جستجوی مقالات مرتبط با کلیدواژه « مقاومت القایی » در نشریات گروه « گیاهپزشکی »

Due to environmental pollution caused by chemical pesticide application, the use of eco-friendly methods such as induced resistance to manage insect pests is necessary. In this study, the induced resistance potential of gibberellic acid, with a concentration of 0.125 g/L, in cabbage was investigated against cabbage aphid Brevicoryne brassicae L. Population growth parameters of cabbage aphid, including intrinsic population growth rate (r), net reproduction rate (R0), finite population growth rate (λ), gross reproduction rate (GRR), and population doubling time (DT) affected by gibberellic acid were significantly reduced compared to the control group (P < 0.05). However, there was not any significant difference between gibberellic acid treatment and the control for mean generation time (T) and the mean fecundity per adult female. The mortality rate of nymphs and adult females, age-specific survival rate (lx), and age-specific fertility (mx) in gibberellic acid treatment were significantly decreased compared to the control (P < 0.05). The mortality rate of first-stage nymphs was higher than the control and other stages. The dispersal percentage of first-stage nymphs and adult females treated with gibberellic acid was increased compared to the control (P < 0.05). Based on the results of this study, gibberellic acid was effective for decreasing the population growth parameters of cabbage aphid, and it can be considered in the integrated management of the pest.

Considering the high damage caused by the tomato leaf miner moth, Tuta abosulata, in tomato crops, the use of chemical pesticides against this pest is increasing and finding alternative methods that can be combined with chemical control can be effective in the optimal management of this pest. One of these methods is establishing induced resistance in tomato plants by using seed priming before planting. Considering the key role of methyl jasmonate in creating induced resistance in plants, in the present study, tomato seeds (var: Elite) were soaked 24 hours before planting using two concentrations of 0.1 and 0.2 mM methyl jasmonate. Then, in the flowering stage of tomato, the biological and demographic parameters of tomato leaf miner moth were investigated using the age-stage two-sex life table. The results showed that seed priming affected the population parameters including Od, F, r and λ in the flowering stage and their value was lower than the control, also these treatments had a smaller population and the length of their larval period was longer than the control. The prediction of the population progress under seed treatment with methyl jasmonate, during 120 days, showed that all four life stages of the insect will have a smaller population than the control on day 120, which hints the negative effect of the treatments on biological and population characteristics of the herbivore and indicates the induction of resistance on the host plant. As a result, methyl jasmonate can be consider in the integrated management programs of tomato leaf miner moth by plant resistance mechanisms

Root and stem rot of cucumber with Fusarium oxysporum f. sp. radicis-cucumerinum is one of the most harmful diseases in cucumber greenhouses in Iran. Chemical fungicides do not have the acceptable ability to control this pathogen. Also, due to their economic costs and adverse effects on the environment, the use of biocontrol agents in the control plant diseases has been considered in recent years. Trichoderma antagonist isolates has been shown to be an effective biocontrol agent against a wide range of fungal pathogens. In this study, the effect of Trichoderma isolates on root rot and cucumber rot fungi was investigated. Three Trichoderma isolates were obtained from the mycology collection of the Department of Plant Protection, University of Tehran. Mean peroxidase activity (POX) as a marker of induced resistance was measured using a spectrophotometer. Also, the effect of Trichoderma isolates on disease control in greenhouse conditions was determined by soaking the soil with spore suspension of antagonist and fungal pathogen. All three Trichoderma isolates T11, T6 and T9 have an acceptable effect on growth inhibition of F. oxysporum f. sp. radicis-cucumerinum. T11 and T9 isolates showed 85.51% and 81.03% inhibition of mycelial growth of F42 strain, respectively. Peroxidase activity was assessed within seven days after inoculation. The highest peroxidase activity was observed on the fourth day in T11 isolate. Based on the results obtained in this study, it can be concluded that T11 isolate (T. harizianum T11) had the greatest effect among Trichoderma isolates in inducing resistance.

Induced resistance is a type of defense system in plants that is activated by a biotic agent and allows plants to resist pathogens or parasites. Strong inducers are usually quite effective and can trigger a plant resistance reaction. These molecules, also called elicitors, can be inanimate or biotic in nature, challenging the plant and reacting to it, which must be done by producing antimicrobial compounds and / or creating mechanisms is related to plant defense. Induction of resistance in plants is strongly influenced by environmental conditions, especially light and temperature during the day and growing conditions. In general, induction of resistance in plants by using live or non-live stimuli or the use of plant cultivars incompatible with the patient, are among the strategies considered by researchers in the management of diseases and plant diseases. Induced resistance to change of grape varieties infected with phytoplasma disease has been observed on different cases. This method is one of the treatment strategies in the management of phytoplasma diseases and diseases caused by fastidious vascular bacteria.

