Pollen-mediated gene flow from transgenic cotton is constrained by physical isolation measures.
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ABSTRACT:
SUBMITTER: Yan S
PROVIDER: S-EPMC5809611 | biostudies-literature | 2018 Feb
REPOSITORIES: biostudies-literature
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Pollen-mediated gene flow from transgenic cotton is constrained by physical isolation measures.
Yan Shuo S Zhu Weilong W Zhang Boyu B Zhang Xinmi X Zhu Jialin J Shi Jizhe J Wu Pengxiang P Wu Fengming F Li Xiangrui X Zhang Qingwen Q Liu Xiaoxia X
Scientific reports 20180212 1
The public concern about pollen-mediated gene flow (PGF) from genetically modified (GM) crops to non-GM crops heats up in recent years over China. In the current study, we conducted greenhouse and field experiments to measure PGF with various physical isolation measures, including 90, 80, 60 and 40 holes/cm<sup>2</sup> separation nets and Sorghum bicolor, Zea mays and Lycopersicon esculentum separation crops between GM cotton and non-GM line (Shiyuan321) by seed DNA test during 2013 to 2015, and ...[more]
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Project description:With the large-scale release of genetically modified (GM) crops, there are ecological concerns on transgene movement from GM crops to non-GM counterparts and wild relatives. In this research, we conducted greenhouse experiments to measure pollen-mediated gene flow (PGF) in the absence and presence of pollinators (Bombus ignitus, Apis mellifera and Pieris rapae) in one GM cotton (resistant to the insect Helicoverpa armigera and the herbicide glyphosate) and two non-GM lines (Shiyuan321 and Hai7124) during 2012 and 2013. Our results revealed that: (1) PGF varied depending on the pollinator species, and was highest with B. ignitus (10.83%) and lowest with P. rapae (2.71%); (2) PGF with B. ignitus depended on the distance between GM and non-GM cottons; (3) total PGF to Shiyuan321 (8.61%) was higher than to Hai7124 (4.10%). To confirm gene flow, we tested hybrids carrying transgenes for their resistance to glyphosate and H. armigera, and most hybrids showed strong resistance to the herbicide and insect. Our research confirmed that PGF depended on pollinator species, distance between plants and the receptor plant.
| S-EPMC4630633 | biostudies-literature
Project description:BackgroundSwitchgrass is C4 perennial grass species that is being developed as a cellulosic bioenergy feedstock. It is wind-pollinated and considered to be an obligate outcrosser. Genetic engineering has been used to alter cell walls for more facile bioprocessing and biofuel yield. Gene flow from transgenic cultivars would likely be of regulatory concern. In this study we investigated pollen-mediated gene flow from transgenic to nontransgenic switchgrass in a 3-year field experiment performed in Oliver Springs, Tennessee, U.S.A. using a modified Nelder wheel design. The planted area (0.6 ha) contained sexually compatible pollen source and pollen receptor switchgrass plants. One hundred clonal switchgrass 'Alamo' plants transgenic for an orange-fluorescent protein (OFP) and hygromycin resistance were used as the pollen source; whole plants, including pollen, were orange-fluorescent. To assess pollen movement, pollen traps were placed at 10 m intervals from the pollen-source plot in the four cardinal directions extending to 20 m, 30 m, 30 m, and 100 m to the north, south, west, and east, respectively. To assess pollination rates, nontransgenic 'Alamo 2' switchgrass clones were planted in pairs adjacent to pollen traps.ResultsIn the eastward direction there was a 98% decrease in OFP pollen grains from 10 to 100 m from the pollen-source plot (Poisson regression, F1,8 = 288.38, P < 0.0001). At the end of the second and third year, 1,820 F1 seeds were collected from pollen recipient-plots of which 962 (52.9%) germinated and analyzed for their transgenic status. Transgenic progeny production detected in each pollen-recipient plot decreased with increased distance from the edge of the transgenic plot (Poisson regression, F1,15 = 12.98, P < 0.003). The frequency of transgenic progeny detected in the eastward plots (the direction of the prevailing wind) ranged from 79.2% at 10 m to 9.3% at 100 m.ConclusionsIn these experiments we found transgenic pollen movement and hybridization rates to be inversely associated with distance. However, these data suggest pollen-mediated gene flow is likely to occur up to, at least, 100 m. This study gives baseline data useful to determine isolation distances and other management practices should transgenic switchgrass be grown commercially in relevant environments.
