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Scientific Opinion on an application by DOW AgroSciences LLC (EFSA‐GMO‐NL‐2010‐89) for placing on the market the genetically modified herbicide‐tolerant maize DAS‐40278‐9 for food and feed uses, im...

Maize DAS-40278-9 was developed by direct Whiskers-mediated transformation to express the aryloxyalkanoate dioxygenase-1 (AAD-1) protein, conferring tolerance to 2,4-dichlorophenoxyacetic acid (2,4-D) and aryloxyphenoxypropionate (AOPP) herbicides. The molecular characterisation of maize DAS-40278-9 did not raise safety issues. The agronomic, phenotypic and compositional characteristics of maize DAS-40278-9 tested under field conditions revealed no differences between maize DAS-40278-9 and its non-genetically modified (GM) comparator that would give rise to food and feed or environmental safety concerns. There were no concerns regarding the potential toxicity and allergenicity of the newly expressed protein AAD-1, and no evidence that the genetic modification might significantly change the overall allergenicity of maize DAS-40278-9. The nutritional characteristics of maize DAS-40278-9 are not expected to differ from those of non-GM maize varieties and no post-market monitoring of food/feed is considered necessary. Maize DAS-40278-9 is as nutritious as its non-GM comparator and other non-GM commercial varieties. There are no indications of an increased likelihood of establishment and spread of occasional feral maize DAS-40278-9 plants, unless these plants are exposed to the intended herbicides. However, this will not result in different environmental impacts compared to conventional maize. Considering the scope of the application, interactions with the biotic and abiotic environment were not considered an issue. Risks associated with the unlikely but theoretically possible horizontal gene transfer from maize DAS-40278-9 to bacteria were not identified. The post-market environmental monitoring plan and reporting intervals are in line with the scope of the application. In conclusion, the EFSA GMO Panel considers that the information available for maize DAS-40278-9 addresses the scientific comments raised by the Member States and that maize DAS-40278-9, as described in this application, is as safe as the non-GM comparator and non-GM maize reference varieties with respect to potential effects on human and animal health and the environment in the context of the scope of this application.
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Withdrawal of maize protection by herbicides and insecticides increases mycotoxins contamination near maximum thresholds

Withdrawal of maize protection by herbicides and insecticides increases mycotoxins contamination near maximum thresholds | plant cell genetics | Scoop.it
Environmental and economic issues affect decision-making for whether or not to control small infestations of pests and pathogens in crops. Even where no crop yield loss is expected, other risks may be evident, such as the slow accumulation of pathogen inocula. The prevalence of toxins, arising from biotic interactions with fungal diseases, can alter crop quality rather than quantity. Thus, farmer decisions for whether to tolerate pest infestation must take into account several direct and immediate and/or delayed potential risks. Published scientific evidence on the co-occurrence of risk factors resulting from the presence of different pests and pathogens are largely absent, and this has stifled the adoption of integrated pest management. Here, we tested how the withdrawal of herbicide and insecticide protection in maize, alone and in combination, might induce higher prevalence of up to 23 mycotoxins in the crop at harvest. The experiment was conducted over 4 years in 29 fields in the south west of France. The test involved a comparison of paired samples collected from treated and untreated plots. All nine major mycotoxins that were observed in more than 4 % of the samples showed highly variable concentrations both between fields and years. The overall trend following the cessation of pesticide protection, however, is for higher levels of mycotoxins and up to a six-fold increased in nivalenol mean concentration (to 202.3 μg kg−1 of maize seeds) compared to its treated control. Overall mycotoxin concentrations approached 55–67 % of their maximum acceptable rate, a situation of reduced security margin that could lead to economic penalties and market restrictions. We found that the removal of herbicides had a greater impact than that of insecticides on the prevalence of mycotoxins, which differs from the expectation stated in the literature. This finding is further reinforced by the observation that certain species of weeds harbor several species of Fusarium. This means that weeds not only play a role as crop competitors but also as reservoirs of inoculum in the field. Our findings illustrate the importance of sanitary evaluation when the implementation of new cropping systems will alter the distribution and occurrence of pests and pathogens.
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Frontiers | Proteomic studies of the abiotic stresses response in model moss – Physcomitrella patens | Plant Proteomics

