Emerging Research...
Follow
Find
10.3K views | +4 today
Rescooped by Jennifer Mach from Plant Pathogenomics
onto Emerging Research in Plant Cell Biology
Scoop.it!

DOE Joint Genome Institute: Adaptable Button Mushroom Serves Up Biomass-Degrading Genes Critical to Managing the Planet’s Carbon Stores

DOE Joint Genome Institute: Adaptable Button Mushroom Serves Up Biomass-Degrading Genes Critical to Managing the Planet’s Carbon Stores | Emerging Research in Plant Cell Biology | Scoop.it

The button mushroom occupies a prominent place in our diet and in the grocery store where it boasts a tasty multibillion-dollar niche, while in nature, Agaricus bisporus is known to decay leaf matter on the forest floor. Now, owing to an international collaboration of two-dozen institutions led by the French National Institute for Agricultural Research (INRA) and the U.S. Department of Energy Joint Genome Institute (DOE JGI), the full repertoire of A. bisporus genes has been determined. In particular, new work shows how its genes are actually deployed not only in leaf decay but also wood decay and in the development of fruiting bodies (the above ground part of the mushroom harvested for food). The work also suggests how such processes have major implications for forest carbon management. The analysis of the inner workings of the world’s most cultivated mushroom was published online the week of October 8 in the journal, the Proceedings of the National Academy of Sciences (PNAS).


Via Kamoun Lab @ TSL
more...
No comment yet.
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
Your new post is loading...
Scooped by Jennifer Mach
Scoop.it!

DNA Topoisomerase 1α Promotes Transcriptional Silencing of Transposable Elements through DNA Methylation and Histone Lysine 9 Dimethylation in Arabidopsis

DNA Topoisomerase 1α Promotes Transcriptional Silencing of Transposable Elements through DNA Methylation and Histone Lysine 9 Dimethylation in Arabidopsis | Emerging Research in Plant Cell Biology | Scoop.it

RNA-directed DNA methylation (RdDM) and histone H3 lysine 9 dimethylation (H3K9me2) are related transcriptional silencing mechanisms that target transposable elements (TEs) and repeats to maintain genome stability in plants. RdDM is mediated by small and long noncoding RNAs produced by the plant-specific RNA polymerases Pol IV and Pol V, respectively. Through a chemical genetics screen with a luciferase-based DNA methylation reporter, LUCL, we found that camptothecin, a compound with anti-cancer properties that targets DNA topoisomerase 1α (TOP1α) was able to de-repress LUCL by reducing its DNA methylation and H3K9me2 levels. Further studies with Arabidopsis top1α mutants showed that TOP1α silences endogenous RdDM loci by facilitating the production of Pol V-dependent long non-coding RNAs, AGONAUTE4 recruitment and H3K9me2 deposition at TEs and repeats. This study assigned a new role in epigenetic silencing to an enzyme that affects DNA topology.

more...
No comment yet.
Scooped by Jennifer Mach
Scoop.it!

Inference of Transcriptional Networks in Arabidopsis through Conserved Noncoding Sequence Analysis

Inference of Transcriptional Networks in Arabidopsis through Conserved Noncoding Sequence Analysis | Emerging Research in Plant Cell Biology | Scoop.it

Transcriptional regulation plays an important role in establishing gene expression profiles during development or in response to (a)biotic stimuli. Transcription factor binding sites (TFBSs) are the functional elements that determine transcriptional activity, and the identification of individual TFBS in genome sequences is a major goal to inferring regulatory networks. We have developed a phylogenetic footprinting approach for the identification of conserved noncoding sequences (CNSs) across 12 dicot plants. Whereas both alignment and non-alignment-based techniques were applied to identify functional motifs in a multispecies context, our method accounts for incomplete motif conservation as well as high sequence divergence between related species. We identified 69,361 footprints associated with 17,895 genes. Through the integration of known TFBSobtained from the literature and experimental studies, we used the CNSs to compile a gene regulatory network in Arabidopsis thaliana containing 40,758 interactions, of which two-thirds act through binding events located in DNase I hypersensitive sites. This network shows significant enrichment toward in vivo targets of known regulators, and its overall quality was confirmed using five different biological validation metrics. Finally, through the integration of detailed expression and function information, we demonstrate how static CNSs can be converted into condition-dependent regulatory networks, offering opportunities for regulatory gene annotation.

more...
No comment yet.
Scooped by Jennifer Mach
Scoop.it!

