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Rescooped by Jennifer Mach from PlantBioInnovation
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Arabidopsis ribosomal proteins control developmental programs through translational regulation of auxin response factors

Abstract

Upstream ORFs are elements found in the 5′-leader sequences of specific mRNAs that modulate the translation of downstream ORFs encoding major gene products. In Arabidopsis, the translational control of auxin response factors (ARFs) by upstream ORFs has been proposed as a regulatory mechanism required to respond properly to complex auxin-signaling inputs. In this study, we identify and characterize the aberrant auxin responses in specific ribosomal protein mutants in which multiple ARF transcription factors are simultaneously repressed at the translational level. This characteristic lends itself to the use of these mutants as genetic tools to bypass the genetic redundancy among members of the ARF family in Arabidopsis. Using this approach, we were able to assign unique functions for ARF2, ARF3, and ARF6 in plant development.


Via Biswapriya Biswavas Misra
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Emerging Research in Plant Cell Biology
A science editor's take on what's new and interesting in the plant kingdom.
Curated by Jennifer Mach
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Smoke and Hormone Mirrors: Action and Evolution of Karrikin and Strigolactone Signaling: Trends in Genetics

Smoke and Hormone Mirrors: Action and Evolution of Karrikin and Strigolactone Signaling: Trends in Genetics | Emerging Research in Plant Cell Biology | Scoop.it

Karrikins and strigolactones are two classes of butenolide molecules that have diverse effects on plant growth. Karrikins are found in smoke and strigolactones are plant hormones, yet both molecules are likely recognized through highly similar signaling mechanisms. Here we review the most recent discoveries of karrikin and strigolactone perception and signal transduction. Two paralogous α/β hydrolases, KAI2 and D14, are respectively karrikin and strigolactone receptors. D14 acts with an F-box protein, MAX2, to target SMXL/D53 family proteins for proteasomal degradation, and genetic data suggest that KAI2 acts similarly. There are striking parallels in the signaling mechanisms of karrikins, strigolactones, and other plant hormones, including auxins, jasmonates, and gibberellins. Recent investigations of host perception in parasitic plants have demonstrated that strigolactone recognition can evolve following gene duplication of KAI2.

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Rescooped by Jennifer Mach from Plant immunity and legume symbiosis
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Frontiers | Ethylene, a Hormone at the Center-Stage of Nodulation | Plant Nutrition

Frontiers | Ethylene, a Hormone at the Center-Stage of Nodulation | Plant Nutrition | Emerging Research in Plant Cell Biology | Scoop.it
Nodulation is the result of a beneficial interaction between legumes and rhizobia. It is a sophisticated process leading to nutrient exchange between the two types of symbionts. In this association, within a nodule, the rhizobia, using energy provided as photosynthates, fix atmospheric nitrogen and convert it to ammonium which is available to the plant. Nodulation is recognized as an essential process in nitrogen cycling and legume crops are known to enrich agricultural soils in nitrogenous compounds. Furthermore, as they are rich in nitrogen, legumes are considered important as staple foods for humans and fodder for animals. To tightly control this association and keep it mutualistic, the plant uses several means, including hormones. The hormone ethylene has been known as a negative regulator of nodulation for almost four decades. Since then, much progress has been made in the understanding of both the ethylene signaling pathway and the nodulation process. Here I have taken a large view, using recently obtained knowledge, to describe in some detail the major stages of the process. I have not only reviewed the steps most commonly covered (the common signaling transduction pathway, and the epidermal and cortical programs), but I have also looked into steps less understood (the pre-infection step with the plant defense response, the bacterial release and the formation of the symbiosome, and nodule functioning and senescence). After a succinct review of the ethylene signaling pathway, I have used the knowledge obtained from nodulation- and ethylene-related mutants to paint a more complete picture of the role played by the hormone in nodule organogenesis, functioning, and senescence. It transpires that ethylene is at the center of this effective symbiosis. It has not only been involved in most of the steps leading to a mature nodule, but it has also been implicated in host immunity and nodule senescence. It is likely responsible for the activation of other hormonal signaling pathways. I have completed the review by citing three studies which makes one wonder whether knowledge gained on nodulation in the last decades is ready to be transferred to agricultural fields.

