrol Agents ◽  
Infested Soil ◽  
Damping Off ◽  
Fresh Weight ◽  
Inoculum Rate

Bioassays were conducted in a greenhouse at 18°C to determine the effectiveness of a seed treatment used in combination with biocontrol agents for the reduction of corn damping-off caused by species of Pythium and Fusarium. Corn seeds were infiltrated with tap water, drained, air-dried, and then coated with biomass of an antagonistic fungus, Gliocladium virens isolate Gl-3, or an antagonistic bacterium, Burkholderia cepacia isolates Bc-B or Bc-1, or a combination of Gl-3 with each of the bacterial isolates. A nonsterile field soil was infested with a combination of pathogens: Pythium ultimum, P. arrhenomanes, and Fusarium graminearum at 2 inoculum rates (1× and 4×). Pre-infiltration enhanced (P ≤ 0.05) disease control with most treatments at both inoculum rates. Treatments with biocontrol agents alone or in combination, as well as the fungicide captan, effectively reduced the disease at a pathogen inoculum rate of 1×, resulting in greater (P ≤ 0.05) seedling stands, plant height, and fresh weight, and lower (P ≤ 0.05) root rot severity compared with untreated seeds in infested soil. At a pathogen inoculum rate of 4×, stands were lower (P ≤ 0.01) and root-rot severity was higher (P ≤ 0.01) compared to those at 1× for all treatments. Nevertheless, coating seeds with all biocontrol agents (alone or in combination), except with Bc-1 alone, reduced disease (P ≤ 0.05) compared to untreated seeds in infested soil. At both inoculum rates of 1× and 4×, coating seeds with Gl-3 + Bc-B was more effective (P ≤ 0.05) in disease control than any other treatment, resulting in stands, growth rate (plant height and fresh weight), and root rot severity similar to plants from untreated seeds in noninfested soil. In addition, when the exudate from a 2-h infiltration of corn seed was added to the seeds during seed coating, seedling stand was often lower and root rot severity was often higher than those from infiltrated seeds (P ≤ 0.05). These results indicated that the infiltration process removed certain exudates, including nutrients and/or stimulants (not detected in this study) that might be utilized by pathogens to initiate seed infection. A thin-layer chromatography (TLC) profile of the exudates showed the presence of eight amino acids and three major carbohydrates.

scholarly journals An improved control efficacy against tobacco bacterial wilt by an engineered Pseudomonas mosselii expressing the ripAA gene from phytopathogenic Ralstonia solanacearum

2019 ◽  
Author(s):  
Tao Zhuo ◽  
Shiting Chen ◽  
Xiaojing Fan ◽  
Xun Hu ◽  
Huasong Zou
Keyword(s):  
Plant Pathogen ◽  
Bacterial Wilt ◽  
Ralstonia Solanacearum ◽  
Biocontrol Agent ◽  
Biocontrol Agents ◽  
Avirulence Gene ◽  
Primary Immune Response ◽  
Systemic Resistance ◽  
Tobacco Plants ◽  
Engineered Strain

AbstractThe environmental bacterium Pseudomonas mosselii produces antagonistic secondary metabolites with inhibitory effects on multiple plant pathogens, including Ralstonia solanacearum, the causal agent of bacterial wilt. In this study, an engineered P. mosselii strain was generated to express R. solanacearum ripAA, which determines incompatible interactions with tobacco plants. The ripAA gene together with its native promoter was integrated into the P. mosselii chromosome. The resulting strain showed no difference in antimicrobial activity against R. solanacearum. Promoter-LacZ fusion and RT-PCR experiments demonstrated that the ripAA gene was transcribed in culture media. Compared with that of the wild type, the engineered strain reduced the disease index by 9.1% for bacterial wilt on tobacco plants. A transcriptome analysis was performed to identify differentially expressed genes in tobacco plants, and the results revealed that ethylene-and jasmonate-dependent defense signaling pathways were induced. These data demonstrated that the engineered P. mosselii expressing ripAA enables improved biological control against tobacco bacterial wilt by the activation of host defense responses.ImportanceNowadays, the use of biocontrol agents is more and more popular in agriculture, but they cannot replaced of chemical agents mostly, due to the poorer control effect. So the study about how to improve the efficacy of biocontrol agents become necessary and urgent. We increase the efficacy against plant pathogen through introducing an avirulence gene from plant pathogen into the biocontrol agent based on “gene to gene” hypothesis. The new engineered strain can improve the systemic resistance and elicit primary immune response of plants. Our research not only provides a new strategy for genetic modification of biocontrol agent, a number of avirulence gene from pathogen or plant can be tested to be expressed in different biocontrol agents to antagonize plant disease, but also help the study of interaction between phythopathogenic avirulence gene and host.