Molecular basis of adaptation to high soil boron in wheat landraces and elite cultivars

Molecular basis of adaptation to high soil boron in wheat landraces and elite cultivars | Emerging Research in Plant Cell Biology | Scoop.it

Environmental constraints severely restrict crop yields in most production environments, and expanding the use of variation will underpin future progress in breeding. In semi-arid environments boron toxicity constrains productivity, and genetic improvement is the only effective strategy for addressing the problem1. Wheat breeders have sought and used available genetic diversity from landraces to maintain yield in these environments; however, the identity of the genes at the major tolerance loci was unknown. Here we describe the identification of near-identical, root-specific boron transporter genes underlying the two major-effect quantitative trait loci for boron tolerance in wheat, Bo1 and Bo4 (ref. 2). We show that tolerance to a high concentration of boron is associated with multiple genomic changes including tetraploid introgression, dispersed gene duplication, and variation in gene structure and transcript level. An allelic series was identified from a panel of bread and durum wheat cultivars and landraces originating from diverse agronomic zones. Our results demonstrate that, during selection, breeders have matched functionally different boron tolerance alleles to specific environments. The characterization of boron tolerance in wheat illustrates the power of the new wheat genomic resources to define key adaptive processes that have underpinned crop improvement.

more...
No comment yet.
Scooped by Jennifer Mach
Scoop.it!

HopW1 from Pseudomonas syringae Disrupts the Actin Cytoskeleton to Promote Virulence in Arabidopsis

HopW1 from Pseudomonas syringae Disrupts the Actin Cytoskeleton to Promote Virulence in Arabidopsis | Emerging Research in Plant Cell Biology | Scoop.it

A central mechanism of virulence of extracellular bacterial pathogens is the injection into host cells of effector proteins that modify host cellular functions. HopW1 is an effector injected by the type III secretion system that increases the growth of the plant pathogen Pseudomonas syringae on the Columbia accession of Arabidopsis. When delivered by P. syringae into plant cells, HopW1 causes a reduction in the filamentous actin (F-actin) network and the inhibition of endocytosis, a known actin-dependent process. When directly produced in plants, HopW1 forms complexes with actin, disrupts the actin cytoskeleton and inhibits endocytosis as well as the trafficking of certain proteins to vacuoles. The C-terminal region of HopW1 can reduce the length of actin filaments and therefore solubilize F-actin in vitro. Thus, HopW1 acts by disrupting the actin cytoskeleton and the cell biological processes that depend on actin, which in turn are needed for restricting P. syringae growth in Arabidopsis.

more...
No comment yet.
Scooped by Jennifer Mach
Scoop.it!

Natural variation reveals that intracellular distribution of ELF3 protein is associated with function in the circadian clock

Natural variation reveals that intracellular distribution of ELF3 protein is associated with function in the circadian clock | Emerging Research in Plant Cell Biology | Scoop.it
Natural selection of variants within the Arabidopsis thaliana circadian clock can be attributed to adaptation to varying environments. To define a basis for such variation, we examined clock speed in a reporter-modified Bay-0 x Shakdara recombinant inbred line and localized heritable variation. Extensive variation led us to identify EARLY FLOWERING3 (ELF3) as a major quantitative trait locus (QTL). The causal nucleotide polymorphism caused a short-period phenotype under light and severely dampened rhythm generation in darkness, and entrainment alterations resulted. We found that ELF3-Sha protein failed to properly localize to the nucleus, and its ability to accumulate in darkness was compromised. Evidence was provided that the ELF3-Sha allele originated in Central Asia. Collectively, we showed that ELF3 protein plays a vital role in defining its light-repressor action in the circadian clock and that its functional abilities are largely dependent on its cellular localization
more...
No comment yet.
Scooped by Jennifer Mach
Scoop.it!

Metagenomic scaffolds enable combinatorial lignin transformation

Metagenomic scaffolds enable combinatorial lignin transformation | Emerging Research in Plant Cell Biology | Scoop.it

Engineering the microbial transformation of lignocellulosic biomass is essential to developing modern biorefining processes that alleviate reliance on petroleum-derived energy and chemicals. Many current bioprocess streams depend on the genetic tractability of Escherichia coli with a primary emphasis on engineering cellulose/hemicellulose catabolism, small molecule production, and resistance to product inhibition. Conversely, bioprocess streams for lignin transformation remain embryonic, with relatively few environmental strains or enzymes implicated. Here we develop a biosensor responsive to monoaromatic lignin transformation products compatible with functional screening in E. coli. We use this biosensor to retrieve metagenomic scaffolds sourced from coal bed bacterial communities conferring an array of lignin transformation phenotypes that synergize in combination. Transposon mutagenesis and comparative sequence analysis of active clones identified genes encoding six functional classes mediating lignin transformation phenotypes that appear to be rearrayed in nature via horizontal gene transfer. Lignin transformation activity was then demonstrated for one of the predicted gene products encoding a multicopper oxidase to validate the screen. These results illuminate cellular and community-wide networks acting on aromatic polymers and expand the toolkit for engineering recombinant lignin transformation based on ecological design principles.

more...
No comment yet.
Scooped by Jennifer Mach
Scoop.it!