Frontiers | Proteomic studies of the abiotic stresses response in model moss – Physcomitrella patens | Plant Proteomics | plant cell genetics | Scoop.it
Moss species Physcomitrella patens has been used as a model system in plant science for several years, because it has a short life cycle and is easy to be handled. With the completion of its genome sequencing, more and more proteomic analyses were conducted to study the mechanisms of P. patens abiotic stress resistance. It can be concluded from these studies that abiotic stresses could lead to the repression of photosynthesis and enhancement of respiration in P. patens, although different stresses could also result in specific responses. Comparative analysis showed that the responses to drought and salinity were very similar to that of abscisic acid, while the response to cold was quite different from these three. Based on previous studies, it is proposed that sub-proteomic studies on organelles or protein modifications, as well as functional characterization of those candidate proteins identified from proteomic studies will help us to further understand the mechanisms of abiotic stress resistance in P. patens.
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Frontiers | The Physcomitrella patens Chloroplast Proteome Changes in Response to Protoplastation | Plant Proteomics

Frontiers | The Physcomitrella patens Chloroplast Proteome Changes in Response to Protoplastation | Plant Proteomics | plant cell genetics | Scoop.it
Plant protoplasts are widely used for genetic manipulation and functional studies in transient expression systems. However, little is known about the molecular pathways involved in a cell response to the combined stress factors resulted from protoplast generation. Plants often face more than one type of stress at a time, and how plants respond to combined stress factors is therefore of great interest. Here, we used protoplasts of the moss Physcomitrella patens as a model to study the effects of short-term stress on the chloroplast proteome. Using label-free comparative quantitative proteomic analysis (SWATH-MS), we quantified 479 chloroplast proteins, 219 of which showed a more than 1.4-fold change in abundance in protoplasts. We additionally quantified 1451 chloroplast proteins using emPAI. We observed degradation of a significant portion of the chloroplast proteome following the first hour of stress imposed by the protoplast isolation process. Electron-transport chain (ETC) components underwent the heaviest degradation, resulting in the decline of photosynthetic activity. We also compared the proteome changes to those in the transcriptional level of nuclear-encoded chloroplast genes. Globally, the levels of the quantified proteins and their corresponding mRNAs showed limited correlation. Genes involved in the biosynthesis of chlorophyll and components of the outer chloroplast membrane showed decreases in both transcript and protein abundance. However, proteins like dehydroascorbate reductase 1 and 2-cys peroxiredoxin B responsible for ROS detoxification increased in abundance. Further, genes such as thylakoid ascorbate peroxidase were induced at the transcriptional level but down-regulated at the proteomic level. Together, our results demonstrate that the initial chloroplast reaction to stress is due changes at the proteomic level.
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Integration of Phytochrome and Cryptochrome Signals Determines Plant Growth during Competition for Light

Integration of Phytochrome and Cryptochrome Signals Determines Plant Growth during Competition for Light | plant cell genetics | Scoop.it
Highlights

•Blue light depletion combined with low R:FR mimics vegetation shade
•Low blue light perception enhances the low R:FR response through PIFs and COP1
•Low blue light perception counteracts a low R:FR-induced negative feedback loop

Summary

Plants in dense vegetation perceive their neighbors primarily through changes in light quality. Initially, the ratio between red (R) and far-red (FR) light decreases due to reflection of FR by plant tissue well before shading occurs. Perception of low R:FR by the phytochrome photoreceptors induces the shade avoidance response [ 1 ], of which accelerated elongation growth of leaf-bearing organs is an important feature. Low R:FR-induced phytochrome inactivation leads to the accumulation and activation of the transcription factors PHYTOCHROME-INTERACTING FACTORs (PIFs) 4, 5, and 7 and subsequent expression of their growth-mediating targets [ 2, 3 ]. When true shading occurs, transmitted light is especially depleted in red and blue (B) wavelengths, due to absorption by chlorophyll [ 4 ]. Although the reduction of blue wavelengths alone does not occur in nature, long-term exposure to low B light induces a shade avoidance-like response that is dependent on the cryptochrome photoreceptors and the transcription factors PIF4 and PIF5 [ 5–7 ]. We show in Arabidopsis thaliana that low B in combination with low R:FR enhances petiole elongation similar to vegetation shade, providing functional context for a low B response in plant competition. Low B potentiates the low R:FR response through PIF4, PIF5, and PIF7, and it involves increased PIF5 abundance and transcriptional changes. Low B attenuates a low R:FR-induced negative feedback loop through reduced gene expression of negative regulators and reduced HFR1 levels. The enhanced response to combined phytochrome and cryptochrome inactivation shows how multiple light cues can be integrated to fine-tune the plant’s response to a changing environment.
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Circadian regulation of sunflower heliotropism, floral orientation, and pollinator visits