| S-EPMC5414321 | biostudies-literature
Project description:The planting of 162 ha of transgenic glyphosate-resistant creeping bentgrass (Agrostis stolonifera) near Madras, OR, USA, allowed a unique opportunity to study gene flow over time from a perennial outcrossing species at the landscape level. While conducting a four year in situ survey, we collected panicles and leaf tissue samples from creeping bentgrass and its sexually compatible species. Seeds from the panicles were planted, and seedlings were tested in the greenhouse for expression of the transgene. Gene flow via pollen was found in all four years, at frequencies of 0.004 to 2.805%. Chloroplast markers, in combination with internal transcribed spacer nuclear sequence analysis, were used to aid in identification of transgenic interspecific and intergeneric hybrid seedlings found during the testing and of established plants that could not be positively identified in the field. Interspecific transgenic hybrids produced on redtop (Agrostis gigantea) plants in situ were identified three of the four years and one intergeneric transgenic creeping bentgrass x rabbitfoot grass (Polypogon monspeliensis) hybrid was identified in 2005. In addition, we confirmed a non-transgenic creeping bentgrass x redtop hybrid in situ, demonstrating that interspecific hybrids have established in the environment outside production fields. Results of this study should be considered for deregulation of transgenic events, studies of population dynamics, and prediction of gene flow in the environment.
| S-EPMC5336273 | biostudies-literature
Project description:Pollen-mediated gene flow (PMGF) is the main mode of transgene flow in flowering plants. The study of pollen and gene flow of transgenic wheat can help to establish the corresponding strategy for preventing transgene escape and contamination between compatible genotypes in wheat. To investigate the pollen dispersal and gene flow frequency in various directions and distances around the pollen source and detect the association between frequency of transgene flow and pollen density from transgenic wheat, a concentric circle design was adopted to conduct a field experiment using transgenic wheat with resistance to wheat yellow mosaic virus (WYMV) as the pollen donor and dwarf male-sterile wheat as the pollen receptor. The results showed that the pollen and gene flow of transgenic wheat varied significantly among the different compass sectors. A higher pollen density and gene flow frequency was observed in the downwind SW and W sectors, with average frequencies of transgene flow of 26.37 and 23.69% respectively. The pollen and gene flow of transgenic wheat declined dramatically with increasing distance from its source. Most of the pollen grains concentrated within 5 m and only a few pollen grains were detected beyond 30 m. The percentage of transgene flow was the highest where adjacent to the pollen source, with an average of 48.24% for all eight compass directions at 0 m distance. Transgene flow was reduced to 50% and 95% between 1.61 to 3.15 m, and 10.71 to 20.93 m, respectively. Our results suggest that climate conditions, especially wind direction, may significantly affect pollen dispersal and gene flow of wheat. The isolation-by-distance model is one of the most effective methods for achieving stringent transgene confinement in wheat. The frequency of transgene flow is directly correlated with the relative density of GM pollen grains in air currents, and pollen competition may be a major factor influencing transgene flow.
| S-EPMC4790897 | biostudies-literature
Project description:Hpa1Xoo-Mediated Transcriptome in Transgenic Cotton Reveals the Constitutively Expressed Diverse Defense genes in Multiple Signaling Pathways Associated with Hypersensitive Cell Death Like other harpins, harpinXoo enables plants to acquire multiple resistance to pathogen and insect attack. However, the molecular model is not fully understood, especially in transgenic plant harpinXoo for genome-wide constitutive expression. Here, we showed that 530 cDNAs differentially expressed in transgenic hpa1Xoo-harboring cotton (T-34) compared to its receiptor (Z35), through analyzing the transcriptome profile in a customized cotton 12k cDNA microarray, which was enriched in 34 pathways. Among them, 123 genes were identified from T-34 as hypersensitive reaction-mediated defense genes, involved in reactive oxygen species-, salicylic acid-, jasmonates-, ethylene-, auxin-, abscisic acid-, and Ca2+-mediated signaling pathways, and we uncovered various components of defense responses associated with recognition of the pathogen-derived elicitor. Apart from elevated genes for basic defense, harpinXoo activated leucine-rich-repeat plant receptor kinases and mitogen-activated protein kinase cascade to strengthen downstream defense responses, including production of antimicrobial compounds in T-34. Defense genes from T-34 were expressed at a much higher level in response to pathogen infection compared with Z35. Simultaneous up- and down-regulation in differentially-expressed genes, and increased expression of genes encoding energy producing and consuming pathways, suggested that energy balance was maintained in the genetically modified cotton without biotic stress. High-energy demand only occurred following pathogen infection.
