جستجوی مقالات مرتبط با کلیدواژه "real-time pcr" در نشریات گروه "گیاهپزشکی"

Tomato bushy stunt virus (TBSV) is one of the important tomato viruses in Iran and all over the world. In this study, the effect of mycorrhizae in Tomato bushy stunt virus infection was investigated. For this purpose inoculum of mycorrhizal fungus Rhizoglomus irregulare was added to the plant growing medium at the time of tomato transplanting and after four weeks, TBSV was inoculated mechanically to the plants. The rate of virus multiplication was evaluated by Real-time PCR at time intervals of 19, 25 and 31 days after inoculation. The treatments included control plants (C), plants infected with TBSV (V), mycorrhizal plants (M) and mycorrhizal plants infected with TBSV (MV). The results of investigating the amount of virus accumulation in plants showed its decrease in MV plants compared to V plants, and this decrease was more obvious in more advanced stages of the disease. Investigating the expression level of AGO2 and MYB33 genes also revealed that these genes had a significant increase in MV plants compared to V plants. This increase indicates an increase in the resistance of MV plants to the virus compared to V plants and it also confirms the lower reproduction of the virus in tomato plants inoculated with mycorrhiza. The results of this research show that the use of mycorrhizal fungi as a stimulant of the plant's defense system may be a good way to defend against this viral disease.

Lime witches' broom disease associated with ‘Candidatus Phytoplasma aurantifolia’ is one of the most serious threats to lime production in Oman, United Arab Emirates and Iranian southern provinces. In this study, under warm condition (35-37°C and 25-27°C day/night) the reaction of four genotypes of Persian lime including TLCR10, TLCRO, TLC876 (tolerant genotypes) and RA (sensitive genotype) to ‘Ca. P. aurantifolia’ was investigated via graft inoculation. Also, under cool condition (24-26°C and 18- 20°C day/night) using the same inoculation method, the reaction of RA genotype to this pathogen was evaluated. Quantitative PCR was used for detection and quantification of ‘Ca. P. aurantifolia’ in the inoculated plants. At 48 weeks post-inoculation, the copy numbers of ‘Ca. P. aurantifolia’ per 100 ng of total plant DNA in TLCRO, TLC876 and TLCR genotypes was very low (17, 10 and 12, respectively) and no disease symptoms were observed. In RA genotype under warm condition, the mean copy numbers of ‘Ca. P. aurantifolia’ per 100 ng of plant total DNA was higher than that of cool condition and showed significant differences (P < 0.01) . Furthermore, the disease symptoms were only appeared under the warm condition. The results of the present study showed that TLC10, TLC876 and TLCRO genotypes had high tolerance to ‘Ca. P. aurantifolia’ and can be introduced as tolerant or resistant cultivars to ‘Ca. P. aurantifolia’. These tolerant genotypes can be used in genetic breeding programs to produce resistant and tolerant cultivars. The results also indicated that higher temperature may change susceptibility of

Verticilliumwilt of olive (VWO) caused by fungus Verticillium dahliae, is one of the most important diseases of olive worldwide. The response of 15 promising olive cultivars and 15 local varieties was evaluated to the fungus. The olive saplings of each genotype were inoculated with suspension of the fungus using root dip method. The degree of susceptibility/resistance of each genotype was evaluated based on both morphological feature and quantification of fungus in the root system of different genotypes. Total DNA was extracted from root of saplings at different sampling intervals: 0, 2, 12, 45 and 80 days post inoculation. The gradual increase for DNA of fungus in saplings was quantified by Real-time PCR technique and utilizing of SYBR Green system with specific primer pairs for ß-tubulin2 gene. Based on both morphological and quantitative Real-time PCR assays: QG-11, DD2-1, treeNo2, PS-5 and Manzanilla were highly susceptible and KH-13, TTS-1, DS-5 code 5 Lorestan and DS-5 were evaluated as resistant genotypes to the VWO. Moreover, we found parallel results for conventional method of screening (based on disease symptoms) and quantification of DNA in root system of olive by Real-time PCR technique. Olive genotypes evaluated as highly susceptible or resistant to the disease in conventional method showed the similar reaction to the fungus in Q-PCR method. This may suggest that conventional method of evaluation for resistance could be replaced by Q-PCR molecular method in high thropout screening of olive germplasm.