Split-gene system for hybrid wheat seed production

Split-gene system for hybrid wheat seed production | Emerging Research in Plant Cell Biology | Scoop.it

Hybrid wheat plants are superior in yield and growth characteristics compared with their homozygous parents. The commercial production of wheat hybrids is difficult because of the inbreeding nature of wheat and the lack of a practical fertility control that enforces outcrossing. We describe a hybrid wheat system that relies on the expression of a phytotoxic barnase and provides for male sterility. The barnase coding information is divided and distributed at two loci that are located on allelic positions of the host chromosome and are therefore “linked in repulsion.” Functional complementation of the loci is achieved through coexpression of the barnase fragments and intein-mediated ligation of the barnase protein fragments. This system allows for growth and maintenance of male-sterile female crossing partners, whereas the hybrids are fertile. The technology does not require fertility restorers and is based solely on the genetic modification of the female crossing partner.

more...
No comment yet.
Rescooped by Jennifer Mach from Plants&Bacteria
Scoop.it!

Molecular Steps in the Immune Signaling Pathway Evoked by Plant Elicitor Peptides: Ca2+-Dependent Protein Kinases, Nitric Oxide, and Reactive Oxygen Species Are Downstream from the Early Ca2+ Signal

Molecular Steps in the Immune Signaling Pathway Evoked by Plant Elicitor Peptides: Ca2+-Dependent Protein Kinases, Nitric Oxide, and Reactive Oxygen Species Are Downstream from the Early Ca2+ Signal | Emerging Research in Plant Cell Biology | Scoop.it

Scooped from: Plant Physiology, 2013.

Authors: Yi Ma, Yichen Zhao, Robin K. Walker and Gerald A. Berkowitz.

 

Abstract:

Endogenous plant elicitor peptides (Peps) can act to facilitate immune signaling and pathogen defense responses. Binding of these peptides to the Arabidopsis (Arabidopsis thaliana) plasma membrane-localized Pep receptors (PEPRs) leads to cytosolic Ca2+ elevation, an early event in a signaling cascade that activates immune responses. This immune response includes the amplification of signaling evoked by direct perception of pathogen-associated molecular patterns by plant cells under assault. Work included in this report further characterizes the Pep immune response and identifies new molecular steps in the signal transduction cascade. The PEPR coreceptor BRASSINOSTEROID-INSENSITIVE1 Associated Kinase1 contributes to generation of the Pep-activated Ca2+ signal and leads to increased defense gene expression and resistance to a virulent bacterial pathogen. Ca2+-dependent protein kinases (CPKs) decode the Ca2+ signal, also facilitating defense gene expression and enhanced resistance to the pathogen. Nitric oxide and reduced nicotinamide adenine dinucleotide phosphate oxidase-dependent reactive oxygen species generation (due to the function of Respiratory Burst Oxidase Homolog proteins D and F) are also involved downstream from the Ca2+ signal in the Pep immune defense signal transduction cascade, as is the case with BRASSINOSTEROID-INSENSITIVE1 Associated Kinase1 and CPK5, CPK6, and CPK11. These steps of the pathogen defense response are required for maximal Pep immune activation that limits growth of a virulent bacterial pathogen in the plant. We find a synergism between function of the PEPR and Flagellin Sensing2 receptors in terms of both nitric oxide and reactive oxygen species generation. Presented results are also consistent with the involvement of the secondary messenger cyclic GMP and a cyclic GMP-activated Ca2+-conducting channel in the Pep immune signaling pathway.


Via Freddy Monteiro
more...
No comment yet.
Scooped by Jennifer Mach
Scoop.it!

Root exudation of phytosiderophores from soil-grown wheat

Root exudation of phytosiderophores from soil-grown wheat | Emerging Research in Plant Cell Biology | Scoop.it
For the first time, phytosiderophore (PS) release of wheat (Triticum aestivum cv Tamaro) grown on a calcareous soil was repeatedly and nondestructively sampled using rhizoboxes combined with a recently developed root exudate collecting tool. As in nutrient solution culture, we observed a distinct diurnal release rhythm; however, the measured PS efflux was c. 50 times lower than PS exudation from the same cultivar grown in zero iron (Fe)-hydroponic culture.Phytosiderophore rhizosphere soil solution concentrations and PS release of the Tamaro cultivar were soil-dependent, suggesting complex interactions of soil characteristics (salinity, trace metal availability) and the physiological status of the plant and the related regulation (amount and timing) of PS release.Our results demonstrate that carbon and energy investment into Fe acquisition under natural growth conditions is significantly smaller than previously derived from zero Fe-hydroponic studies. Based on experimental data, we calculated that during the investigated period (21–47 d after germination), PS release initially exceeded Fe plant uptake 10-fold, but significantly declined after c. 5 wk after germination.Phytosiderophore exudation observed under natural growth conditions is a prerequisite for a more accurate and realistic assessment of Fe mobilization processes in the rhizosphere using both experimental and modeling approaches.
more...
No comment yet.
Scooped by Jennifer Mach
Scoop.it!

