جستجوی مقالات مرتبط با کلیدواژه « trichoderma » در نشریات گروه « زیست شناسی »

Improper use of soil resources leads to reduced fertility and soil degradation, and ultimately reduced crop production. Chemical fertilizers are a very strong competitor to biofertilizers because they are cheaper, easier to access, and faster return on investment. Accordingly, the aim of this study was conducted to evaluate the rhizosphere bacteria that stimulate plant growth and provide biosecurity with the approach of modifying the root structure of plants. The study showed that the rhizosphere supports the development and activity of a large and diverse community of microbial organisms, including organisms in plant growth, which can be used in the biological control of plant diseases. Bacillus sp. and Pseudomonas sp. It also causes an increase in all biological diseases. These microorganisms are investigated in the present study. Findings showed that reducing production costs on a large scale is a difficult task but can be achieved with careful research. In addition, the analysis of the benefits, risks, and limitations of the use of Rhizobacteria requires a more comprehensive and detailed investigation. Because the choice of appropriate method of plant disease control is based on balance.

This study investigated tannase production by Trichoderma viride (Tv), Trichoderma harzianum (Th), Trichoderma longibrachiatum (Tl) and Trichoderma ressei (Tr) in the medium containing tannin as sole carbon and energy source. Morphologic characteristic of Trichoderma species (T) were determined in culture containing malt-yeast-glucose. Trichoderma species were cultured in Trichoderma fermentation medium (TFM) which contained 1% Tanic acid. The weights of proteins produced by T in TFM were determined by SDS PAGE. Trichoderma colonies were flat, and then gradually showed white unsmooth appearance and finally turned to green. The largest and smallest spores were belonged to Tl and Tr, respectively. The highest and lowest spore numbers in MYG were belonged Th (5.48 × 106) and Tv (12.26 × 106), respectively. The largest growth rate of mycelium was observed in Tl and the lowest in Tr (1.25 and 0.45 cm/d, respectively). The level of protein produced in TFM by Tr was lower (P<0.05) than the other species. The tannase production and its specific activity were similar across species. The enzyme specific activity in Tl was significantly more (P<0.05) than Tv (1.33 and 0.68 ul/mg protein). The molecular weight of the produced tannase was 131 kDa with two subunits weighing approximately 62 and 69 kDa. The results showed that Trichoderma species have the ability to grow and produce tannase in the medium containing tannin as the sole carbon and energy source.

This research was conducted with the aim of isolating and identifying cowpea root and crown pathogens in Khuzestan province. In addition, the antifungal effectiveness of nine selected strains of five Trichoderma species was surveyed on four root and crown pathogens of cowpea.

Out of twenty strainsobtained, four of them were selected for further investigation including pathogenicity test and siderophore assay. The relative amount of the siderophore produced by nine selected strains from five Trichoderma speciesand pathogens was assayed by the chrome Azurol S method (CAS). The radial growth of the pathogen’s colonies in front of the Trichodermastrains was analyzed using a completely randomized design, with three replicates. The pathogenic strains of ITS region were amplified and sequenced. The obtained sequences were compared with the reference strains using BLASTn search and the maximum likelihood (ML) phylogenetic analysis.

In the present study, the following pathogens were identified: Rhizoctonia solani, Fusarium chlamydosporum, F. falciforme, and Macrophomina phaseolina. In CAS assay, all of the Trichoderma strains and pathogens produced the siderophore into growth media under iron starvation.Strains of T. koningiopsis SCUA-Arak-96 and T. pleuroticola SCUA-Isf-15 produced the minimum and maximum siderophore with 31% and 85%, respectively. In the dual culture test, most Trichoderma strains significantly reduced the growth of pathogenic fungi. The most antifungal effect was observed in T. virens SCUA-Ham-65 strain on F. chlamydosporum and F. falciforme pathogens, with 30% and 29% growth inhibitory, respectively.

The results of the present study showed thatR. solani, F. chlamydosporum, F. falciforme, and M. phaseolina were the most important pathogens of the cowpea causing root and crown rot in Khuzestan province. Trichoderma strains produced the siderophore which chelates minimal iron of environment. In addition, they inhibit the growth of the plant pathogens in vitro.