Via Christophe Jacquet
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Rescooped by Jennifer Mach from Plant pathogenic fungi
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Science Signaling: 2015: Signaling Breakthroughs of the Year - Plant Innate Immune Response

Science Signaling: 2015: Signaling Breakthroughs of the Year - Plant Innate Immune Response | Emerging Research in Plant Cell Biology | Scoop.it

Plants are subject to attack by pathogens, and, like animals, the plant innate immune response involves both surface and cytoplasmic receptors. Intracellular nucleotide-binding leucine-rich repeat receptors involved in the plant innate immune response are structurally and functionally similar to animal Nod-like receptors (NLRs), which play a key role in inflammasome activation. Plant NLRs, which detect pathogen-derived virulence factors (effectors) frequently directed against plant defenses triggered by the plasma membrane-localized immune receptors, can function in pairs, with both partners required for activation of an immune response. In work that he described as representing “a paradigmatic shift in our understanding of how immune receptors work,” Cyril Zipfel nominated three papers (24–26) describing an intriguing twist on effector detection. Le Roux et al. (24) and Sarris et al. (25) showed how integration of a “decoy” or “sensor” domain that mimics host targets baits pathogenic virulence factors to one member of a plant NLR pair, thereby activating the partner NLR to initiate defense signaling. In a third breakthrough paper on this theme, Maqbool et al. (26) determined the structural basis for effector interaction with a different class of integrated domain and demonstrated that a high binding affinity between the NLR domain and the effector is required to activate immunity. The emerging theme from these papers is that the very mechanisms that enable pathogen virulence factors to cripple the initial wave of the immune response have been turned to their own destruction.


Via Kamoun Lab @ TSL, Steve Marek
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A proposed regulatory framework for genome-edited crops

A proposed regulatory framework for genome-edited crops | Emerging Research in Plant Cell Biology | Scoop.it

Crop breeding is being revolutionized by rapid progress in DNA sequencing and targeted alteration of DNA sequences by genome editing. Here we propose a regulatory framework for precision breeding with 'genome-edited crops' (GECs) so that society can fully benefit from the latest advances in plant genetics and genomics.

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Genome reduction uncovers a large dispensable genome and adaptive role for copy number variation in asexually propagated Solanum tuberosum

Genome reduction uncovers a large dispensable genome and adaptive role for copy number variation in asexually propagated Solanum tuberosum | Emerging Research in Plant Cell Biology | Scoop.it

Clonally reproducing plants have the potential to bear a significantly greater mutational load than sexually reproducing species. To investigate this possibility, we examined the breadth of genome-wide structural variation in a panel of monoploid/doubled monoploid clones generated from native populations of diploid potato (Solanum tuberosum), a highly heterozygous asexually propagated plant. As rare instances of purely homozygous clones, they provided an ideal set for determining the degree of structural variation tolerated by this species, and deriving its minimal gene complement. Extensive copy number variation (CNV) was uncovered, impacting 219.8 Mb (30.2%) of the potato genome with nearly 30% of genes subject to at least partial duplication or deletion, revealing the highly heterogeneous nature of the potato genome. Dispensable genes (>7,000) were associated with limited transcription and/or a recent evolutionary history, with lower deletion frequency observed in genes conserved across angiosperms. Association of CNV with plant adaptation was highlighted by enrichment in gene clusters encoding functions for environmental stress response, with gene duplication playing a part in species-specific expansions of stress-related gene families. This study revealed unique impacts of CNV in a species with asexual reproductive habits, and how CNV may drive adaption through evolution of key stress pathways.


Via Pierre-Marc Delaux, Saclay Plant Sciences
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Mobile small RNAs regulate genome-wide DNA methylation

Mobile small RNAs regulate genome-wide DNA methylation | Emerging Research in Plant Cell Biology | Scoop.it

RNA silencing at the transcriptional and posttranscriptional levels regulates endogenous gene expression, controls invading transposable elements (TEs), and protects the cell against viruses. Key components of the mechanism are small RNAs (sRNAs) of 21–24 nt that guide the silencing machinery to their nucleic acid targets in a nucleotide sequence-specific manner. Transcriptional gene silencing is associated with 24-nt sRNAs and RNA-directed DNA methylation (RdDM) at cytosine residues in three DNA sequence contexts (CG, CHG, and CHH). We previously demonstrated that 24-nt sRNAs are mobile from shoot to root inArabidopsis thaliana and confirmed that they mediate DNA methylation at three sites in recipient cells. In this study, we extend this finding by demonstrating that RdDM of thousands of loci in root tissues is dependent upon mobile sRNAs from the shoot and that mobile sRNA-dependent DNA methylation occurs predominantly in non-CG contexts. Mobile sRNA-dependent non-CG methylation is largely dependent on the DOMAINS REARRANGED METHYLTRANSFERASES 1/2 (DRM1/DRM2) RdDM pathway but is independent of the CHROMOMETHYLASE (CMT)2/3 DNA methyltransferases. Specific superfamilies of TEs, including those typically found in gene-rich euchromatic regions, lose DNA methylation in a mutant lacking 22- to 24-nt sRNAs (dicer-like 2, 3, 4 triple mutant). Transcriptome analyses identified a small number of genes whose expression in roots is associated with mobile sRNAs and connected to DNA methylation directly or indirectly. Finally, we demonstrate that sRNAs from shoots of one accession move across a graft union and target DNA methylation de novo at normally unmethylated sites in the genomes of root cells from a different accession.

