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Physcomitrella patens studies reveal that ethylene-mediated submergence responses arose relatively early in land-plant evolution - Yasumura - The Plant Journal - Wiley Online Library

Physcomitrella patens studies reveal that ethylene-mediated submergence responses arose relatively early in land-plant evolution - Yasumura - The Plant Journal - Wiley Online Library | plant cell genetics | Scoop.it

The colonization of land by multicellular green plants was a fundamental step in the evolution of life on earth. Land plants evolved from fresh-water aquatic algae, and the transition to a terrestrial environment required the acquisition of developmental plasticity appropriate to water availability conditions ranging from drought to flood. Here we show that extant bryophytes exhibit submergence-induced developmental plasticity, suggesting that submergence responses evolved relatively early in land plant evolution. We also show that a major component of the bryophyte submergence response is controlled by the phytohormone ethylene, using a perception mechanism that has subsequently been conserved throughout land plant evolution. Thus a plant environmental response mechanism, with major ecological and agricultural importance, likely had its origins in the very earliest stages of land colonization.

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Why the European Union needs a national GMO opt-in mechanism

On March 27, 2017, the European Union (EU; Brussels) Appeal Committee on Genetically Modified Food and Feed and Environmental Risk voted on draft regulations for approving the placement of three genetically modified (GM) maize events on the market for cultivation in the EU1. The Appeal Committee once again did not reach a qualified majority for either approval or rejection. The March vote result was similar to the preceding vote in the Regulatory Committee 2001/18/EC on January 27, 2017 (ref. 2). This case was the first of its kind since the amendment of the EU legislation on GM crop cultivation (Directive 2015/412, the so-called 'opt-out Directive')3 came into force in 2015. The opt-out Directive allows EU member states to restrict or prohibit cultivation of GM crops in their territory based on “compelling grounds such as those related to: (a) environmental policy objectives; (b) town and country planning; (c) land use; (d) socioeconomic impacts; (e) avoidance of GMO presence in other products [e.g. crops that would be subject to cross-border 'contamination']; (f) agricultural policy objectives; and (g) public policy”3. This possibility was introduced to acknowledge that decisions on the cultivation of GM crops raise complicated issues other than safety, which are best dealt with at a national level and also to improve the process for authorizing GM crops in the EU.

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Jonathan Lapleau's curator insight, January 11, 9:20 AM
We need to improve the European regulatory system for GMO, this letter explain why and how.
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ScienceDirect

ScienceDirect | plant cell genetics | Scoop.it
Highlights • Two novel methods were combined to estimate a realistic worst case hazard index for pesticide residues in the Danish population. • The methods were able to refine previous estimates especially with regard to below LOQ (left censored) data. • Cumulative health risk assessment conducted for the Danish population. • Perspectives on hazard level of pesticides; comparisons with mycotoxins, caffeine and alcohol. Abstract Relatively few studies are available on realistic cumulative risk assessments for dietary pesticide exposure. Despite available studies showing low risk, public concern remains. A method to estimate realistic residue levels based on information from spraying journals and supervised residue trials was described in a previous publication. The present article proposes a new method to estimate average residue levels in imported foods based on residue monitoring data and knowledge about agronomic practices. The two methods were used in combination to estimate average pesticide residue levels in 47 commodities on the Danish market. The chronic consumer exposure was estimated in six Danish diets. The Hazard Index (HI) method was used to assess consumer risk. Despite the conservative (cautious) risk assessment approach, low HI values where obtained. The HI was 16% for adults and 44% for children, combining the risk of all pesticides in the diet. Conclusion: the present study adds support to the evidence showing that adverse health effects of chronic pesticide residue exposure in the Danish population are very unlikely. The HI for pesticides for a Danish adult was on level with that of alcohol for a person consuming the equivalent of 1 glass of wine every seventh year.
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Transgenic Bt cotton expressing Cry1Ac/Cry2Ab or Cry1Ac/EPSPS does not affect the plant bug Adelphocoris suturalis or the pollinating beetle Haptoncus luteolus - Env Pollution (2017) 

Transgenic Bt cotton expressing Cry1Ac/Cry2Ab or Cry1Ac/EPSPS does not affect the plant bug Adelphocoris suturalis or the pollinating beetle Haptoncus luteolus - Env Pollution (2017)  | plant cell genetics | Scoop.it
The widespread cultivation of transgenic Bt cotton makes assessing the potential effects of this recombinant crop on non-target organisms a priority... The plant bug Adelphocoris suturalis is now a major pest of cotton in southern China and the beetle Haptoncus luteolus is one of the most ancient cotton pollinators. 

