جستجوی مقالات مرتبط با کلیدواژه "pathogen" در نشریات گروه "گیاهپزشکی"

In order to evaluate the effectiveness of chemical control in the management of Fusarium diseases of corn, the present study was conducted using eight fungicides including Carboxin-Tiram (Vitavax -Tiram, 75% WP) as reference fungicide, Difenoconazole (Dividend DS 3%), Tebuconazole (Raxil DS 2%), Azoxy-strobin + Difenoconazole (Ortiva Top SC 32.5%), Trifloxystrobin (Flint WG50%), Protioconazole + Tebuconazole (Lamardur FS40%), Fludioxonyl + Metallaxyl M (Maxim XL FS) and Azoxystrobin + Metalaxyl M (Uniform SE 44.6 %) in three phases: laboratory, growth chamber and field. According to the results, all fungicides used in this research showed significant performance and effectiveness in control of Fusarium corn diseases compared to check in most of the traits evaluated, and application of them recommended as seed treatment before planting. In laboratory, Maxim and Raxil were considered as the most effective fungicides comparing the reference fungicide, Carboxin-Tiram. The most effective fungicides in growth chamber were Maxim, Lamardor, Ortivatop and Dividend, each of which showed higher efficiency than the reference fungicide in one or more traits. In field investigations in Golestan province, Maxim, Uniform and Ortivatop (with 93.9, 91.4 and 88.2% of check, respectively), in Ardabil province Maxim and Lamardor (with 51.5 and 41.7 % of check, respectively) and in Mazandaran province, Lamardor and Raxil (with 54.4% and 43.5% of check, respectively) were more effective compared with the infected control and showed better efficiency than the reference fungicide in most traits.

During the visit of some banana cultivation areas in 2021 and 2022, sampling of leaves and roots with symptoms of leaf spot and wilting was done in Sistan and Baluchistan, and Hormozgan provinces. After being transferred to the laboratory, twenty-eight isolates belonging to the genus Fusarium sensu lato were isolated from the infected samples.. The isolates were identified by carnation leaf agar and SNA under 12 hours of near UV light and 12 hours of darkness. The results of the morphological investigation and phylogenetic analysis based on Elongation factor 1-α (EF 1-α) gene region showed that isolates belonged to Fusarium oxysporum (12 isolates), Fusarium incarnatum (10 isolates), Neocosmospora sp. (7 isolates), and two unknown isolates of Fusarium. The pathogenicity test was conducted to compare the pathogenicity of the species on the Dwarf Cavendish banana variety. Pathogenicity test results showed the isolates could cause leaf spot (Fusarium sp. and Fusarium incarnatum) and wilting (Fusarium oxysporum, Fusarium incarnatum and Neocosmospora sp.) in banana plants under greenhouse conditions. Based on our knowledge, this is the first report of F. incarnatum and Neocosmospora sp. pathogenicity of banana in Iran.

In the spring and summer of 2021, stems and branches of Jand trees (Prosopis cineraria L.) with canker symptoms were collected from the forests of Sahara-Sandy region, Sistan, and Baluchestan province, Iran. Disease incidence was calculated by counting the number of infected trees and part of each tree, ranging from 70 to 100%. Stems and branches with canker symptoms and necrosis were incubated at room temperature in a moist chamber and Water-Agar 2%. After seven days' incubation, black conidia and conidiophores developed. A fungus belonging to the genus Alternaria was isolated from surface-sterilized samples. To identify isolates by morphological criteria, purified cultures were incubated at 23-25°C on Potato Carrot Agar (PCA) medium under 8/16 h light/ dark cycle photoperiod for 5-7 days (Simmons, 2007). Based on morphological characteristics such as colony color, sporulation pattern, sizes of primary and secondary conidiophores, conidia, and surface ornamentation of conidia, isolates were grouped into infectoria sections of Alternaria. On PDA after 7 days, colonies dark with gray aerial mycelia. Conidia were obclavate in long or short chains predominantly with longitudinal septa (Figure 2). The isolate was further identified by sequencing the internal transcribed spacer (ITS) region, glyceraldehyde 3-phosphate dehydrogenase (gpd), and plasma membrane ATPase (ATPase) (White et al. 1990; Berbee et al., 1999). In phylogenetic tree is constructed for the Infectoriae section based on three gene regions (Poursafar et al. 2017; Marin-Felix et al., 2019), the S3BK isolate lied with Alternaria infectoria CBS 210.86, and A. frumenti CBS 119401 in the same clade.

