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Yield of glyphosate-resistant sugar beets and efficiency of weed management systems with glyphosate and conventional herbicides under German and Polish crop production - Springer

In sugar beet production, weed control is one of the most important and most expensive practices to ensure yield. Since glyphosate-resistant sugar beets are not yet approved for cultivation in the EU, little commercial experience exists with these sugar beets in Europe. Experimental field trials were conducted at five environments (Germany, Poland, 2010, 2011) to compare the effects of glyphosate with the effects of conventional weed control programs on the development of weeds, weed control efficiency and yield. The results show that the glyphosate weed control programs compared to the conventional methods decreased not only the number of herbicide applications but equally in magnitude decreased the dosage of active ingredients. The results also showed effective weed control with glyphosate when the weed covering was greater and sugar beets had a later growth stage of four true leaves. Glyphosate-resistant sugar beets applied with the glyphosate herbicide two or three times had an increase in white sugar yield from 4 to 18 % in comparison to the high dosage conventional herbicide systems. In summary, under glyphosate management sugar beets can positively contribute to the increasingly demanding requirements regarding efficient sugar beet cultivation and to the demands by society and politics to reduce the use of chemical plant protection products in the environment.

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Redefining agricultural yields: from tonnes to people nourished per hectare - Abstract - Environmental Research Letters - IOPscience

Redefining agricultural yields: from tonnes to people nourished per hectare - Abstract - Environmental Research Letters - IOPscience | plant cell genetics | Scoop.it
Worldwide demand for crops is increasing rapidly due to global population growth, increased biofuel production, and changing dietary preferences. Meeting these growing demands will be a substantial challenge that will tax the capability of our food system and prompt calls to dramatically boost global crop production. However, to increase food availability, we may also consider how the world's crops are allocated to different uses and whether it is possible to feed more people with current levels of crop production. Of particular interest are the uses of crops as animal feed and as biofuel feedstocks. Currently, 36% of the calories produced by the world's crops are being used for animal feed, and only 12% of those feed calories ultimately contribute to the human diet (as meat and other animal products). Additionally, human-edible calories used for biofuel production increased fourfold between the years 2000 and 2010, from 1% to 4%, representing a net reduction of available food globally. In this study, we re-examine agricultural productivity, going from using the standard definition of yield (in tonnes per hectare, or similar units) to using the number of people actually fed per hectare of cropland. We find that, given the current mix of crop uses, growing food exclusively for direct human consumption could, in principle, increase available food calories by as much as 70%, which could feed an additional 4 billion people (more than the projected 2–3 billion people arriving through population growth). Even small shifts in our allocation of crops to animal feed and biofuels could significantly increase global food availability, and could be an instrumental tool in meeting the challenges of ensuring global food security.
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Effects of density and sowing pattern on weed suppression and grain yield in three varieties of maize under high weed pressure

Effects of density and sowing pattern on weed suppression and grain yield in three varieties of maize under high weed pressure | plant cell genetics | Scoop.it
We tested the hypothesis that improved weed suppression by maize can be achieved through increased crop density and spatial uniformity. Field experiments on three varieties of maize sown at three densities (5, 7 and 10.5 seeds m−2) and in two spatial patterns (grid pattern and rows) under very high weed pressure from Brachiaria brizantha were performed in 2012 and 2013. We measured weed biomass 1 month after sowing and at harvest, and grain yield at harvest. Density, variety and sowing pattern all had strong and significant effects on both weed biomass and yield. On average, weed biomass was reduced (by 72% in the first year and 58% in the second year), and grain yield was increased (by 48% and 44%) at the highest density in the grid pattern compared with standard sowing practices (medium density, row pattern). There was a significant density × variety interaction, which is evidence for genetic differences in the response of the varieties to density in characteristics that influence weed suppression. The variety that suppressed weeds best at high density had the lowest variation in the angle of insertion of the oldest living leaf at harvest (leaf 6), supporting the hypothesis that reduced phenotypic plasticity may be advantageous for weed suppression under high density and spatial uniformity. Increased density and uniformity can contribute to weed management in maize in many cases, potentially reducing the need for herbicides or mechanical weed control.
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Recombination products suggest the frequent occurrence of aberrant gene replacement in the moss Physcomitrella patens

