Sub-lethal glyphosate exposure alters flowering phenology and causes transient male-sterility in Brassica spp.

Background: Herbicide resistance in weedy plant populations can develop through different mechanisms such as gene flow of herbicide resistance transgenes from crop species into compatible weedy species or by natural evolution of herbicide resistance or tolerance following selection pressure. Results from our previous studies suggest that sub-lethal levels of the herbicide glyphosate can alter the pattern of gene flow between glyphosate resistant Canola®, Brassica napus, and glyphosate sensitive varieties of B. napus and B.

Changes in constructed Brassica communities treated with glyphosate drift.

We constructed a mixed-species community designed to simulate roadside and field edge plant communities and exposed it to glyphosate drift in order to test three hypotheses: (1) higher fitness in transgenic Brassica carrying the CP4 EPSPS transgene that confers resistance to glyphosate will result in significant changes in the plant community relative to control communities; (2) given repeated years of glyphosate drift selective pressure, the increased fitness of the transgenic Brassica with CP4 EPSPS will contribute to an increase in the proportion of transgenic progeny produced in plant communities; and (3) the increased fitness of Brassica carrying the CP4 EPSPS transgene will contribute to decreased levels of mycorrhizal infection and biomass in a host species (Trifolium incarnatum). Due to regulatory constraints that prevented the use of outdoor plots for our studies, in 2005 we established multispecies communities in five large cylindrical outdoor sunlit mesocosms (plastic greenhouses) designed for pollen confinement. Three of the community members were sexually compatible Brassica spp.

Glyphosate-drift but not herbivory alters the rate of transgene flow from single and stacked trait transgenic canola (Brassica napus) to nontransgenic B. napus and B. rapa.

• Transgenic plants can offer agricultural benefits, but the escape of transgenes is an environmental concern. In this study we tested the hypothesis that glyphosate drift and herbivory selective pressures can change the rate of transgene flow between the crop Brassica napus (canola), and weedy species and contribute to the potential for increased transgene escape risk and persistence outside of cultivation. • We constructed plant communities containing single transgenic B.

Changes in fitness-associated traits due to the stacking of transgenic glyphosate resistance and insect resistance in Brassica napus L.

Increasingly, genetically modified crops are being developed to express multiple 'stacked' traits for different types of transgenes, for example, herbicide resistance, insect resistance, crop quality and tolerance to environmental stresses. The release of crops that express multiple traits could result in ecological changes in weedy environments if feral crop plants or hybrids formed with compatible weeds results in more competitive plants outside of agriculture. To examine the effects of combining transgenes, we developed a stacked line of canola (Brassica napus L.

Glyphosate drift promotes changes in fitness and transgene gene flow in canola (Brassica napus) and hybrids.

Background And Aims: With the advent of transgenic crops, genetically modified, herbicide-resistant Brassica napus has become a model system for examining the risks and potential ecological consequences of escape of transgenes from cultivation into wild compatible species. Escaped transgenic feral B. napus and hybrids with compatible weedy species have been identified outside of agriculture and without the apparent selection for herbicide resistance.

A composite transcriptional signature differentiates responses towards closely related herbicides in Arabidopsis thaliana and Brassica napus.

In this study, genome-wide expression profiling based on Affymetrix ATH1 arrays was used to identify discriminating responses of Arabidopsis thaliana to five herbicides, which contain active ingredients targeting two different branches of amino acid biosynthesis. One herbicide contained glyphosate, which targets 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), while the other four herbicides contain different acetolactate synthase (ALS) inhibiting compounds. In contrast to the herbicide containing glyphosate, which affected only a few transcripts, many effects of the ALS inhibiting herbicides were revealed based on transcriptional changes related to ribosome biogenesis and translation, secondary metabolism, cell wall modification and growth.

Response of Six Potato Cultivars to Amount of Applied Water and Verticillium dahliae.

ABSTRACT Six potato cultivars were grown with or without the addition of Verticillium dahliae inoculum and were watered at 50, 75, or 100% estimated consumptive use. The applied water x cultivar interaction was significant (P = 0.009 and P = 0.

Simultaneous one-tube quantification of host and pathogen DNA with real-time polymerase chain reaction.

ABSTRACT Phaeocryptopus gaeumannii is a widespread foliar parasite of Douglas-fir. Although normally innocuous, the fungus also causes the defoliating disease Swiss needle cast in heavily infected needles. The extent of P.