Jennifer Mach's insight:

Image courtesy of @SalkInstitute.

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Rescooped by Jennifer Mach from Plant roots and rhizosphere
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An aquaporin PvTIP4;1 from Pteris vittata may mediate arsenite uptake - New Phytologist -

An aquaporin PvTIP4;1 from Pteris vittata may mediate arsenite uptake - New Phytologist - | Emerging Research in Plant Cell Biology | Scoop.it
The fern Pteris vittata is an arsenic hyperaccumulator. The genes involved in arsenite (As(III)) transport are not yet clear. Here, we describe the isolation and characterization of a new P. vittata aquaporin gene, PvTIP4;1, which may mediate As(III) uptake.
PvTIP4;1 was identified from yeast functional complement cDNA library of P. vittata. Arsenic toxicity and accumulating activities of PvTIP4;1 were analyzed in Saccharomyces cerevisiae and Arabidopsis. Subcellular localization of PvTIP4;1–GFP fusion protein in P. vittata protoplast and callus was conducted. The tissue expression of PvTIP4;1 was investigated by quantitative real-time PCR. Site-directed mutagenesis of the PvTIP4;1 aromatic/arginine (Ar/R) domain was studied.
Heterologous expression in yeast demonstrates that PvTIP4;1 was able to facilitate As(III) diffusion. Transgenic Arabidopsis showed that PvTIP4;1 increases arsenic accumulation and induces arsenic sensitivity. Images and FM4-64 staining suggest that PvTIP4;1 localizes to the plasma membrane in P. vittata cells. A tissue location study shows that PvTIP4;1 transcripts are mainly expressed in roots. Site-directed mutation in yeast further proved that the cysteine at the LE1 position of PvTIP4;1 Ar/R domain is a functional site.
PvTIP4;1 is a new represented tonoplast intrinsic protein (TIP) aquaporin from P. vittata and the function and location results imply that PvTIP4;1 may be involved in As(III) uptake.

Via Christophe Jacquet
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Adaptation of Root Function by Nutrient-Induced Plasticity of Endodermal Differentiation: Cell

Adaptation of Root Function by Nutrient-Induced Plasticity of Endodermal Differentiation: Cell | Emerging Research in Plant Cell Biology | Scoop.it

Plant roots forage the soil for minerals whose concentrations can be orders of magnitude away from those required for plant cell function. Selective uptake in multicellular organisms critically requires epithelia with extracellular diffusion barriers. In plants, such a barrier is provided by the endodermis and its Casparian strips—cell wall impregnations analogous to animal tight and adherens junctions. Interestingly, the endodermis undergoes secondary differentiation, becoming coated with hydrophobic suberin, presumably switching from an actively absorbing to a protective epithelium. Here, we show that suberization responds to a wide range of nutrient stresses, mediated by the stress hormones abscisic acid and ethylene. We reveal a striking ability of the root to not only regulate synthesis of suberin, but also selectively degrade it in response to ethylene. Finally, we demonstrate that changes in suberization constitute physiologically relevant, adaptive responses, pointing to a pivotal role of the endodermal membrane in nutrient homeostasis.

Jennifer Mach's insight:

Well-written abstract (or "summary", whatever Cell wants to call it).

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Rescooped by Jennifer Mach from Plant-Microbe Symbiosis
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Transcriptome analysis of secondary cell wall development in Medicago truncatula

Transcriptome analysis of secondary cell wall development in Medicago truncatula | Emerging Research in Plant Cell Biology | Scoop.it
Background
Legumes are important to humans by providing food, feed and raw materials for industrial utilizations. Some legumes, such as alfalfa, are potential bioenergy crops due to their high biomass productivity. Global transcriptional profiling has been successfully used to identify genes and regulatory pathways in secondary cell wall thickening in Arabidopsis, but such transcriptome data is lacking in legumes.

