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Rescooped by Jennifer Mach from Plant Biology Teaching Resources (Higher Education)
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YouTube: Plant interaction with friendly microorganisms gives pathogens their break (2012)

In two papers to be published in Current Biology, researchers from JIC and The Sainsbury Laboratory on the Norwich Research Park, and Rothamsted Research and the University of York identify genes that help plants interact with microbes in the soil.

 

Professor Giles Oldroyd of the John Innes Centre explains how plant roots form beneficial interactions with soil microbes. Almost all plants associate with mycorrhizal fungi to help in the uptake of nutrients such as phosphate. Some plants, particularly legumes, also associate with bacteria that ‘fix’ atmospheric nitrogen into a form the plant can use as fertiliser.

 

These two interactions are mediated within the plant by a common signalling pathway. The researchers have identified a specific mycorrhizal transcription factor. They also show how the signalling pathway has been recruited by pathogenic microbes, presenting a challenge to the plant. Its ability to form beneficial interactions can leave it vulnerable to invasion by pathogens.

 

Wang, E., Schornack, S., Marsh, J.F., Gobbato, E., Schwessinger, B., Eastmond, P., Schultze, M., Kamoun, S., and Oldroyd, G.E.D. (2012). A common signaling process that promotes mycorrhizal and oomycete colonization of plants. Curr. Biol. http://dx.doi.org/10.1016/j.cub.2012.09.043

 

Gobbato, E., Marsh, J.F., Vernie´ , T., Wang, E., Maillet, F., Kim, J., Miller, J.B., Sun, J., Bano, S.A., Ratet, P., et al. (2012). A GRAS-type transcription factor with a specific function in mycorrhizal signalling. Curr. Biol. http://dx.doi.org/10.1016/j.cub


Via Kamoun Lab @ TSL, Mary Williams
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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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Endogone, one of the oldest plant-associated fungi, host unique Mollicutes-related endobacteria

Endogone, one of the oldest plant-associated fungi, host unique Mollicutes-related endobacteria | Emerging Research in Plant Cell Biology | Scoop.it
Glomeromycota have been considered the most ancient group of fungi capable of positively interacting with plants for many years. Recently, other basal fungi, the Endogone Mucoromycotina fungi, have been identified as novel plant symbionts, challenging the paradigm of Glomeromycota as the unique ancestral symbionts of land plants. Glomeromycota are known to host endobacteria and recent evidences show that also some Mucoromycotina contain endobacteria. In order to examine similarities between basal groups of plant-associated fungi, we tested whether Endogone contained endobacteria.Twenty-nine Endogone were investigated in order to identify Mollicutes-related endobacteria (Mre). Fruiting bodies were processed for transmission electron microscopy and molecularly investigated using fungal and Mre-specific primers.We demonstrate that Mre are present inside 13 out of 29 Endogone: endobacteria are directly embedded in the fungal cytoplasm and their 16S rDNA sequences cluster together with the ones retrieved from Glomeromycota, forming, however, a separate new clade.Our findings provide new insights on the evolutionary relations between Glomeromycota, Mucoromycotina and endobacteria, raising new questions on the role of these still enigmatic microbes in the ecology, evolution and diversification of their fungal hosts during the history of plant–fungal symbiosis.
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Plant pathogenic bacteria target the actin microfilament network involved in the trafficking of disease defense components

Plant pathogenic bacteria target the actin microfilament network involved in the trafficking of disease defense components | Emerging Research in Plant Cell Biology | Scoop.it

Cells of infected organisms transport disease defense-related molecules along actin filaments to deliver them to their sites of action to combat the pathogen. To accomadate higher demand for intracellular traffic, plant F-actin density increases transiently during infection or treatment of Arabidopsis with pathogen-associated molecules. Many animal and plant pathogens interfere with actin polymerization and depolymerization to avoid immune responses. Pseudomonas syringae, a plant extracellular pathogen, injects HopW1 effector into host cells to disrupt the actin cytoskeleton and reduce vesicle movement in order to elude defense responses. In some Arabidopsis accessions, however, HopW1 is recognized and causes resistance via an actin-independent mechanism. HopW1 targets isoform 7 of vegetative actin (ACT7) that is regulated by phytohormones and environmental factors. We hypothesize that dynamic changes of ACT7 filaments are involved in plant immunity.