Bt crop effects on functional guilds of non-target arthropods: a meta-analysis.

Background: Uncertainty persists over the environmental effects of genetically-engineered crops that produce the insecticidal Cry proteins of Bacillus thuringiensis (Bt). We performed meta-analyses on a modified public database to synthesize current knowledge about the effects of Bt cotton, maize and potato on the abundance and interactions of arthropod non-target functional guilds.

Methodology/principal Findings: We compared the abundance of predators, parasitoids, omnivores, detritivores and herbivores under scenarios in which neither, only the non-Bt crops, or both Bt and non-Bt crops received insecticide treatments.

Long-distance GM pollen movement of creeping bentgrass using modeled wind trajectory analysis.

The importance of understanding the role of atmospheric conditions in pollen dispersal has grown in recent years with increased field-testing of genetically modified (GM) crop plants. An atmospheric model was used to characterize wind trajectories at 10 m and 100 m above GM pollen source fields located within a 4452-ha "control" area north of Madras, Oregon, USA, designated by the Oregon Department of Agriculture (ODA). The area was used in 2003 for the growth of GM creeping bentgrass (Agrostis stolonifera) engineered to be resistant to glyphosate herbicide.

Establishment of transgenic herbicide-resistant creeping bentgrass (Agrostis stolonifera L.) in nonagronomic habitats.

Concerns about genetically modified (GM) crops include transgene flow to compatible wild species and unintended ecological consequences of potential transgene introgression. However, there has been little empirical documentation of establishment and distribution of transgenic plants in wild populations. We present herein the first evidence for escape of transgenes into wild plant populations within the USA; glyphosate-resistant creeping bentgrass (Agrostis stolonifera L.

Comparison of taxonomic, colony morphotype and PCR-RFLP methods to characterize microfungal diversity.

We compared three methods for estimating fungal species diversity in soil samples. A rapid screening method based on gross colony morphological features and color reference standards was compared with traditional fungal taxonomic methods and PCR-RFLP for estimation of ecological indices of soil microfungal community composition. Normalized counts of colony morphotypes on dichloran rose bengal medium were used to estimate species richness (S) and evenness (J) and to calculate Shannon's diversity (H) and Simpson's (SI) dominance indices.

Evidence for landscape-level, pollen-mediated gene flow from genetically modified creeping bentgrass with CP4 EPSPS as a marker.

Sampling methods and results of a gene flow study are described that will be of interest to plant scientists, evolutionary biologists, ecologists, and stakeholders assessing the environmental safety of transgenic crops. This study documents gene flow on a landscape level from creeping bentgrass (Agrostis stolonifera L.), one of the first wind-pollinated, perennial, and highly outcrossing transgenic crops being developed for commercial use.

Interactive effects of CO2 and O3 on a ponderosa pine plant/litter/soil mesocosm.

To study individual and combined impacts of two important atmospheric trace gases, CO2 and O3, on C and N cycling in forest ecosystems; a multi-year experiment using a small-scale ponderosa pine (Pinus ponderosa Laws.) seedling/soil/litter system was initiated in April 1998. The experiment was conducted in outdoor, sun-lit chambers where aboveground and belowground ecological processes could be studied in detail.

Fingerprinting of mixed bacterial strains and BIOLOG gram-negative (GN) substrate communities by enterobacterial repetitive intergenic consensus sequence-PCR (ERIC-PCR).

PCR-based genomic fingerprinting by use of enterobacterial repetitive intergenic consensus primers (ERIC-PCR) was evaluated for its use in fingerprinting DNA of mixed Gram-negative bacterial strains and BIOLOG Gram-negative (GN) microplate substrate communities. ERIC-PCR fingerprints of six different pure bacterial strains and a combined mixture of the strains were compared with fingerprints obtained by two more established methods: amplified ribosomal DNA restriction analysis (ARDRA) and random amplified polymorphic DNA analysis (RAPD-PCR). The ERIC-PCR fingerprint of the mixed strains was highly reproducible and was more species-specific and representative of the individual strain fingerprints than the ARDRA and RAPD-PCR fingerprints, respectively.

Comparison of Parental and Transgenic Alfalfa Rhizosphere Bacterial Communities Using Biolog GN Metabolic Fingerprinting and Enterobacterial Repetitive Intergenic Consensus Sequence-PCR (ERIC-PCR).