Circadian regulation of sunflower heliotropism, floral orientation, and pollinator visits | plant cell genetics | Scoop.it
Young sunflower plants track the Sun from east to west during the day and then reorient during the night to face east in anticipation of dawn. In contrast, mature plants cease movement with their flower heads facing east. We show that circadian regulation of directional growth pathways accounts for both phenomena and leads to increased vegetative biomass and enhanced pollinator visits to flowers. Solar tracking movements are driven by antiphasic patterns of elongation on the east and west sides of the stem. Genes implicated in control of phototropic growth, but not clock genes, are differentially expressed on the opposite sides of solar tracking stems. Thus, interactions between environmental response pathways and the internal circadian oscillator coordinate physiological processes with predictable changes in the environment to influence growth and reproduction.
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Effect of bearing position on phenolics profiles in the skins of four cultivars of grapevine (Vitis vinifera L.)

Effect of bearing position on phenolics profiles in the skins of four cultivars of grapevine (Vitis vinifera L.) | plant cell genetics | Scoop.it
The fan-shaped trellis training system, resulting in grapevines (Vitis vinifera L.) with more than two trunks, has been widely used in northern China. The fruiting zone of grapevines trained to the fan-shaped trellis system is distributed from the top to the bottom of the canopy. The phenolics profiles of the skins of ‘Cabernet Sauvignon’, ‘Merlot’, ‘Chardonnay’, and ‘Italian Riesling’ grape berries were analysed to measure the effect of differences in bearing position on the phenolic compound and anthocyanin compositions of grape berries.The results showed that the upper bearing position significantly increased the concentrations of most phenolic compounds in grape berry skins. Among the non-anthocyanin and anthocyanin phenolic compounds identified in this study, the upper bearing position promoted the accumulation of delphinidin-, cyanidin-, and petunidin-glucosides in the skin of the two red grape cultivars. However, lowering the bearing position was associated with greater methylation of anthocyanins, and the flow of photosynthate towards the biosynthesis of kaempferol. These results were correlated with micrometeorological alterations in the canopy at the different bearing positions. The findings of this study suggest that higher bearing positions can increase the accumulation of phenolic compounds in grape berry skins in four different grapevine cultivars.
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Down the Rabbit Hole–Carrots, Genetics and Art

Down the Rabbit Hole–Carrots, Genetics and Art | plant cell genetics | Scoop.it
The large, unbranched cultivated carrot (Daucus carota subspecies sativus) is a popular vegetable with high sugar and dietary provitamin A carotenoid contents. The orange-coloured one is best known, but there are also white, yellow, red, and purple varieties. By contrast, the wild carrot Daucus carota subspecies carota (commonly referred to as Queen Anne's Lace) is a weedy plant that does not accumulate any detectable levels of carotenoid pigments in roots i. When visiting the museums of his native country in the late 1950s, the Dutch agronomer Otto Banga started to ponder the question on the origin of the modern carrot. He observed that paintings from the Dutch Golden Century (∼17th century) show an enormous diversity of carrots: white, red, yellow, and orange versions (Figure 1A). However, he noticed the orange carrot featuring more prominently on pictures that were painted later in the 17th century. He concluded that the orange carrot as we currently know it, appeared in the late 16th to early 17th century, and that it was likely first cultivated in The Netherlands [1]. Here, in view of the recent carrot genome assembly [2], we noncomprehensively discuss the origin of the carrot, explain how art can help in our understanding of its development, and elaborate upon some of the molecular mechanisms and underlying genetic network responsible for the observed colour differences.
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Compartmentalized Metabolic Engineering for Artemisinin Biosynthesis and Effective Malaria Treatment by Oral Delivery of Plant Cells