2010-12-01 | GSE20446 | GEO
Project description:Hpa1Xoo-Mediated Transcriptome in Transgenic Cotton Reveals the Constitutively Expressed Diverse Defense genes in Multiple Signaling Pathways Associated with Hypersensitive Cell Death Like other harpins, harpinXoo enables plants to acquire multiple resistance to pathogen and insect attack. However, the molecular model is not fully understood, especially in transgenic plant harpinXoo for genome-wide constitutive expression. Here, we showed that 530 cDNAs differentially expressed in transgenic hpa1Xoo-harboring cotton (T-34) compared to its receiptor (Z35), through analyzing the transcriptome profile in a customized cotton 12k cDNA microarray, which was enriched in 34 pathways. Among them, 123 genes were identified from T-34 as hypersensitive reaction-mediated defense genes, involved in reactive oxygen species-, salicylic acid-, jasmonates-, ethylene-, auxin-, abscisic acid-, and Ca2+-mediated signaling pathways, and we uncovered various components of defense responses associated with recognition of the pathogen-derived elicitor. Apart from elevated genes for basic defense, harpinXoo activated leucine-rich-repeat plant receptor kinases and mitogen-activated protein kinase cascade to strengthen downstream defense responses, including production of antimicrobial compounds in T-34. Defense genes from T-34 were expressed at a much higher level in response to pathogen infection compared with Z35. Simultaneous up- and down-regulation in differentially-expressed genes, and increased expression of genes encoding energy producing and consuming pathways, suggested that energy balance was maintained in the genetically modified cotton without biotic stress. High-energy demand only occurred following pathogen infection. Using kanamycin-resistance tests, positive plants were successfully screened from transgenic cotton T-34 T6 progenies; all the receiptor Z35 plants gave negative results. We randomly selected three positive plants for polymerase chain reaction (PCR) analysis; the different positive bands (420, 310 and 180 bp) were confirmed as harpinXoo, the 35s promoter, and the NOS terminator, respectively, by sequencing and BLAST searches (www.ncbi.nlm.nih.gov.). For further analysis, the positive results were confirmed by Southern and western blots. Three positive bands were obtained in each T-34 sample located at about 4, 6 and 10 kb in the Southern blot. This pattern suggests that T-34 incorporated the harpinXoo transgene at multiple chromosomal locations. Western blot analysis showed that the harpinXoo protein was constitutively expressed in T-34 transgenic lines, whereas it was barely detectable in Z35 (data not shown). The transgenic plants contained a selectable ‘marker’ gene, neomycin phosphotransferase II (nptII). Previous research showed that expression of marker genes (e.g. nptII, uidA, hph and uidA-gfp) did not contribute to visible phenotypes in transgenic plants. The non-targeted transgenic and non-transgenic plants were equivalent in their global patterns of transcription (El Ouakfaoui and Miki, 2005). Thus, the present study examined the many differences between T-34 and its receiptor Z35 in regard to the whole genome expression of G. hirsutum using microarrays to monitor changes in individual gene expression level effected by harpinXoo. All experiments were conducted using the 12k cotton cDNA microarray, and cotton true leaves and roots at the 4–5-true-leaf-stage. The use of this microarray enabled a quantitative approach to examine changes in transcript level for all genes within the G. hirsutum genome; as a result, inferences can be drawn regarding the molecular effects of transgenic cotton expressing harpinXoo. There were three biological replicates in the experiment for each organ.
2010-12-01 | E-GEOD-20446 | biostudies-arrayexpress
Project description:Coexistence allows growers and consumers the choice of producing or purchasing conventional or organic crops with known standards for adventitious presence of genetically engineered (GE) seed. Flax (Linum usitatissimum L.) is multipurpose oilseed crop in which product diversity and utility could be enhanced for industrial, nutraceutical and pharmaceutical markets through genetic engineering. If GE flax were released commercially, pollen-mediated gene flow will determine in part whether GE flax could coexist without compromising other markets. As a part of pre-commercialization risk assessment, we quantified pollen-mediated gene flow between two cultivars of flax. Field experiments were conducted at four locations during 2006 and 2007 in western Canada using a concentric donor (20 × 20 m) receptor (120 × 120 m) design. Gene flow was detected through the xenia effect of dominant alleles of high ?-linolenic acid (ALA; 18:3(cis?9,12,15)) to the low ALA trait. Seeds were harvested from the pollen recipient plots up to a distance of 50 m in eight directions from the pollen donor. High ALA seeds were identified using a thiobarbituric acid test and served as a marker for gene flow. Binomial distribution and power analysis were used to predict the minimum number of seeds statistically required to detect the frequency of gene flow at specific ? (confidence interval) and power (1-?) values. As a result of the low frequency of gene flow, approximately 4 million seeds were screened to derive accurate quantification. Frequency of gene flow was highest near the source: averaging 0.0185 at 0.1 m but declined rapidly with distance, 0.0013 and 0.00003 at 3 and 35 m, respectively. Gene flow was reduced to 50% (O??) and 90% (O??) between 0.85 to 2.64 m, and 5.68 to 17.56 m, respectively. No gene flow was detected at any site or year > 35 m distance from the pollen source, suggesting that frequency of gene flow was ? 0.00003 (P = 0.95). Although it is not possible to eliminate all adventitious presence caused by pollen-mediated gene flow, through harvest blending and the use of buffer zones between GE and conventional flax fields, it could be minimized. Managing other sources of adventitious presence including seed mixing and volunteer populations may be more problematic.