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.

Trichoderma species are important biocontrol agents of plant pathogens. However, potential of Trichoderma species in insect pest management, remain poorly understood.  In this study, the effect of T. harzianum TR6 on the life table parameters of black bean aphid, Aphis fabae, was evaluated under glasshouse conditions as compared to control. The Vicia faba and black bean aphid were grown in a growth chamber at 25 ± 2 0C, %50 ± 5 RH and a photoperiod of 14 L : 10 D hours. Then, five ml of fungal spore suspension (with concentration of 1 × 106 ml-1) was added into the soil of sown mugs with a sterile syringe. The results obtained in this study revealed that T. harzianum scientifically affected the biological properties of black bean aphid in comparison with the control. Treatment with T. harzianum resulted in the highest developmental time (20.36 days) and the lowest fertility rate in black bean aphid. There was significant differences in terms of inherent rate of population increase (P≤0.5) compared to the control. The highest rate was occurred in control treatment (0.42 ± 0.01 day-1) and the lowest in treatment with T. harzianum (0.16 ± 0.01 day-1). The life expectancy of black bean aphids, which was grown on T. harzianum treated soil, was significantly lower than control. According to the results, it can be stated that treatment of faba bean plant with T. harzianum can be effective in reducing the population of the aphids of the bean.

In this research, the effect of Bacillus methylotrophicus in biological control of Pectobacterium carotovorum subsp. carotovorum, the causal agent of potato soft rot disease, as well as the effects of silicon and silicon nanoparticles, the two systemic acquired resistance inducing compounds, against both pathogenic and antagonistic bacteria was evaluated in laboratory and glasshouse conditions. In the disc diffusion and well diffusion assays, silicon and silicon nanoparticles did not produce any inhibitory zone around the tested bacteria, but the antagonistic bacterium, B. methylotrophicus, produced an inhibitory zone of growth in the same and chloroform assays with a radius of 9, 8.5 and 15 millimeters, respectively. Although, silicon nanoparticles slightly reduced populations of both pathogenic and antagonistic bacteria after 6 and 10 hours post culturing in liquid medium, but after 24 hours, the differences between them and control treatment were not significant. Silicon did not inhibit the growth of the tested bacteria in liquid medium. At glasshouse conditions, all treatments of silicon and silicon nanoparticles as well as antagonistic bacterium were significantly increased the fresh and dry root and shoot weight in compare to positive control, but the best result was achieved by combined treatments of silicon or silicon nanoparticles with antagonistic bacterium. All the treatments completely inhibited disease development on potato plants in compare to positive control and no disease symptoms were observed whereas in control treatments all the tubers showed maceration and rotting symptoms and were destroyed.

Plant hormones are the compounds that are increased followed by the attack of herbivores to enhance plant defense ability. The idea of external application of hormones on crop plants to induce resistance to herbivores has been studied by examining the behavioral and physiological responses of tomato leafminer, Tuta absoluta (Lepidoptera: Gelechiidae) on three tomato cultivars including Dehghan, Falat-111 and Mobil in response to jasmonic acid and salicylic acid hormone treatments by measuring the oviposition preference of the females, survivorship and development time of each immature stage and the concentration of soluble carbohydrates and phenols in the leaves. Oviposition preference of females and embryo development time on the susceptible cultivar, Falat-111, were significantly reduced and increased respectively in jasmonic acid treatment units. Larval development rate showed the highest response to hormonal treatments in the semi-resistant cultivar, Dehghan. Survivorship and development rates of the pupae were also significantly reduced under the influence of jasmonic acid treatments on all three cultivars. Despite significant differences in leaf soluble carbohydrates and phenols concentrations between control and sprayed tomato cultivars as well as a significant positive correlation between changes in carbohydrates and phenols concentrations in the experimental units, no significant correlation was observed between the aforementioned plant contents and insect biological variables. The results showed that these hormones in combination with appropriate plant varieties can be used to induce behavioral and physiological changes in the pest.