Stay-green alleles individually enhance grain yield in sorghum under drought by modifying canopy development and water uptake patterns

Stay-green alleles individually enhance grain yield in sorghum under drought by modifying canopy development and water uptake patterns | Emerging Research in Plant Cell Biology | Scoop.it
Stay-green is an integrated drought adaptation trait characterized by a distinct green leaf phenotype during grain filling under terminal drought. We used sorghum (Sorghum bicolor), a repository of drought adaptation mechanisms, to elucidate the physiological and genetic mechanisms underpinning stay-green.Near-isogenic sorghum lines (cv RTx7000) were characterized in a series of field and managed-environment trials (seven experiments and 14 environments) to determine the influence of four individual stay-green (Stg1–4) quantitative trait loci (QTLs) on canopy development, water use and grain yield under post-anthesis drought.The Stg QTL decreased tillering and the size of upper leaves, which reduced canopy size at anthesis. This reduction in transpirational leaf area conserved soil water before anthesis for use during grain filling. Increased water uptake during grain filling of Stg near-isogenic lines (NILs) relative to RTx7000 resulted in higher post-anthesis biomass production, grain number and yield. Importantly, there was no consistent yield penalty associated with the Stg QTL in the irrigated control.These results establish a link between the role of the Stg QTL in modifying canopy development and the subsequent impact on crop water use patterns and grain yield under terminal drought.
more...
No comment yet.
Scooped by Jennifer Mach
Scoop.it!

Comparative Analysis of Miscanthus and Saccharum Reveals a Shared Whole-Genome Duplication but Different Evolutionary Fates

Comparative Analysis of Miscanthus and Saccharum Reveals a Shared Whole-Genome Duplication but Different Evolutionary Fates | Emerging Research in Plant Cell Biology | Scoop.it

Multiple polyploidizations with divergent consequences in the grass subtribe Saccharinae provide a singular opportunity to study in situ adaptation of a genome to the duplicated state, heretofore known primarily from paleogenomics. We show that allopolyploidy in a common Miscanthus-Saccharum ancestor ∼3.8 to 4.6 million years ago closely coincides in time with their divergence from theSorghum lineage. Subsequent Saccharum-specific autopolyploidy may have created pseudo-paralogous chromosome groups with random pairing within a group but infrequent pairing between groups. High chromosome number may reduce differentiation among Saccharum pseudo-paralogs by increasing opportunities for recombinations, with the lower chromosome numbers ofMiscanthus favoring the return to disomic inheritance. The widespread tendency of plant chromosome numbers to recursively return to a narrow range following genome duplication appears to be occurring now in Saccharum spontaneumbased on rich polymorphism for chromosome number among genotypes, with past reductions indicated by condensations of two ancestral chromosomes inMiscanthus (now n = 19) and perhaps as many as 10 in the Narenga-Sclerostachya clade (n = 15).

more...
No comment yet.
Rescooped by Jennifer Mach from Plant Biology Teaching Resources (Higher Education)
Scoop.it!

Plant ubiquitin ligases as signaling hubs : Nature Structural & Molecular Biology

Plant ubiquitin ligases as signaling hubs : Nature Structural & Molecular Biology | Emerging Research in Plant Cell Biology | Scoop.it
The past decade has witnessed an explosion in the identification of ubiquitin-ligase complexes as the missing receptors for important small-molecule hormones regulating plant growth and development. These breakthroughs were initiated by genetic approaches, with structural analysis providing mechanistic insights into how hormone perception and signaling are coupled to protein ubiquitination. Although there are still many unknowns, plants have imparted valuable lessons about the pharmacology of ubiquitin modification.

Via Suayib Üstün, Mary Williams
more...
No comment yet.
Scooped by Jennifer Mach
Scoop.it!