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.

Strictosidine synthase is a key enzyme in the biosynthesis of plant alkaloids. The homologous of the strictosidine synthase domain has been found in different organisms such as Arabidopsis thaliana. Bioinformatics and expression studies on one of the strictosidine synthase-like gene (SSL6) in Arabidopsis plants showed that gene responded to the signaling molecules, fungal and viral pathogens. The functional role of SSL6 has been further studied using an Arabidopsis knockout mutant with a T-DNA inserted into exon 1. The plants were inoculated with Alternaria brassicicola, which had incompatible interaction with A. thaliana. The fungal biomass was quantified by quantitative real-time PCR and spore count techniques. The assays indicated that T-DNA mediated ssl6 mutant was more susceptible than Col-0 genotype. The chlorophyll content and the size of necrotic lesions were significantly smaller in the ssl6 mutant compared with the Col-0. This is the first report with reference to the functional analysis of SSL6 suggesting that might be SSL6 plays an important role, among other factors, in plant defense against A. brassicicola.

In this research the effect of mixed infection of witches’ broom disease of lime (WBDL) (16SrII-B) and lettuce phyllody (LP) (16SrIX-D) phytoplasmas on symptom expression and phytoplasma density in periwinkle plants (Catharanthus roseus (L.) G. Don) were investigated. Four healthy periwinkle plants of the same age were first inoculated with LP phytoplasma and after three weeks with WBDL phytoplasma using detached fragments of inoculative dodder (Cuscuta campestris Yank.). Disease symptoms and phytoplasma population in plants inoculated with both phytoplasmas were compared with those in plants inoculated with either WBDL or LP phytoplasma. In doubly inoculated periwinkle plants the disease symptoms mitigated to mild reduction of leaf size and internodes which strongly differed from those in periwinkle plants singly inoculated with either WBDL or LP phytoplasma. Plants with mixed infection lived longer than those inoculated singly with either phytoplasma. Both WBDL and LP phytoplasmas could be detected in singly and doubly infected plants by conventional and real time PCR assays using specific primer pairs. Analysis of the data obtained by real-time PCR showed that the population of both WBDL and LP phytoplasmas in the mixed infection was significantly lower than that in plants singly inoculated with WBDL or LP phytoplasma. It seems that interaction of WBDL and LP phytoplasmas in mixed infection of periwinkle is of the mutual suppression type.

Rice bacterial brown stripe, caused by Acidovorax avenae subsp. avenae is recognized by producing water-soaked and brown stripes on leaves and sheaths of rice seedlings in nursery. Contamination of ecosystems upon excessive use of pesticides and emergence of resistance in pathogens to these chemicals makes continuous research on development of new control methods and strategies to combat plant pathogens an essential task. Plant disease resistance genes are useful genetic resources that can be employed to develop resistant varieties as the best alternative to other control measures. This research aimed to study the role of NH1, PR1, POX and PR10, pathogenesis related proteins and PDR20 gene in two Iranian rice cultivars inoculated with an incompatible strain of bacterial brown stripe using the Quantitative Real-time PCR technique. After Screening of 5 Iranian rice cultivars, Tarom and Sahel were selected as susceptible and resistant cultivars, respectively. The results of this study showed that the expression level of thesegenes has greatly increased in Sahel cultivar in comparison to Tarom (susceptible) cultivar. Increased expression level of the aforementioned genes, proves the role of these genes in resistance of rice plants against bacterial brown stripe disease.

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.