Artemisinin is highly effective against drug-resistant malarial parasites, which affects nearly half of the global population and kills >500 000 people each year. The primary cost of artemisinin is the very expensive process used to extract and purify the drug from Artemisia annua. Elimination of this apparently unnecessary step will make this potent antimalarial drug affordable to the global population living in endemic regions. Here we reported the oral delivery of a non-protein drug artemisinin biosynthesized (∼0.8 mg/g dry weight) at clinically meaningful levels in tobacco by engineering two metabolic pathways targeted to three different cellular compartments (chloroplast, nucleus, and mitochondria). The doubly transgenic lines showed a three-fold enhancement of isopentenyl pyrophosphate, and targeting AACPR, DBR2, and CYP71AV1 to chloroplasts resulted in higher expression and an efficient photo-oxidation of dihydroartemisinic acid to artemisinin. Partially purified extracts from the leaves of transgenic tobacco plants inhibited in vitro growth progression of Plasmodium falciparum-infected red blood cells. Oral feeding of whole intact plant cells bioencapsulating the artemisinin reduced the parasitemia levels in challenged mice in comparison with commercial drug. Such novel synergistic approaches should facilitate low-cost production and delivery of artemisinin and other drugs through metabolic engineering of edible plants.
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Glyphosate and adverse pregnancy outcomes, a systematic review of observational studies

Background

A study in frog and chicken embryos, and reports of a high incidence of birth defects in regions of intensive GM-soy planting have raised concerns on the teratogenic potential of glyphosate-based herbicides. These public concerns prompted us to conduct a systematic review of the epidemiological studies testing hypotheses of associations between glyphosate exposure and adverse pregnancy outcomes including birth defects.
Methods

A systematic and comprehensive literature search was performed in MEDLINE, TOXLINE, Bireme-BVS and SCOPUS databases using different combinations of exposure and outcome terms. A case–control study on the association between pesticides and congenital malformations in areas of extensive GM soy crops in South America, and reports on the occurrence of birth defects in these regions were reviewed as well.
Results

The search found ten studies testing associations between glyphosate and birth defects, abortions, pre-term deliveries, small for gestational date births, childhood diseases or altered sex ratios. Two additional studies examined changes of time-to-pregnancy in glyphosate-exposed populations. Except for an excess of Attention Deficit Hyperactivity Disorder - ADHD (OR = 3.6, 1.3-9.6) among children born to glyphosate appliers, no significant associations between this herbicide and adverse pregnancy outcomes were described. Evidence that in South American regions of intensive GM-soy planting incidence of birth defects is high remains elusive.
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The next green movement: Plant biology for the environment and sustainability

The next green movement: Plant biology for the environment and sustainability | plant cell genetics | Scoop.it
From domestication and breeding to the genetic engineering of crops, plants provide food, fuel, fibers, and feedstocks for our civilization. New research and discoveries aim to reduce the inputs needed to grow crops and to develop plants for environmental and sustainability applications. Faced with population growth and changing climate, the next wave of innovation in plant biology integrates technologies and approaches that span from molecular to ecosystem scales. Recent efforts to engineer plants for better nitrogen and phosphorus use, enhanced carbon fixation, and environmental remediation and to understand plant-microbiome interactions showcase exciting future directions for translational plant biology. These advances promise new strategies for the reduction of inputs to limit environmental impacts and improve agricultural sustainability.
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Sweet potato Vitamin A research wins World Food Prize - BBC (2016) 

Sweet potato Vitamin A research wins World Food Prize - BBC (2016)  | plant cell genetics | Scoop.it

Four scientists have been awarded the 2016 World Food Prize for enriching sweet potatoes, which resulted in health benefits for millions of people… "the single most [successful] example of biofortification", resulting in Vitamin A-boosted crops. Three of the 2016 laureates… have been recognised for their work developing the vitamin-enriched orange-fleshed sweet potato. The fourth winner, Dr Howard Bouis who founded HarvestPlus at the International Food Policy Research Institute, has been honoured for his work over 25 years to ensure biofortification was developed into an international plant breeding strategy across more than 40 countries. 