Results
A systematic microarray assay and high through-put real time PCR analysis of secondary cell wall development were performed along stem maturation in Medicago truncatula. More than 11,000 genes were differentially expressed during stem maturation, and were categorized into 10 expression clusters. Among these, 279 transcription factor genes were correlated with lignin/cellulose biosynthesis, therefore representing putative regulators of secondary wall development. The b-ZIP, NAC, WRKY, C2H2 zinc finger (ZF), homeobox, and HSF gene families were over-represented. Gene co-expression network analysis was employed to identify transcription factors that may regulate the biosynthesis of lignin, cellulose and hemicellulose. As a complementary approach to microarray, real-time PCR analysis was used to characterize the expression of 1,045 transcription factors in the stem samples, and 64 of these were upregulated more than 5-fold during stem maturation. Reverse genetics characterization of a cellulose synthase gene in cluster 10 confirmed its function in xylem development.

Conclusions
This study provides a useful transcriptome and expression resource for understanding cell wall development, which is pivotal to enhance biomass production in legumes.

Via Jean-Michel Ané
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Rescooped by Jennifer Mach from Plant and Seed Biology
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High-fidelity CRISPR–Cas9 nucleases with no detectable genome-wide off-target effects : Nature

High-fidelity CRISPR–Cas9 nucleases with no detectable genome-wide off-target effects : Nature | Emerging Research in Plant Cell Biology | Scoop.it

CRISPR–Cas9 nucleases are widely used for genome editing but can induce unwanted off-target mutations. Existing strategies for reducing genome-wide off-target effects of the widely usedStreptococcus pyogenes Cas9 (SpCas9) are imperfect, possessing only partial or unproven efficacies and other limitations that constrain their use. Here we describe SpCas9-HF1, a high-fidelity variant harbouring alterations designed to reduce non-specific DNA contacts. SpCas9-HF1 retains on-target activities comparable to wild-type SpCas9 with >85% of single-guide RNAs (sgRNAs) tested in human cells. Notably, with sgRNAs targeted to standard non-repetitive sequences, SpCas9-HF1 rendered all or nearly all off-target events undetectable by genome-wide break capture and targeted sequencing methods. Even for atypical, repetitive target sites, the vast majority of off-target mutations induced by wild-type SpCas9 were not detected with SpCas9-HF1. With its exceptional precision, SpCas9-HF1 provides an alternative to wild-type SpCas9 for research and therapeutic applications. More broadly, our results suggest a general strategy for optimizing genome-wide specificities of other CRISPR-RNA-guided nucleases.


Via Loïc Lepiniec
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Rescooped by Jennifer Mach from microbial pathogenesis and plant immunity
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PLOS Pathog: An Oomycete CRN Effector Reprograms Expression of Plant HSP Genes by Targeting their Promoters

PLOS Pathog: An Oomycete CRN Effector Reprograms Expression of Plant  HSP  Genes by Targeting their Promoters | Emerging Research in Plant Cell Biology | Scoop.it
Author Summary Phytophthora is a genus of plant-damaging oomycetes and contains over 100 species, most of which can cause enormous economic losses on crops and environmental damage to natural ecosystems. Phytophthora pathogens produce hundreds of effectors that act inside host cells during interaction with their host organisms. Some of these effectors may target distinct host proteins to suppress host defense and promote infection. In this study we discovered a P . sojae effector PsCRN108 that suppresses plant basal defense and reprograms expression of many host genes. Among them, ~45% of total Heat Shock Protein ( HSP ) genes were down-regulated. Using a GUS expression assay, we found that the effector suppressed the induction of genes driven by the AtHSP90 . 1 promoter or a synthetic Heat Shock Element (HSE). We found that PsCRN108 preferentially targets conserved HSE’s, and can interfere with their binding to a plant heat shock transcription factor AtHsfA1a. Thus, we conclude that the effector directly targets host DNA, which is a novel mechanism by which Phytophthora pathogens overcome host defense responses.