Tan spot disease caused by Pyrenophora tritici-repentis is a destructive disease in wheat production areas around the world. The disease has a high prevalence and distribution in the Golestan, Mazandaran, and northern regions of Ardabil province. Due to the lack of suitable resistant varieties in Iran, the damage caused by the disease is high. In this study, the evaluation of 50 wheat lines resistance belonging to the 9HLBSN treasury of the International Maize and Wheat Research Center (CIMMYT) was investigated using race1 of the pathogen. By inducing the fungal isolates to produce abundant conidia, the infection was established in the wheat seedlings through inoculation of the suspension of fungal conidia. The results of this study demonstrated that lines number 1, 17, 18, 22, 25, 29, 33, 34, 35, 36, 37, 38, 44, 45, and 47 had a susceptible reaction, and other lines which included 70% of investigated lines, were resistant. In addition, the mean disease index in different lines was calculated and compared. In terms of the mean disease index on the evaluated lines, 13 groups were obtained, which had 8, 8, 8, 4, 3, 5, 12, 23, 24, 28, 28, 26, and 22 members, respectively. Considering the susceptibility of most of the country's commercial cultivars to this disease, the resistant lines obtained in this study are good sources of resistance to be used in the breeding programs of wheat.

To evaluate the effect of Fusarium verticillioides on fresh weight, chlorophyll index, the activity of superoxide dismutase isoforms, and leaf proteins using two-dimensional gel electrophoresis in two corn lines, a factorial experiment based on a completely randomized design with five replications was performed with two corn lines B73 and MO17, infected with and without F. verticillioides under greenhouse conditions. The results showed that the effect of F. verticillioides on fresh weight was not significant, but it was significant on chlorophyll index in both corn lines. Electrophoretic analyses were carried out using 8% slab polyacrylamide gels. Superoxide dismutase was observed in three isoforms into polyacrylamide gels, and also these isoform activates were increased in plants infected by F. verticillioides. Leaf tissue proteome analysis of two corn lines showed that eight reproducible protein spots had significant alterations under F. verticillioides. These eight differentially expressed proteins were involved in the defense system and regulation processes. Isoform 2 of Mitogen-activated protein kinase 12 and Peroxiredoxin-2E, chloroplastic proteins involved in the defense system had overexpression under F. verticillioides in both corn lines. It seems that increased superoxide dismutase isoforms and proteins involved in the defense system can reduce F. verticillioides damage in the corn seedlings.

In this study, the effect of mycoendobiont fungi isolated from white button mushroom against Mycogone perniciosa, Lecanicillium fungicula and Trichoderma harzianum, as its important pathogens, was investigated for use in biological control and replacement of chemical compound. Isolates of mycoendobiont fungi were isolated from the cap, gills and stalk of healthy white button mushroom, collected from major mushroom growing farms in Iran. These isolates screened against aggressive strains mentioned above in dual culture tests and the most effective isolates were selected for greenhouse experiments. White button mushroom spawn was treated with the mycoendobiont fungi and disease incidence and growth parameters were measured. All mycoendobiont isolates tested were able to inhibit and compete with pathogens and controlled the incidence of wet bubble disease (M. perniciosa) from 21.42% to 97.61%, dry bubble disease (L. fungicula) from 60.63% to 96.80% and green mold disease (T. harzianum) from 64.28 to 96.93%. This test was performed in a completely randomized design with Three replications. Mycoendobiont isolates of Fusarium venenatum and Clonostachys rosea had the greatest inhibitory effect on the growth of all pathogens. In addition, Scedosporium apiospermum had a high growth inhibitory effect against M. perniciosa and T. harzianum. According to the results, mycoendobiont fungi of white button mushroom could be considered as the biocontrol agents and growth promoting with the aim of applying them in future.

