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Seed decay is a major problem caused by pathogens that adversely affect seed yield and quality in agricultural production. Herein, the effect of 28 KHz ultrasound treatment for 20, 40 and 60 min and 1.5% sodium hypochlorite solution for 20 min was assessed for the decontamination of roselle (Hibiscus sabdariffa L.) seeds. In addition, seed germination indices, seedling growth traits, total phenolic content and the activity of defense-related enzymes, viz. peroxidase, superoxide dismutase, catalase and malondialdehyde were measured in the treated seeds. An isolate of Fusarium solani was obtained from roselle seeds and identified as the causal agent of roselle seed rot based on morphological and molecular characteristics. After six days of seed storage, the microbial infection caused the highest seed rot in the control seeds on the average of 56.67%, whereas ultrasound treatment for 60 min could remarkably reduce the seed decay by 3.33%. At the end of seed storage, the fungal load showed the highest (7.72 Log CFU ml-1) and lowest (6.99 Log CFU ml-1) rates in the control and ultrasound treatment for 60 min, respectively. Total phenolic content was significantly increased in ultrasound treatment for 60 min compared to control and sodium hypochlorite treatments. Moreover, the activity of peroxidase, superoxide dismutase and catalase was noticeably improved in ultrasound treatment for 60 min. Furthermore, ultrasound treatment did not show any adverse effects on seed germination indices and seedling growth traits of the roselle plants. Overall, ultrasound treatment for 60 min could effectively decrease roselle seed decay and the fungal load without changing seed and seedling quality.
Assuntos
Hibiscus , Hipoclorito de Sódio/farmacologia , Descontaminação , Superóxido Dismutase/farmacologia , Peroxidase , SementesRESUMO
BACKGROUND: Abiotic environmental stresses, especially drought stress, is one of the most important problems in arid and semi-arid regions. Like other major crops, Brassica napus is vulnerable to drought stress. OBJECTIVE: The present study was conducted to evaluate efficacy of Sargassum angustifolium extract on mitigating adverse effects of drought stress on B. napus seedlings during vegetative growth under greenhouse conditions. MATERIALS AND METHODS: Seedlings were periodically sprayed with the seaweed extract until they reached 7-leaf stage. Then water deficit stress was imposed and measurements were performed at morphological, biochemical and molecular levels on three phases: 80% field capacity for 20 days (Phase I), 60% field capacity for 20 days (Phase II) and 40% field capacity for 20 days (Phase III). Real-Time PCR assay was carried out to monitor the changes in expression of the genes involved in proline biosynthesis. RESULTS: Morphological measurements revealed that seaweed treatment improved shoot height and dry weight compared to control (p<0.05). Biochemical analyses indicated that foliar application of seaweed extract significantly enhanced the photosynthetic pigments' content, free radical scavenging and superoxide dismutase activity (p<0.05). Moreover, proline content was significantly increased in plant tissues treated with seaweed extract (p<0.05). The results of Real-Time PCR assay showed that the increase in proline content is due to enhanced expression of P5CS which is involved in biosynthesis of proline, and to decreased expression of PRODH which catalyzes proline degradation. CONCLUSIONS: Overall, the results obtained in this research suggest that application of S. angustifolium extract as a biostimulant is able to protect canola seedlings against deteriorating effects of drought stress.
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BACKGROUND: Wheat dwarf virus (WDV) is a leafhopper-transmitted DNA virus which causes yellowing and stunting in wheat and barley fields leading to considerable crop loss around the world. Mainly, two host-specific forms of WDV have been characterized in wheat and barley (WDV-Wheat and WDV-Barley, respectively). OBJECTIVES: This study was aimed to amplify, sequence and describe subgenomic DNAs (sgDNAs) associated with WDV infection among wheat and barley plants. The nucleotide sequence of sgDNAs were then compared to that of parental genomic DNAs (gDNAs) and the differences were shown. MATERIALS AND METHODS: A total of 65 symptomatic plants were surveyed for WDV infection using double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) and polymerase chain reaction (PCR). Rolling circle amplification followed by restriction analysis (RCA-RA) was applied to identify both gDNAs and sgDNAs in the infected wheat and barley plants. Nucleotide sequence of eight full-length WDV genomes and five sgDNAs were determined. RESULTS: Genomic sequences of WDV-Wheat and WDV-Barley isolates obtained in this study were identified as WDV-F and WDV-B, respectively, forming a separate cluster in the phylogenetic tree with the highest bootstrap support (100%). Sequence analysis of sgDNA molecules revealed that they have undergone different mutation events including deletions in viral genes, duplication of coding regions, and insertion of host-derived sequences. CONCLUSIONS: The association of different types of sgDNAs were found in WDV-infected wheat and barley plants. The sgDNAs exhibited remarkable changes compared to their parental molecules and they might play a role in symptom severity, host genome evolution and emergence of new virus variants/species.
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BACKGROUND: Sensitive detection of Maize Iranian mosaic virus (MIMV) in its insect vector, Laodelphax striatellus is essential for effective forecast and control of this viral disease. OBJECTIVES: Three methods of ELISA, RT-PCR and IC-RT-PCR were compared regarding their sensitivity for detection of MIMV in the single planthopper with a series of various dilutions. MATERIALS AND METHODS: To detect MIMV from a single insect vector, the sensitivity of three methods including ELISA, RT-PCR and IC-RT-PCR was evaluated. RESULTS: Compared to the other methods, the IC-RT-PCR showed more sensitivity and detected virus at least at the 160 dilution. While, both ELISA and RT-PCR methods could detect up to the 120. CONCLUSION: The results reported herein showed that IC-RT-PCR is a sensitive and simple method to detect MIMV from a single insect vector with high efficiency and reliability. These findings might be useful in the prediction of viral disease incidence in host plants and this method can also be effective to detect other viruses in their insect vectors.
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Background: Newcastle disease is an important avian infectious disease that brings about vast economic damage for poultry industry. Transgenic plants represent a cost-effective system for the production of therapeutic proteins and are widely used for the production of poultry vaccines. In an attempt to develop a recombinant vaccine, a plant expression binary vector pBI121, containing the genes encoding Hemagglutinin-Neuraminidase (HN) and Fusion (F) epitopes of Newcastle Disease Virus (NDV) under the control of CaMV35S promoter and NOS terminator was constructed and introduced into the tobacco ( Nicotiana tabacum) plant by Agrobacterium-mediated transformation. Results: Putative transgenic plants were screened in a selection medium containing 50 mg/L kanamycin and 30 mg/L meropenem. Integration of the foreign gene in plant genome was confirmed by PCR. Expression of foreign gene was analyzed at transcription level by RT-PCR and at translation level by means of dot blotting and ELISA. All analyses confirmed the expression of recombinant protein. Conclusion: Developments in genetic engineering have led to plant-based systems for recombinant vaccine production. In this research, tobacco plant was used to express F and HN epitopes of NDV. Our results indicate that for the production of recombinant vaccine, it is a novel strategy to use concatenated epitopes without their genetic fusion onto larger scaffold structure such as viral coat protein.