> Abstract Rhizosphere bacterial communities of parental and two transgenic alfalfa (Medicago sativa L.) of isogenic background were compared based on metabolic fingerprinting using Biolog GN microplates and DNA fingerprinting of bacterial communities present in Biolog GN substrate wells by enterobacterial repetitive intergenic consensus sequence-PCR (ERIC-PCR). The two transgenic alfalfa expressed either bacterial (Bacillus licheniformis) genes for alpha-amylase or fungal (Phanerochaete chrysosporium) genes for Mn-dependent lignin peroxidase (Austin S, Bingham ET, Matthews DE, Shahan MN, Will J, Burgess RR, Euphytica 85:381-393).

A highly selective PCR protocol for detecting 16S rRNA genes of the genus Pseudomonas (sensu stricto) in environmental samples.

Pseudomonas species are plant, animal, and human pathogens; exhibit plant pathogen-suppressing properties useful in biological control; or express metabolic versatilities valued in biotechnology and bioremediation. Specific detection of Pseudomonas species in the environment may help us gain a more complete understanding of the ecological significance of these microorganisms. The objective of this study was to develop a PCR protocol for selective detection of Pseudomonas (sensu stricto) in environmental samples.

A carbon starvation survival gene of Pseudomonas putida is regulated by sigma 54.

By using mini-Tn5 transposon mutagenesis, two mutants of Pseudomonas putida ATCC 12633 were isolated which showed a marked increase in their sensitivity to carbon starvation; these mutants are presumably affected in the Pex type of proteins that P. putida induces upon carbon starvation (M. Givskov, L.

An effective method to extract DNA from environmental samples for polymerase chain reaction amplification and DNA fingerprint analysis.

A rapid direct-extraction method was used to obtain DNA from environmental soil samples. Heat, enzymes, and guanidine isothiocyanate were utilized to lyse cells. The DNA was purified by agarose gel electrophoresis, amplified with 16S rRNA-based primers by use of the polymerase chain reaction, and then digested with the restriction endonuclease PalI.

Tn5-mediated integration of the delta-endotoxin gene from Bacillus thuringiensis into the chromosome of root-colonizing pseudomonads.

Gene replacement mediated by Tn5 sequences was used to integrate the Bacillus thuringiensis subsp. kurstaki HD-1 delta-endotoxin gene (tox) into the chromosome of two corn root-colonizing strains of Pseudomonas fluorescens. A Tn5 transposase deletion element containing the tox gene (delta Tn5-tox) was substituted for a Tn5 element previously present in the P.

Integration of the delta-endotoxin gene of Bacillus thuringiensis into the chromosome of root-colonizing strains of pseudomonads using Tn5.

The delta-endotoxin gene (tox) from Bacillus thuringiensis subsp. kurstaki HD-1 was cloned into Tn5 and the resulting Tn5-tox element transposed from a vector plasmid into the chromosome of six corn-root-colonizing strains of Pseudomonas fluorescens and Agrobacterium radiobacter. Chromosomal integration of the tox gene maximized stability and minimized the potential for horizontal transfer of the tox gene to other bacterial species.

Induction of a Sensitive Response to Helminthosporium maydis Race T Toxin in Resistant Mitochondria of Corn (Zea mays L.) by Removal of the Outer Mitochondrial Membrane.

Mitochondria isolated from Texas cytoplasmically male sterile (Tms) and normal (N) versions of corn (Zea mays L.) exhibit differential sensitivity to toxin(s) produced by Helminthosporium maydis race T, the causal organism of southern corn leaf blight. Malate dehydrogenase was inhibited by toxin(s) in intact Tms mitochondria but was unaffected in N mitochondria.

Cobalt as a mitochondrial density marker in a study of cytoplasmic exchange during mating of Schizophyllum commune.

A slow in vivo uptake of cobalt from a growth medium resulted in an increase in density of mitochondria of Schizophyllum commune. Differential labeling of donor and resident mycelia, and subsequent analysis of resident mycelia surrounding donor implants, detected cobalt-dense mitochondria and demonstrated exchange of mitochondria after hyphal fusion. Transfer of mitochondria occurred in fully compatible, common-A, and common-AB matings, but was not detected in common-B matings of the tetrapolar Basidiomycete S.