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Rescooped by Jennifer Mach from Plant roots and rhizosphere
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The divining root: moisture-driven responses of roots at the micro- and macro-scale

The divining root: moisture-driven responses of roots at the micro- and macro-scale | Emerging Research in Plant Cell Biology | Scoop.it
Water is fundamental to plant life, but the mechanisms by which plant roots sense and respond to variations in water availability in the soil are poorly understood. Many studies of responses to water deficit have focused on large-scale effects of this stress, but have overlooked responses at the sub-organ or cellular level that give rise to emergent whole-plant phenotypes. We have recently discovered hydropatterning, an adaptive environmental response in which roots position new lateral branches according to the spatial distribution of available water across the circumferential axis. This discovery illustrates that roots are capable of sensing and responding to water availability at spatial scales far lower than those normally studied for such processes. This review will explore how roots respond to water availability with an emphasis on what is currently known at different spatial scales. Beginning at the micro-scale, there is a discussion of water physiology at the cellular level and proposed sensory mechanisms cells use to detect osmotic status. The implications of these principles are then explored in the context of cell and organ growth under non-stress and water-deficit conditions. Following this, several adaptive responses employed by roots to tailor their functionality to the local moisture environment are discussed, including patterning of lateral root development and generation of hydraulic barriers to limit water loss. We speculate that these micro-scale responses are necessary for optimal functionality of the root system in a heterogeneous moisture environment, allowing for efficient water uptake with minimal water loss during periods of drought.

Via Christophe Jacquet
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Mycorrhiza Symbiosis Increases the Surface for Sunlight Capture in Medicago truncatula for Better Photosynthetic Production

Mycorrhiza Symbiosis Increases the Surface for Sunlight Capture in  Medicago truncatula  for Better Photosynthetic Production | Emerging Research in Plant Cell Biology | Scoop.it
Arbuscular mycorrhizal (AM) fungi play a prominent role in plant nutrition by supplying mineral nutrients, particularly inorganic phosphate (Pi), and also constitute an important carbon sink. AM stimulates plant growth and development, but the underlying mechanisms are not well understood. In this study, Medicago truncatula plants were grown with Rhizophagus irregularis BEG141 inoculum (AM), mock inoculum (control) or with Pi fertilization. We hypothesized that AM stimulates plant growth through either modifications of leaf anatomy or photosynthetic activity per leaf area. We investigated whether these effects are shared with Pi fertilization, and also assessed the relationship between levels of AM colonization and these effects. We found that increased Pi supply by either mycorrhization or fertilization led to improved shoot growth associated with increased nitrogen uptake and carbon assimilation. Both mycorrhized and Pi-fertilized plants had more and longer branches with larger and thicker leaves than the control plants, resulting in an increased photosynthetically active area. AM-specific effects were earlier appearance of the first growth axes and increased number of chloroplasts per cell section, since they were not induced by Pi fertilization. Photosynthetic activity per leaf area remained the same regardless of type of treatment. In conclusion, the increase in growth of mycorrhized and Pi-fertilized Medicago truncatula plants is linked to an increase in the surface for sunlight capture, hence increasing their photosynthetic production, rather than to an increase in the photosynthetic activity per leaf area.

Via Christophe Jacquet
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Rescooped by Jennifer Mach from Plant evolution
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Robust biological nitrogen fixation in a model grass-bacterial association

Robust biological nitrogen fixation in a model grass-bacterial association | Emerging Research in Plant Cell Biology | Scoop.it

Nitrogen-fixing rhizobacteria can promote plant growth; however, it is controversial whether biological nitrogen fixation (BNF) from associative interaction contributes to growth promotion. The roots of Setaria viridis, a model C4 grass, were effectively colonized by bacterial inoculants resulting in a significant enhancement of growth. Nitrogen-13 tracer studies provided direct evidence for tracer uptake by the host plant and incorporation into protein. Indeed, plants showed robust growth under nitrogen limiting conditions when inoculated with an ammonium excreting strain of Azospirillum brasilense. 11C-labeling experiments showed that patterns in central carbon metabolism and resource allocation exhibited by nitrogen starved plants were largely reversed by bacterial inoculation, such that they resembled plants grown under nitrogen sufficient conditions. Adoption of S. viridis as a model should promote research into the mechanisms of associative nitrogen fixation with the ultimate goal of greater adoption of BNF for sustainable crop production.