Recombination products suggest the frequent occurrence of aberrant gene replacement in the moss Physcomitrella patens | plant cell genetics | Scoop.it
In gene replacement, a variant of gene targeting, transformed DNA integrates into the genome by homologous recombination (HR) to replace resident sequences. Gene replacement in the moss Physcomitrella patens is extremely efficient, but often large amounts of additional DNA are integrated at the target locus. A detailed analysis of recombination junctions of PpCOL2 gene knockout mutants shows that the integrated DNA can be highly rearranged. Our data suggest that the replaced sequences were excised by HR and became integrated back into the genome by non-homologous end-joining (NHEJ). RAD51-mediated strand-invasion and subsequent strand-exchange is central to the two-end invasion pathway, the major gene replacement pathway in yeast. In this pathway, integration is initiated by the free ends of a single replacement vector-derived donor molecule which then integrates as an entity. Gene replacement in P. patens is entirely RAD51-dependent suggesting the existence of a pathway mechanistically similar to two-end invasion. However, invasion of the two ends does not seem to be stringently coordinated in P. patens. Actually, often only one fragment end became integrated by HR, or one-sided integration of two independent donor fragments occurred simultaneously leading to a double-strand break that is subsequently sealed by NHEJ and thus causes the observed rearrangements.
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EU Banned Pesticides to Help Bees, But Now Other Bugs Are Invading

EU Banned Pesticides to Help Bees, But Now Other Bugs Are Invading | plant cell genetics | Scoop.it

The European Union has a bug problem. 

After regulators in late 2013 banned pesticides called neonicotinoids, linked in some studies to the unintended deaths of bees, farmers across the continent applied older chemicals to which many pests had developed a resistance, allowing them to survive. Now, infestations may lead to a 15 percent drop in this year’s European harvest of rapeseed, the region’s primary source of vegetable oil used to make food ingredients and biodiesel, according to researcher Oil World. 

“When we remove a tool from the box, that puts even more pressure on the tools we’ve got left,” said farmer Martin Jenkins, who has seen flea beetles for the first time in almost a decade on his 750 acres of rapeseed outside Cambridge, England. “More pesticides are being used, and even more ridiculous is there will be massively less rapeseed.” 

At issue for the EU was protecting bees that farmers rely upon to pollinate more than 80 percent of Europe’s crops and wild plants, valued at 22 billion euros ($26 billion) annually. While research on how neonicotinoids affect beneficial insects hasn’t been conclusive, regulators said the risks were worth imposing a two-year ban that began in December 2013. The Canadian province of Ontario proposed similar restrictions last year, and new rules are under review in the U.S., the biggest oilseed producer. 

Corn, Sunflowers 

The ban left European farmers without effective alternatives, leading to widespread insect damage, Hamburg-based Oil World said in a December report. Output of rapeseed may fall to a three-year low of 20.5 million metric tons in 2015, down from a record 24 million last year, it said. The EU is the world’s largest producer of rapeseed, which is known in North America mostly as canola. 

French corn and Spanish sunflowers may also be affected, said Copa-Cogeca, the Brussels-based lobbyist for the continent’s growers. 

The EU restricted the main types of neonicotinoids, a class of chemicals similar to nicotine, while still permitting two less-toxic varieties. Bayer AG (BAYN), which markets the products as Poncho and Votivo, and Syngenta AG make the pesticide. Monsanto Co., DuPont Co. and Dow Chemical Co. (DOW) sell seeds coated in it. 

Older Chemistry 

“Farmers have had to go back to older chemistry and chemistry that is increasingly less effective,” said Nick von Westenholz, the chief executive officer of the U.K.’s Crop Protection Association, an industry lobbyist. “Companies would like to innovate and bring newer stuff, but the neonicotinoid example is not a tempting one.” 

While the EU’s approval process for new pesticides can take years, some research is under way. The U.K. last month granted over 650,000 pounds ($979,485) in funding to a project led by Arch UK Biocides Ltd. for a chemical based on spider venom that is harmless to bees. 

Some studies, including one in May from the Harvard School of Public Health, have linked neonicotinoids to Colony Collapse Disorder, a syndrome marked by bees abandoning their hives in winter and dying. Bayer scientists dubbed the research “seriously flawed,” noting that colony failures observed in the study were prompted in part because bees were fed artificially high levels of pesticides. 

Other research was less conclusive. Some versions of the insecticide were harmful in lab experiments and had little effect on healthy colonies in the field, according to a report by Wageningen University in the Netherlands. 

Question Mark 

“The risk to bee populations and the wider environment from using this chemical that has a very big question mark over it is not a risk worth taking,” said Helen Browning, the chief executive officer of the Soil Association, a U.K. charity focused on sustainable farming. “There are alternative approaches,” such as barrier crops around fields, she said. 