Via Suayib Üstün, Jim Alfano
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Jim Alfano's curator insight, January 6, 10:44 AM

Interesting effector story

Rescooped by Jennifer Mach from Plants and Microbes
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Nature Genetics: A recently evolved hexose transporter variant confers resistance to multiple pathogens in wheat (2015)

Nature Genetics: A recently evolved hexose transporter variant confers resistance to multiple pathogens in wheat (2015) | Emerging Research in Plant Cell Biology | Scoop.it

As there are numerous pathogen species that cause disease and limit yields of crops, such as wheat (Triticum aestivum), single genes that provide resistance to multiple pathogens are valuable in crop improvement1, 2. The mechanistic basis of multi-pathogen resistance is largely unknown. Here we use comparative genomics, mutagenesis and transformation to isolate the wheat Lr67 gene, which confers partial resistance to all three wheat rust pathogen species and powdery mildew. The Lr67 resistance gene encodes a predicted hexose transporter (LR67res) that differs from the susceptible form of the same protein (LR67sus) by two amino acids that are conserved in orthologous hexose transporters. Sugar uptake assays show that LR67sus, and related proteins encoded by homeoalleles, function as high-affinity glucose transporters. LR67res exerts a dominant-negative effect through heterodimerization with these functional transporters to reduce glucose uptake. Alterations in hexose transport in infected leaves may explain its ability to reduce the growth of multiple biotrophic pathogen species.


News & Views at http://www.nature.com/ng/journal/v47/n12/full/ng.3456.html


Via Kamoun Lab @ TSL
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Arabidopsis COP1 SUPPRESSOR 2 Represses COP1 E3 Ubiquitin Ligase Activity through Their Coiled-Coil Domains Association

Arabidopsis  COP1 SUPPRESSOR 2 Represses COP1 E3 Ubiquitin Ligase Activity through Their Coiled-Coil Domains Association | Emerging Research in Plant Cell Biology | Scoop.it
Author Summary CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1) is a key regulator of light mediated developmental processes and it works as an E3 ubiquitin ligase controlling the abundance of multiple transcription factors. In the work presented here, we identified a novel repressor of COP1, the COP1 SUPPRESSOR 2 (CSU2), via a forward genetic screen. Mutations in CSU2 completely suppress cop1-6 constitutive photomorphogenic phenotype in darkness. CSU2 interacts and co-localizes with COP1 in nuclear speckles via the coiled-coil domain association. CSU2 negatively regulates COP1 E3 ubiquitin ligase activity, and repress COP1 mediated HY5 degradation in cell-free extracts.
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REDUCED CHLOROPLAST COVERAGE genes from Arabidopsis thaliana help to establish the size of the chloroplast compartment

REDUCED CHLOROPLAST COVERAGE genes from Arabidopsis thaliana help to establish the size of the chloroplast compartment | Emerging Research in Plant Cell Biology | Scoop.it

Eukaryotic cells require mechanisms to establish the proportion of cellular volume devoted to particular organelles. These mechanisms are poorly understood. From a screen for plastid-to-nucleus signaling mutants in Arabidopsis thaliana, we cloned a mutant allele of a gene that encodes a protein of unknown function that is homologous to two other Arabidopsis genes of unknown function and to FRIENDLY, which was previously shown to promote the normal distribution of mitochondria in Arabidopsis. In contrast to FRIENDLY, these three homologs of FRIENDLY are found only in photosynthetic organisms. Based on these data, we proposed that FRIENDLY expanded into a small gene family to help regulate the energy metabolism of cells that contain both mitochondria and chloroplasts. Indeed, we found that knocking out these genes caused a number of chloroplast phenotypes, including a reduction in the proportion of cellular volume devoted to chloroplasts to 50% of wild type. Thus, we refer to these genes as REDUCED CHLOROPLAST COVERAGE (REC). The size of the chloroplast compartment was reduced most in rec1 mutants. The REC1 protein accumulated in the cytosol and the nucleus. REC1 was excluded from the nucleus when plants were treated with amitrole, which inhibits cell expansion and chloroplast function. We conclude that REC1 is an extraplastidic protein that helps to establish the size of the chloroplast compartment, and that signals derived from cell expansion or chloroplasts may regulate REC1.REDUCED CHLOROPLAST COVERAGE genes from Arabidopsis thaliana help to establish the size of the chloroplast compartment Robert M. Larkina,b,c,1, Giovanni Stefanob, Michael E. Ruckleb,c,2, Andrea K. Stavoeb,3, Christopher A.