We conducted laboratory experiments to evaluate the toxicity of the Bt cotton varieties ZMSJ, which expresses the toxins Cry1Ac and Cry2Ab, and ZMKCKC, which expresses Cry1Ac and EPSPS, on adult A. suturalis and H. luteolus. 

No significant increase in the mortality of either species was detected after feeding on Bt cotton leaves or pollen for 7 days. Trace amounts of Cry1Ac and Cry2Ab proteins could be detected in both species but in vitro binding experiments found no evidence of Cry1Ac and Cry2Ab binding proteins. 

These results demonstrate that feeding on the leaves or pollen of these two Bt cotton varieties has no toxic effects on adult A. suturalis or H. luteolus. 



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Crop Science Abstract - Crop Breeding & Genetics Isolation of Mutations Conferring Increased Glyphosate Resistance in Spring Wheat | Digital Library

A mutation breeding approach was used to explore the feasibility of isolating glyphosate-resistant (GR) wheat (Triticum aestivum L.) lines. Although transgenic GR wheat cultivars were developed, they were never introduced due to lack of consumer acceptance and concern over management of volunteer wheat in rotation. Large-scale screening experiments recovered ethyl methanesulfonate mutants able to resist 360 to 480 g acid equivalent (ae) ha−1 glyphosate in four spring wheat cultivars, ‘Hollis’, ‘Louise’, ‘Macon’, and ‘Tara2002’, indicating that it is possible to recover resistance in a wide range of genetic backgrounds (glyphosate is typically applied at 840 g ae ha−1 in transgenic crops). Glyphosate rates of 420 to 530 g ae ha−1 were sufficient to kill the susceptible wild-type parents. Seven GR mutants were characterized: GRH9-5, GRH9-8, GRL1, GRL33, GRL65, GRM14, and GRT20. Glyphosate resistance was examined at the whole-plant level in dose–response experiments. Three mutant lines—GRL33, GRH9-5, and GRT20—exhibited resistance based on a significant increase in the dose required to retard growth compared with the corresponding susceptible wild type. According to F2 segregation analysis, GRL1, GRL65, and GRT20 segregated as a single dominant gene, whereas GRL33, GRH9-5, and GRH9-8 appeared to be either a single semidominant or polygenic trait. Although GRL1 was associated with an amino acid substitution (L239F) in TaEPSPS-7D1, no nucleotide changes were observed in the coding regions of wheat 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene in GRL33 and GRH9-8. Results suggest that glyphosate resistance can result from multiple genetic mechanisms in wheat.
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Anaesthetics stop diverse plant organ movements, affect endocytic vesicle recycling and ROS homeostasis, and block action potentials in Venus flytraps | Annals of Botany | Oxford Academic

Anaesthetics stop diverse plant organ movements, affect endocytic vesicle recycling and ROS homeostasis, and block action potentials in Venus flytraps | Annals of Botany | Oxford Academic | plant cell genetics | Scoop.it