| S-EPMC3183899 | biostudies-other
Project description:Background and aimsWild olive ( Olea europaea subsp. europaea var. sylvestris ) is important from an economic and ecological point of view. The effects of anthropogenic activities may lead to the genetic erosion of its genetic patrimony, which has high value for breeding programmes. In particular, the consequences of the introgression from cultivated stands are strongly dependent on the extent of gene flow and therefore this work aims at quantitatively describing contemporary gene flow patterns in wild olive natural populations.MethodsThe studied wild population is located in an undisturbed forest, in southern Spain, considered one of the few extant hotspots of true oleaster diversity. A total of 225 potential father trees and seeds issued from five mother trees were genotyped by eight microsatellite markers. Levels of contemporary pollen flow, in terms of both pollen immigration rates and within-population dynamics, were measured through paternity analyses. Moreover, the extent of fine-scale spatial genetic structure (SGS) was studied to assess the relative importance of seed and pollen dispersal in shaping the spatial distribution of genetic variation.Key resultsThe results showed that the population under study is characterized by a high genetic diversity, a relatively high pollen immigration rate (0·57), an average within-population pollen dispersal of about 107 m and weak but significant SGS up to 40 m. The population is a mosaic of several intermingled genetic clusters that is likely to be generated by spatially restricted seed dispersal. Moreover, wild oleasters were found to be self-incompatible and preferential mating between some genotypes was revealed.ConclusionsKnowledge of the within-population genetic structure and gene flow dynamics will lead to identifying possible strategies aimed at limiting the effect of anthropogenic activities and improving breeding programmes for the conservation of olive tree forest genetic resources.
| S-EPMC5571374 | biostudies-literature
Project description:A field experiment was conducted to quantify pollen mediated gene flow (PMGF) from glyphosate-resistant (GR) to glyphosate-susceptible (GS) giant ragweed under simulated field conditions using glyphosate resistance as a selective marker. Field experiments were conducted in a concentric design with the GR giant ragweed pollen source planted in the center and GS giant ragweed pollen receptors surrounding the center in eight directional blocks at specified distances (between 0.1 and 35?m in cardinal and ordinal directions; and additional 50?m for ordinal directions). Seeds of GS giant ragweed were harvested from the pollen receptor blocks and a total of 100,938 giant ragweed plants were screened with glyphosate applied at 2,520?g ae ha-1 and 16,813 plants confirmed resistant. The frequency of PMGF was fit to a double exponential decay model selected by information-theoretic criteria. The highest frequency of gene flow (0.43 to 0.60) was observed at ?0.5?m from the pollen source and reduced rapidly with increasing distances; however, gene flow (0.03 to 0.04) was detected up to 50?m. The correlation between PMGF and wind parameters was inconsistent in magnitude, direction, and years.
| S-EPMC5719015 | biostudies-literature
Project description:RNA interference (RNAi) has been developed as an efficient technology. RNAi insect-resistant transgenic plants expressing double-stranded RNA (dsRNA) that is ingested into insects to silence target genes can affect the viability of these pests or even lead to their death. HaHR3, a molt-regulating transcription factor gene, was previously selected as a target expressed in bacteria and tobacco plants to control Helicoverpa armigera by RNAi technology. In this work, we selected the dsRNA-HaHR3 fragment to silence HaHR3 in cotton bollworm for plant mediated-RNAi research. A total of 19 transgenic cotton lines expressing HaHR3 were successfully cultivated, and seven generated lines were used to perform feeding bioassays. Transgenic cotton plants expressing dsHaHR3 were shown to induce high larval mortality and deformities of pupation and adult eclosion when used to feed the newly hatched larvae, and 3rd and 5th instar larvae of H. armigera. Moreover, HaHR3 transgenic cotton also demonstrated an improved cotton yield when compared with controls.
| S-EPMC5618523 | biostudies-literature