The number of approved crop chemicals has fallen in the EU by more than 75 percent in two decades, according to the Andersons Centre, a farm consultancy in Leicestershire, England. 

In Germany, most rapeseed farmers have sprayed crops at least twice with alternative chemicals known as pyrethroids this season, said Manuela Specht, a division head at oilseed trade group known as UFOP in Berlin. In past years, they only sprayed once or not at all, she said. Prolonged exposure to some pyrethroids can stunt bee growth, a University of London study showed last year. 

For Jenkins, the U.K. farmer, he’s balancing a fight against pests that grow stronger over time with trying to maintain food production. In addition to flea beetles in rapeseed, he’s got an infestation of black grass, a weed that chokes his wheat fields. Two of the chemicals that he used to use are now banned, and the plant is resistant to permitted treatments of Bayer’s Atlantis, he said. 

“We’re growing less tons of food on our farm than we were 10 years ago,” Jenkins said. “An attack 10 years ago we could remedy with an alternative bit of chemistry, but that is no longer the case.”

 
Via Stéphane Bisaillon
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The politics of Golden Rice

The politics of Golden Rice | plant cell genetics | Scoop.it
(2014). The politics of Golden Rice. GM Crops & Food: Vol. 5, Politics and GM crops, pp. 210-222. doi: 10.4161/21645698.2014.967570
Genetic knowledge applicable to crop improvement has erupted over the past 60 years, and the techniques of introducing genes from one organism to another have enabled new varieties of crops not achievable by previously available methodologies of crop breeding. Research and particularly development of these GMO-crops to a point where they are useful for growers and consumers in most countries is subject to complex national and international rules arising out of the UN's Cartagena Protocol on Biosafety to the Convention on Biological Diversity, with 167 country signatories. (The USA and Canada are not signatories.) The Protocol was developed based on concerns initially expressed in the 1970's that such technology presented unusual risks to man and the environment. Those ideas have comprehensively and authoritatively been proven to be wrong. The Protocol has nevertheless spawned significant regulatory obstacles to the development of GMO-crop technology at great cost to global society and in conflict with many other UN objectives. The suspicion induced by the Protocol is also widely used, overtly or covertly, for political purposes. These points are illustrated by reference to the not-for-profit Golden Rice project.
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From the Concept of Totipotency to Biofortified Cereals - Annual Review of Plant Biology, 66(1): Ingo Potrykus

From the Concept of Totipotency to Biofortified Cereals - Annual Review of Plant Biology, 66(1): Ingo Potrykus | plant cell genetics | Scoop.it
I was a college teacher when opportunity opened a path into academia. A fascination with totipotency channeled me into research on tissue culture. As I was more interested in contributions to food security than in scientific novelty, I turned my attention to the development of genetic modification technology for cereals. From my cell culture experience, I had reasons not to trust Agrobacterium for that purpose, and I developed direct gene transfer instead. In the early 1990s, I became aware of the problem of micronutrient deficiency, particularly vitamin A deficiency in rice-eating populations. Golden Rice, which contains increased amounts of provitamin A, was probably instrumental for the concept of biofortification to take off. I realized that this rice would remain an academic exercise if product development and product registration were not addressed, and this is what I focused on after my retirement. Although progress is slowly being made, had I known what this pursuit would entail, perhaps I would not have started. Hopefully Golden Rice will reach the needy during my lifetime.
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The GMO case in France: Politics, lawlessness and postmodernism

The GMO case in France: Politics, lawlessness and postmodernism | plant cell genetics | Scoop.it
The GMO debacle in France is analyzed in the light of the balance of forces around this controversy, the changes in position of governments and the opponents’ strategic use of intimidation. These factors have caused insurmountable difficulties for scientific experimentations and assessment of the technology, as well as for farmers attempting to grow GM maize in this country. The change from a “modern” to a “postmodern” framing of official public debates and scientific institutions has not appeased confrontations concerning GMOs.
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A model system for analyzing intercellular communication through plasmodesmata using moss protonemata and leaves - Online First - Springer

A model system for analyzing intercellular communication through plasmodesmata using moss protonemata and leaves - Online First - Springer | plant cell genetics | Scoop.it

Plant growth, development, and environmental responses require the proper regulation of intercellular movement of signals and nutrients. For this, plants have specialized cytoplasmic channels, the plasmodesmata (PD), which allow the symplasmic movement of micro- and macromolecules between neighboring cells. Internal and external signals spatio-temporally regulate the movement of molecules through the PD to control plant development and environmental responses. Although some aspects of targeted movement of molecules have been revealed, the mechanisms of non-targeted, diffusible flow of molecules through PD, and its regulation and function, remain poorly understood, particularly at the cellular level. Previously, we developed a system to quantitatively analyze non-targeted movement of a photoconvertible fluorescent protein, Dendra2, at the single-cell level in the filamentous protonemata tissue of the moss Physcomitrella patens. In protonemata, one-dimensional intercellular communication can be easily observed and quantitatively analyzed at the cellular level. In this review, we describe how protonemata and leaves of P. patens can be used to study symplasmic movement through PD, and discuss how this system can help improve our understanding of PD regulation and function in development and environmental responses in plants.

