جستجوی مقالات مرتبط با کلیدواژه "fusarium head blight" در نشریات گروه "گیاهپزشکی"

Fusarium Head Blight (FHB) is one of the most important diseases of wheat causing considerable yield losse annually. Commonly management practices of the disease are not effective, so adopting new strategies to control are seriously needed. For this purpose, in the present study, efficiency of commercial and local Trichoderma strains was evaluated in the control of Fusarium Head Blight on wheat. For isolation of the pathogen and antagonists, samples were taken from infected wheat spicke and wheat rhizosphere, respectively. Identification of fungal isolates (Trichoderma and Fusarium isolates) was performed based on combination of morphological characteristics and molecular data. Accordingly, the identity of the 10 isolates of the pathogen and 13 isolates of the antagonists was determined as Fusarium graminearum and Trichoderma harzianum, respectively. In lab, after a preliminiary screening, a superior Trichoderma isolate from wheat rhizosphere (T. harzianum Tr5), one commercial product (T. harzianum T22) and T. longibrachiatum N(prepared from culture collection of Tabriz University,) were used to study their antagonistic activity against F. graminearum under laboratory and greenhouse conditions. Antagonistic strains were furhter assessed in the production of chitinase and protease enzymes. The results of laboratory tests showed that all fungal antagonist strains significantly inhibited the growth of the pathogen compared to control. In dual culture assay, the highest inhibitory percent was detected in the interaction of F. graminearum with T. harzianum Tr5and T. longibrachiatum N. Furthermore, only T. harzianum Tr5 was able to show mycoparasitism mechanism directly. The volatile compounds of the antagonist strains showed the lowest inhibitory against pathogen, without any significant difference between them. In non-volatile compounds assay, the highest inhibitory percentage was detected for T. longibrachiatum N and the lowest inhibitory percentage was detected for T. harzianum Tr5 and T. harzianum T22, respectively. All antagonists were able to produce chitinase and protease enzymes, with more capability for local isolates. Finally, the results of the greenhouse assay were positively in consistent with the laboratory tests. The results of greenhouse assay showed that the antagonist isolates significantly inhibited the adverse effects of the pathogen on weight loss of wheat grain.

In this study, 224 wheat genotypes which had good agronomic characteristics were selected between 1700 collection of Cereal Research Department, Seed and Plant Improvement Institute, to evaluating against diseases FHB, leaf rust and powdery mildew resistance in field condition in Golestan province. After land preparation, seed of each genotype were planted on a line with length 1.5 meters below mist irrigation systems. Spikes at 50% flowering (stage 65 of the Zadoks) were inoculated with spore suspension of fungi isolates of Fusarium head blight (Fusarium graminearum, F. culmorum) within three days of one another in two stages. To evaluate genotypes resistant to leaf rust, in stem elongation (stage 35 of the Zadoks), were sprayed with a mixture of spores of the pathogen. Genotypes were evaluated to powdery mildew with naturally infected area. Notes the reaction of genotypes diseases mentioned above, the standard method of assessment for all diseases. The results showed that, 60 percent of genotype in disease incidence of Fusarium head blight were moderately susceptible and 30% were susceptible reaction and the rest were moderately resistant and resistant, but in disease severity FHB, 30% of moderately susceptible reaction, 37% susceptible and the rest were placed in resistant and moderately resistant groups. In the disease index FHB of genotypes showed that 20 percent moderately susceptible, 22% susceptible, 34% moderately resistant and 24 percent showed good relative strength. Results evaluated genotypes reaction to leaf rust races in the region showed that 43% resistant, 47% susceptible and others 10 percent were moderately resistant or moderately susceptible. In this study, 17% of genotypes were resistant, 25% moderately resistant, 27% moderately susceptible and 31% were quite susceptible. After analysis of the data, 20 genotypes were favorable partial resistance to any of the diseases studied, were introduced as sources of resistance and molecular genetics of resistance to genetic unit Cereal Research Department, Seed and Plant Improvement Institute.

An improved method of conidia production is described and compared to a conventional method growing Fusarium species on LSPDA medium under near-ultraviolet (NUV) light for 21 days. In the improved procedure, Fusarium spp. were grown in PDB for three days and subsequently spread as aliquots onto LSPDA, SNPMA and WA media. To remove excess water, the cultures were dried in a laminar flow cabinet for 20 to 30 min. Air-dried plates were incubated under NUV light at 25 ºC for 3 days. To compare aggressiveness of conidia produced by either method, wheat ears were inoculated at the mid-flowering. Disease incidence (% infected kernels) and Fusarium head blight severity as well as fungal biomass produced in the infected kernels were determined. The improved method effectively triggered sporulation of Fusarium spp. and gave high yields of conidia per unit of area within two days of incubation on solid media which is significantly higher compared to spore quantities produced with the conventional method. The average number of conidia produced by Fusarium spp. using the improved and conventional methods ranged from 56 to 156 and 0.8 to 38.6×106 (per plate), respectively. Spore production quantity was highly variable with the conventional method using different Fusarium species. However, morphology of conidia was similar in both assays. The aggressiveness of Fusarium inocula produced by both methods was not significantly different with respect to the ability to cause FHB and to colonize wheat kernels (P≤0.05). Microscopy examination showed the high conidiation rate from phialides on hypha.