Announcing this year's winners, USAID administrator Gayle Smith said: "These four extraordinary World Food Prize Laureates have proven that science matters, and that when matched with dedication, it can change people's lives." Vitamin A deficiency (VAD) is considered to be one of the most harmful forms of malnutrition in the developing world. It can cause blindness, limits growth, weakens immunity and increases mortality. The condition affects more than 140 million pre-school children in 118 nations, and more than seven million pregnant women. It is said to be the leading cause of child blindness in developing countries… 


Biofortification [is] the process "by which the nutritional quality of food crops is improved through agronomic practices, conventional plant breeding, or modern biotechnology… Biofortification may therefore present a way to reach populations where supplementation and conventional fortification activities may be difficult to implement"… 


Dr Borlaug, often called the father of the Green Revolution, established the World Food Prize 30 years ago to recognise "exceptionally significant" achievements by individuals. In 1970, Dr Borlaug won the Nobel Peace Prize in recognition of his contribution to world peace through his work to increase global food supplies… 


Growth in global agricultural productivity, for the third year in a row, was not advancing at the rate required to meet future demand for food… unless this emerging trend was reversed, the "world may not be able to sustainably provide the food, feed, fibre and biofuels needed for a booming global population"… Productive techniques and technology were "essential for producers of all scales as climate change and extreme weather events threaten the sustainability of agricultural value chains"… 


http://www.bbc.com/news/science-environment-37619154



Via Alexander J. Stein
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LudusScope: Accessible Interactive Smartphone Microscopy for Life-Science Education

LudusScope: Accessible Interactive Smartphone Microscopy for Life-Science Education | plant cell genetics | Scoop.it
For centuries, observational microscopy has greatly facilitated biology education, but we still cannot easily and playfully interact with the microscopic world we see. We therefore developed the LudusScope, an accessible, interactive do-it-yourself smartphone microscopy platform that promotes exploratory stimulation and observation of microscopic organisms, in a design that combines the educational modalities of build, play, and inquire. The LudusScope’s touchscreen and joystick allow the selection and stimulation of phototactic microorganisms such as Euglena gracilis with light. Organismal behavior is tracked and displayed in real time, enabling open and structured game play as well as scientific inquiry via quantitative experimentation. Furthermore, we used the Scratch programming language to incorporate biophysical modeling. This platform is designed as an accessible, low-cost educational kit for easy construction and expansion. User testing with both teachers and students demonstrates the educational potential of the LudusScope, and we anticipate additional synergy with the maker movement. Transforming observational microscopy into an interactive experience will make microbiology more tangible to society, and effectively support the interdisciplinary learning required by the Next Generation Science Standards.
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Seeds of doubt: Mendel’s choice of Hieracium to study inheritance, a case of right plant, wrong trait

Seeds of doubt: Mendel’s choice of Hieracium to study inheritance, a case of right plant, wrong trait | plant cell genetics | Scoop.it
Seeds of doubt: Mendel’s choice of Hieracium to study inheritance, a case of right plant, wrong trait
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Origin and function of stomata in the moss Physcomitrella patens

Origin and function of stomata in the moss Physcomitrella patens | plant cell genetics | Scoop.it
Stomata are microscopic valves on plant surfaces that originated over 400 million years (Myr) ago and facilitated the greening of Earth's continents by permitting efficient shoot–atmosphere gas exchange and plant hydration1. However, the core genetic machinery regulating stomatal development in non-vascular land plants is poorly understood2,​3,​4 and their function has remained a matter of debate for a century5. Here, we show that genes encoding the two basic helix–loop–helix proteins PpSMF1 (SPEECH, MUTE and FAMA-like) and PpSCREAM1 (SCRM1) in the moss Physcomitrella patens are orthologous to transcriptional regulators of stomatal development in the flowering plant Arabidopsis thaliana and essential for stomata formation in moss. Targeted P. patens knockout mutants lacking either PpSMF1 or PpSCRM1 develop gametophytes indistinguishable from wild-type plants but mutant sporophytes lack stomata. Protein–protein interaction assays reveal heterodimerization between PpSMF1 and PpSCRM1, which, together with moss–angiosperm gene complementations6, suggests deep functional conservation of the heterodimeric SMF1 and SCRM1 unit is required to activate transcription for moss stomatal development, as in A. thaliana7. Moreover, stomata-less sporophytes of ΔPpSMF1 and ΔPpSCRM1 mutants exhibited delayed dehiscence, implying stomata might have promoted dehiscence in the first complex land-plant sporophytes.
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A hypergravity environment increases chloroplast size, photosynthesis, and plant growth in the moss Physcomitrella patens