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β-Carboxysomal proteins assemble into highly organized structures in Nicotiana chloroplasts - Lin - 2014 - The Plant Journal - Wiley Online Library

β-Carboxysomal proteins assemble into highly organized structures in Nicotiana chloroplasts - Lin - 2014 - The Plant Journal - Wiley Online Library | plant cell genetics | Scoop.it
The photosynthetic efficiency of C3 plants suffers from the reaction of ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) with O2 instead of CO2, leading to the costly process of photorespiration. Increasing the concentration of CO2 around Rubisco is a strategy used by photosynthetic prokaryotes such as cyanobacteria for more efficient incorporation of inorganic carbon. Engineering the cyanobacterial CO2-concentrating mechanism, the carboxysome, into chloroplasts is an approach to enhance photosynthesis or to compartmentalize other biochemical reactions to confer new capabilities on transgenic plants. We have chosen to explore the possibility of producing β-carboxysomes from Synechococcus elongatus PCC7942, a model freshwater cyanobacterium. Using the agroinfiltration technique, we have transiently expressed multiple β-carboxysomal proteins (CcmK2, CcmM, CcmL, CcmO and CcmN) in Nicotiana benthamiana with fusions that target these proteins into chloroplasts, and that provide fluorescent labels for visualizing the resultant structures. By confocal and electron microscopic analysis, we have observed that the shell proteins of the β-carboxysome are able to assemble in plant chloroplasts into highly organized assemblies resembling empty microcompartments. We demonstrate that a foreign protein can be targeted with a 17-amino-acid CcmN peptide to the shell proteins inside chloroplasts. Our experiments establish the feasibility of introducing carboxysomes into chloroplasts for the potential compartmentalization of Rubisco or other proteins.
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Optimization of crop productivity in tomato using induced mutations in the florigen pathway : Nature Genetics : Nature Publishing Group

Optimization of crop productivity in tomato using induced mutations in the florigen pathway : Nature Genetics : Nature Publishing Group | plant cell genetics | Scoop.it
Zachary Lippman and colleagues report the recovery in tomato of novel, chemically induced alleles in the SFT (florigen) gene and a newly identified suppressor of the SELF PRUNING gene. These alleles, in combination with previous florigen pathway mutations, allow for the quantitative fine-tuning of fruit yield, which may be applicable to other crop species.
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The beet Y locus encodes an anthocyanin MYB-like protein that activates the betalain red pigment pathway : Nature Genetics : Nature Publishing Group

The beet Y locus encodes an anthocyanin MYB-like protein that activates the betalain red pigment pathway : Nature Genetics : Nature Publishing Group | plant cell genetics | Scoop.it
Nearly all flowering plants produce red/violet anthocyanin pigments. Caryophyllales is the only order containing families that replace anthocyanins with unrelated red and yellow betalain pigments1, 2. Close biological correlation of pigmentation patterns suggested that betalains might be regulated by a conserved anthocyanin-regulating transcription factor complex consisting of a MYB, a bHLH and a WD repeat–containing protein (the MBW complex)3. Here we show that a previously uncharacterized anthocyanin MYB-like protein, Beta vulgaris MYB1 (BvMYB1), regulates the betalain pathway in beets. Silencing BvMYB1 downregulates betalain biosynthetic genes and pigmentation, and overexpressing BvMYB1 upregulates them. However, unlike anthocyanin MYBs, BvMYB1 will not interact with bHLH members of heterologous anthocyanin MBW complexes because of identified nonconserved residues. BvMYB1 resides at the historic beet pigment-patterning locus, Y, required for red-fleshed beets4. We show that Y and y express different levels of BvMYB1 transcripts. The co-option of a transcription factor regulating anthocyanin biosynthesis would be an important evolutionary event allowing betalains to largely functionally replace anthocyanins.
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The GMO case in France: Politics, lawlessness and postmodernism