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Deeply Diverged Alleles in the Arabidopsis AREB1 Transcription Factor Drive Genome-Wide Differences in Transcriptional Response to the Environment

Deeply Diverged Alleles in the Arabidopsis AREB1 Transcription Factor Drive Genome-Wide Differences in Transcriptional Response to the Environment | Emerging Research in Plant Cell Biology | Scoop.it

Gene regulatory variation is an important driver of the evolution of physiological and developmental responses to the environment. The abscisic acid (ABA) signaling pathway has long been studied as a key component of the cellular response to abiotic stresses in plants. We identify two haplotypes in an Arabidopsis thaliana transcription factor, AREB1, which plays a central role in ABA-mediated response to osmotic stress. These two haplotypes show the sequence signature of long-term maintenance of genetic diversity, suggesting a role for a diversifying selection process such as balancing selection. We find that the two haplotypes, distinguished by a large number of single nucleotide polymorphisms and the presence or absence of four small insertion/deletions in AREB1 intron 1 and exon 2, are at roughly equal frequencies in Arabidopsis, and show high linkage disequilibrium and deep sequence divergence. We use a transgenic approach, along with mRNA Sequencing-based assay of genome-wide expression levels, and find considerable functional divergence between alleles representing the two haplotype groups. Specifically, we find that, under benign soil–water conditions, transgenic lines containing different AREB1 alleles differ in the expression of a large number of genes associated with pathogen response. There are relatively modest gene expression differences between the two transgenic lines under restricted soil water content. Our finding of pathogen-related activity expands the known roles of AREB1 inA. thaliana and reveals the molecular basis of gene-by-environment interaction in a putatively adaptive plant regulatory protein.

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Imprinting in plants as a mechanism to generate seed phenotypic diversity

Normal plant development requires epigenetic regulation to enforce changes in developmental fate. Genomic imprinting is a type of epigenetic regulation in which identical alleles of genes are expressed in a parent-of-origin dependent manner. Deep sequencing of transcriptomes has identified hundreds of imprinted genes with scarce evidence for the developmental importance of individual imprinted loci. Imprinting is regulated through global DNA demethylation in the central cell prior to fertilization and directed repression of individual loci with the Polycomb Repressive Complex 2 (PRC2). There is significant evidence for transposable elements and repeat sequences near genes acting as cis-elements to determine imprinting status of a gene, implying that imprinted gene expression patterns may evolve randomly and at high frequency. Detailed genetic analysis of a few imprinted loci suggests an imprinted pattern of gene expression is often dispensable for seed development. Few genes show conserved imprinted expression within or between plant species. These data are not fully explained by current models for the evolution of imprinting in plant seeds. We suggest that imprinting may have evolved to provide a mechanism for rapid neofunctionalization of genes during seed development to increase phenotypic diversity of seeds.

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Rescooped by Jennifer Mach from Plant Biology Teaching Resources (Higher Education)
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Regulation of Specialized Metabolism by WRKY Transcription Factors

Regulation of Specialized Metabolism by WRKY Transcription Factors | Emerging Research in Plant Cell Biology | Scoop.it

WRKY transcription factors (TFs) are well known for regulating plant abiotic and biotic stress tolerance. However, much less is known about how WRKY TFs affect plant-specialized metabolism. Analysis of WRKY TFs regulating the production of specialized metabolites emphasizes the values of the family outside of traditionally accepted roles in stress tolerance. WRKYs with conserved roles across plant species seem to be essential in regulating specialized metabolism. Overall, the WRKY family plays an essential role in regulating the biosynthesis of important pharmaceutical, aromatherapy, biofuel, and industrial components, warranting considerable attention in the forthcoming years.

 

 


Via Christophe Jacquet, Mary Williams
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Rescooped by Jennifer Mach from TAL effector science
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Creation of fragrant rice by targeted knockout of the OsBADH2 gene using TALEN technology - Plant Biotech. J.