scholarly journals Cocolonization of the Rhizosphere by PathogenicAgrobacterium Strains and Nonpathogenic Strains K84 and K1026, Used for Crown Gall Biocontrol

1999 ◽  
Vol 65 (5) ◽  
pp. 1936-1940 ◽  
Author(s):  
Ramón Penyalver ◽  
María M. López
Keyword(s):  
Population Size ◽  
Crown Gall ◽  
Pathogenic Bacteria ◽  
Wild Type Strain ◽  
Biocontrol Agent ◽  
Genetically Engineered ◽  
Infested Soil ◽  
Wild Type ◽  
Gall Formation ◽  
Control Activity

ABSTRACT The crown gall biocontrol agent strain K84 and three mutants derived from it, K1026 (Tra− deletion mutant of pAgK84), K84 Agr− (lacking pAgK84), and K1143 (lacking pAgK84 and pNoc), significantly reduced gall formation caused by two pathogenic strains resistant to agrocin 84 in peach × almond seedlings planted in infested soil. Cocolonization of roots by pathogenic and nonpathogenic strains was observed in these biocontrol experiments under field conditions. In spite of the efficient biocontrol observed, average populations consisting of 102 and 106pathogenic agrobacteria per g of root were found 8 months after planting. The total numbers of pathogenic bacteria on roots were similar for plants treated with the biocontrol strains and for the untreated plants. Strain K84 and the genetically engineered organism K1026 survived at a level of 106 agrocin 84-producing bacteria per g of root. The population size of genetically engineered strain K1026 was not significantly different than the population size of wild-type strain K84 8 months after root inoculation. Strains K84 and K1026 controlled two pathogens resistant to agrocin 84 without reducing the total number of pathogenic bacteria in the root system. In addition, this study shows that some biological control activity of strain K84 against agrocin 84-resistant pathogens is independent of plasmids pAgK84 and pNoc.

scholarly journals Transformants of Trichoderma longibrachiatum Overexpressing the β-1,4-Endoglucanase Gene egl1 Show Enhanced Biocontrol of Pythium ultimum on Cucumber

1998 ◽  
Vol 88 (7) ◽  
pp. 673-677 ◽  
Author(s):  
Quirico Migheli ◽  
Luis González-Candelas ◽  
Laura Dealessi ◽  
Andrea Camponogara ◽  
Daniel Ramón-Vidal
Keyword(s):  
Type Strain ◽  
Wild Type Strain ◽  
Pythium Ultimum ◽  
Growth Conditions ◽  
Infested Soil ◽  
Constitutive Promoter ◽  
Wild Type ◽  
Endoglucanase Activity ◽  
Trichoderma Longibrachiatum ◽  
Biocontrol Activity

Nine transformants of Trichoderma longibrachiatum with extra copies of the egl1 gene were studied for mitotic stability, endoglucanase production, and biocontrol activity against Pythium ultimum on cucumber seedlings. The transformants showed a significantly higher level of expression of the egl1 gene in comparison to the wild type under both inducing and noninducing growth conditions. Transformants with the egl1 gene under the control of a constitutive promoter had the highest enzymatic activity. Both the endoglucanase activity and the transforming sequences were stable under nonselective conditions. When applied to cucumber seeds sown in P. ultimum-infested soil, T. longibrachiatum transformants with increased inducible or constitutive egl1 expression generally were more suppressive than the wild-type strain.

scholarly journals Systemic Resistance Induced by Trichoderma spp.: Interactions Between the Host, the Pathogen, the Biocontrol Agent, and Soil Organic Matter Quality

2006 ◽  
Vol 96 (2) ◽  
pp. 186-189 ◽  
Author(s):  
H. A. J. Hoitink ◽  
L. V. Madden ◽  
A. E. Dorrance
Keyword(s):  
Disease Control ◽  
Biocontrol Agent ◽  
Systemic Disease ◽  
Systemic Resistance ◽  
Trichoderma Spp ◽  
Organic Matter Quality ◽  
Trichoderma Isolate ◽  
Polymerase Chain ◽  
Soil Organic Matter Quality