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Rescooped by Jennifer Mach from Plant & Evolution
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The mechanisms whereby the green alga Chlorella ohadii, isolated from desert soil crust, exhibits unparalleled photodamage resistance

Excess illumination damages the photosynthetic apparatus with severe implications with regard to plant productivity. Unlike model organisms, the growth of Chlorella ohadii, isolated from desert soil crust, remains unchanged and photosynthetic O2evolution increases, even when exposed to irradiation twice that of maximal sunlight.Spectroscopic, biochemical and molecular approaches were applied to uncover the mechanisms involved.D1 protein in photosystem II (PSII) is barely degraded, even when exposed to antibiotics that prevent its replenishment. Measurements of various PSII parameters indicate that this complex functions differently from that in model organisms and suggest that C. ohadii activates a nonradiative electron recombination route which minimizes singlet oxygen formation and the resulting photoinhibition. The light-harvesting antenna is very small and carotene composition is hardly affected by excess illumination. Instead of succumbing to photodamage, C. ohadii activates additional means to dissipate excess light energy. It undergoes major structural, compositional and physiological changes, leading to a large rise in photosynthetic rate, lipids and carbohydrate content and inorganic carbon cycling.The ability of C. ohadii to avoid photodamage relies on a modified function of PSII and the dissipation of excess reductants downstream of the photosynthetic reaction centers. The biotechnological potential as a gene source for crop plant improvement is self-evident.


Via Pierre-Marc Delaux
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Rescooped by Jennifer Mach from Plant Biology Teaching Resources (Higher Education)
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The genome of the seagrass Zostera marina reveals angiosperm adaptation to the sea : Nature : Nature Publishing Group

The genome of the seagrass Zostera marina reveals angiosperm adaptation to the sea : Nature : Nature Publishing Group | Emerging Research in Plant Cell Biology | Scoop.it

"Seagrasses colonized the sea on at least three independent occasions to form the basis of one of the most productive and widespread coastal ecosystems on the planet. Here we report the genome of Zostera marina (L.), the first, to our knowledge, marine angiosperm to be fully sequenced. This reveals unique insights into the genomic losses and gains involved in achieving the structural and physiological adaptations required for its marine lifestyle, arguably the most severe habitat shift ever accomplished by flowering plants. Key angiosperm innovations that were lost include the entire repertoire of stomatal genes, genes involved in the synthesis of terpenoids and ethylene signalling, and genes for ultraviolet protection and phytochromes for far-red sensing."


Via Mary Williams
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Mary Williams's curator insight, January 28, 4:38 AM

This is a really interesting paper! Seagrass - the dolphins of the plant kingdom (from sea to land and back to sea).

Rescooped by Jennifer Mach from Plant & Evolution
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A single homeobox gene triggers phase transition, embryogenesis and asexual reproduction

A single homeobox gene triggers phase transition, embryogenesis and asexual reproduction | Emerging Research in Plant Cell Biology | Scoop.it

Plants characteristically alternate between haploid gametophytic and diploid sporophytic stages. Meiosis and fertilization respectively initiate these two different ontogenies1. Genes triggering ectopic embryo development on vegetative sporophytic tissues are well described2,3; however, a genetic control of embryo development from gametophytic tissues remains elusive. Here, in the moss Physcomitrella patens we show that ectopic overexpression of the homeobox gene BELL1 induces embryo formation and subsequently reproductive diploid sporophytes from specific gametophytic cells without fertilization. In line with this,BELL1 loss-of-function mutants have a wild-type phenotype, except that their egg cells are bigger and unable to form embryos. Our results identify BELL1 as a master regulator for the gametophyte-to-sporophyte transition in P. patens and provide mechanistic insights into the evolution of embryos that can generate multicellular diploid sporophytes. This developmental innovation facilitated the colonization of land by plants about 500 million years ago4 and thus shaped our current ecosystems.


Via Jean-Pierre Zryd, Pierre-Marc Delaux
Jennifer Mach's insight:

I wanted a bit more in the title... maybe 

"A single homeobox gene triggers phase transition, embryogenesis and asexual reproduction in Physcomitrella patens "

#title

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Rescooped by Jennifer Mach from Ag Biotech News
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Can Pyramids and Seed Mixtures Delay Resistance to Bt Crops? - Carrière &al (2016) - Trends in Biotechnology

Can Pyramids and Seed Mixtures Delay Resistance to Bt Crops? - Carrière &al (2016) - Trends in Biotechnology | Emerging Research in Plant Cell Biology | Scoop.it

The primary strategy for delaying the evolution of pest resistance to transgenic crops that produce insecticidal proteins from Bacillus thuringiensis (Bt) entails refuges of plants that do not produce Bt toxins and thus allow survival of susceptible pests. Recent advances include using refuges together with Bt crop ‘pyramids’ that make two or more Bt toxins effective against the same pest, and planting seed mixtures yielding random distributions of pyramided Bt and non-Bt corn plants within fields.