Fusarium head blight (FHB) is economically one of the most important fungal diseases of wheat in the world. The aim of this research was to determine the antifungal metabolites of native Bacillus isolates. Bacillus strains isolated from soil of wheat and barley fields (Rural areas of southern Tehran, autumn 2012), and exhibited in vitro antagonistic activity against some Fusarium species isolated from infected wheat seeds (Wheat fields of Parsabad at Moghan, Ardebil Summer 2012). An attempt was made to partially purify and characterize the diffusible antifungal metabolite/s produced by the selected Bacillus strain in Nutrient broth medium. High Performance Liquid Chromatography (HPLC) of partially purified extract of the strain showed the presence of lipopeptide antibiotic iturin as a major peak that was comparable to that of standard iturin A (11.80 min) from Sigma–Aldrich. The structure was further confirmed by Fourier Transform-Infrared Spectrum (FTIR) and Liquid Chromatographic Mass Spectrometric (LCMS) analysis as iturin A. LCMS analysis also showed the presence of fengycin with iturin A. The genome of the selected isolate of Bacillus had shown 99/9 percent similarity by B. aryabhattai and the genome of the selected isolates of Fusarium had shown 99 percent similarity by F. graminearum. According to the results of this experiment, the antifungal effects of native Bacillus strains and also their effects in the biological control of wheat FHB disease were confirmed.

The majority of viruses infected fungi which have been reported contain double-strand RNA (dsRNA) genomes. Mycoviruses are introducing as agent of the biological control of fungi according to hypersensitive properties. In this research, eight isolates belong to Fusariumgenus include ofF. graminearum, F. culmorum, F. tricinctum, F. proliferatum and F. incarnatum survived to dsRNA infection. Due to using of hazardous material such as phenol and complicated procedure in different dsRNA extraction protocols in mentioned research phenol and chlorophorm was removed , using less tissue and dsRNA extraction time was reduced compared to other methods. Result showed that four isolates infected by dsRNA also, mentioned method has sufficient efficiency and convenient for dsRNA extraction from fungi tissue. Also, dsRNA was reported fromF. incarnatum (F. semitectum) for first time.

Fusarium culmorum which is considered as the causal agent of Fusarium head blight، can produce deoxynivalenol (DON)، nivalenol (NIV) and their acetylated derivatives. This study has been assessed in order to detect the Tri13 gene using primer pairs Tri13DONR/Tri13F and Tri13R/Tri13NIVF، to investigate the potential of F. culmorum isolates in the production of DON and NIV in West Azarbayjan province، Iran. In this study، 98 F. culmorum isolates were obtained from Urmia، Khoy، Miandoab، Maku، Tekab and Mahabad regions. For this purpose، F. culmorum isolates were identified based on the morphological characteristics as well as specific primer pairs، C51F/C51R. Production of DON and NIV were detected in these isolates according to Tri13 gene. Results showed that 60. 2 percent of isolates have the potential to produce DON and 39. 8 percent of isolates have ability to produce NIV.

To evaluate resistance of wheat advanced and elite lines to fusarium head blight (Fusarium graminearum), 61 genotypes obtinedfrom Cereal Research Department of Seed and Plant Improvement Institute were grown at agricultural research field of Agricultural and Natural Resources Reserch Center of Gorgan in 2012 using a randomized complete block design with three replications. Inoculums of the pathogen was increased on wheat straw in laboratory and a mixture suspension of spores of  five isolates were sprayed on plants at two growth stages of heading and anthesis.After development of disease in field, disease incidence, disease severity and disease index were assessed for each line. Based on the results, none of the lines were immune or resistant, but lines ARWYT-N-90-2, ERWYT-N-90-20 and ERWYT-N-90-4 with lower disease index exhibited an acceptable level of resistance.

Deoxynivalenol (DON) is a major mycotoxin produced by the fungus Fusarium graminearum during infection and is known to be harmful to both animal and human health. DON is believed to act as a virulence factor in fungal pathogenesis by inhibiting eukaryotic protein synthesis. The putative site of action of DON is 60s ribosomal protein L3 (RPL3). Previously, single amino acid changes in RPL3 conferring DON resistance have been described in yeast. Sequence characterization of six wheat genes encoding RPL3 has shown that there is no amino acid alteration between resistant and susceptible cultivars. The main goal of this study, was to determine any induced changes in transcriptional levels of RPL3 (A and B type) genes under stress conditions caused by Fusarium Head Blight (FHB) in wheat. In order to detect expression levels of RPL3 genes, we extracted RNA from both inoculated and non-inoculated spikes of sensitive and tolerant cultivars, during 1, 3 and 7 days post-infection. Quantitative RT-PCRs were performed with A and B type-specific RPL3 primers to detect the expression differences. Primary data indicated a decrease in the genes expression level in Sumai3 and Falat cultivars 24 hours post-infection. On the other hand, increased level of RPL3A transcript in Frontana 7 days post-infection may reveal the role of this specific protein in inducing the resistance in this cultivar.