Several factors affect the ability of Trichoderma spp. to provide systemic disease control. This paper focuses on the role of the substrate in which plants are grown, resistance of the host to disease, and the ability of introduced Trichoderma inoculum to spread under commercial conditions. Several reports reveal that foliar disease control provided by Trichoderma spp. is more effective on plants grown in compost-amended media compared with in lower-in-microbial-carrying-capacity sphagnum peat media. In Rhododendron spp., host resistance affects control of Phytophthora dieback provided by Trichoderma spp. For example, T. hamatum 382 (T382) significantly (P = 0.05) suppressed the disease on susceptible cv. Roseum Elegans while plant vigor was increased. The disease was not suppressed, however, on highly susceptible cvs. Aglo and PJM Elite even though the vigor of these plants was increased. Using a strain-specific polymerase chain reaction assay under commercial conditions, it was demonstrated that introduced inoculum of T382 did not spread frequently from inoculated to control compost-amended media. Other Trichoderma isolates typically are abundant in control media within days after potting unless inoculated with a specific Trichoderma isolate. Thus, the low population of isolates that can induce systemic resistance in composting and potting mix environments may explain why most compost-amended substrates do not naturally suppress foliar diseases.

scholarly journals Effects on Capsicum annuum Plants Colonized with Trichoderma atroviride P. Karst Strains Genetically Modified in Taswo1, a Gene Coding for a Protein with Expansin-like Activity

Plants ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 1919
Author(s):  
Ricardo Sánchez-Cruz ◽  
Richa Mehta ◽  
Karina Atriztán-Hernández ◽  
Olivia Martínez-Villamil ◽  
María del Rayo Sánchez-Carbente ◽  
...  
Keyword(s):  
Capsicum Annuum ◽  
Systemic Acquired Resistance ◽  
Plant Cell Wall ◽  
Acquired Resistance ◽  
Systemic Resistance ◽  
Marker Genes ◽  
Trichoderma Atroviride ◽  
Wild Type ◽  
Promoting Effect ◽  
Mutant Strains

Here, we analyzed the effects on Capsicum annuum plants of Trichoderma atroviride P. Karst strains altered in the expression of SWOLLENIN (SWO1), a protein with amorphogenic activity on plant cell wall components. Strains of T. atroviride that overexpressed the Taswo1 gene were constructed as well as deletion mutants. A novel, cheap and accurate method for assessing root colonization was developed. Colonization assays showed that the Taswo1 overexpressing strains invaded the host root better than the WT, resulting in a stronger plant growth-promoting effect. The expression of plant defense marker genes for both the systemic acquired resistance and induced systemic resistance pathways was enhanced in plants inoculated with Taswo1 overexpressing strains, while inoculation with deletion mutant strains resulted in a similar level of expression to that observed upon inoculation with the wild-type strain. Response to pathogen infection was also enhanced in the plants inoculated with the Taswo1 overexpressing strains, and surprisingly, an intermediate level of protection was achieved with the mutant strains. Tolerance to abiotic stresses was also higher in plants inoculated with the Taswo1 overexpressing strains but was similar in plants inoculated with the wild-type or the mutant strains. Compatible osmolyte production in drought conditions was studied. This study may contribute to improving Trichoderma biocontrol and biofertilization abilities.

Streblus asper Lour. exerts MAPK and SKN-1 mediated anti-aging, anti-photoaging activities and imparts neuroprotection by ameliorating Aβ in Caenorhabditis elegans

2021 ◽  
pp. 1-17
Author(s):  
Mani Iyer Prasanth ◽  
James Michael Brimson ◽  
Dicson Sheeja Malar ◽  
Anchalee Prasansuklab ◽  
Tewin Tencomnao
Keyword(s):  
Oxidative Stress ◽  
Caenorhabditis Elegans ◽  
Stress Resistance ◽  
Vital Role ◽  
Transgenic Strain ◽  
Wild Type ◽  
Neuroprotective Effects ◽  
C Elegans ◽  
Streblus Asper

BACKGROUND: Streblus asper Lour., has been reported to have anti-aging and neuroprotective efficacies in vitro. OBJECTIVE: To analyze the anti-aging, anti-photoaging and neuroprotective efficacies of S. asper in Caenorhabditis elegans. METHODS: C. elegans (wild type and gene specific mutants) were treated with S. asper extract and analyzed for lifespan and other health benefits through physiological assays, fluorescence microscopy, qPCR and Western blot. RESULTS: The plant extract was found to increase the lifespan, reduce the accumulation of lipofuscin and modulate the expression of candidate genes. It could extend the lifespan of both daf-16 and daf-2 mutants whereas the pmk-1 mutant showed no effect. The activation of skn-1 was observed in skn-1::GFP transgenic strain and in qPCR expression. Further, the extract can extend the lifespan of UV-A exposed nematodes along with reducing ROS levels. Additionally, the extract also extends lifespan and reduces paralysis in Aβ transgenic strain, apart from reducing Aβ expression. CONCLUSIONS: S. asper was able to extend the lifespan and healthspan of C. elegans which was independent of DAF-16 pathway but dependent on SKN-1 and MAPK which could play a vital role in eliciting the anti-aging, anti-photoaging and neuroprotective effects, as the extract could impart oxidative stress resistance and neuroprotection.