Creation of fragrant rice by targeted knockout of the OsBADH2 gene using TALEN technology - Plant Biotech. J. | Emerging Research in Plant Cell Biology | Scoop.it

(via T. Lahaye, thx)

Shan et al, 2015

Fragrant rice is favoured worldwide because of its agreeable scent. The presence of a defective badh2 allele encoding betaine aldehyde dehydrogenase (BADH2) results in the synthesis of 2-acetyl-1-pyrroline (2AP), which is a major fragrance compound. Here, transcription activator-like effector nucleases (TALENs) were engineered to target and disrupt the OsBADH2 gene. Six heterozygous mutants (30%) were recovered from 20 transgenic hygromycin-resistant lines. Sanger sequencing confirmed that these lines had various indel mutations at the TALEN target site. All six transmitted the BADH2 mutations to the T1 generation; and four T1 mutant lines tested also efficiently transmitted the mutations to the T2 generation. Mutant plants carrying only the desired DNA sequence change but not the TALEN transgene were obtained by segregation in the T1 and T2 generations. The 2AP content of rice grains of the T1 lines with homozygous mutations increased from 0 to 0.35–0.75 mg/kg, which was similar to the content of a positive control variety harbouring the badh2-E7 mutation. We also simultaneously introduced three different pairs of TALENs targeting three separate rice genes into rice cells by bombardment and obtained lines with mutations in one, two and all three genes. These results indicate that targeted mutagenesis using TALENs is a useful approach to creating important agronomic traits.


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The Phylogenetically-Related Pattern Recognition Receptors EFR and XA21 Recruit Similar Immune Signaling Components in Monocots and Dicots

The Phylogenetically-Related Pattern Recognition Receptors EFR and XA21 Recruit Similar Immune Signaling Components in Monocots and Dicots | Emerging Research in Plant Cell Biology | Scoop.it

During plant immunity, surface-localized pattern recognition receptors (PRRs) recognize pathogen-associated molecular patterns (PAMPs). The transfer of PRRs between plant species is a promising strategy for engineering broad-spectrum disease resistance. Thus, there is a great interest in understanding the mechanisms of PRR-mediated resistance across different plant species. Two well-characterized plant PRRs are the leucine-rich repeat receptor kinases (LRR-RKs) EFR and XA21 from Arabidopsis thaliana (Arabidopsis) and rice, respectively. Interestingly, despite being evolutionary distant, EFR and XA21 are phylogenetically closely related and are both members of the sub-family XII of LRR-RKs that contains numerous potential PRRs. Here, we compared the ability of these related PRRs to engage immune signaling across the monocots-dicots taxonomic divide. Using chimera between Arabidopsis EFR and rice XA21, we show that the kinase domain of the rice XA21 is functional in triggering elf18-induced signaling and quantitative immunity to the bacteria Pseudomonas syringae pv.tomato (Pto) DC3000 and Agrobacterium tumefaciens in Arabidopsis. Furthermore, the EFR:XA21 chimera associates dynamically in a ligand-dependent manner with known components of the EFR complex. Conversely, EFR associates with Arabidopsis orthologues of rice XA21-interacting proteins, which appear to be involved in EFR-mediated signaling and immunity in Arabidopsis. Our work indicates the overall functional conservation of immune components acting downstream of distinct LRR-RK-type PRRs between monocots and dicots.

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Rescooped by Jennifer Mach from Plant-Microbe Symbioses
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Soybean kinome: functional classification and gene expression patterns

Soybean kinome: functional classification and gene expression patterns | Emerging Research in Plant Cell Biology | Scoop.it
The protein kinase (PK) gene family is one of the largest and most highly conserved gene families in plants and plays a role in nearly all biological functions. While a large number of genes have been predicted to encode PKs in soybean, a comprehensive functional classification and global analysis of expression patterns of this large gene family is lacking. In this study, we identified the entire soybean PK repertoire or kinome, which comprised 2166 putative PK genes, representing 4.67% of all soybean protein-coding genes. The soybean kinome was classified into 19 groups, 81 families, and 122 subfamilies. The receptor-like kinase (RLK) group was remarkably large, containing 1418 genes. Collinearity analysis indicated that whole-genome segmental duplication events may have played a key role in the expansion of the soybean kinome, whereas tandem duplications might have contributed to the expansion of specific subfamilies. Gene structure, subcellular localization prediction, and gene expression patterns indicated extensive functional divergence of PK subfamilies. Global gene expression analysis of soybean PK subfamilies revealed tissue- and stress-specific expression patterns, implying regulatory functions over a wide range of developmental and physiological processes. In addition, tissue and stress co-expression network analysis uncovered specific subfamilies with narrow or wide interconnected relationships, indicative of their association with particular or broad signalling pathways, respectively. Taken together, our analyses provide a foundation for further functional studies to reveal the biological and molecular functions of PKs in soybean.