The GMO case in France: Politics, lawlessness and postmodernism | plant cell genetics | Scoop.it
The GMO debacle in France is analyzed in the light of the balance of forces around this controversy, the changes in position of governments and the opponents’ strategic use of intimidation. These factors have caused insurmountable difficulties for scientific experimentations and assessment of the technology, as well as for farmers attempting to grow GM maize in this country. The change from a “modern” to a “postmodern” framing of official public debates and scientific institutions has not appeased confrontations concerning GMOs.
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Photoprotection of photosystems in fluctuating light intensities

Photoprotection of photosystems in fluctuating light intensities | plant cell genetics | Scoop.it
Oxygenic photosynthetic organisms experience strong fluctuations in light intensity in their natural terrestrial and aquatic growth environments. Recent studies with both plants and cyanobacteria have revealed that Photosystem (PS) I is the potential target of damage upon abrupt changes in light intensity. Photosynthetic organisms have, however, developed powerful mechanisms in order to protect their photosynthetic apparatus against such potentially hazardous light conditions. Although the electron transfer chain has remained relatively unchanged in both plant chloroplasts and their cyanobacterial ancestors, the photoprotective and regulatory mechanisms of photosynthetic light reactions have experienced conspicuous evolutionary changes. In cyanobacteria, the specific flavodiiron proteins (Flv1 and Flv3) are responsible for safeguarding PSI under rapidly fluctuating light intensities, whilst the thylakoid located terminal oxidases are involved in the protection of PSII during 12h diurnal cycles involving abrupt, square-wave, changes from dark to high light. Higher plants such as Arabidopsis thaliana have evolved different protective mechanisms. In particular, the PGR5 protein controls electron flow during sudden changes in light intensity by allowing the regulation mostly via the Cytochrome b6f complex. Besides the function of PGR5, plants have also acquired other dynamic regulatory mechanisms, among them the STN7-related LHCII protein phosphorylation that is similarly responsible for protection against rapid changes in the light environment. The green alga Chlamydomonas reinhardtii, as an evolutionary intermediate between cyanobacteria and higher plants, probably possesses both protective mechanisms. In this review, evolutionarily different photoprotective mechanisms under fluctuating light conditions are described and their contributions to cyanobacterial and plant photosynthesis are discussed.
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Frontiers: Strategies for transferring resistance into wheat: from wide crosses to GM cassettes (2014)

Frontiers: Strategies for transferring resistance into wheat: from wide crosses to GM cassettes (2014) | plant cell genetics | Scoop.it

The domestication of wheat in the Fertile Crescent 10,000 years ago led to a genetic bottleneck. Modern agriculture has further narrowed the genetic base by introducing extreme levels of uniformity on a vast spatial and temporal scale. This reduction in genetic complexity renders the crop vulnerable to new and emerging pests and pathogens. The wild relatives of wheat represent an important source of genetic variation for disease resistance. For nearly a century farmers, breeders, and cytogeneticists have sought to access this variation for crop improvement. Several barriers restricting interspecies hybridization and introgression have been overcome, providing the opportunity to tap an extensive reservoir of genetic diversity. Resistance has been introgressed into wheat from at least 52 species from 13 genera, demonstrating the remarkable plasticity of the wheat genome and the importance of such natural variation in wheat breeding. Two main problems hinder the effective deployment of introgressed resistance genes for crop improvement: (1) the simultaneous introduction of genetically linked deleterious traits and (2) the rapid breakdown of resistance when deployed individually. In this review, we discuss how recent advances in molecular genomics are providing new opportunities to overcome these problems.


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The Sainsbury Lab's curator insight, December 8, 2014 5:30 AM

The domestication of wheat in the Fertile Crescent 10,000 years ago led to a genetic bottleneck. Modern agriculture has further narrowed the genetic base by introducing extreme levels of uniformity on a vast spatial and temporal scale. This reduction in genetic complexity renders the crop vulnerable to new and emerging pests and pathogens. The wild relatives of wheat represent an important source of genetic variation for disease resistance. For nearly a century farmers, breeders, and cytogeneticists have sought to access this variation for crop improvement. Several barriers restricting interspecies hybridization and introgression have been overcome, providing the opportunity to tap an extensive reservoir of genetic diversity. Resistance has been introgressed into wheat from at least 52 species from 13 genera, demonstrating the remarkable plasticity of the wheat genome and the importance of such natural variation in wheat breeding. Two main problems hinder the effective deployment of introgressed resistance genes for crop improvement: (1) the simultaneous introduction of genetically linked deleterious traits and (2) the rapid breakdown of resistance when deployed individually. In this review, we discuss how recent advances in molecular genomics are providing new opportunities to overcome these problems.

