Search Results for: Rhizosphere

Abstract: In commercial agriculture, populations and interactions of rhizosphere microflora are potentially affected by the use of specific agrichemicals, possibly by affecting gene expression in these organisms. To investigate this, we examined changes in bacterial gene expression within the rhizosphere of glyphosate-tolerant corn (Zea mays) and soybean (Glycine max) in response to long-term glyphosate (PowerMAX™, …

Abstract: Glyphosate is a non-selective, broad-spectrum herbicide that kills plants by inhibiting the enzyme 5-enolpyruvylshikimic acid-3-phosphate synthase (EPSPS), which is necessary for synthesis of aromatic amino acids. A secondary mode of action involves infection of roots of glyphosate-susceptible plants by soil-borne micro-organisms due to decreased production of plant protection compounds known as phytoalexins. Varieties of …

Abstract: More and more investigations indicate that genetic modification has no significant or persistent effects on microbial community composition in the rice rhizosphere. Very few studies, however, have focused on its impact on functional microorganisms. This study completed a 13C-CO2pulse-chase labeling experiment comparing the potential effects of cry1Ab gene transformation on 13C tissue distribution and …

Abstract: There is a common understanding that the widely used herbicide glyphosate is easily degraded and adsorbed in soils and thus, harmless for use in agriculture. We can demonstrate, however, that this conclusion is wrong and dangerous for farmers because in former risk assessments the behaviour of glyphosate in the rhizosphere was not properly considered. …

Abstract: Current crop production relies heavily on use of transgenic, glyphosate-resistant cultivars (GR). The impacts of widespread cultivation of genetically-modified (GM) crops and the use of one herbicide class on agroecosystems, especially considering potential effects on biological processes, have received considerable attention. This paper reviews impacts of glyphosate on rhizosphere microorganisms and activities and summarizes …

Abstract: Glyphosate-resistant (GR) soybean production increases each year because of the efficacy of glyphosate for weed management. A new or ‘second’ generation of GR soybean (GR2) is now commercially available for farmers that is being promoted as higher yielding relative to the previous, ‘first generation’ (GR1) cultivars. Recent reports show that glyphosate affects the biology …

Abstract: Glyphosate is the most widely used non-selective, systemic herbicide. It is easily translocated from shoot to roots and released into the rhizosphere, where it is immobilized at the soil matrix or microbially degraded. However, contradictory results are reported in the literature concerning the bio-availability of glyphosate residues in soils and the potential risks for …

Abstract: Results obtained from several studies suggest that the pre-seeding application of the widely used herbicide glyphosate can alter the microbial community of the rhizosphere of non-target plants, as well as soil processes mediated by microorganisms. Although this impact should be related to the response of weed plants to glyphosate application, little is known on …

Abstract: Greenhouse studies were conducted to determine the following: if treating henbit or downy brome with glyphosate increased populations of Fusarium solani f. sp. pisi and Pythium ultimum in soil and rhizosphere soil; if treating henbit or downy brome with glyphosate increased root colonization and infection by E solani f sp. pisi or P ultimum; …

Abstract: We investigated the dynamics of N and P availability in the rhizosphere of Bt and non‐Bt cotton crops during their growth. In a net‐house pot culture experiment at the Indian Agricultural Research Institute, New Delhi, Bt‐cotton (cv. MRC‐6301 Bt) and its non‐transgenic near‐isoline (MRC‐6301) were grown on a sandy loam soil until maturity. A …

Abstract: The widespread use of glyphosate‐resistant (GR) cropping systems may impact rhizosphere microbial associations and crop productivity. It was previously reported that glyphosate accumulation in the rhizosphere may stimulate colonization of soybean [Glycine max (L.) Merr.] roots by soilborne Fusarium. Field studies often reveal inconsistent root colonization by Fusarium, especially during growing seasons characterized by …