A hypergravity environment increases chloroplast size, photosynthesis, and plant growth in the moss Physcomitrella patens | plant cell genetics | Scoop.it
The physiological and anatomical responses of bryophytes to altered gravity conditions will provide crucial information for estimating how plant physiological traits have evolved to adapt to significant increases in the effects of gravity in land plant history. We quantified changes in plant growth and photosynthesis in the model plant of mosses, Physcomitrella patens, grown under a hypergravity environment for 25 days or 8 weeks using a custom-built centrifuge equipped with a lighting system. This is the first study to examine the response of bryophytes to hypergravity conditions. Canopy-based plant growth was significantly increased at 10×g, and was strongly affected by increases in plant numbers. Rhizoid lengths for individual gametophores were significantly increased at 10×g. Chloroplast diameters (major axis) and thicknesses (minor axis) in the leaves of P. patens were also increased at 10×g. The area-based photosynthesis rate of P. patens was also enhanced at 10×g. Increases in shoot numbers and chloroplast sizes may elevate the area-based photosynthesis rate under hypergravity conditions. We observed a decrease in leaf cell wall thickness under hypergravity conditions, which is in contrast to previous findings obtained using angiosperms. Since mosses including P. patens live in dense populations, an increase in canopy-based plant numbers may be effective to enhance the toughness of the population, and, thus, represents an effective adaptation strategy to a hypergravity environment for P. patens.
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Origin and function of stomata in the moss Physcomitrella patens

Origin and function of stomata in the moss Physcomitrella patens | plant cell genetics | Scoop.it
Stomata are microscopic valves on plant surfaces that originated over 400 million years (Myr) ago and facilitated the greening of Earth's continents by permitting efficient shoot–atmosphere gas exchange and plant hydration1. However, the core genetic machinery regulating stomatal development in non-vascular land plants is poorly understood2,​3,​4 and their function has remained a matter of debate for a century5. Here, we show that genes encoding the two basic helix–loop–helix proteins PpSMF1 (SPEECH, MUTE and FAMA-like) and PpSCREAM1 (SCRM1) in the moss Physcomitrella patens are orthologous to transcriptional regulators of stomatal development in the flowering plant Arabidopsis thaliana and essential for stomata formation in moss. Targeted P. patens knockout mutants lacking either PpSMF1 or PpSCRM1 develop gametophytes indistinguishable from wild-type plants but mutant sporophytes lack stomata. Protein–protein interaction assays reveal heterodimerization between PpSMF1 and PpSCRM1, which, together with moss–angiosperm gene complementations6, suggests deep functional conservation of the heterodimeric SMF1 and SCRM1 unit is required to activate transcription for moss stomatal development, as in A. thaliana7. Moreover, stomata-less sporophytes of ΔPpSMF1 and ΔPpSCRM1 mutants exhibited delayed dehiscence, implying stomata might have promoted dehiscence in the first complex land-plant sporophytes.
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Phytochrome B integrates light and temperature signals in Arabidopsis

Phytochrome B integrates light and temperature signals in Arabidopsis | plant cell genetics | Scoop.it
Combining heat and light responses

Plants integrate a variety of environmental signals to regulate growth patterns. Legris et al. and Jung et al. analyzed how the quality of light is interpreted through ambient temperature to regulate transcription and growth (see the Perspective by Halliday and Davis). The phytochromes responsible for reading the ratio of red to far-red light were also responsive to the small shifts in temperature that occur when dusk falls or when shade from neighboring plants cools the soil.

Science, this issue p. 897, p. 886; see also p. 832
Abstract

Ambient temperature regulates many aspects of plant growth and development, but its sensors are unknown. Here, we demonstrate that the phytochrome B (phyB) photoreceptor participates in temperature perception through its temperature-dependent reversion from the active Pfr state to the inactive Pr state. Increased rates of thermal reversion upon exposing Arabidopsis seedlings to warm environments reduce both the abundance of the biologically active Pfr-Pfr dimer pool of phyB and the size of the associated nuclear bodies, even in daylight. Mathematical analysis of stem growth for seedlings expressing wild-type phyB or thermally stable variants under various combinations of light and temperature revealed that phyB is physiologically responsive to both signals. We therefore propose that in addition to its photoreceptor functions, phyB is a temperature sensor in plants.
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Phototropic solar tracking in sunflower plants: an integrative perspective

Phototropic solar tracking in sunflower plants: an integrative perspective | plant cell genetics | Scoop.it
Background One of the best-known plant movements, phototropic solar tracking in sunflower (Helianthus annuus), has not yet been fully characterized. Two questions are still a matter of debate. (1) Is the adaptive significance solely an optimization of photosynthesis via the exposure of the leaves to the sun? (2) Is shade avoidance involved in this process? In this study, these concepts are discussed from a historical perspective and novel insights are provided.