Evolutionary developmental transcriptomics reveals a gene network module regulating interspecific diversity in plant leaf shape

Evolutionary developmental transcriptomics reveals a gene network module regulating interspecific diversity in plant leaf shape | Emerging Research in Plant Cell Biology | Scoop.it

Despite a long-standing interest in the genetic basis of morphological diversity, the molecular mechanisms that give rise to developmental variation are incompletely understood. Here, we use comparative transcriptomics coupled with the construction of gene coexpression networks to predict a gene regulatory network (GRN) for leaf development in tomato and two related wild species with strikingly different leaf morphologies. The core network in the leaf developmental GRN contains regulators of leaf morphology that function in global cell proliferation with peripheral gene network modules (GNMs). The BLADE-ON-PETIOLE(BOP) transcription factor in one GNM controls the core network by altering effective concentration of the KNOTTED-like HOMEOBOX gene product. Comparative network analysis and experimental perturbations ofBOP levels suggest that variation in BOP expression could explain the diversity in leaf complexity among these species through dynamic rewiring of interactions in the GRN. The peripheral location of the BOP-containing GNM in the leaf developmental GRN and the phenotypic mimics of evolutionary diversity caused by alteration in BOP levels identify a key role for this GNM in canalizing the leaf morphospace by modifying the maturation schedule of leaves to create morphological diversity.

more...
No comment yet.
Scooped by Jennifer Mach
Scoop.it!

Using plants to elucidate the mechanisms of cytonuclear co-evolution

Using plants to elucidate the mechanisms of cytonuclear co-evolution | Emerging Research in Plant Cell Biology | Scoop.it

The presence of both cytoplasmic and nuclear genomes within eukaryotic cells raises fascinating questions about co-evolution between genomic compartments that experience fundamentally different mutation rates and modes of inheritance. The highly mutagenic environments found in the mitochondria of some eukaryotes have generated interest in the role that mitochondrial mutation accumulation plays in phenomena such as intracellular gene transfer, compensatory evolution in the nucleus and the evolution of reproductive isolation. Although plant systems have played an important historical role in the study of cytonuclear co-evolution, they remain underutilized in many respects. In particular, the enormous natural variation in DNA substitution rates, gene content and genome architecture in plant mitochondria – much of which has even been found within a single genus – provides opportunities to resolve longstanding evolutionary questions about the consequences of mitochondrial mutation accumulation. This review summarizes some of the classic questions about cytonuclear co-evolution that could be addressed by taking advantage of the variation in plants and highlights a recent analysis of the effect of mitochondrial mutation accumulation on rates of molecular evolution in the nucleus.

more...
No comment yet.
Scooped by Jennifer Mach
Scoop.it!

Evolution of the BBAA Component of Bread Wheat during Its History at the Allohexaploid Level

Evolution of the BBAA Component of Bread Wheat during Its History at the Allohexaploid Level | Emerging Research in Plant Cell Biology | Scoop.it

Subgenome integrity in bread wheat (Triticum aestivum; BBAADD) makes possible the extraction of its BBAA component to restitute a novel plant type. The availability of such a ploidy-reversed wheat (extracted tetraploid wheat [ETW]) provides a unique opportunity to address whether and to what extent the BBAA component of bread wheat has been modified in phenotype, karyotype, and gene expression during its evolutionary history at the allohexaploid level. We report here that ETW was anomalous in multiple phenotypic traits but maintained a stable karyotype. Microarray-based transcriptome profiling identified a large number of differentially expressed genes between ETW and natural tetraploid wheat (Triticum turgidum), and the ETW-downregulated genes were enriched for distinct Gene Ontology categories. Quantitative RT-PCR analysis showed that gene expression differences between ETW and a set of diverse durum wheat (T. turgidum subsp durum) cultivars were distinct from those characterizing tetraploid cultivars per se. Pyrosequencing revealed that the expression alterations may occur to either only one or both of the B and A homoeolog transcripts in ETW. A majority of the genes showed additive expression in a resynthesized allohexaploid wheat. Analysis of a synthetic allohexaploid wheat and diverse bread wheat cultivars revealed the rapid occurrence of expression changes to the BBAA subgenomes subsequent to allohexaploidization and their evolutionary persistence.

more...
No comment yet.
Scooped by Jennifer Mach
Scoop.it!

Minichromosomes and artificial chromosomes in Arabidopsis

Minichromosomes and artificial chromosomes in Arabidopsis | Emerging Research in Plant Cell Biology | Scoop.it

Minichromosomes have been extensively used as tools for revealing the functional structures of eukaryotic chromosomes. However, the definition of a minichromosome is still ambiguous. Based on previous reports on various eukaryotes, minichromosomes are defined here to be chromosomes that are smaller than one third the size of the smallest chromosome in the given species. InArabidopsis thaliana, therefore, chromosomes <8.5 Mb in length are classified as minichromosomes, although to date only six different minichromosomes have been found or created, probably due to their extremely small sizes that limit detection. Minichromosomes vary from 1.7 to 8.4 Mb in length and are much shorter than authentic chromosomes (25.3 to 38.0 Mb). Linear and circular minichromosomes have been identified, and both types are maintained as experimental lines. Most of the circular, ring-shaped minichromosomes in Arabidopsis are relatively stable at mitosis and transmissible to the next generation, regardless of the centromere form (dicentric or monocentric). Recently, a ring minichromosome was artificially generated by a combination of the Cre/LoxP and Ac/Ds systems. This artificial ring chromosome, AtARC1, has several advantages over the previously reported minichromosomes as a chromosome vector; therefore, this method of generating artificial ring chromosomes is expected to be improved for application to other plant species including important crops.

more...
No comment yet.
Rescooped by Jennifer Mach from MycorWeb Plant-Microbe Interactions
Scoop.it!