In recent years, the use biofertilizers as an alternative to some chemical fertilizers have been considered. On the other hand, chemical fertilizers increase the yield of agricultural products. Also, replacing part of chemical fertilizer with biological fertilizer can bring good economic benefits for farmers, including reducing soil pollution, increasing soil fertility, and improving plant growth. The purpose of this study is to investigate the Azotobacter, chemical, urea, combinations of biological and chemical fertilizer (50/50 and 30/70 ) and, Trichoderma fungi were arranged in the black seeds, so this experiment were randomized complete block design and three replications for each test in the field. all treatments of fertilizers increased shoot and root length, root fresh weight, root dry weight, shoot dry weight, capsule number, seed number in capsule, 1000 seed weight, capsule number, antioxidant activity, and phytosterol. Bio-fertilize increased leaf protein content, leaf catalase enzyme activity, chl b content, and phytosterol combinations of biological and chemical fertilizer increased chl a content, Total chlorophyll, leaf and seed protein content. Trichoderma increased seed protein content. Bio-fertilize and combinations of biological and chemical fertilizer provide plant nutrition and increased growth. Biofertilizers in form of a combination of biological and chemical fertilizer reduced the excessive consumption of chemical fertilizers and the resulting pollution caused by it and will lead to better performance. According to the available results, combined fertilizer treatments and Trichoderma fungi had the greatest effect on the measured parameters.

Damping-off is an important disease of cucumber in Iran. Greenhouses cucumber production were visited in Kohgiluyeh and Boyer-Ahmad Province, in south-west Iran, and sampled from infected seedlings to evaluate the appropriate biological control method for the disease. The pathogens were isolated and purified from infected tissues of the seedlings, and their morphological characteristics were studied and Phytophthora capsici and Phytophthora megasperma were known. One hyper-virulent isolate of each pathogen was selected from nine isolates after the pathogenesis test, and were subjected to hyper- parasitism and dual-culture tests against 20 Iranian isolates of Trcihoderma harzianum. All isolates of this fungus had the potential for hyper-parasites of the pathogens. They also showed a significant inhibitory effect on colony growth of pathogens from 26.4 to 73.03 percent in dual-culture. Then, ability of five superior isolates of T. harzianum was tested in controlling cucumber damping-off disease caused by the hyper-virulent isolates of the pathogens in greenhouse. All isolate of            T. harzianum were able to significantly reduce the disease severity, and two isolates controlled the disease without significant differences with healthy control. The efficacy of Iranian isolates T. harzianum in the biological control of this disease is reported for the first time.

The bean common blight caused by Xanthomonas axonpodis pv. phaseoli is one of the most important pathogens of bean, which is a serious problem to produce this crop in western regions of the country. Due to the severe damage of this pathogen, using fungal and bacterial bio-control agents can be as an efficient way to reduce the damage of disease on bean. The aim of this study was to evaluate the controller effects of fungal and bacterial biological agents including Trichoderma harzianum, T. virens, Bacillus subtillis and Pseudomonas fluorescence in laboratory and greenhouse conditions on bacteria of bean common blight.
In order to study the effects of biological agent against Xap, in the first stage, was to investigate the percentage growth inhibition of Xapby biological agents under laboratory conditions. In the next step, the interaction of biological agent and pathogenesis bacteria on bean plant was evaluated in a completely randomized design, four replications and biological agent’s treatments are under the greenhouse conditions. Indices such as root and shoot fresh weight, root and shoot dry weight, height roots and stems of beans and disease severity were measured to analyse the control power of the biological agents.
In laboratory conditions, fungal biological agents of T. harzianum with an average diameter of inhibitor halo of 42 mm and inhibiting 56.67% of the growth had highest controller effect on pathogenesis bacteria. However, in greenhouse conditions, P. fluorescence bacteria had better performance and all plant indices under this treatment showed a significant growth. The combined treatment of P. fleurescence T. virens was the best treatment in this experiment with reducing 79.4% of disease symptoms. Treatments P. fleurescence. harzianum and B. subtillis. fleurescence with amount of 69.6 and 55.9% reduced the symptoms, respectively, and are in following levels.
Discussion and Therefore, the use of biological agents can largely reduce the bean common blight, so that it can be an efficient and environmentally friendly method used.