Blast is one of the most important and destructive rice diseases in the world. Nanoparticles are antimicrobial agents used as biological and non–biological stimulants and can induce resistance in plant against pathogens. Effects of different biological and non–biological nanoparticles on inhibition of various plant fungal pathogens has been proved. However, no study has been done about the effect of biological nanoparticles on control of this disease through induction of resistance and expression of defense genes. In this study, in addition to direct effect of biological silver nanoparticles synthesized using Trichoderma harzianum fungus in vitro, its indirect effect was investigated by inducing systemic resistance in susceptible local Tarom cultivar on pathogenic fungus Magnaporthe oryzae under greenhouse conditions. For this purpose, expression of several important defense genes investigated in biological silver nanoparticle–treated plants in comparison with control plant (without biological silver nanoparticle) using real–time qPCR technique at different times after pathogen inoculation. The results showed a positive effect of different concentrations of biological nanoparticles in reduction of pathogen growth in comparison with the control treatment so that the amount of inhibition of pathogen growth in different concentrations (36, 27, 18, 9, 4.5 ppm) was 92, 81, 56, 28 and 7 percent compared to the control treatment, respectively. Phenotypic study of rice plant interaction with the fungus causing blast disease in presence of biological nanoparticle showed that there was no significant difference between the disease severities in biological nanoparticle–treated plants compared to control plants. Also, accumulation of transcripts of NPR1, PR2, PR3 and LOX genes between two mentioned treatments did not show significant increase. Therefore, indirect effect of biological silver nanoparticle on pathogenic fungus by induced resistance and increasing the rice plant defense genes is not considerable.

The fungal infection of rice seeds with Fusarium species, is a major problem for farmers in Iran and the world. Determining the pathogenicity of Fusarium species in rice fields might be helpful in development of strategies for management of the relevant diseases. In this research, the pathogenicity of forty seven isolates of Fusarium belonged to Fusarium fujikuroi, F. incarnatum, F.prolifratum, F. thapsinum, F. andyazi, F. oxysporum, F. graminearum and F. merismides obtained from rice seeds in Mazandaran, Guilan, Golestan, Khuzestan and Fars provinces were investigated. The pathogenicity test was performed by rice seed dressing method using spore suspension as inoculum in invitro, nursery and the paddy field. Percentage of healthy, unhealthy and dead seedlings recorded and percentage of disease incidence was determined. Also, the transmission rate of bakanae disease by seeds from the laboratory to the nursery and the paddy was determined. The results showed that all isolates were pathogenic on rice seedling and reduced germination percentage compared to control, and only one isolate of F. merismoides was non-pathogenic. F. fujikuroi isolates had the highest disease incidence rate. In addition, there was a significant difference among Fusarium species, isolates of each species and the five provinces in terms of disease incidence. Based on the disease incidence, 2.1% of the isolates placed in the non-pathogenic group, 25.6% of the isolates were in the moderate pathogenic, 34.1% of the isolates were pathogenic and 38.2% considered as severe pathogenic group. In this research, the rate of disease transmission from contaminated seeds to the nursery was 38%., but after seed disinfection, with fungicide, the transmission rate of the disease dropped from 38% to 3.6%. These results show the importance of rice seed treatment with fungicides for the control of bakanae disease.

During survey of rice fields in Fars and Khuzestan provinces at mature grain stage, 42 seed samples were collected. Fusarium isolates were obtained from these samples by planting seeds on selective Fusarium medium (Pepton-PCNB-Agar, PPA) by two methods i.e.; surface sterilization by sodium hypochlorite (NaClO 1%) and without disinfection. Cultivated samples were kept in incubator at 25±1° C and intermittent light (12 hours of light and 12 hours of darkness). Morphological identification of 26 purified Fusarium isolates was performed on the WA, PDA, CLA and SNA. Phylogenetic relationships of 18 isolates on the basis of TEF1-α gene region and ITS1-5.8S-ITS2 region sequences were investigated. The results revealed that Fusarium isolates belonged to two species complexes FIESC (Fusarium incarnatum-equiseti species complex, 50%) and GFSC (Gibberella fujikuroi species complex, 46%). Fusarium fujikuroi species in Fars and F. semitectum species in Khuzestan were most frequent. Two species F. fujikuroi and F. andiyazi belonging to the GFSC species complex were identified in two separate clades in phylogentic tree based on TEF1-α. On the basis of TEF1-α gene, F. merismoides was not identified, but the ITS region sequence was identified as Fusicolla acetilerea and differentiated this species from Fusarium species in the phylogenetic tree.