Abstract Background and Aims Anaesthesia for medical purposes was introduced in the 19th century. However, the physiological mode of anaesthetic drug actions on the nervous system remains unclear. One of the remaining questions is how these different compounds, with no structural similarities and even chemically inert elements such as the noble gas xenon, act as anaesthetic agents inducing loss of consciousness. The main goal here was to determine if anaesthetics affect the same or similar processes in plants as in animals and humans. Methods A single-lens reflex camera was used to follow organ movements in plants before, during and after recovery from exposure to diverse anaesthetics. Confocal microscopy was used to analyse endocytic vesicle trafficking. Electrical signals were recorded using a surface AgCl electrode. Key Results Mimosa leaves, pea tendrils, Venus flytraps and sundew traps all lost both their autonomous and touch-induced movements after exposure to anaesthetics. In Venus flytrap, this was shown to be due to the loss of action potentials under diethyl ether anaesthesia. The same concentration of diethyl ether immobilized pea tendrils. Anaesthetics also impeded seed germination and chlorophyll accumulation in cress seedlings. Endocytic vesicle recycling and reactive oxygen species (ROS) balance, as observed in intact Arabidopsis root apex cells, were also affected by all anaesthetics tested. Conclusions Plants are sensitive to several anaesthetics that have no structural similarities. As in animals and humans, anaesthetics used at appropriate concentrations block action potentials and immobilize organs via effects on action potentials, endocytic vesicle recycling and ROS homeostasis. Plants emerge as ideal model objects to study general questions related to anaesthesia, as well as to serve as a suitable test system for human anaesthesia.

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Meta-analysis approach to assess effect of tillage on microbial biomass and enzyme activities

Meta-analysis approach to assess effect of tillage on microbial biomass and enzyme activities | plant cell genetics | Scoop.it
Measures of soil biology are critical for the assessment of soil quality under different agricultural management practices. By modifying soil microclimate, tillage exerts the most important control on soil microbial communities. The objective of this study is to assess the effect of tillage on soil microbial biomass and enzyme activities. A meta-analysis was conducted utilizing 139 observations from 62 studies from around the world; the selected effect size (ES) was logn of the response ratio (RR), the mean of the tilled treatment divided by the mean of the no-till control. This ES was calculated for seven different microbial properties – microbial biomass carbon (MBC) and nitrogen (MBN), metabolic quotient (qCO2), fluorescein diacetate (FDA), dehydrogenase (DHA), β-glucosidase, and urease. Microbial biomass, metabolic quotient and enzyme activities were evaluated due their prevalent usage in evaluation of soil quality and use in soil quality indices. Overall, microbial biomass and all of the enzyme activities were greater under no-till compared to tillage. One exception to this was that under chisel tillage, there was no difference in MBC between the tilled plots and no-till. The qCO2 was greater under tillage than under no-till indicating more active microbes in tilled soil, perhaps compensating for the reduced quantity. In contrast, when looking at only long-term experiments, qCO2 was similar under both tillage and no-till, which may indicate that eventually microbes in no-till plots become as active as those in tilled plots even with the larger microbial community. The findings of this study illustrate that no-till and even reduced tillage, such as chisel tillage, promote larger microbial communities and greater enzymatic activity.
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Low number of fixed somatic mutations in a long-lived oak tree

Low number of fixed somatic mutations in a long-lived oak tree | plant cell genetics | Scoop.it

Because plants do not possess a defined germline, deleterious somatic mutations can be passed to gametes, and a large number of cell divisions separating zygote from gamete formation may lead to many mutations in long-lived plants. We sequenced the genome of two terminal branches of a 234-year-old oak tree and found several fixed somatic single-nucleotide variants whose sequential appearance in the tree could be traced along nested sectors of younger branches. Our data suggest that stem cells of shoot meristems in trees are robustly protected from the accumulation of mutations.

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Stable Production of the Antimalarial Drug Artemisinin in the Moss Physcomitrella patens

Stable Production of the Antimalarial Drug Artemisinin in the Moss Physcomitrella patens | plant cell genetics | Scoop.it

Malaria is a real and constant danger to nearly half of the world’s population of 7.4 billion people. In 2015, 212 million cases were reported along with 429,000 estimated deaths. The World Health Organization recommends artemisinin-based combinatorial therapies, and the artemisinin for this purpose is mainly isolated from the plant Artemisia annua. However, the plant supply of artemisinin is irregular, leading to fluctuation in prices. Here, we report the development of a simple, sustainable, and scalable production platform of artemisinin. The five genes involved in artemisinin biosynthesis were engineered into the moss Physcomitrella patens via direct in vivo assembly of multiple DNA fragments. In vivo biosynthesis of artemisinin was obtained without further modifications. A high initial production of 0.21 mg/g dry weight artemisinin was observed after only 3 days of cultivation. Our study shows that P. patens can be a sustainable and efficient production platform of artemisinin that without further modifications allow for industrial-scale production. A stable supply of artemisinin will lower the price of artemisinin-based treatments, hence become more affordable to the lower income communities most affected by malaria; an important step toward containment of this deadly disease threatening millions every year.