 

We conclude that conditions often deviate from those favoring the success of pyramids and seed mixtures, particularly against pests with low inherent susceptibility to Bt toxins. For these problematic pests, promising approaches include using larger refuges and integrating Bt crops with other pest management tactics.

Conditions in the field often deviate substantially from those promoting success of the refuge strategy for delaying insect pest resistance to pyramided Bt crops, particularly in pests with low inherent susceptibility to Bt toxins... 


The refuge strategy has been successful for delaying resistance to Bt crops in pests with high inherent susceptibility to Bt toxins, but larger refuges are needed and Bt crops must be integrated with other pest management tactics to sustain their efficacy against pests with low inherent susceptibility to Bt toxins.

 

http://dx.doi.org/10.1016/j.tibtech.2015.12.011

 


Via Alexander J. Stein
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Essential RNA-Based Technologies and Their Applications in Plant Functional Genomics: Trends in Biotechnology

Essential RNA-Based Technologies and Their Applications in Plant Functional Genomics: Trends in Biotechnology | Emerging Research in Plant Cell Biology | Scoop.it

Genome sequencing has not only extended our understanding of the blueprints of many plant species but has also revealed the secrets of coding and non-coding genes. We present here a brief introduction to and personal account of key RNA-based technologies, as well as their development and applications for functional genomics of plant coding and non-coding genes, with a focus on short tandem target mimics (STTMs), artificial microRNAs (amiRNAs), and CRISPR/Cas9. In addition, their use in multiplex technologies for the functional dissection of gene networks is discussed.

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Rescooped by Jennifer Mach from Plant immunity and legume symbiosis
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Cell Host & Microbe: A Bacterial Effector Co-opts Calmodulin to Target the Plant Microtubule Network (2016)

Cell Host & Microbe: A Bacterial Effector Co-opts Calmodulin to Target the Plant Microtubule Network (2016) | Emerging Research in Plant Cell Biology | Scoop.it

The bacterial pathogen Pseudomonas syringae depends on effector proteins secreted by its type III secretion system for the pathogenesis of plants. The majority of these effector proteins are known suppressors of immunity, but their plant targets remain elusive. Using Arabidopsis thaliana as a model host, we report that the HopE1 effector uses the host calcium sensor, calmodulin (CaM), as a co-factor to target the microtubule-associated protein 65 (MAP65), an important component of the microtubule network. HopE1 interacted with MAP65 in a CaM-dependent manner, resulting in MAP65-GFP dissociation from microtubules. Transgenic Arabidopsis expressing HopE1 had reduced secretion of the immunity protein PR-1 compared to wild–type plants. Additionally, Arabidopsis map65-1 mutants were immune deficient and were more susceptible to P. syringae. Our results suggest a virulence strategy in which a pathogen effector is activated by host calmodulin to target MAP65 and the microtubule network, thereby inhibiting cell wall-based extracellular immunity.


Via Jim Alfano, Kamoun Lab @ TSL, Christophe Jacquet
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Jim Alfano's curator insight, January 13, 1:03 PM

Real proud of my research team for bringing this paper together. Ming Guo, in particular, for leading the effort.

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The global pipeline of GM crops out to 2020

The global pipeline of GM crops out to 2020 | Emerging Research in Plant Cell Biology | Scoop.it

Although a few arable crops and agronomic traits will likely dominate commercial varieties for the foreseeable future, with many being stacked together, more quality traits and specialty crops are being introduced into the pipeline.

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The global spectrum of plant form and function

The global spectrum of plant form and function | Emerging Research in Plant Cell Biology | Scoop.it


Earth is home to a remarkable diversity of plant forms and life histories, yet comparatively few essential trait combinations have proved evolutionarily viable in today’s terrestrial biosphere. By analysing worldwide variation in six major traits critical to growth, survival and reproduction within the largest sample of vascular plant species ever compiled, we found that occupancy of six-dimensional trait space is strongly concentrated, indicating coordination and trade-offs. Three-quarters of trait variation is captured in a two-dimensional global spectrum of plant form and function. One major dimension within this plane reflects the size of whole plants and their parts; the other represents the leaf economics spectrum, which balances leaf construction costs against growth potential. The global plant trait spectrum provides a backdrop for elucidating constraints on evolution, for functionally qualifying species and ecosystems, and for improving models that predict future vegetation based on continuous variation in plant form and function.