In this research, the effects of spermidin polyamine on induce resistance of tomato to fusarium wilting disease caused by Fusarium oxysporum fsp. Lycopercisi was assayed. For this reason, a designed factorial experimental based on randomized completed block design in greenhouse condition was done. A solution of spermidin at 1 and 0.1 mM concentration was used by the spray on infected and non infected plants at 4 leaf stage. Sampling was performed at two time interval (48 and 72h) after inoculation. The level of several antioxidants enzyme and also expression of some transcription factors as related to pathogenesis (npr1, eds1 and pds genes) were measured by spectophotometery and real time PCR, respectively. The results showed that approximately, the highest enzyme activity was related to infected tomato plants treated with 1mM spermidin after 72h post inoculation with fusarium oxysporum fsp. Lycopercisi. Gene expression analysis showed that all tested genes were affected by spermidin application in infected plants. The highest and lowest expression level was observed for npr1 and pds genes, respectively. Based on these results we suggest that exogenous application of sprmidin with appropriate concentration to plant under stress condition could improve plant growth condition which can be resulted to plant resistance against pathogen attack

Bean yellow mosaic virus (BYMV) which belongs to Potyvirus genus, is able to infect wide range of plants because of its wide host range. This virus is transmitted by mechanical inoculation and aphid vectors in non-persistent manner. In this research the effects of six treatments including: synthesized silver nano particles of P. fluorescens CHA0, preparations of T. harizianum and P. fluorescens CHA0, olive (Olea europaea) and yarrow (Achillea millefolium) extracts and potassium phosphite on damage reduction in three common bean genotypes against a BYMV isolate was investigated. This experiment was carried out in a completely randomized factorial design. For this purpose, treatments were applied on plants immediately afterward first symptoms in mechanically inoculated plants were appeared. Virus concentration in treated plants was evaluated by DAS-ELISA test using BYMV polycolonal antibody. Evaluation of vegetative and reproductive parameters, measurement of peroxidase and polyphenol oxidase enzymes activity and virus accumulation indicated that potassium phosphite, silver nano particles of P. fluorescens CHA0 and yarrow extracts had highest influence on virus accumulation

Plants are usually attacked by several pathogens. Different defense pathways in plants have evolved in reaction to pathogens. Plant defense responses have been shown to be regulated by various plant hormones. Brassinosteroids are plant-specific steroid hormones that play important roles in regulating growth and developmental processes. In addition to acting as a regulator of plant growth, they also play a role in defense responses to pathogens. Many researches have been done on their role in plant resistance to fungi, bacteria and viruses, which are described in this article. Further understanding of the role of these hormones in plant defense responses can be useful in inducing resistance or producing plants resistant to pathogens.

The green peach aphid, Myzus persicae (Sulzer), is a polyphagous insect that can cause damage on a lot of crops in the field and greenhouse conditions. In this research, the effect of five treatments of Arbuscular Mycorrhizal Fungi (AMF) including Glomus caledonium, G. etanicatum, G. geosporum, G. intradicese and G. mosseae together with control treatmenton total amount of phenol content in bell pepper and also their impact on biological parameters of M. persicae were investigated. Based on the results, the highest amount of the total phenolic compound in the plant infested with aphid was observed on G. mosseaeandG. intradicese (686.1 and 664.3 mg/mL, respectively) and the lowest amount was on control (410.8 mg/mL).The shortest and longestadult longevity of the green peach aphid were observed on G. mosseae(16.00 days)and control (22.35 days), respectively. The net reproductive rate (R0) varied from 37.54 to 53.34 offspring/individual, with the lowest and highest values obtained on G. mosseae and control, respectively.Also, the lowest intrinsic rate of increase (r) and finite rate of increase (λ) of the aphid were recorded on G. mosseae treatment (0.2867 and 1.3320 day-1, resp.) compared to other treatments. The results of this study showed that G. mosseae treatment significantly reduced the population growth of M. persicae. Therefore, G. mosseae can be used to produce induced resistance in bell pepper to this aphid, which can be useful in the IPM program of this pest.