Bharat Employment's curator insight, January 20, 11:42 PM

www.bharatemployment.com

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Archaeogenomic insights into the adaptation of plants to the human environment: pushing plant–hominin co-evolution back to the Pliocene

Archaeogenomic insights into the adaptation of plants to the human environment: pushing plant–hominin co-evolution back to the Pliocene | plant cell genetics | Scoop.it
The colonization of the human environment by plants, and the consequent evolution of domesticated forms is increasingly being viewed as a co-evolutionary plant–human process that occurred over a long time period, with evidence for the co-evolutionary relationship between plants and humans reaching ever deeper into the hominin past. This developing view is characterized by a change in emphasis on the drivers of evolution in the case of plants. Rather than individual species being passive recipients of artificial selection pressures and ultimately becoming domesticates, entire plant communities adapted to the human environment. This evolutionary scenario leads to systems level genetic expectations from models that can be explored through ancient DNA and Next Generation Sequencing approaches. Emerging evidence suggests that domesticated genomes fit well with these expectations, with periods of stable complex evolution characterized by large amounts of change associated with relatively small selective value, punctuated by periods in which changes in one-half of the plant–hominin relationship cause rapid, low-complexity adaptation in the other. A corollary of a single plant–hominin co-evolutionary process is that clues about the initiation of the domestication process may well lie deep within the hominin lineage.
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To what extent does organic farming rely on nutrient inflows from conventional farming? - IOPscience

To what extent does organic farming rely on nutrient inflows from conventional farming? - IOPscience | plant cell genetics | Scoop.it
Organic farming is increasingly recognized as a prototype for sustainable agriculture. Its guidelines ban the use of artificial fertilizers. However, organic farms may import nutrients from conventional farming through material exchanges. In this study, we aimed at estimating the magnitude of these flows through the quantification of nitrogen, phosphorus and potassium inflows from conventional farming to organic farming. Material inflows and outflows were collected for two cropping years on 63 farms. The farms were located in three French agricultural districts distributed over a gradient of farming activity defined by both the stocking rate and the ratio of the farm area under arable crops. Our results showed that on average, inflows from conventional farming were 23%, 73% and 53% for nitrogen, phosphorus and potassium, respectively. These inflows were strongly determined by the farm production systems. However, for farms similar in terms of production systems, the inflows also depended on the local context, such as the proximity of organic livestock farms: the reliance of organic farming on conventional farming was lower in mixed than in specialized districts. These results highlight the necessity to quantify the contribution of nutrient inflows from conventional farming when assessing organic farming and development scenarios.
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Recombination products suggest the frequent occurrence of aberrant gene replacement in the moss Physcomitrella patens - Wendeler - The Plant Journal - Wiley Online Library

Recombination products suggest the frequent occurrence of aberrant gene replacement in the moss Physcomitrella patens - Wendeler - The Plant Journal - Wiley Online Library | plant cell genetics | Scoop.it
In gene replacement, a variant of gene targeting, transformed DNA integrates into the genome by homologous recombination (HR) to replace resident sequences. Gene replacement in the moss Physcomitrella patens is extremely efficient, but often large amounts of additional DNA are integrated at the target locus. A detailed analysis of recombination junctions of PpCOL2 gene knockout mutants shows that the integrated DNA can be highly rearranged. Our data suggest that the replaced sequences were excised by HR and became integrated back into the genome by non-homologous end-joining (NHEJ). RAD51-mediated strand-invasion and subsequent strand-exchange is central to the two-end invasion pathway, the major gene replacement pathway in yeast. In this pathway, integration is initiated by the free ends of a single replacement vector-derived donor molecule which then integrates as an entity. Gene replacement in P. patens is entirely RAD51-dependent suggesting the existence of a pathway mechanistically similar to two-end invasion. However, invasion of the two ends does not seem to be stringently coordinated in P. patens. Actually, often only one fragment end became integrated by HR, or one-sided integration of two independent donor fragments occurred simultaneously leading to a double-strand break that is subsequently sealed by NHEJ and thus causes the observed rearrangements.
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The Inventiveness of Nature: An Interview with Werner Arber

The Inventiveness of Nature: An Interview with Werner Arber | plant cell genetics | Scoop.it

Nature is much more complex than we believe. I don′t think there is much work so far on horizontal gene transfer between higher eukaryotes and microorganisms. It is always true that you can get new insights if you develop new methodologies. This will come.