Scope and Methods Results from the primary literature on heliotropic growth movements led to the conclusion that these responses cease before anthesis, so that the flowering heads point to the East. Based on observations on 10-week-old plants, the diurnal East–West oscillations of the upper fifth of the growing stem and leaves in relation to the position of the sun (inclusive of nocturnal re-orientation) were documented, and photon fluence rates on the leaf surfaces on clear, cloudy and rainy days were determined. In addition, the light–response curve of net CO2 assimilation was determined on the upper leaves of the same batch of plants, and evidence for the occurrence of shade-avoidance responses in growing sunflower plants is summarized.

Conclusions. Only elongating, vegetative sunflower shoots and the upper leaves perform phototropic solar tracking. Photon fluence response and CO2 assimilation measurements cast doubt on the ‘photosynthesis-optimization hypothesis’ as the sole explanation for the evolution of these plant movements. We suggest that the shade-avoidance response, which maximizes light-driven CO2 assimilation, plays a major role in solar tracking populations of competing sunflower plants, and an integrative scheme of these growth movements is provided.
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Evaluating the Economic and Environmental Impacts of a Global GMO Ban

Evaluating the Economic and Environmental Impacts of a Global GMO Ban | plant cell genetics | Scoop.it
The objective of this research is to assess the global economic and greenhouse gas emission impacts of banning GMO crops. This is done by modeling two counterfactual scenarios and evaluating them apart and in combination using a well-know Computable General Equilibrium (CGE) model, GTAP-BIO. The first scenario models the impact of a global GMO ban. The second scenario models the impact of increased GMO penetration. The focus is on the price and welfare impacts, and land use change greenhouse gas (GHG) emissions associated with GMO technologies. Much of the prior work on the economic impacts of GMO technology has relied on a combination of partial equilibrium analysis and econometric techniques. However, CGE modelling is a way of analyzing economy-wide impacts that take into account the linkages in the global economy. Here the goal is to contribute to the literature on the benefits of GMO technology by estimating the impacts on price, supply and welfare. Food price impacts range from an increase of 0.27% to 2.2%, depending on the region. Total welfare losses associated with loss of GMO technology total up to $9.75 billion. The loss of GMO traits as an intensification technology has not only economic impacts, but also environmental ones. The full environmental analysis of GMO is not undertaken here. Rather we model the land use change owing to the loss of GMO traits and calculate the associated increase in GHG emissions. We predict a substantial increase in GHG emissions if GMO technology is banned.
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Scientists Should Oppose the Drive of Postmodern Ideology

Postmodernism is an ideology whose aim is to deconstruct Enlightenment values [2]. Implicitly, postmodernism considers that scientists cannot be trusted, and that their research must be subject to a democratic process, more precisely to a ‘participative democracy’. Undeniably, human activity enabled by science and technology may create risks. The principle of ‘communities’ (Box 1) having a say in the implementation of a technology that bears risks for them is perfectly pertinent. However, whether ‘stakeholders’ or ‘other publics’ should participate by principle in upstream research is a different question. Participation of non-professional researchers or laypersons in scientific activities has always existed and is valuable, for example, to collect large amounts of data. In the latter case, the common goal of all participants is more science, and it does not interfere with the scientific method. The implications are completely different when the participating ‘public’ wants a different science, depending (to quote the NAS report) on its ‘interests, concerns, hopes, fears and values’.

This report goes further, stating that engaging communities, stakeholders, and the public is critical not only for ‘development and potential release of gene drive technology’ but also for ‘successful decision making regarding the research’. The report endorses the view that PE will create ‘mutual learning’ that will foster ‘reflective deliberation’.