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Frontiers | Testing of Auxotrophic Selection Markers for Use in the Moss Physcomitrella Provides New Insights into the Mechanisms of Targeted Recombination | Plant Science

Frontiers | Testing of Auxotrophic Selection Markers for Use in the Moss Physcomitrella Provides New Insights into the Mechanisms of Targeted Recombination | Plant Science | plant cell genetics | Scoop.it
The moss Physcomitrella patens is unique among plants in that homologous recombination can be used to knock out genes, just like in yeast. Furthermore, transformed plasmids can be rescued from Physcomitrella back into E. coli, similar to yeast. In the present study, we have tested if a third important tool from yeast molecular genetics, auxotrophic selection markers, can be used in Physcomitrella. Two auxotrophic moss strains were made by knocking out the PpHIS3 geThe moss Physcomitrella patens is unique among plants in that homologous recombination can be used to knock out genes, just like in yeast. Furthermore, transformed plasmids can be rescued from Physcomitrella back into E. coli, similar to yeast. In the present study, we have tested if a third important tool from yeast molecular genetics, auxotrophic selection markers, can be used in Physcomitrella. Two auxotrophic moss strains were made by knocking out the PpHIS3 gene encoding imidazoleglycerol-phosphate dehydratase, and the PpTRP1 gene encoding phosphoribosylanthranilate isomerase, disrupting the biosynthesis of histidine and tryptophan, respectively. The resulting PpHIS3∆ and PpTRP1∆ knockout strains were unable to grow on medium lacking histidine or tryptophan. The PpHIS3∆ strain was used to test selection of transformants by complementation of an auxotrophic marker. We found that the PpHIS3∆ strain could be complemented by transformation with a plasmid expressing the PpHIS3 gene from the CaMV 35S promoter, allowing the strain to grow on medium lacking histidine. Both linearized plasmids and circular supercoiled plasmids could complement the auxotrophic marker, and plasmids from both types of transformants could be rescued back into E. coli. Plasmids rescued from circular transformants were identical to the original plasmid, whereas plasmids rescued from linearized transformants had deletions generated by recombination between micro-homologies in the plasmids. Our results show that cloning by complementation of an auxotrophic marker works in Physcomitrella, which opens the door for using auxotrophic selection markers in moss molecular genetics. This will facilitate the adaptation of shuttle plasmid dependent methods from yeast molecular genetics for use in Physcomitrella.
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Genome sequence of the progenitor of the wheat D genome Aegilops tauschii

Genome sequence of the progenitor of the wheat D genome Aegilops tauschii | plant cell genetics | Scoop.it

Aegilops tauschii is the diploid progenitor of the D genome of hexaploid wheat1 (Triticum aestivum, genomes AABBDD) and an important genetic resource for wheat2,3,4. The large size and highly repetitive nature of the Ae. tauschii genome has until now precluded the development of a reference-quality genome sequence5. Here we use an array of advanced technologies, including ordered-clone genome sequencing, whole-genome shotgun sequencing, and BioNano optical genome mapping, to generate a reference-quality genome sequence for Ae. tauschii ssp. strangulata accession AL8/78, which is closely related to the wheat D genome. We show that compared to other sequenced plant genomes, including a much larger conifer genome, the Ae. tauschii genome contains unprecedented amounts of very similar repeated sequences. Our genome comparisons reveal that the Ae. tauschii genome has a greater number of dispersed duplicated genes than other sequenced genomes and its chromosomes have been structurally evolving an order of magnitude faster than those of other grass genomes. The decay of colinearity with other grass genomes correlates with recombination rates along chromosomes. We propose that the vast amounts of very similar repeated sequences cause frequent errors in recombination and lead to gene duplications and structural chromosome changes that drive fast genome evolution.