 

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RNA-Directed DNA Methylation: The Evolution of a Complex Epigenetic Pathway in Flowering Plants - Annual Review of Plant Biology, 66(1):

RNA-Directed DNA Methylation: The Evolution of a Complex Epigenetic Pathway in Flowering Plants - Annual Review of Plant Biology, 66(1): | plant cell genetics | Scoop.it
RNA-directed DNA methylation (RdDM) is an epigenetic process in plants that involves both short and long noncoding RNAs. The generation of these RNAs and the induction of RdDM rely on complex transcriptional machineries comprising two plant-specific, RNA polymerase II (Pol II)–related RNA polymerases known as Pol IV and Pol V, as well as a host of auxiliary factors that include both novel and refashioned proteins.Wepresent current views on the mechanism of RdDM with a focus on evolutionary innovations that occurred during the transition from a Pol II transcriptional pathway, which produces mRNA precursors and numerous noncoding RNAs, to the Pol IV and PolV pathways, which are specialized for RdDM and gene silencing. We describe recently recognized deviations from the canonical RdDM pathway, discuss unresolved issues, and speculate on the biological significance of RdDM for flowering plants, which have a highly developed Pol V pathway.
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Activation of Defense Mechanisms against Pathogens in Mosses and Fl... - PubMed - NCBI

Activation of Defense Mechanisms against Pathogens in Mosses and Fl... - PubMed - NCBI | plant cell genetics | Scoop.it
During evolution, plants have developed mechanisms to cope with and adapt to different types of stress, including microbial infection. Once the stress is sensed, signaling pathways are activated, leading to the induced expression of genes with different roles in defense. Mosses (Bryophytes) are non-vascular plants that diverged from flowering plants more than 450 million years ago, allowing comparative studies of the evolution of defense-related genes and defensive metabolites produced after microbial infection. The ancestral position among land plants, the sequenced genome and the feasibility of generating targeted knock-out mutants by homologous recombination has made the moss Physcomitrella patens an attractive model to perform functional studies of plant genes involved in stress responses. This paper reviews the current knowledge of inducible defense mechanisms in P. patens and compares them to those activated in flowering plants after pathogen assault, including the reinforcement of the cell wall, ROS production, programmed cell death, activation of defense genes and synthesis of secondary metabolites and defense hormones. The knowledge generated in P. patens together with comparative studies in flowering plants will help to identify key components in plant defense responses and to design novel strategies to enhance resistance to biotic stress.
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Genome Biology | Abstract | Organization and evolution of transposable elements along the bread wheat chromosome 3B

BackgroundThe 17 Gb bread wheat genome has massively expanded through the proliferation of transposable elements and two recent rounds of polyploidization. The assembly of a 774?Mb reference sequence of wheat chromosome 3B provided us with the opportunity to explore the impact of transposable elements (TEs) on the complex wheat genome structure and evolution at a resolution and scale never reached so far.ResultsWe develop an automated workflow, CLARI-TE, for TE modeling in complex genomes. We delineate precisely 56,488 intact and 196,391 fragmented TEs along the 3B pseudomolecule, accounting for 85% of the sequence, and reconstruct 30,199 nested insertions. TEs have been mostly silent for the last one million years, and the 3B chromosome has been shaped by a succession of bursts that occurred between 1 to 3 million years ago. Accelerated TE elimination in the high-recombination distal regions is a driving force towards chromosome partitioning. CACTAs overrepresented in the high-recombination distal regions are significantly associated with recently duplicated genes. In addition, we identify 140 CACTA-mediated gene capture events with 17 genes potentially created by exon shuffling and show that 19 captured genes are transcribed and under selection pressure, suggesting the important role of CACTAs in the recent wheat adaptation.ConclusionAccurate TE modeling uncovers the dynamics of TEs in a highly complex and polyploid genome. It provides novel insights into chromosome partitioning and highlights the role of CACTA transposons in the high level of gene duplication in wheat.
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Genetic transformation of moss Ceratodon purpureus by means of polycationic carriers of DNA - Springer