The common pistachio psylla, Agonoscena pistaciae is the most important pest of pistachio trees which causes serious damage to pistachio crops. In the present study, we investigated some physiological-biochemical responses of pistachio Akbari cultivar at different feeding periods (2 to 192 h). Hydrogen peroxide contents as stress index had no significant differences between treatments (except for 2 and 96 h treatments). Also a significant decrease was gained in activities of superoxide dismutase (SOD) and catalase (CAT). The lowest activity of SOD, CAT and ascorbate peroxidase (APX) observed at 144 and 192 h. The amount of total protein increased significantly in response to the pest feeding and the lowest concentration observed at the onset of experiment. Total phenolic content increased following psylla feeding while no significant changes observed in total soluble carbohydrates. Amount of the pigments fluctuated in different times of feeding and their elevation after 144 h indicated optimal plant growth under stress conditions. The highest amounts of carotenoids, total phenolic content and total protein after 144 h were associated with the lowest activities of defensive enzymes. Our results showed an appropriate combination of enzymatic and non-enzymatic antioxidants leads to plant conservation and homeostasis regulation under stress conditions.

In this study, the effect of grafting of tomato on eggplant rootstock were investigated on growth indices of the tomato plant and biological parameters of Tuta absoluta (Meyrick) (Lep.: Gelechiidae). In order to evaluate of fertility and fecundity, a pair of adult insects (male and female) of T. absoluta, with less than 24 h age, were kept on each plant (grafted and non-grafted). Then, one egg (in 15 replications) was placed on each plant to measure the developmental period of embryonic, larval and papal stages until adult insect emergence. Seventy-five days after grafting, except the stem diameter, all growth indices of grafted plants including plant height, number of nodes and leaves were significantly higher than non-grafted plants. Also, weight of fresh and dry root of grafted plants were higher compare to non-grafted plants. Larval and pupal developmental period of T. absoluta fed on grafted plants were significantly higher than non-grafted plants. Besides, the mean fecundity of the adult female of T. absoluta was lower on grafted plants. Amount of total phenol content in different days after infestation with T. absoluta indicated a significant increase in grafted plant. Results of this research clearly showed that the grafting of tomato plants on eggplant rootstocks could be an effective approach for increasing of plant growth and subsequently its resistance to T. absoluta.

In this research, interaction between Fusarium graminearum  and wheat including the change in rate of some anti-oxidant enzyme activity and expression level of PR2 (b,1-3gluconase), PR3 (chitinase) andPR4 (wheatwin) genes was studied. Tajan cultivar was used in greenhouse and experimental condition in a completely randomized blocks design with four repetitions. Spraying of aerial parts of plants by methyl- jasmonat at 200, 400 and 600 ppm concentration was done one, three and five days after inoculation with fungal spore of Fusarium graminearum (105 spore per milliliter).Also, inhibition effect of methyl jasmonat on growth of fungal colony was investigated on PDA culture medium.The results showed that the total phenol production and peroxidase, polyphenol oxidase and guaiacol peroxidase reached to highest level three  days after inoculation at concentration of 600 ppm and reduced significantly 5 days after inoculation. Gene expression analysis at three days after inoculation time interval showed the highest and lowest expression level for b, one-three gluconase and chitnase respectively. Assay of growth inhibition effect by methyjasmonat showed that this material has the highest inhibition activity at concentration of 600 ppm. These results indicate that exogenous application of methyl jasmonat as chemical inducer to induce plant resistance against head scab disease could be considered in plant disease management.

In this paper, developmental time, survival rate, and reproduction of Tetranychus urticae Koch on common bean under the influence of Biolog siderophoric (an induced resistance compound in plants) were investigated. The laboratory conditions in this study were 75±10% R.H. and 16L: 8D at three constant temperatures (25±1, 30±1 and 35±1 °C). The soil of each pot received 0.2 ml of Biolog siderophoric diluted in 100 ml water. Leave discs of the treated plants were collected after 48 h for the experiments.Results showed that total developmental time of T. urticae was 35.87± 0.02, 56.45±0.05, and 30.23±0.02 days at 25, 30 and 35 °C, respectively. Developmental time of different stages increased as the temperature elevated from 25 to 30 °C, but decreased as the temperature was raised from 30 to 35 °C. The intrinsic rate of increase (r) was 0.16±0.0007, 0.10±0.0006, and 0.18±0.0007 day-1, at 25, 30 and 35°C, respectively. There was a significant difference among the intrinsic rate of increase at the three temperatures. The net reproduction rate (R0) was 48.25±0.72, 25.76±0.43 and 39.42±0.49 offspring at the mentioned temperatures. There was a significant difference between the net reproduction rates at the three temperatures. Our results showed that biolog siderophoric had the best effect on reducing the population of T. urticae at 30 °C, due to the lowest intrinsic rate of increase and the most longevity occurred in this temperature.