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Persulfidation proteome reveals the regulation of protein function by hydrogen sulfide in diverse biological processes in Arabidopsis | Journal of Experimental Botany | Oxford Academic

Persulfidation proteome reveals the regulation of protein function by hydrogen sulfide in diverse biological processes in Arabidopsis | Journal of Experimental Botany | Oxford Academic | plant cell genetics | Scoop.it
Hydrogen sulfide-mediated signaling pathways regulate many physiological and pathophysiological processes in mammalian and plant systems. The molecular mechanism by which hydrogen sulfide exerts its action involves the post-translational modification of cysteine residues to form a persulfidated thiol motif, a process called protein persulfidation. We have developed a comparative and quantitative proteomic analysis approach for the detection of endogenous persulfidated proteins in wild-type Arabidopsis and L-CYSTEINE DESULFHYDRASE 1 mutant leaves using the tag-switch method. The 2015 identified persulfidated proteins were isolated from plants grown under controlled conditions, and therefore, at least 5% of the entire Arabidopsis proteome may undergo persulfidation under baseline conditions. Bioinformatic analysis revealed that persulfidated cysteines participate in a wide range of biological functions, regulating important processes such as carbon metabolism, plant responses to abiotic and biotic stresses, plant growth and development, and RNA translation. Quantitative analysis in both genetic backgrounds reveals that protein persulfidation is mainly involved in primary metabolic pathways such as the tricarboxylic acid cycle, glycolysis, and the Calvin cycle, suggesting that this protein modification is a new regulatory component in these pathways.
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“La Vie en Rose”: Biosynthesis, Sources and Applications of Betalain Pigments

“La Vie en Rose”: Biosynthesis, Sources and Applications of Betalain Pigments | plant cell genetics | Scoop.it

This review discusses betalain metabolism in light of recent advances in the field, with an up-to-date survey of characterized genes and enzymes that take part in betalain biosynthesis, catabolism and transcriptional regulation. Currently-used and potential new sources for betalains are discussed, together with a summary of possible applications of betalains in research and commercial use.

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Insights into Land Plant Evolution Garnered from the Marchantia polymorpha Genome, cell

Insights into Land Plant Evolution Garnered from the Marchantia polymorpha Genome, cell | plant cell genetics | Scoop.it
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The push and pull of plant specialized metabolism underlies a long‐standing, colorful mystery

The push and pull of plant specialized metabolism underlies a long‐standing, colorful mystery | plant cell genetics | Scoop.it


This article is a Commentary on Lopez‐Nieves et al., 217: 896–908.

Three types of compounds – chlorophylls, carotenoids and anthocyanins – are responsible for generating the vast majority of colors in the plant world. However, in 1918, a PhD student working with Richard Willstätter – the 1915 Chemistry Nobel Prize Winner who studied chlorophyll – recognized that the red color in beets is different (Ainley & Robinson, 1937). The red, purple and blue colors in many plants are a result of accumulation of anthocyanins, which lack nitrogen. However, the red pigment in beets – composed of the compound betanin – was found to contain nitrogen. Betanin soon came to be annotated (Ainley & Robinson, 1937) – with some suspicion (Pucher et al., 1938) – as a ‘nitrogenous anthocyanin’, with one or more amino acids conjugated to an anthocyanin backbone. However, this inference was proved incorrect when, in 1957, it was demonstrated that the nitrogen in betanin was actually contained in a pyrrole ring and not in a conjugated amino acid (Peterson & Joslyn, 1958). This intriguing difference between

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Speed breeding is a powerful tool to accelerate crop research and breeding

Speed breeding is a powerful tool to accelerate crop research and breeding | plant cell genetics | Scoop.it