Via Jean-Michel Ané
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Rescooped by Jennifer Mach from Plant evolution
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Cytoplasmic Nucleation and Atypical Branching Nucleation Generate Endoplasmic Microtubules in Physcomitrella patens

The mechanism underlying microtubule (MT) generation in plants has been primarily studied using the cortical MT array, in which fixed-angled branching nucleation and katanin-dependent MT severing predominate. However, little is known about MT generation in the endoplasm. Here, we explored the mechanism of endoplasmic MT generation in protonemal cells of Physcomitrella patens. We developed an assay that utilizes flow cell and oblique illumination fluorescence microscopy, which allowed visualization and quantification of individual MTdynamics. MT severing was infrequently observed, and disruption of katanin did not severely affect MT generation. Branching nucleation was observed, but it showed markedly variable branch angles and was occasionally accompanied by the transport of nucleated MTs. Cytoplasmic nucleation at seemingly random locations was most frequently observed and predominated when depolymerized MTs were regrown. The MT nucleator γ-tubulin was detected at the majority of the nucleation sites, at which a single MT was generated in random directions. When γ-tubulin was knocked down, MT generation was significantly delayed in the regrowth assay. However, nucleation occurred at a normal frequency in steady state, suggesting the presence of a γ-tubulin-independent backup mechanism. Thus, endoplasmic MTs in this cell type are generated in a less ordered manner, showing a broader spectrum of nucleation mechanisms in plants.


Via Pierre-Marc Delaux
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Which biotech foods are most acceptable to the public?

Which biotech foods are most acceptable to the public? | Emerging Research in Plant Cell Biology | Scoop.it

New discoveries are prompting questions about which types of genetically engineered foods and applications are likely to be most accepted by the public. Results of a survey of over 1000 US consumers reveals that people prefer eating beef to eating corn or apples if the foods are not genetically engineered, but exactly the opposite is true if the foods are genetically engineered. Eating fresh food is preferred to processed, but much less so if both food types are genetically engineered. Desirability of genetic engineering depends on the reason for the biotechnology application.

Questions about public acceptance of agricultural biotechnology have been reignited by recent events and scientific progress. Results from a nationwide survey revealed that consumers assign larger “genetically engineered discounts” to fresh than processed foods and to meats than fruits or cereal grains. Consumers considered the motivations for adoption of genetic engineered foods desirable, in particular motivations related to protection of US origin, lower prices, and higher nutritional content. Genetically engineered foods that are processed that provide direct benefits to consumers, like improved nutritional content, are likely to be most acceptable to the public, particularly if benefits related to price-impacts and national competitiveness are understood by the public.

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The concept of the sexual reproduction cycle and its evolutionary significance

The concept of the sexual reproduction cycle and its evolutionary significance | Emerging Research in Plant Cell Biology | Scoop.it

The concept of a “sexual reproduction cycle (SRC)” was first proposed by Bai and Xu (2013) to describe the integration of meiosis, sex differentiation, and fertilization. This review discusses the evolutionary and scientific implications of considering these three events as part of a single process. Viewed in this way, the SRC is revealed to be a mechanism for efficiently increasing genetic variation, facilitating adaptation to environmental challenges. It also becomes clear that, in terms of cell proliferation, it is appropriate to contrast mitosis with the entire SRC, rather than with meiosis alone. Evolutionarily, it appears that the SRC was first established in unicellular eukaryotes and that all multicellular organisms evolved within that framework. This concept provides a new perspective into how sexual reproduction evolved, how generations should be defined, and how developmental processes of various multicellular organisms should properly be compared.

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Twin Plants from Supernumerary Egg Cells in Arabidopsis: Current Biology

