1,177 research outputs found
Salinity affects metabolomic profiles of different trophic levels in a food chain
No full textSalinization is one of the most important abiotic stressors in an ecosystem. To examine how exposing a host plant to excess salt affects the consequent performance and metabolism of insects in a food chain, we determined the life history traits and the metabolite profiles in rice (Oryza sativa), the herbivore Sitobion avenae, and its predator Harmonia axyridis. When compared with performance under normal (non-stressed) conditions, exposing plants to 50？mM NaCl significantly delayed the timing of development for S. avenae fed on rice and H. axyridis and also reduced the body mass of the latter. Our GC？MS-based analysis revealed clear differences in metabolite profiles between trophic levels or treatment conditions. Salinity apparently increased the levels of main components in rice, but decreased levels of major components in S. avenae and H. axyridis. In addition, 16 metabolites showed salinity-related contrasts in this trophic interaction for our rice？S. avenae？H. axyridis system. Salinity impeded the accumulation of metabolites, especially several sugars, amino acids, organic acids, and fatty acids in both insects, a response that was possibly associated with the negative impacts on their growth and reproduction under stress conditions.
Compositional differences in hybrids between protoporphyrinogen IX oxidase (PPO)-inhibiting herbicide-resistant transgenic rice and weedy rice accessions
No full textWe characterized the metabolites in grains of transgenic protoporphyrinogen IX oxidase-inhibiting herbicide-resistant rice and weedy accessions using GC？MS and examined whether the chemical composition of their hybrids differed from that of the parents. We found that the metabolite profiles of transgenic rice and weedy rice were clearly separated. Although the metabolite profiles of F2 progeny were partially separated from their parents, zygosity did not affect the profiles. The F2 progeny had similar or intermediate levels of most major nutritional components compared with their parents. However, levels of galactopyranose, trehalose, xylofuranose, mannitol, and benzoic acid were higher in the F2 progeny. Some fatty acids and organic acids also showed prominent quantitative differences between the F2 progeny and the parents. Changes in the metabolite levels of transgenic crop-weed hybrids compared to their parents might influence not only the ecological consequences of the hybrids, but also the nutritional quality and food safety.
Real-time quantitative PCR with SYBR green I for living modified roundup ready soybean
No full textConcerns on the safety of living modified (LM) crops have led to mandatory-labeling legislation of LM crops in many countries including Korea. An real-time PCR method for quantification of LM Roundup Ready soybean (RRS) with the double-stranded DNA intercalating dye, SYBR Green I, is described. Pairs of primers that specifically PCR-amplify the targeted 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) and le1 gene sequences were selected by means of analysis of melting-curve plot of PCR products. Then, the specificity and general performance of the selected primer pairs were further increased by selecting optimum primer concentration by means of serial analyses of combination of different concentrations of each primer in the selected primer pairs. Using 1, 2, and 5% RRS test samples and applying the real-time PCR with SYBR Green I, mean values deviated from true values by 5.5 to 25%. The precision of the real-time PCR with SYBR Green I was comparable with that of the real-time PCR with TaqMan chemistry, which is widely used for the quantification of LM crops today. The results suggest that the real-time PCR with SYBR Green I, which does not require the high-cost dye labelling step for the initial primer or probe design, could be an alternative method for the quantification of LM Crops.open
Metabolomic changes in grains of well‐watered and drought‐stressed transgenic rice
No full textBACKGROUND: Drought induces a number of physiological and biochemical responses in cereals. This study was designed to examine the metabolite changes in grains of drought-tolerant transgenic rice (Oryza sativa L.) that overexpresses AtCYP78A7 encoding cytochrome P450 protein using proton nuclear magnetic resonance (1H-NMR) and gas chromatography/mass spectrometry. RESULTS: Principal component analysis showed that the 1H-NMR-based profile was clearly separated by soil water status of well-watered and water-deficit. A discrimination of metabolites between transgenic and non-transgenic grains appeared under both watering regimes. Variations in the levels of amino acids and sugars led to the discrimination of metabolites among genotypes. In particular, drought significantly enhanced the levels of γ-aminobutyric acid (GABA, 244.6%), fructose (155.7%), glucose (211.0%), glycerol (57.2%), glycine (65.8%) and aminoethanol (192.4%) in the transgenic grains compared with the non-transgenic control grains. CONCLUSION: These changes in amounts of metabolites may assist in improving drought tolerance in transgenic rice by playing crucial roles in stress-responsive pathways including GABA biosynthesis, sucrose metabolism and antioxidant defenses.open