The growing human population and a changing environment have raised significant concern for global food security, with the current improvement rate of several important crops inadequate to meet future demand1. This slow improvement rate is attributed partly to the long generation times of crop plants. Here, we present a method called ‘speed breeding’, which greatly shortens generation time and accelerates breeding and research programmes. Speed breeding can be used to achieve up to 6 generations per year for spring wheat (Triticum aestivum), durum wheat (T. durum), barley (Hordeum vulgare), chickpea (Cicer arietinum) and pea (Pisum sativum), and 4 generations for canola (Brassica napus), instead of 2–3 under normal glasshouse conditions. We demonstrate that speed breeding in fully enclosed, controlled-environment growth chambers can accelerate plant development for research purposes, including phenotyping of adult plant traits, mutant studies and transformation. The use of supplemental lighting in a glasshouse environment allows rapid generation cycling through single seed descent (SSD) and potential for adaptation to larger-scale crop improvement programs. Cost saving through light-emitting diode (LED) supplemental lighting is also outlined. We envisage great potential for integrating speed breeding with other modern crop breeding technologies, including high-throughput genotyping, genome editing and genomic selection, accelerating the rate of crop improvement.

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Physcomitrella MADS-box genes regulate water supply and sperm movement for fertilization

Physcomitrella MADS-box genes regulate water supply and sperm movement for fertilization | plant cell genetics | Scoop.it

MIKC classic (MIKCC)-type MADS-box genes encode transcription factors that function in various developmental processes, including angiosperm floral organ identity. Phylogenetic analyses of the MIKCC-type MADS-box family, including genes from non-flowering plants, suggest that the increased numbers of these genes in flowering plants is related to their functional divergence; however, their precise functions in non-flowering plants and their evolution throughout land plant diversification are unknown. Here, we show that MIKCC-type MADS-box genes in the moss Physcomitrella patens function in two ways to enable fertilization. Analyses of protein localization, deletion mutants and overexpression lines of all six genes indicate that three MIKCC-type MADS-box genes redundantly regulate cell division and growth in the stems for appropriate external water conduction, as well as the formation of sperm with motile flagella. The former function appears to be maintained in the flowering plant lineage, while the latter was lost in accordance with the loss of sperm.

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Bioproduction of a betalain color palette in Saccharomyces cerevisiae

Bioproduction of a betalain color palette in Saccharomyces cerevisiae | plant cell genetics | Scoop.it
Betalains are a family of natural pigments found exclusively in the plant order Caryophyllales. All members of this chemical family are biosynthesized through the common intermediate betalamic acid, which is capable of spontaneously condensing with various primary and secondary amines to produce betalains. Of particular interest is the red-violet betanin, most commonly obtained from Beta vulgaris (beet) as a natural food dye. We demonstrate the first complete microbial production of betanin in Saccharomyces cerevisiae from glucose, an early step towards a fermentation process enabling rapid, on-demand production of this natural dye. A titer of 17 mg/L was achieved, corresponding to a color intensity obtained from 10 g/L of beetroot extract. Further, we expanded the spectrum of betalain colors by condensing betalamic acid with various amines fed to an engineered strain of S. cerevisiae. Our work establishes a platform for microbial production of betalains of various colors as a potential alternative to land- and resource-intensive agricultural production.
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The P. patens chromosome‐scale assembly reveals moss genome structure and evolution

The P. patens chromosome‐scale assembly reveals moss genome structure and evolution | plant cell genetics | Scoop.it