Plant diseases damage to agricultural crops in every year. Different approaches may be used to prevent the growth and reduce damage of plant diseases gents. Including methods is using of biological control. That is an environmentally sound and effective means of reducing plant diseases effects. Actually, the rhizosphere supports the development and activity of a huge and diversified microbial community, including microorganisms capable to promote plant growth, which could be used by these organisms for biological control of plant pathogens. Among the plant growth-promoting factors can be named as Trichoderma sp. fungus and strains of Bacillus sp. and Pseudomonas sp. had widely used in biological control of plant diseases. These biological agents make use of different mechanisms to control plant diseases, such as activate defense responses, antibiosis, stimulate plant growth, antibiotics production, increase nutrient uptake, siderophore and HCN production. Therefore, propagation and inoculation of these biological agent to plants, can decrease usage of chemical fertilizers and pesticides. Integrating mechanistic and ecological knowledge on these microorganism populations in soil will be a prerequisite to develop novel management strategies for sustainable agriculture

Chitinolytic enzymes are involved to break down chitin waste products such as chitin shells of crustaceans and cell walls of fungi and production of chitin oligosaccharides. Ideal catalytic properties of these enzymes make them an attractive target for use in industry or as a biocontrol. In this study to amplify and cloning of chit36 gene from native Iranian isolate, Trichoderma atroviride PTCC5220, Specific primers (chit36pf/chi36r) were designed and then intended to produce in periplasmic form, amplified fragment was cloned into pET26b() vector. The new construct was transformed into E. coli BL21-DE3 bacteria. The results of SDS-PAGE showed no evidence of protein expression in any of the conditions of temperature and different levels of IPTG at different cell fractions. So expression of Chit36 protein with the removal of signal peptide (to produce cytoplasmic form) with histidine sequence at the carboxyl end was planned. Bacteria containing recombinant construct were evaluated at different induction conditions. Despite detection of any band in any induction conditions using SDS-PAGE, low expression of proteins in two colonies were confirmed by Western blot assay. In order to optimize the expression condition, recombinant protein expression levels relative to the total bacterial protein in different induction conditions was evaluated using the quantitative measurements of protein bands on SDS-PAGE gels. The results showed that the best condition to induce expression is at OD600 : 0.3 and 1 mM IPTG and incubation time of 6 hours. In these conditions expression level of recombinant protein relative to total protein was 45.57%.

Trichoderma harzianum crude extract was prepared and its controlling effect on a wide range of Gram positive and negative bacteria، and a few fungal species was evaluated via disk assay techniques. The extract was able to control pathogenic bacteria including Escherichia coli، Bacillus subtilis، Pseudomonas fluorescens، Salmonella typhi، Staphylococcus aureus، two Xanthomonas citri pathovars (NIGEB-88 and NIGEB-9322)، and two fungal pathogens، namely Macrophomina phaseolina and Rhizoctonia solani. However، it failed to control a pectobacter، Erwinia amylovora. The biocontrol efficacy of crude extract was lost once treated with trypsin and reduced in the presence of SDS، indicating the protein nature of the effective materials in the fungal extract. The antimicrobial protein was resisted 100 °C for 30 min and was active in a wide range of pH (4-9). Our data is indicative of an efficient isolation of novel fungal thermostable antimicrobial proteins with the potential to be used as a biocontrol agent in the future.

Walnut is one of the most important trees that are cultivated in the large area in Iran. Various microorganisms comprising useful and harmful agents are associated with walnut root and rhizosphere. Almost all of the studies carried out for identification of microorganisms related to walnut until now، have been achieved on plant pathogen agents. Therefore in this research isolation and identification of Trichoderma spp. associated to walnut root and rhizosphere was studied. Sampling has performed of 68 places from Hamedan province and 235 isolates of Trichoderma were obtained. Macroscopic and microscopic features such as shape and size of conidium، conidiophore، phialide، chlamydospore، presence of aerial and submerged mycelia on culture media and growth rate as well as temperature examination data were used for identification of Trichoderma species. Consequently six species comprising T. atroviride، T. brevicompactum، T. citrinoviride، T. harzianum، T. ghanense and T. longibrachiatum were identified. Regarding to positive role of Trichoderma related to root and rhizosphere that cause increasing health and improving growth of plants، this study recommend a kind of horticultural management that could be able to protect and support these fungi in walnut root and rhizosphere.