Performance of hybrids between abiotic stress-tolerant transgenic rice and its weedy relatives under water-stressed conditions
No full textGene transfer from transgenic crops to their weedy relatives may introduce undesired ecological consequences that can increase the fitness and invasiveness of weedy populations. Here, we examined the rate of gene flow from abiotic stress-tolerant transgenic rice that over-express AtCYP78A7, a gene encoding cytochrome P450 protein, to six weedy rice accessions and compared the phenotypic performance and drought tolerance of their hybrids over generations. The rate of transgene flow from AtCYP78A7-overexpressing transgenic to weedy rice varied between 0% and 0.0396%. F1 hybrids containing AtCYP78A7 were significantly taller and heavier, but the percentage of ripened grains, grain numbers and weight per plant were significantly lower than their transgenic and weedy parents. The homozygous and hemizygous F2 progeny showed higher tolerance to drought stress than the nullizygous F2 progeny, as indicated by leaf rolling scores. Shoot growth of nullizygous F3 progeny was significantly greater than weedy rice under water-deficient conditions in a rainout shelter, however, that of homozygous F3 progeny was similar to weedy rice, indicating the cost of continuous expression of transgene. Our findings imply that gene flow from AtCYP78A7-overexpressing transgenic to weedy rice might increase drought tolerance as shown in the pot experiment, however, increased fitness under stressed conditions in the field were not observed for hybrid progeny containing transgenes.
Growth stage-based metabolite profiling of drought-tolerant transgenic rice under well-watered and deficit conditions
No full textMetabolite profiling of transgenic crops is useful when evaluating the intended and unintended effects of genetic modifications. Our study objective was to investigate variations in metabolites from drought-tolerant transgenic rice (Oryza sativa L.) that over-expresses AtCYP78A7, a gene encoding cytochrome P450 protein. Two transgenic Lines, '10B-5' and '18A-4', plus the wild-type 'Hwayoung', were cultivated under either well-watered or water-deficit conditions in a rainout shelter. Their shoots were collected at the tillering, heading, and ripening stages and polar extracts were subsequently analyzed by 1H-NMR and GC-MS. Principal component analysis revealed that the metabolite profiles could be clearly distinguished during those stages. Soil-water conditions also contributed to the variation in profiles. However, a marked discrimination of metabolites between transgenic and non-transgenic rice was apparent only under water-deficit conditions at the heading stage. This was mainly a result of differences in the sugar-related NMR profiles among genotypes. Our data suggested that the genetic contribution to metabolite profiles is constrained by growth stage and water status. In addition, sugar content is of great importance when separating metabolite profiles in shoots from rice plants that over-express AtCYP78A7.open
Gene flow from GM cabbage to non-GM control
No full textUnderstanding the gene flow from genetically modified (GM) crops to conventional crops is important to prevent
and mitigate seed contamination caused by pollen-mediated gene flow. We conducted a field test to investigate the gene
flow from diamondback moth resistant GM cabbage (Brassica oleracea var. capitata) containing cry1Ac1 gene, to a
non-GM control line AD126. GM and non-GM cabbage plants were cultivated in the field and pollinated using Bombus
terrestris under the nets during the flowering periods. After seeds were collected from non-GM plants, hybrids between
them and the GM cabbages were screened by multiplex PCR targeting cry1Ac1 gene. Out of 878 germinated seedlings,
168 hybrids were found and the average gene flow frequency was 19.7%. Because cabbage is mainly pollinated by insect
pollinators, large-scale field tests are needed to study gene flow of GM cabbage.open
Characterization of SMV resistance of soybean produced by genetic transformation of SMV-CP gene in RNAi