Pyricularia oryzae is the causal agent of rice blast disease, the most destructive, and an important disease of rice worldwide. To identify of host plants for P. oryzae in the north of Iran, and separation of this species from P. grisea, the infected tissues were sampled from rice, corn, sorghum, barley and wheat cultivation regions, tea, citrus orchards, and forest in southern of Caspian Sea from Astara in Guilan province to Gonbad-e Qabus in Golestan province during spring, summers and fall of 2012 and 2013. Out of 80 isolated pathogen, 50 and 30 isolates were identified as P. oryzae and P. grisea on the basis of morphological characteristics respectively. In order to investigation of phylogenetic relationships of studied isolates, ITS region of ribosomal DNA and MCM7 were amplified. Three major clades in cladogram of ITS and MCM7 were identified. Species of the P. oryzae and P. grisea put in clade one. Species that stand into this group have phylogenetic, morphology and host differences. Two other group associated with Magnaporthe sensu lato. Pathogenicity test of P. oryzae species were applied on corn (susceptible line B73), barnyard grass, foxtail, rice, eleusine and paspalum in greenhouse. The results showed that this species cause blast and leaf spot symptoms on corn, barnyard-grass, and foxtail. In this study, corn, banana, bermuda grass, paspalum and eleusine are reported as new hosts for the fungus in Iran.

Thionins and defensins are small (5kDa)، basic، cysteine–rich polypeptides with antifungal properties. In this study، expression of Thionin and PDF1. 2 genes after inoculation of Magnaporthe oryzae to cultivars Khazar (resistant) and Tarom (susceptible) was analyzed. The treatments were subjected to Quantitative Real-time PCR at different times (from 0 to 96 hours after inoculation، hai). The peak expression of PDF1. 2 gene in both cultivars was at 24 hai (about 20 fold of 0 hai). Expression of Thionin gene showed a peak at 48 hai (about 8 fold of 0 hai). Expression profiles of both tested genes were more and less similar in both cultivars but the transcript level of Khazar was higher than Tarom. T-Student’s analysis of data showed significant differences between two cultivars (P values of <0. 05). The results showed that these antimicrobial polypeptides can play an important role in resistance of cv. Khazar against rice blast fungus، M. oryzae.

Root rot caused by Fusarium verticillioides is one of the most important rice diseases in Ilam. In order to determine genetic diversity، 56 samples were collected from rice paddies of different regions in Ilam province. Molecular test was carried out with a set of five pairs of SSR primers after purification and identification of isolates. The SSR primers amplified a total 26 alleles. The average of allele number was 5. 2 per each primer. 40 alleles were observed in 5H08 and 5H09 loci as highest allele numbers and 24 alleles were observed in 5H12 locus as lowest. The polymorphism index content value was the highest in primers 5H07 with 0. 37 and the lowest in primers 4H18 with 0. 14. The average of PIC was 0. 25 in all primers. Cluster analysis using Neighbor joining method and Jaccard''s coefficient، divided the isolates into 10 groups at 8% similarity level. Result of AMOVA showed 98% of genetic diversity was in relation to isolates and only 2% was in related to different geographical regions. Therefore there is the high genetic similarity between isolates from different geographic regions. High genetic similarity can be attributed to emigration of gene or genotype as a result of various factors.

There are some strategies for adaptation to environmental changes in plants, including a range of molecular-biochemical and also intent or induced mechanisms. The proper response of plant is occurred when it receives extracellular signals and transfers those inside the cell. Ethylene, identified as a plant hormone which regulates the plant reactions under some circumstances. Ethylene production has been enhanced in response to biological stresses like plant infection by pathogens or herbivores attack. Most of induced defense genes are regulated by transduction pathways signal. The biosynthesis pathway of ethylene from the amino acid methionine has been studied well. In this pathway, the produced ethylene activates the resistant genes resulting to incidence of plant resistance. The responsible genes in rice and also the ethylene-expressed resistance genes have been discussed in this review.

The importance of plant protection is increasing with the need of optimizing the quality of agricultural yields. This is essential to search for suitable and appropriate microorganisms for biological control and also study and practice on how to use the optimal conditions for the successful management of plant diseases. One of these microorganisms is the fungus-like, Pythium oligandrum that live saprophytic in the soil. This microorganism has antagonistic and hyper parasitic effects on some of soil borne pathogens. This is not virulent on the 12 species of plants, belonging to six families and only present on their root surface. It is used for control of the wide range of pathogens of the field crops and also can stimulate plant growth, result in increasing the yield.