The Plant Membrane-Associated REMORIN1.3 Accumulates in Discrete Perihaustorial Domains and Enhances Susceptibility to Phytophthora infestans

The Plant Membrane-Associated REMORIN1.3 Accumulates in Discrete Perihaustorial Domains and Enhances Susceptibility to Phytophthora infestans | Emerging Research in Plant Cell Biology | Scoop.it

Filamentous pathogens such as the oomycete Phytophthora infestans infect plants by developing specialized structures termed haustoria inside the host cells. Haustoria are thought to enable the secretion of effector proteins into the plant cells. Haustorium biogenesis, therefore, is critical for pathogen accommodation in the host tissue. Haustoria are enveloped by a specialized host-derived membrane, the extrahaustorial membrane (EHM), which is distinct from the plant plasma membrane. The mechanisms underlying the biogenesis of the EHM are unknown. Remarkably, several plasma membrane-localized proteins are excluded from the EHM, but the remorin REM1.3 accumulates around P. infestans haustoria. Here, we used overexpression, colocalization with reporter proteins, and superresolution microscopy in cells infected by P. infestans to reveal discrete EHM domains labeled by REM1.3 and the P. infestans effector AVRblb2. Moreover, SYNAPTOTAGMIN1, another previously identified perihaustorial protein, localized to subdomains that are mainly not labeled by REM1.3 and AVRblb2. Functional characterization of REM1.3 revealed that it is a susceptibility factor that promotes infection by P. infestans. This activity, and REM1.3 recruitment to the EHM, require the REM1.3 membrane-binding domain. Our results implicate REM1.3 membrane microdomains in plant susceptibility to an oomycete pathogen.


Via Francis Martin
more...
No comment yet.
Scooped by Jennifer Mach
Scoop.it!

Cell elongation is regulated through a central circuit of interacting transcription factors in the Arabidopsis hypocotyl

Cell elongation is regulated through a central circuit of interacting transcription factors in the Arabidopsis hypocotyl | Emerging Research in Plant Cell Biology | Scoop.it
As the major mechanism of plant growth and morphogenesis, cell elongation is controlled by many hormonal and environmental signals. How these signals are coordinated at the molecular level to ensure coherent cellular responses remains unclear. In this study, we illustrate a molecular circuit that integrates all major growth-regulating signals, including auxin, brassinosteroid, gibberellin, light, and temperature. Analyses of genome-wide targets, genetic and biochemical interactions demonstrate that the auxin-response factor ARF6, the light/temperature-regulated transcription factor PIF4, and the brassinosteroid-signaling transcription factor BZR1, interact with each other and cooperatively regulate large numbers of common target genes, but their DNA-binding activities are blocked by the gibberellin-inactivated repressor RGA. In addition, a tripartite HLH/bHLH module feedback regulates PIFs and additional bHLH factors that interact with ARF6, and thereby modulates auxin sensitivity according to developmental and environmental cues. Our results demonstrate a central growth-regulation circuit that integrates hormonal, environmental, and developmental controls of cell elongation in Arabidopsis hypocotyl.
more...
No comment yet.
Scooped by Jennifer Mach
Scoop.it!

Arabidopsis noncoding RNA mediates control of photomorphogenesis by red light

Arabidopsis noncoding RNA mediates control of photomorphogenesis by red light | Emerging Research in Plant Cell Biology | Scoop.it

Seedling photomorphogenesis is a sophisticated developmental process that is controlled by both the transcriptional and posttranscriptional regulation of gene expression. Here, we identify an Arabidopsisnoncoding RNA, designated HIDDEN TREASURE 1 (HID1), as a factor promoting photomorphogenesis in continuous red light (cR). We show that HID1 acts through PHYTOCHROME-INTERACTING FACTOR 3(PIF3), which encodes a basic helix–loop–helix transcription factor known to be a key repressor of photomorphogenesis. Knockdown of HID1 in hid1 mutants leads to a significant increase in the expression of PIF3, which in turn drives the development of elongated hypocotyls in cR. We identified two major stem-loops in HID1 that are essential for its modulation of hypocotyl growth in cR-grown seedlings. Furthermore, our data reveal that HID1 is assembled into large nuclear protein–RNA complex(es) and that it associates with the chromatin of the first intron of PIF3 to repress its transcription. Strikingly, phylogenetic analysis reveals that many land plants have conserved homologs of HID1 and that its rice homolog can rescue the mutant phenotype when expressed in Arabidopsis hid1 mutants. We thus concluded that HID1 is a previously uncharacterized noncoding RNA whose function represents another layer of regulation in the precise control of seedling photomorphogenesis.

more...
No comment yet.
Scooped by Jennifer Mach
Scoop.it!