Sexual reproduction of flowering plants is distinguished by double fertilization—the two sperm cells delivered by a pollen tube fuse with the two gametic cells of the female gametophyte, the egg and the central cell—inside the ovule to give rise to the embryo and the nutritive endosperm, respectively [ 1 ]. The pollen tube is attracted by nongametic synergid cells, and how these two cells of the female gametophyte are specified is currently unclear. Here, we show that ALTERED MERISTEM PROGRAM 1 (AMP1), encoding a protein associated with the endoplasmic reticulum [ 2 ], is required for synergid cell fate during Arabidopsis female gametophyte development. Loss of AMP1 function leads to supernumerary egg cells at the expense of synergids, enabling the generation of dizygotic twins. However, if twin embryos are formed, endosperm formation is prevented, eventually resulting in ovule abortion. The latter can be overcome by the delivery of supernumerary sperm cells in tetraspore (tes) pollen [ 3 ], enabling the formation of twin plants. Thus, both primary and supernumerary egg cells are fully functional in amp1 mutant plants. Sporophytic AMP1 expression is sufficient to prevent cell-fate change of synergids, indicating that one or more AMP1-dependent mobile signals from outside the female gametophyte can contribute to its patterning, in addition to the previously reported lateral inhibition between gametophytic cells [ 4–6 ]. Our results provide insight into the mechanism of synergid fate specification and emphasize the importance of specifying only one egg cell within the female gametophyte to ensure central-cell fertilization by the second sperm cell.

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Dual roles of an Arabidopsis ESCRT component FREE1 in regulating vacuolar protein transport and autophagic degradation

Dual roles of an Arabidopsis ESCRT component FREE1 in regulating vacuolar protein transport and autophagic degradation | Emerging Research in Plant Cell Biology | Scoop.it
Protein turnover can be achieved via the lysosome/vacuole and the autophagic degradation pathways. Evidence has accumulated revealing that efficient autophagic degradation requires functional endosomal sorting complex required for transport (ESCRT) machinery. However, the interplay between the ESCRT machinery and the autophagy regulator remains unclear. Here, we show that FYVE domain protein required for endosomal sorting 1 (FREE1), a recently identified plant-specific ESCRT component essential for multivesicular body (MVB) biogenesis and plant growth, plays roles both in vacuolar protein transport and autophagic degradation. FREE1 also regulates vacuole biogenesis in both seeds and vegetative cells of Arabidopsis. Additionally, FREE1 interacts directly with a unique plant autophagy regulator SH3 DOMAIN-CONTAINING PROTEIN2 and associates with the PI3K complex, to regulate the autophagic degradation in plants. Thus, FREE1 plays multiple functional roles in vacuolar protein trafficking and organelle biogenesis as well as in autophagic degradation via a previously unidentified regulatory mechanism of cross-talk between the ESCRT machinery and autophagy process.

Via Suayib Üstün
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Rescooped by Jennifer Mach from Plant Stress Physiology
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Transposable Elements Contribute to Activation of Maize Genes in Response to Abiotic Stress

Transposable Elements Contribute to Activation of Maize Genes in Response to Abiotic Stress | Emerging Research in Plant Cell Biology | Scoop.it

"Our analysis suggests that a small number of maize transposable element families may contribute to the response of nearby genes to abiotic stress by providing stress-responsive enhancer-like functions. The specific insertions of transposable elements are" often polymorphic within a species. Our data demonstrate that allelic variation for insertions of the transposable elements associated with stress-responsive expression can contribute to variation in the regulation of nearby genes. Thus novel insertions of transposable elements provide a potential mechanism for genes to acquire cis-regulatory influences that could contribute to heritable variation for stress response."


Via Mary Williams, R K Upadhyay
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The mRNA decay factor PAT1 functions in a pathway including MAP kinase 4 and immune receptor SUMM2

The mRNA decay factor PAT1 functions in a pathway including MAP kinase 4 and immune receptor SUMM2 | Emerging Research in Plant Cell Biology | Scoop.it

Multi‐layered defense responses are activated in plants upon recognition of invading pathogens. Transmembrane receptors recognize conserved pathogen‐associated molecular patterns (PAMPs) and activate MAP kinase cascades, which regulate changes in gene expression to produce appropriate immune responses. For example,Arabidopsis MAP kinase 4 (MPK4) regulates the expression of a subset of defense genes via at least one WRKY transcription factor. We report here that MPK4 is found in complexes in vivo with PAT1, a component of the mRNA decapping machinery. PAT1 is also phosphorylated by MPK4 and, upon flagellin PAMP treatment, PAT1 accumulates and localizes to cytoplasmic processing (P) bodies which are sites for mRNA decay.Pat1 mutants exhibit dwarfism and de‐repressed immunity dependent on the immune receptor SUMM2. Since mRNA decapping is a critical step in mRNA turnover, linking MPK4 to mRNA decay via PAT1 provides another mechanism by which MPK4 may rapidly instigate immune responses.