Abstract: The development and use of genetically modified plants (GMPs), as well as their ecological risks have been a topic of considerable public debate since they were first released in 1996. To date, no consistent conclusions have been drawn dealing with ecological risks on soil microorganisms of GMPs for the present incompatible empirical data. Arbuscular …

Abstract: Most soybean (Glycine max L. Merr.) cultivars grown in the U.S. are Roundup Ready®, genetically modified for resistance to the herbicide glyphosate. The objectives of this study were to examine the impacts of glyphosate applications on symbiotic N2 fixation in glyphosate-resistant (GR) soybean and to evaluate the responses of rhizobial isolates and nifH gene …

Abstract: Transgenic potato plants with the nptII gene coding for neomycin phosphotransferase (kanamycin resistance) as a selection marker were examined for the spread of recombinant DNA into the environment. We used the recombinant fusion of nptII with the tg4 terminator for a novel biomonitoring technique. This depended on natural transformation of Acinetobacter sp. strain BD413 …

Abstract: The insecticidal toxin encoded by the cry1Ab gene from Bacillus thuringiensis was released in root exudates from transgenic Bt corn during 40 days of growth in soil amended to 0, 3, 6, 9, or 12% (v/v) with montmorillonite or kaolinite in a plant growth room and from plants grown to maturity in the field. …

Abstract: Recent applications of biotechnology, especially genetic engineering, have revolutionized crop improvement and increased the availability of valuable new traits. A current example is the use of the insecticidal Cry proteins from the bacterium, Bacillus thuringiensis (Bt), to improve crops, known as Btcrops, by reducing injury from various crop pests. The adoption of genetically modified …

Abstract: The effects of the insecticidal Cry1Ab protein from Bacillus thuringiensis (Bt) on the nematode, Caenorhabditis elegans, were studied with soil from experimental fields cultivated with transgenic Bt corn (MON810) and with trypsinized Cry1Ab protein expressed in Escherichia coli. The content of Cry1Ab protein was above the detection limit of an ELISA test in only …

Abstract: Antibiotic resistance rates have increased in both clinical and environmental bacteria over the past several decades. While the causes underlying these trends have been investigated in a clinical setting, little work has been done to estimate the contribution of antibiotic resistance genes (ARGs) derived from non-traditional sources like transgenic (GM) crops. The cultivation and …

Abstract: Transgenic or genetically modified plants possess novel genes that impart beneficial characteristics such as herbicide resistance. One of the least understood areas in the environmental risk assessment of genetically modified crops is their impact on soil- and plant-associated microbial communities. The potential for interaction between transgenic plants and plant residues and the soil microbial …

Abstract: Soil microorganisms are highly exposed to glyphosate-based herbicides (GBH), especially to Roundup® which is widely used worldwide. However, studies on the effects of GBH formulations on specific non-rhizosphere soil microbial species are scarce. We evaluated the toxicity of a commercial formulation of Roundup® (R450), containing 450 g/L of glyphosate (GLY), on the soil filamentous …

Abstract: The herbicide Roundup applied to Roundup Ready soybean consistently affects root-associated Fusarium. Populations increased 2-5 times 5 d after Roundup application and continued increasing for >2 wk. Soybean receiving no herbicide or conventional tank-mix had no noticeable increase in fungal populations. Specific effects of increased Fusarium are unknown; however, such imbalances in soil communities …

Text: What’s unspeakable in horizontal gene transfer? Horizontal gene transfer is the transfer of genes across species including those in different kingdoms. It goes counter to both modern genetics and the theory of evolution. Disappointingly, little of the momentous significance of the process comes across in a volume replete with detailed examples. GM foods – …

Abstract: Evidence clearly shows that cationic micronutrients in spray solutions reduce the herbicidal effectiveness of glyphosate for weed control due to the formation of metal-glyphosate complexes. The formation of these glyphosate-metal complexes in plant tissue may also impair micronutrient nutrition of nontarget plants when exposed to glyphosate drift or glyphosate residues in soil. In the …