The draft genome of the moss model, Physcomitrella patens, comprised approximately 2,000 unordered scaffolds. In order to enable analyses of genome structure and evolution we generated a chromosome-scale genome assembly using genetic linkage as well as (end) sequencing of long DNA fragments. We find that 57% of the genome comprises transposable elements (TEs), some of which may be actively transposing during the life cycle. Unlike in flowering plant genomes, gene- and TE-rich regions show an overall even distribution along the chromosomes. However, the chromosomes are mono-centric with peaks of a class of Copia elements potentially coinciding with centromeres. Gene body methylation is evident in 5.7% of the protein-coding genes, typically coinciding with low GC and low expression. Some giant virus insertions are transcriptionally active and might protect gametes from viral infection via siRNA mediated silencing. Structure-based detection methods show that the genome evolved via two rounds of whole genome duplications (WGDs), apparently common in mosses but not in liverworts and hornworts. Several hundred genes are present in colinear regions conserved since the last common ancestor of plants. These syntenic regions are enriched for functions related to plant-specific cell growth and tissue organization. The P. patens genome lacks the TE-rich pericentromeric and gene-rich distal regions typical for most flowering plant genomes. More non-seed plant genomes are needed to unravel how plant genomes evolve, and to understand whether the P. patens genome structure is typical for mosses or bryophytes.

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Identification of a Novel Maize Protein Important for Paramutation at the purple plant1 Locus

Identification of a Novel Maize Protein Important for Paramutation at the purple plant1 Locus | plant cell genetics | Scoop.it
Paramutation occurs at a specific locus when one epiallele, referred to as paramutagenic, facilitates a heritable change in the regulation of the other epiallele, which is referred to as paramutable (reviewed in Arteaga-Vazquez and Chandler, 2010). Because these two states have the same DNA sequence but differ epigenetically, they are referred to as epialleles, or states, rather than alleles. Generally, transcription from paramutable epialleles is heritably repressed following exposure to paramutagenic alleles. Paramutation was first discovered in the 1950s as an epigenetic phenomenon affecting maize (Zea mays) anthocyanin production regulated by red1 (r1) and booster1 (b1). For example, the paramutable B-I epiallele produces strong anthocyanin expression, but when crossed to the low-anthocyanin paramutagenic B′ epiallele, the B-I allele is converted in trans into a heritable, low-anthocyanin, paramutagenic B′ epiallele. Paramutation seems to involve sequences affecting transcription, such as an 853-bp tandem repeat 100 kb upstream of B-I, which acts as a transcriptional enhancer.
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How to get old without aging

How to get old without aging | plant cell genetics | Scoop.it

The low number of mutations in multiple sectors from a 234-year-old oak tree reveals possible mechanisms to avoid the irreversible build-up of mutations in long-lived plants. How do trees manage to survive for hundreds or even thousands of years1,2? How do they avoid the gradual accumulation of mutations due to DNA replication errors and environmental influences such as ultraviolet radiation? In this issue of Nature Plants, Schmid-Siegert et al.3 address this long-standing question by studying genetic diversity in a tree on their campus. The tree is locally known as Napoleon’s Oak and commemorates the visit of the victorious general in the year 1800. Napoleon has been dead now for almost two centuries and so are all his contemporaries, but the oak that bears his name has grown into a magnificent tree. Why do trees live so much longer than us humans? The authors decided to count the number of mutations in Napoleon’s Oak through a great citizens’ outreach project (http://www.napoleome.ch).

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A Review of Biotechnological Artemisinin Production in Plants

A Review of Biotechnological Artemisinin Production in Plants | plant cell genetics | Scoop.it

Malaria is still an eminent threat to major parts of the world population mainly in sub-Saharan Africa. Researchers around the world continuously seek novel solutions to either eliminate or treat the disease. Artemisinin, isolated from the Chinese medicinal herb Artemisia annua, is the active ingredient in artemisinin-based combination therapies used to treat the disease. However, naturally artemisinin is produced in small quantities, which leads to a shortage of global supply. Due to its complex structure, it is difficult chemically synthesize. Thus to date, A. annua remains as the main commercial source of artemisinin. Current advances in genetic and metabolic engineering drives to more diverse approaches and developments on improving in planta production of artemisinin, both in A. annua and in other plants. In this review, we describe efforts in bioengineering to obtain a higher production of artemisinin in A. annua and stable heterologous in planta systems. The current progress and advancements provides hope for significantly improved production in plants.