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A maize wall-associated kinase confers quantitative resistance to head smut

A maize wall-associated kinase confers quantitative resistance to head smut | Emerging Research in Plant Cell Biology | Scoop.it

Head smut is a systemic disease in maize caused by the soil-borne fungus Sporisorium reilianumthat poses a grave threat to maize production worldwide. A major head smut quantitative resistance locus, qHSR1, has been detected on maize chromosome bin2.09. Here we report the map-based cloning of qHSR1 and the molecular mechanism of qHSR1-mediated resistance. Sequential fine mapping and transgenic complementation demonstrated that ZmWAK is the gene within qHSR1 conferring quantitative resistance to maize head smut. ZmWAK spans the plasma membrane, potentially serving as a receptor-like kinase to perceive and transduce extracellular signals. ZmWAK was highly expressed in the mesocotyl of seedlings where it arrested biotrophic growth of the endophytic S. reilianum. Impaired expression in the mesocotyl compromisedZmWAK-mediated resistance. Deletion of the ZmWAK locus appears to have occurred after domestication and spread among maize germplasm, and the ZmWAK kinase domain underwent functional constraints during maize evolution.

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The NPR1-dependent salicylic acid signalling pathway is pivotal for enhanced salt and oxidative stress tolerance in Arabidopsis

The NPR1-dependent salicylic acid signalling pathway is pivotal for enhanced salt and oxidative stress tolerance in Arabidopsis | Emerging Research in Plant Cell Biology | Scoop.it
The role of endogenous salicylic acid (SA) signalling cascades in plant responses to salt and oxidative stresses is unclear. Arabidopsis SA signalling mutants, namely npr1-5 (non-expresser of pathogenesis related gene1), which lacks NPR1-dependent SA signalling, and nudt7 (nudix hydrolase7), which has both constitutively expressed NPR1-dependent and NPR1-independent SA signalling pathways, were compared with the wild type (Col-0) during salt or oxidative stresses. Growth and viability staining showed that, compared with wild type, the npr1-5 mutant was sensitive to either salt or oxidative stress, whereas the nudt7 mutant was tolerant. Acute salt stress caused the strongest membrane potential depolarization, highest sodium and proton influx, and potassium loss from npr1-5 roots in comparison with the wild type and nudt7 mutant. Though salt stress-induced hydrogen peroxide production was lowest in the npr1-5 mutant, the reactive oxygen species (ROS) stress (induced by 1mM of hydroxyl-radical-generating copper-ascorbate mix, or either 1 or 10mM hydrogen peroxide) caused a higher potassium loss from the roots of the npr1-5 mutant than the wild type and nudt7 mutant. Long-term salt exposure resulted in the highest sodium and the lowest potassium concentration in the shoots of npr1-5 mutant in comparison with the wild type and nudt7 mutant. The above results demonstrate that NPR1-dependent SA signalling is pivotal to (i) controlling Na+ entry into the root tissue and its subsequent long-distance transport into the shoot, and (ii) preventing a potassium loss through depolarization-activated outward-rectifying potassium and ROS-activated non-selective cation channels. In conclusion, NPR1-dependent SA signalling is central to the salt and oxidative stress tolerance in Arabidopsis.

Via Christophe Jacquet, Jim Alfano, Suayib Üstün
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Rescooped by Jennifer Mach from Plant roots and rhizosphere
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Genetic control of distal stem cell fate within root and embryonic meristems

Genetic control of distal stem cell fate within root and embryonic meristems | Emerging Research in Plant Cell Biology | Scoop.it
The root meristem consists of populations of distal and proximal stem cells, and an organizing center known as the quiescent center. During embryogenesis, initiation of the root meristem occurs when an asymmetric cell division of the hypophysis forms the distal stem cells and quiescent center. We have identified NO TRANSMITTING TRACT (NTT) and two closely related paralogs as being required for the initiation of the root meristem. All three genes are expressed in the hypophysis and their expression is dependent on the auxin-signaling pathway. Expression of these genes is necessary for distal stem cell fate within the root meristem, while misexpression is sufficient to transform other stem cell populations to a distal stem cell fate in both the embryo and mature roots.