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Genome-wide dissection of the maize ear genetic architecture using multiple populations

Improvement of grain yield is an essential long-term goal of maize (Zea mays) breeding to meet continual and increasing food demands worldwide, but the genetic basis remains unclear.We used 10 different recombination inbred line (RIL) populations genotyped with high-density markers and phenotyped in multiple environments to dissect the genetic architecture of maize ear traits.Three methods were used to map the quantitative trait loci (QTLs) affecting ear traits. We found 17–34 minor- or moderate-effect loci that influence ear traits, with little epistasis and environmental interactions, totally accounting for 55.4–82% of the phenotypic variation. Four novel QTLs were validated and fine mapped using candidate gene association analysis, expression QTL analysis and heterogeneous inbred family validation.The combination of multiple different populations is a flexible and manageable way to collaboratively integrate widely available genetic resources, thereby boosting the statistical power of QTL discovery for important traits in agricultural crops, ultimately facilitating breeding programs.
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Control of grain size and rice yield by GL2-mediated brassinosteroid responses

Given the continuously growing population and decreasing arable land, food shortage is becoming one of the most serious global problems in this century1. Grain size is one of the determining factors for grain yield and thus is a prime target for genetic breeding2,3. Although a number of quantitative trait loci (QTLs) associated with rice grain size have been identified in the past decade, mechanisms underlying their functions remain largely unknown4,5. Here we show that a grain-length-associated QTL, GL2, has the potential to improve grain weight and grain yield up to 27.1% and 16.6%, respectively. We also show that GL2 is allelic to OsGRF4 and that it contains mutations in the miR396 targeting sequence. Because of the mutation, GL2 has a moderately increased expression level, which consequently activates brassinosteroid responses by upregulating a large number of brassinosteroid-induced genes to promote grain development. Furthermore, we found that GSK2, the central negative regulator of rice brassinosteroid signalling, directly interacts with OsGRF4 and inhibits its transcription activation activity to mediate the specific regulation of grain length by the hormone. Thus, this work demonstrates the feasibility of modulating specific brassinosteroid responses to improve plant productivity.

Jennifer Mach's insight:

One of three studies in the new Nature Plants on factors affecting rice grain yield. See News and Views here:

http://www.nature.com/articles/nplants2015210

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PLOS Biology: A Latex Metabolite Benefits Plant Fitness under Root Herbivore Attack (2015)

PLOS Biology: A Latex Metabolite Benefits Plant Fitness under Root Herbivore Attack (2015) | Emerging Research in Plant Cell Biology | Scoop.it

Dandelion plants protect their roots from the larva of the common cockchafer beetle by accumulating and releasing a sesquiterpene lactone deterrent in their exuded latex.

 

Plants produce large amounts of secondary metabolites in their shoots and roots and store them in specialized secretory structures. Although secondary metabolites and their secretory structures are commonly assumed to have a defensive function, evidence that they benefit plant fitness under herbivore attack is scarce, especially below ground. Here, we tested whether latex secondary metabolites produced by the common dandelion (Taraxacum officinaleagg.) decrease the performance of its major native insect root herbivore, the larvae of the common cockchafer (Melolontha melolontha), and benefit plant vegetative and reproductive fitness under M. melolontha attack. Across 17 T. officinale genotypes screened by gas and liquid chromatography, latex concentrations of the sesquiterpene lactone taraxinic acid β-D-glucopyranosyl ester (TA-G) were negatively associated with M. melolontha larval growth. Adding purified TA-G to artificial diet at ecologically relevant concentrations reduced larval feeding. Silencing the germacrene A synthase ToGAS1, an enzyme that was identified to catalyze the first committed step of TA-G biosynthesis, resulted in a 90% reduction of TA-G levels and a pronounced increase in M. melolontha feeding. Transgenic, TA-G-deficient lines were preferred by M. melolontha and suffered three times more root biomass reduction than control lines. In a common garden experiment involving over 2,000 T. officinale individuals belonging to 17 different genotypes, high TA-G concentrations were associated with the maintenance of high vegetative and reproductive fitness under M. melolontha attack. Taken together, our study demonstrates that a latex secondary metabolite benefits plants under herbivore attack, a result that provides a mechanistic framework for root herbivore driven natural selection and evolution of plant defenses below ground.


Via Kamoun Lab @ TSL
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