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Use of CRISPR systems in plant genome editing: toward new opportunities in agriculture

Use of CRISPR systems in plant genome editing: toward new opportunities in agriculture | plant cell genetics | Scoop.it
Initially discovered in bacteria and archaea, CRISPR–Cas9 is an adaptive immune system found in prokaryotes. In 2012, scientists found a way to use it as a genome editing tool. In 2013, its application in plants was successfully achieved. This breakthrough has opened up many new opportunities for researchers, including the opportunity to gain a better understanding of plant biological systems more quickly. The present study reviews agricultural applications related to the use of CRISPR systems in plants from 52 peer-reviewed articles published since 2014. Based on this literature review, the main use of CRISPR systems is to achieve improved yield performance, biofortification, biotic and abiotic stress tolerance, with rice ( Oryza sativa ) being the most studied crop.
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Health effect of agricultural pesticide use in China: implications for the development of GM crops

It is notable that the adoption of GM glyphosate-tolerant crops increases glyphosate use but reduces non-glyphosate herbicide use; and adoption of GM insect-resistant crops significantly reduces insecticide use. While the health hazard of pesticide use has been well documented, little literature evaluates the health effects of different pesticides related to GM crops in an integrated framework. This study aims to associate the uses of different pesticides related to GM crops with the blood chemistry panel and peripheral nerve conduction of Chinese farmers. Pesticides used by farmers were recorded and classified as glyphosate, non-glyphosate herbicides, chemical lepidopteran insecticides, biological lepidopteran insecticides, non-lepidopteran insecticides and fungicides. The multivariate regression results show that none of the examined 35 health indicators was associated with glyphosate use, while the use of non-glyphosate herbicides was likely to induce renal dysfunction and decrease of serum folic acid. The use of chemical lepidopteran insecticides might be associated with hepatic dysfunction, serum glucose elevation, inflammation and even severe nerve damage. In this context, if GM crops are adopted, the alterations in pesticide use may benefit farmer health in China and globe, which has positive implications for the development of GM crops.
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Relaxation of tyrosine pathway regulation underlies the evolution of betalain pigmentation in Caryophyllales

Relaxation of tyrosine pathway regulation underlies the evolution of betalain pigmentation in Caryophyllales | plant cell genetics | Scoop.it
Diverse natural products are synthesized in plants by specialized metabolic enzymes, which are often lineage-specific and derived from gene duplication followed by functional divergence. However, little is known about the contribution of primary metabolism to the evolution of specialized metabolic pathways.
Betalain pigments, uniquely found in the plant order Caryophyllales, are synthesized from the aromatic amino acid l-tyrosine (Tyr) and replaced the otherwise ubiquitous phenylalanine-derived anthocyanins. This study combined biochemical, molecular and phylogenetic analyses, and uncovered coordinated evolution of Tyr and betalain biosynthetic pathways in Caryophyllales.
We found that Beta vulgaris, which produces high concentrations of betalains, synthesizes Tyr via plastidic arogenate dehydrogenases (TyrAa/ADH) encoded by two ADH genes (BvADHα and BvADHβ). Unlike BvADHβ and other plant ADHs that are strongly inhibited by Tyr, BvADHα exhibited relaxed sensitivity to Tyr. Also, Tyr-insensitive BvADHα orthologs arose during the evolution of betalain pigmentation in the core Caryophyllales and later experienced relaxed selection and gene loss in lineages that reverted from betalain to anthocyanin pigmentation, such as Caryophyllaceae.
These results suggest that relaxation of Tyr pathway regulation increased Tyr production and contributed to the evolution of betalain pigmentation, highlighting the significance of upstream primary metabolic regulation for the diversification of specialized plant metabolism.
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Scooped by Jean-Pierre Zryd
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Ancient trans-Acting siRNAs Confer Robustness and Sensitivity onto the Auxin Response

Ancient trans-Acting siRNAs Confer Robustness and Sensitivity onto the Auxin Response | plant cell genetics | Scoop.it

Plavskin et al. show that, in moss, ancient TAS3-derived tasiRNAs confer sensitivity
and robustness onto the plant response to the phytohormone auxin and stochastically
modulate development in response to environmental cues. These properties provide a basis for the repeated cooption of small RNA target modules over the course of plant evolution.

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