No full textSoybean mosaic virus (SMV), a species of the Potyvirus genus in the Potyviridae family, is one of the most typical viral diseases and results in yield and quality loss of cultivated soybean. Due to the depletion of genetic resources for resistance breeding, a trial of genetic transformation to improve disease resistance has been performed by introducing the SMV-CP gene by the RNA interference (RNAi) method via Agrobacterium-mediated transformation. Among 30 transgenic plants produced, 7 lines with enough seeds were infected with SMV and two lines (3 and 4) showed viral resistance to SMV infection. In genomic Southern blot analysis, all the lines tested contained at least one T-DNA insertion. Subsequent investigation confirmed that no viral CP gene expression was detected in two SMV-resistant lines after artificial inoculation of SMV, while non-transgenic control and other transgenic lines expressed substantial amounts of the viral gene. Viral symptoms affected seed morphology, and clean seeds were harvested from the resistant lines. Also, strong viral gene expression was detected from the seeds of susceptible lines. In further generations, the same phenotypic appearance was maintained among non-transgenic and transgenic plants. Finally, the presence of helper component-proteinase (HC-Pro), known as a suppressor of gene silencing apparatus, was checked among transgenic lines. No expression of HC-Pro in resistant lines indicated that the viral CP-RNAi transformation into soybean somehow created a functional gene silencing system and resulted in a viral-resistant phenotype.open
Drought-simulation facility for assessing tolerance and risks of genetically modified crops
No full textWe designed and constructed a drought-simulation facility for use in producing droughttolerant transgenic crops and assessing their associated risks. This facility consists of soil storage containers and rainout shelters. Each container is equipped with an efficient drainage system so that proper drought conditions can be maintained by controlling water flow to and from the soil. The polyvinyl roof and sidewalls close automatically during rain events to exclude rainfall from plots within the containers but re-open under dry conditions. Water is supplied via sub-surface drip irrigation. The soil water content is monitored at 30-min intervals by sensors installed at depths of 10, 20, 30, and 40 cm. For testing its performance, the field within the facility was divided into two systems, well-watered and water-deficit. Three cultivars of rice were grown. During the experiment, the soil water content was relatively lower in the water-deficit system. Regardless of cultivar, the mean values for plant height; panicle length; grain number, weight, and width; 1000-grain weight; and overall yield were significantly lower in that system when compared with those parameters in the well-watered system.open
Effects of transgenic poplars expressing increased levels of cellular cytokinin on rhizosphere microbial communities
No full textConsiderable effort has been made in biotechnology to increase plant biomass. Altering cellular levels of plant hormones, including cytokinin, by genetic modification, has been one way to achieve the goal as it is involved in a variety of processes related to plant growth and development. However, the alteration inevitably may change physiological and biochemical characteristics of plants, and thus could affect the relationship between plants and other organisms interacting with the plants such as microorganisms inhabiting in the rhizosphere. To determine if these indirect effects on rhizosphere microorganisms, mediated by hormonal changes in plants, do occur, we investigated the microbial biomass and community structure associated with transgenic Populus trees with altered cellular cytokinin levels, using phospholipid fatty acid (PLFA) analysis. Three transgenic lines expressing increased levels of cellular cytokinin (T1403, T1410, and T1413) and their non-transgenic isoline (BH) were planted at three locations (Suwon, Cheongwon, and Jinju) in 2011. Soil samples were collected near the base of each tree monthly, from May to September. Indicator PLFAs were utilized to calculate the microbial (bacterial and fungal) biomass, and PLFA profiles were developed to characterize the structure of those communities. Over the growing season, soils from Cheongwon and Jinju had similar microbial biomasses (PLFAs indicating functional groups) whereas, at Suwon, the biomass associated with the rhizosphere of Line T1413 was significantly different from that of the other transgenics and the control. At Cheongwon and Jinju, the structure of the rhizosphere microbial communities differed significantly between Lines T1403 or T1410 and BH, but only in May and June. By contrast, those structures were similar in all sampling months for each line at Suwon. Our results indicate that the influence resulting from genetic modification of the poplar trees on the rhizosphere microbial community is only temporary and inconsistent depending upon location and genetic line.open
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