scholarly journals Using Commercial Compost as Control Measures against Cucumber Root-Rot Disease

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Kamel Kamal Sabet ◽  
Magdy Mohamed Saber ◽  
Mohamed Adel-Aziz El-Naggar ◽  
Nehal Samy El-Mougy ◽  
Hatem Mohamed El-Deeb ◽  
...  
Keyword(s):  
Root Rot ◽  
Control Measure ◽  
Disease Incidence ◽  
Pathogenic Fungi ◽  
Pythium Ultimum ◽  
Control Measures ◽  
Infested Soil ◽  
Fungal Isolates ◽  
Cucumber Root

Five commercial composts were evaluated to suppress the root-rot pathogens (Fusarium solani (Mart.) App. and Wr, Pythium ultimum Trow, Rhizoctonia solani Kuhn, and Sclerotium rolfsii Sacc.) of cucumber plants under in vitro and greenhouse conditions. In vitro tests showed that all tested unautoclaved and unfiltrated composts water extracts (CWEs) had inhibitor effect against pathogenic fungi, compared to autoclaved and filtrated ones. Also, the inhibitor effects of 40 bacteria and 15 fungi isolated from composts were tested against the mycelial growth of cucumber root-rot pathogens. Twenty two bacteria and twelve fungal isolates had antagonistic effect against root-rot pathogens. The antagonistic fungal isolates were identified as 6 isolates belong to the genus Aspergillus spp., 5 isolates belong to the genus Penicillium spp. and one isolate belong to the genus Chaetomium spp. Under greenhouse conditions, the obtained results in pot experiment using artificial infested soil with cucumber root-rot pathogens showed that the compost amended soil reduced the percentage of disease incidence, pathogenic fungi population, and improved the cucumber vegetative parameters as shoot length, root length, fresh weight, and dry weight. These results suggested that composts are consequently considered as control measure against cucumber root-rot pathogens.

A GacS deficiency does not affectPseudomonas chlororaphisPA23 fitness when growing on canola, in aged batch culture or as a biofilm

2006 ◽  
Vol 52 (12) ◽  
pp. 1177-1188 ◽  
Author(s):  
N Poritsanos ◽  
C Selin ◽  
W G.D Fernando ◽  
S Nakkeeran ◽  
T.R. de Kievit
Keyword(s):  
Antifungal Activity ◽  
Batch Culture ◽  
Hydrogen Cyanide ◽  
Fungal Pathogen ◽  
Biocontrol Agent ◽  
Antifungal Compounds ◽  
Pseudomonas Chlororaphis ◽  
Wild Type ◽  
Biocontrol Activity ◽  
Competition Assays

Pseudomonas chlororaphis PA23 is a biocontrol agent that protects against the fungal pathogen Sclerotinia sclerotiorum. Employing transposon mutagenesis, we isolated a gacS mutant that no longer exhibited antifungal activity. Pseudomonas chlororaphis PA23 was previously reported to produce the nonvolatile antibiotics phenazine 1-carboxylic acid and 2-hydroxyphenazine. We report here that PA23 produces additional compounds, including protease, lipase, hydrogen cyanide, and siderophores, that may contribute to its biocontrol ability. In the gacS mutant background, generation of these products was markedly reduced or delayed with the exception of siderophores, which were elevated. Not surprisingly, this mutant was unable to protect canola from disease incited by S. sclerotiorum. The gacS mutant was able to sustain itself in the canola phyllosphere, therefore, the loss of biocontrol activity can be attributed to a reduced production of antifungal compounds and not a declining population size. Competition assays between the mutant and wild type revealed equivalent fitness in aged batch culture; consequently, the gacS mutation did not impart a growth advantage in the stationary phase phenotype. Under minimal nutrient conditions, the gacS-deficient strain produced a tenfold less biofilm than the wild type. However, no difference was observed in the ability of the mutant biofilm to protect cells from lethal antibiotic challenge.Key words: Pseudomonas, biocontrol, gacS, fitness, biofilms.

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