Genetic Control of Maize Shoot Apical Meristem Architecture

Genetic Control of Maize Shoot Apical Meristem Architecture | Emerging Research in Plant Cell Biology | Scoop.it

The shoot apical meristem contains a pool of undifferentiated stem cells, and generates all above-ground organs of the plant. During vegetative growth, cells differentiate from the meristem to initiate leaves while the pool of meristematic cells is preserved; this balance is determined in part by genetic regulatory mechanisms. To assess vegetative meristem growth and genetic control in Zea mays, we investigated its morphology at multiple time points and identified three stages of growth. We measured meristem height, width, plastochron internode length, and associated traits from 86 individuals of the intermated B73 x Mo17 recombinant inbred line population. For meristem height-related traits, the parents exhibited markedly different phenotypes, with B73 being very tall, Mo17 short, and the population distributed between. In the outer cell layer, differences appeared to be related to number of cells rather than cell size. In contrast, B73 and Mo17 were similar in meristem width traits and plastochron internode length, with transgressive segregation in the population. Multiple loci (6-9 for each trait) were mapped, indicating meristem architecture is controlled by many regions; none of these coincided with previously described mutants impacting meristem development. Major loci for height and width explaining 16% and 19% of the variation were identified on chromosomes 5 and 8, respectively. Significant loci for related traits frequently coincided, while those for unrelated traits did not overlap. Using three near-isogenic lines, a locus explaining 16% of the parental variation in meristem height was validated. Published expression data were leveraged to identify candidate genes in significant regions.

more...
No comment yet.
Scooped by Jennifer Mach
Scoop.it!

The Phragmoplast-Orienting Kinesin-12 Class Proteins Translate the Positional Information of the Preprophase Band to Establish the Cortical Division Zone in Arabidopsis thaliana

The Phragmoplast-Orienting Kinesin-12 Class Proteins Translate the Positional Information of the Preprophase Band to Establish the Cortical Division Zone in Arabidopsis thaliana | Emerging Research in Plant Cell Biology | Scoop.it

The preprophase band (PPB) is a faithful but transient predictor of the division plane in somatic cell divisions. Throughout mitosis the PPBs positional information is preserved by factors that continuously mark the division plane at the cell cortex, the cortical division zone, by their distinct spatio-temporal localization patterns. However, the mechanism maintaining these identity factors at the plasma membrane after PPB disassembly remains obscure. The pair of kinesin-12 class proteins PHRAGMOPLAST ORIENTING KINESIN1 (POK1) and POK2 are key players in division plane maintenance. Here, we show that POK1 is continuously present at the cell cortex, providing a spatial reference for the site formerly occupied by the PPB. Fluorescence recovery after photobleaching analysis combined with microtubule destabilization revealed dynamic microtubule-dependent recruitment of POK1 to the PPB during prophase, while POK1 retention at the cortical division zone in the absence of cortical microtubules appeared static. POK function is strictly required to maintain the division plane identity factor TANGLED (TAN) after PPB disassembly, although POK1 and TAN recruitment to the PPB occur independently during prophase. Together, our data suggest that POKs represent fundamental early anchoring components of the cortical division zone, translating and preserving the positional information of the PPB by maintaining downstream identity markers.

more...
No comment yet.
Scooped by Jennifer Mach
Scoop.it!

Natural soil microbes alter flowering phenology and the intensity of selection on flowering time in a wild Arabidopsis relative

Natural soil microbes alter flowering phenology and the intensity of selection on flowering time in a wild Arabidopsis relative | Emerging Research in Plant Cell Biology | Scoop.it

Plant phenology is known to depend on many different environmental variables, but soil microbial communities have rarely been acknowledged as possible drivers of flowering time. Here, we tested separately the effects of four naturally occurring soil microbiomes and their constituent soil chemistries on flowering phenology and reproductive fitness of Boechera stricta, a wild relative of Arabidopsis. Flowering time was sensitive to both microbes and the abiotic properties of different soils; varying soil microbiota also altered patterns of selection on flowering time. Thus, soil microbes potentially contribute to phenotypic plasticity of flowering time and to differential selection observed between habitats. We also describe a method to dissect the microbiome into single axes of variation that can help identify candidate organisms whose abundance in soil correlates with flowering time. This approach is broadly applicable to search for microbial community members that alter biological characteristics of interest.

more...
No comment yet.
Scooped by Jennifer Mach
Scoop.it!