Via Christophe Jacquet
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Plant, Cell & Environment Special Issue - Reactive Oxygen and Nitrogen in Plants

Plant, Cell & Environment Special Issue - Reactive Oxygen and Nitrogen in Plants | Emerging Research in Plant Cell Biology | Scoop.it
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Rescooped by Jennifer Mach from Plant Gene Seeker -PGS
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The Plant Cell Reviews Dynamic Aspects of Plant Hormone Signaling and Crosstalk

The Plant Cell Reviews Dynamic Aspects of Plant Hormone Signaling and Crosstalk | Emerging Research in Plant Cell Biology | Scoop.it

The Roles of ROS and ABA in Systemic Acquired Acclimation

Ron Mittler and Eduardo Blumwald

Plant Cell 2015 tpc.114.133090; First Published on January 20, 2015; doi:10.1105/tpc.114.133090 OPEN

http://www.plantcell.org/content/early/2015/01/20/tpc.114.133090.abstract

 

SCFTIR1/AFB-Based Auxin Perception: Mechanism and Role in Plant Growth and Development

Mohammad Salehin, Rammyani Bagchi, and Mark Estelle

Plant Cell 2015 tpc.114.133744; First Published on January 20, 2015; doi:10.1105/tpc.114.133744

http://www.plantcell.org/content/early/2015/01/20/tpc.114.133744.abstract

 

The PB1 Domain in Auxin Response Factor and Aux/IAA Proteins: A Versatile Protein Interaction Module in the Auxin Response

Tom J. Guilfoyle

Plant Cell 2015 tpc.114.132753; First Published on January 20, 2015; doi:10.1105/tpc.114.132753 OPEN

http://www.plantcell.org/content/early/2015/01/20/tpc.114.132753.abstract

 

PIN-Dependent Auxin Transport: Action, Regulation, and Evolution

Maciek Adamowski and Jiří Friml

Plant Cell 2015 tpc.114.134874; First Published on January 20, 2015; doi:10.1105/tpc.114.134874

http://www.plantcell.org/content/early/2015/01/20/tpc.114.134874.abstract

 

The Yin-Yang of Hormones: Cytokinin and Auxin Interactions in Plant Development

G. Eric Schaller, Anthony Bishopp, and Joseph J. Kieber

Plant Cell 2015 tpc.114.133595; First Published on January 20, 2015; doi:10.1105/tpc.114.133595

http://www.plantcell.org/content/early/2015/01/20/tpc.114.133595.abstract


Via Mary Williams, Christophe Jacquet, Andres Zurita
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Rescooped by Jennifer Mach from Plant roots and rhizosphere
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Shoot and root branch growth angle control—the wonderfulness of lateralness

Shoot and root branch growth angle control—the wonderfulness of lateralness | Emerging Research in Plant Cell Biology | Scoop.it

Highlights

Gravitropic setpoint angles are growth angles that are maintained relative to gravity.
Non-vertical branch growth is an important adaptive trait that is poorly understood.
Auxin is central to the gravity-dependent, non-vertical growth of lateral branches.
Non-vertical GSAs arise via balancing gravitropic and antigravitropic components.

The overall shape of plants, the space they occupy above and below ground, is determined principally by the number, length, and angle of their lateral branches. The function of these shoot and root branches is to hold leaves and other organs to the sun, and below ground, to provide anchorage and facilitate the uptake of water and nutrients. While in some respects lateral roots and shoots can be considered mere iterations of the primary root-shoot axis, in others there are fundamental differences in their biology, perhaps most conspicuously in the regulation their angle of growth. Here we discuss recent advances in the understanding of the control of branch growth angle, one of the most important but least understood components of the wonderful diversity of plant form observed throughout nature.


Via Christophe Jacquet
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Optimizing pyramided transgenic Bt crops for sustainable pest management

Optimizing pyramided transgenic Bt crops for sustainable pest management | Emerging Research in Plant Cell Biology | Scoop.it

Transgenic crop pyramids producing two or more Bacillus thuringiensis (Bt) toxins that kill the same insect pest have been widely used to delay evolution of pest resistance. To assess the potential of pyramids to achieve this goal, we analyze data from 38 studies that report effects of ten Bt toxins used in transgenic crops against 15 insect pests. We find that compared with optimal low levels of insect survival, survival on currently used pyramids is often higher for both susceptible insects and insects resistant to one of the toxins in the pyramid. Furthermore, we find that cross-resistance and antagonism between toxins used in pyramids are common, and that these problems are associated with the similarity of the amino acid sequences of domains II and III of the toxins, respectively. This analysis should assist in future pyramid design and the development of sustainable resistance management strategies.

  
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