Genetic transformation of moss Ceratodon purpureus by means of polycationic carriers of DNA - Springer | plant cell genetics | Scoop.it
There is much progress in application of genetic engineering for improving the biological properties of different organisms. Viral and nonviral carriers are used for delivery of genetic material into target cells. Polymeric materials of natural and synthetic origin are the most promising gene delivery agents. These polymers demonstrated high efficiency of DNA delivery into animal cells, although they were not very effective in plant cells. Here, the procedure for genetic transformation of Ceratodon purpureus (Hedw.) Brid. moss protoplasts is described. The method is based on the application of surface-active polymeric carriers of the poly-DMAEM structure and controlled length and charge. This allows obtaining more transient and stable moss transformants per microgram of plasmid DNA when compared with known protocol based on using polyethyleneglycol. It is easier, more convenient, and cheaper than the “gene gun” method. Prospects for further improvement of structure and functional characteristics of new polymeric carriers are considered for delivery of genetic material into plant cells.
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The genome sequence of the orchid Phalaenopsis equestris : Nature Genetics : Nature Publishing Group

The genome sequence of the orchid Phalaenopsis equestris : Nature Genetics : Nature Publishing Group | plant cell genetics | Scoop.it
Zhong-Jian Liu, Lai-Qiang Huang, Yi-Bo Luo, Hong-Hwa Chen and Yves Van de Peer report the first genome sequence of a crassulacean acid metabolism (CAM) plant, the orchid Phalaenopsis equestris. They identify genes encoding CAM pathway enzymes and find that gene duplication was likely a key process in the evolution of CAM photosynthesis.
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An Env-derived multi-epitope HIV chimeric protein produced in the moss Physcomitrella patens is immunogenic in mice - Online First - Springer

An Env-derived multi-epitope HIV chimeric protein produced in the moss Physcomitrella patens is immunogenic in mice - Online First - Springer | plant cell genetics | Scoop.it
The need for economical and efficient platforms for vaccine production demands the exploration of emerging host organisms. In this study, the production of an antigenic protein is reported employing the moss Physcomitrella patens as an expression host. A multi-epitope protein from the Human Immunodeficiency Virus (HIV) based on epitopes from gp120 and gp41 was designed as a candidate subunit vaccine and named poly-HIV. Transgenic moss plants were generated carrying the corresponding poly-HIV transgene under a novel moss promoter and subsequently seven positive lines were confirmed by PCR. The poly-HIV protein accumulated up to 3.7 µg g−1 fresh weight in protonema cultures. Antigenic and immunogenic properties of the moss-produced recombinant poly-HIV are evidenced by Western blots and by mice immunization assays. The elicitation of specific antibodies in mice was observed, reflecting the immunogenic potential of this moss-derived HIV antigen. This is the first report on the production of a potential vaccine in the moss system and opens the avenue for glycoengineering approaches for the production of HIV human-like glycosylated antigens as well as other vaccine prototypes under GMP conditions in moss bioreactors.
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Unexpected Diversity of Feral Genetically Modified Oilseed Rape (Brassica napus L.) Despite a Cultivation and Import Ban in Switzerland

Unexpected Diversity of Feral Genetically Modified Oilseed Rape (Brassica napus L.) Despite a Cultivation and Import Ban in Switzerland | plant cell genetics | Scoop.it

Despite cultivation and seed import bans of genetically modified (GM) oilseed rape (Brassica napus L.), feral GM plants were found growing along railway lines and in port areas at four sites in Switzerland in 2011 and 2012. All GM plants were identified as glyphosate-resistant GM event GT73 (Roundup Ready, Monsanto). The most affected sites were the Rhine port of Basel and the St. Johann freight railway station in Basel. To assess the distribution and intra- and interspecific outcrossing of GM oilseed rape in more detail, we monitored these two sites in 2013. Leaves and seed pods of feral oilseed rape plants, their possible hybridization partners and putative hybrid plants were sampled in monthly intervals and analysed for the presence of transgenes by real-time PCR. Using flow cytometry, we measured DNA contents of cell nuclei to confirm putative hybrids. In total, 2787 plants were sampled. The presence of GT73 oilseed rape could be confirmed at all previously documented sampling locations and was additionally detected at one new sampling location within the Rhine port. Furthermore, we found the glufosinate-resistant GM events MS8xRF3, MS8 and RF3 (all traded as InVigor, Bayer) at five sampling locations in the Rhine port. To our knowledge, this is the first time that feral MS8xRF3, MS8 or RF3 plants were detected in Europe. Real-time PCR analyses of seeds showed outcrossing of GT73 into two non-GM oilseed rape plants, but no outcrossing of transgenes into related wild species was observed. We found no hybrids between oilseed rape and related species. GM plants most frequently occurred at unloading sites for ships, indicating that ship cargo traffic is the main entry pathway for GM oilseed rape. In the future, it will be of major interest to determine the source of GM oilseed rape seeds.


Via Christophe Jacquet
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