Detection of genomic variations and DNA polymorphisms and impact on analysis of meiotic recombination and genetic mapping

Detection of genomic variations and DNA polymorphisms and impact on analysis of meiotic recombination and genetic mapping | Emerging Research in Plant Cell Biology | Scoop.it

DNA polymorphisms are important markers in genetic analyses and are increasingly detected by using genome resequencing. However, the presence of repetitive sequences and structural variants can lead to false positives in the identification of polymorphic alleles. Here, we describe an analysis strategy that minimizes false positives in allelic detection and present analyses of recently published resequencing data from Arabidopsis meiotic products and individual humans. Our analysis enables the accurate detection of sequencing errors, small insertions and deletions (indels), and structural variants, including large reciprocal indels and copy number variants, from comparisons between the resequenced and reference genomes. We offer an alternative interpretation of the sequencing data of meiotic products, including the number and type of recombination events, to illustrate the potential for mistakes in single-nucleotide polymorphism calling. Using these examples, we propose that the detection of DNA polymorphisms using resequencing data needs to account for nonallelic homologous sequences.

Jennifer Mach's insight:
From Twitter:Weigel Lab ‏@PlantEvolution  Already debunked by Wijnkers et al @eLifehttp://ow.ly/yr7bz ; MT @hendersi: Erroneous gene conversion ID http://www.pnas.org/content/early/2014/06/19/1321897111.full.pdf+html ;…
more...
No comment yet.
Scooped by Jennifer Mach
Scoop.it!

PHYTOCHROME C plays a major role in the acceleration of wheat flowering under long-day photoperiod

PHYTOCHROME C plays a major role in the acceleration of wheat flowering under long-day photoperiod | Emerging Research in Plant Cell Biology | Scoop.it

Phytochromes are dimeric proteins that function as red and far-red light sensors influencing nearly every phase of the plant life cycle. Of the three major phytochrome families found in flowering plants, PHYTOCHROME C (PHYC) is the least understood. In Arabidopsis and rice, PHYC is unstable and functionally inactive unless it heterodimerizes with another phytochrome. However, when expressed in anArabidopsis phy-null mutant, wheat PHYC forms signaling active homodimers that translocate into the nucleus in red light to mediate photomorphogenic responses. Tetraploid wheat plants homozygous for loss-of-function mutations in all PHYC copies (phyCAB) flower on average 108 d later than wild-type plants under long days but only 19 d later under short days, indicating a strong interaction between PHYC and photoperiod. This interaction is further supported by the drastic down-regulation in the phyCAB mutant of the central photoperiod gene PHOTOPERIOD 1 (PPD1) and its downstream target FLOWERING LOCUS T1, which are required for the promotion of flowering under long days. These results implicate light-dependent, PHYC-mediated activation of PPD1 expression in the acceleration of wheat flowering under inductive long days. Plants homozygous for the phyCAB mutations also show altered profiles of circadian clock and clock-output genes, which may also contribute to the observed differences in heading time. Our results highlight important differences in the photoperiod pathways of the temperate grasses with those of well-studied model plant species.

more...
No comment yet.
Rescooped by Jennifer Mach from Rhizobium Research
Scoop.it!

Nature Communications: A single evolutionary innovation drives the deep evolution of symbiotic N2-fixation in angiosperms

Nature Communications: A single evolutionary innovation drives the deep evolution of symbiotic N2-fixation in angiosperms | Emerging Research in Plant Cell Biology | Scoop.it

Symbiotic associations occur in every habitat on earth, but we know very little about their evolutionary histories. Current models of trait evolution cannot adequately reconstruct the deep history of symbiotic innovation, because they assume homogenous evolutionary processes across millions of years. Here we use a recently developed, heterogeneous and quantitative phylogenetic framework to study the origin of the symbiosis between angiosperms and nitrogen-fixing (N2) bacterial symbionts housed in nodules. We compile the largest database of global nodulating plant species and reconstruct the symbiosis’ evolution. We identify a single, cryptic evolutionary innovation driving symbiotic N2-fixation evolution, followed by multiple gains and losses of the symbiosis, and the subsequent emergence of ‘stable fixers’ (clades extremely unlikely to lose the symbiosis). Originating over 100 MYA, this innovation suggests deep homology in symbiotic N2-fixation. Identifying cryptic innovations on the tree of life is key to understanding the evolution of complex traits, including symbiotic partnerships.


Via Mary Williams, IvanOresnik
more...
No comment yet.