1,720,971 research outputs found
A new selectable marker gene from alfalfa
No full textAbstract comunicazione orale 12th Congress of the International Association of Plant Biotechnology and 2010 In vitro Biology Meeting, St. Louis, MO, USA, June 6-11, 2010
An overview of the last 10 years of genetically engineered crop safety research.
No full textThe technology to produce genetically engineered (GE) plants is celebrating its 30th anniversary
and one of the major achievements has been the development of GE crops. The safety of GE
crops is crucial for their adoption and has been the object of intense research work often
ignored in the public debate. We have reviewed the scientific literature on GE crop safety
during the last 10 years, built a classified and manageable list of scientific papers, and analyzed
the distribution and composition of the published literature. We selected original research
papers, reviews, relevant opinions and reports addressing all the major issues that emerged
in the debate on GE crops, trying to catch the scientific consensus that has matured since GE plants became widely cultivated worldwide. The scientific research conducted so far has not detected any significant hazards directly connected with the use of GE crops; however, the debate is still intense. An improvement in the efficacy of scientific communication could have a significant impact on the future of agricultural GE. Our collection of scientific records is available to researchers, communicators and teachers at all levels to help create an informed, balanced public perception on the important issue of GE use in agricultur
Assessment of simple marker-free genetic transformation techniques in alfalfa
No full textMethods to avoid the presence of selectable
marker genes (SMG) in transgenic plants are available but
not implemented in many crop species. We assessed the
efficiency of simple marker-free Agrobacterium-mediated
transformation techniques in alfalfa: regeneration without
selection, or marker-less, and co-transformation with two
vectors, one containing the SMG and one containing a nonselected
gene. To easily estimate the efficiency of markerless
transformation, the nptII and the GUS markers were
used as non-selected genes. After Agrobacterium treatment,
somatic embryos were regenerated without selection.
The percentage of transgenic embryos was determined by a
second cycle of regeneration using the embryos as starting
material, in the presence of kanamycin, by PCR screening
of T1 progenies, and by the GUS test. In two experiments,
from 0 to 1.7% of the somatic embryos were transgenic.
Co-transformation was performed with two vectors, one
with the hemL SMG and one with the unselected nptII
gene, each carried by a different culture of Agrobacterium.
Only 15 putative co-transformed plants were regenerated
from two experiments, with an average co-transformation
percentage of 3.7. Southern blot hybridizations and/or T1
progeny segregation were used to confirm transgene integration,
and qPCR was also used to estimate the T-DNA
copy number. In the T1 progenies obtained by crossing
with a non-transgenic pollinator, marker-free segregants were obtained. Both marker-free approaches showed very
low efficiency
A point mutation in the Medicago sativa GSA gene provides a novel, efficient, selectable marker for plant genetic engineering
No full textBacterial selectable marker genes (SMG) conferring antibiotic resistance are valuable tools in plant genetic
engineering, but public concern and regulatory requirements have stimulated the development of alternative
selection systems. We have previously demonstrated that a mutated Synechococcus elongatus HemL
gene encoding glutamate 1-semialdehyde aminotransferase (GSA) is an efficient SMG in alfalfa. In fact,
GSA is irreversibly inhibited by gabaculine (3-amino-2,3-dihydrobenzoic acid), but the mutated enzyme
is gabaculine insensitive. With the aim to develop a plant derived SMG, we cloned and sequenced the
Medicago sativa GSA cDNA and reproduced one of the two mutations associated with gabaculine resistance
in Synechococcus, a transversion resulting in a methionine to isoleucine (M→I) substitution. This
mutated gene was assessed as a SMG in tobacco and alfalfa Agrobacterium transformation, in comparison
with the wild type gene. In tobacco, about 43% of the leaf explants produced green shoots, whereas
in alfalfa 47% of the explants produced green embryos in the presence of 30 microM gabaculine when the
M→I GSA was introduced. Escapes were absent in tobacco and only 6% in alfalfa. No effect on the plant
phenotype was noticed. We propose this new SMG as a widely acceptable alternative to those currently
used
Expression of an Evolved Engineered Variant of a Bacterial Glycine Oxidase Leads to Glyphosate Resistance in Alfalfa
No full texttThe main strategy for resistance to the herbicide glyphosate in plants is the overexpression of an herbicideinsensitive, bacterial 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS). A glyphosate resistancestrategy based on the ability to degrade the herbicide can be useful to reduce glyphosate phytotox-icity to the crops. Here we present the characterization of glyphosate resistance in transgenic alfalfa(Medicago sativa L.) expressing a plant-optimized variant of glycine oxidase (GO) from Bacillus subtilis,evolved in vitro by a protein engineering approach to efficiently degrade glyphosate. Two constructswere used, one with (GOTP+) and one without (GOTP−) the pea rbcS plastid transit peptide. Molecularand biochemical analyses confirmed the stable integration of the transgene and the correct localizationof the plastid-imported GO protein. Transgenic alfalfa plants were tested for glyphosate resistance bothin vitro and in vivo. Two GOTP+lines showed moderate resistance to the herbicide in both conditions.Optimization of expression of this GO variant may allow to attain sufficient field resistance to glyphosateherbicides, thus providing a resistance strategy based on herbicide degradatio
Mitochondrial DNA editing in potato through mitoTALEN and mitoTALECD: molecular characterization and stability of editing events
Full text linkBackground
The aim of this study was to evaluate and characterize the mutations induced by two TALE-based approaches, double-strand break (DSB) induction by the FokI nuclease (mitoTALEN) and targeted base editing by the DddA cytidine deaminase (mitoTALECD), to edit, for the first time, the mitochondrial genome of potato, a vegetatively propagated crop. The two methods were used to knock out the same mitochondrial target sequence (orf125).
Results
Targeted chondriome deletions of different sizes (236–1066 bp) were induced by mitoTALEN due to DSB repair through ectopic homologous recombination of short direct repeats (11–12 bp) present in the target region. Furthermore, in one case, the induced DSB and subsequent repair resulted in the amplification of an already present substoichiometric molecule showing a 4288 bp deletion spanning the target sequence. With the mitoTALECD approach, both nonsense and missense mutations could be induced by base substitution. The deletions and single nucleotide mutations were either homoplasmic or heteroplasmic. The former were stably inherited in vegetative offspring.
Conclusions
Both editing approaches allowed us to obtain plants with precisely modified mitochondrial genomes at high frequency. The use of the same plant genotype and mtDNA region allowed us to compare the two methods for efficiency, accuracy, type of modifications induced and stability after vegetative propagation
Biotechnological and digital revolution for climate-smart plant breeding
Full text linkClimate change, associated with global warming, extreme weather events, and increasing incidence of weeds, pests and pathogens, is strongly influencing major cropping systems. In this challenging scenario, miscellaneous strategies are needed to expedite the rate of genetic gains with the purpose of developing novel varieties. Large plant breeding populations, efficient high-throughput technologies, big data management tools, and downstream biotechnology and molecular techniques are the pillars on which next generation breeding is based. In this review, we describe the toolbox the breeder has to face the challenges imposed by climate change, remark on the key role bioinformatics plays in the analysis and interpretation of big “omics” data, and acknowledge all the benefits that have been introduced into breeding strategies with the biotechnological and digital revolution
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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