Science and technology studies (STS) is a social ‘science’ school of thought concerned with the defense of such a ‘co-construction’ of science. ‘Reflective deliberation’, like participative democracy, and more generally ‘democracy’ used in conjunction with science (e.g., ‘CRISPR democracy’ [3]), is a typical marker for postmodern sociology: ‘reflective deliberation stands at the core of the citizens’ forum model’ [4]. This model aims to undermine ‘technocratic and elitist approaches to policy making’ (which is a legitimate conversation) but also to science itself. The strategy is to introduce ‘new players’ (citizens, stakeholders, etc.) to challenge the scientific method.
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An RNAi-Based Control of Fusarium graminearum Infections Through Spraying of Long dsRNAs Involves a Plant Passage and Is Controlled by the Fungal Silencing Machinery

An RNAi-Based Control of  Fusarium graminearum  Infections Through Spraying of Long dsRNAs Involves a Plant Passage and Is Controlled by the Fungal Silencing Machinery | plant cell genetics | Scoop.it
Meeting the increasing food and energy demands of a growing population will require the development of ground-breaking strategies that promote sustainable plant production. Host-induced gene silencing has shown great potential for controlling pest and diseases in crop plants. However, while delivery of inhibitory noncoding double-stranded (ds)RNA by transgenic expression is a promising concept, it requires the generation of transgenic crop plants which may cause substantial delay for application strategies depending on the transformability and genetic stability of the crop plant species. Using the agronomically important barley—Fusarium graminearum pathosystem, we alternatively demonstrate that a spray application of a long noncoding dsRNA (791 nt CYP3-dsRNA), which targets the three fungal cytochrome P450 lanosterol C-14α-demethylases, required for biosynthesis of fungal ergosterol, inhibits fungal growth in the directly sprayed (local) as well as the non-sprayed (distal) parts of detached leaves. Unexpectedly, efficient spray-induced control of fungal infections in the distal tissue involved passage of CYP3-dsRNA via the plant vascular system and processing into small interfering (si)RNAs by fungal DICER-LIKE 1 (FgDCL-1) after uptake by the pathogen. We discuss important consequences of this new finding on future RNA-based disease control strategies. Given the ease of design, high specificity, and applicability to diverse pathogens, the use of target-specific dsRNA as an anti-fungal agent offers unprecedented potential as a new plant protection strategy.
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In retrospect: Fifty years of C4 photosynthesis : Nature : Nature Research

In retrospect: Fifty years of C4 photosynthesis : Nature : Nature Research | plant cell genetics | Scoop.it
Fifty years ago, Hatch and Slack1 published an analysis of photosynthesis that gave birth to a new field. Their work not only stimulated intense biochemical research to define the mechanisms of a new photosynthetic pathway, but also fed into many other disciplines. Ecologists found that the pathway could explain species distributions. Geologists gained greater insight into changes in the isotope composition of sediments and fossils. And evolutionary biologists started to investigate the highly complex pathway, which is found in many plant lineages and is now considered one of the most remarkable examples of convergent evolution — a process in which the same feature evolves independently in different unrelated species.
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Pour une évaluation basée sur les propriétés des variétés et non sur les méthodes - GM crops—lessons from medicine

Pour une évaluation basée sur les propriétés des variétés et non sur les méthodes - GM crops—lessons from medicine | plant cell genetics | Scoop.it
In Canada, a trait-based regulatory system is used in which the actual trait, such as drought or disease resistance, rather than the method used to derive it, is the basis for regulation. Such a trait-based system is analogous to the regulation of new agents in medicine, which takes into account the context in which the product will be applied. For example, therapeutic antibodies for diseases as diverse as cancer and arthritis are not regulated simply on the basis that they are antibodies—rather, they are assessed in terms of the proteins they target, the benefit to patients, and the risks of adverse events. The focus is on a benefit-to-risk ratio that is reassessed throughout the life cycle of the product (as evidence accumulates). With new medicines for life-threatening diseases, there will usually be a greater acceptance of risk in the absence of existing effective treatments—that is, the consequences of doing nothing are taken into account. Therefore, patients, as well as regulators, accept a lower benefit-to-risk ratio than would be considered appropriate for a disease that is self-limiting and rarely life-threatening, such as the common cold.
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Field Guide to Plant Model Systems

Field Guide to Plant Model Systems | plant cell genetics | Scoop.it
For the past several decades, advances in plant development, physiology, cell biology, and genetics have relied heavily on the model (or reference) plant Arabidopsis thaliana. Arabidopsis resembles other plants, including crop plants, in many but by no means all respects. Study of Arabidopsis alone provides little information on the evolutionary history of plants, evolutionary differences between species, plants that survive in different environments, or plants that access nutrients and photosynthesize differently. Empowered by the availability of large-scale sequencing and new technologies for investigating gene function, many new plant models are being proposed and studied.
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