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Rescooped by Jennifer Mach from Plant Biology Teaching Resources (Higher Education)
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Dev. Cell - A Protodermal miR394 Signal Defines a Region of Stem Cell Competence in the Arabidopsis Shoot Meristem

Dev. Cell - A Protodermal miR394 Signal Defines a Region of Stem Cell Competence in the Arabidopsis Shoot Meristem | Emerging Research in Plant Cell Biology | Scoop.it

"A long-standing question in plants and animals is how spatial patterns are maintained within stem cell niches despite ongoing cell divisions. Here we address how, during shoot meristem formation in Arabidopsis thaliana, the three apical cell layers acquire stem cell identity. "


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Mary Williams's curator insight, January 17, 2013 10:50 PM

I like it like it! Lovely work!

 

If you like it, you might like this one too, out in PLOS Genetics (http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003218) "POWERDRESS and Diversified Expression of the MIR172 Gene Family Bolster the Floral Stem Cell Network" by Xuemei Chen's group at UC Riverside.

Emerging Research in Plant Cell Biology
A science editor's take on what's new and interesting in the plant kingdom.
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Quantitative trait loci and candidate genes underlying genotype by environment interaction in the response of Arabidopsis thaliana to drought

Quantitative trait loci and candidate genes underlying genotype by environment interaction in the response of Arabidopsis thaliana to drought | Emerging Research in Plant Cell Biology | Scoop.it

Drought stress was imposed on two sets of Arabidopsis thaliana genotypes grown in sand under short day conditions and analysed for several shoot and root growth traits. The response to drought was assessed for quantitative trait locus (QTL) mapping in a genetically diverse set of Arabidopsis accessions using genome-wide association (GWA) mapping, and conventional linkage analysis of a recombinant inbred line (RIL) population. Results showed significant genotype by environment interaction (GxE) for all traits in response to different watering regimes. For the RIL population, the observed GxE was reflected in 17 QTL by environment interactions (QxE), while 17 additional QTLs were mapped not showing QxE. GWA mapping identified 58 SNPs associated with loci displaying QxE and an additional 16 SNPs associated with loci not showing QxE. Many candidate genes potentially underlying these loci were suggested. The genes forRPS3C and YLS7 were found to contain conserved amino acid differences when comparing Arabidopsis accessions with strongly contrasting drought response phenotypes, further supporting their candidacy. One of these candidate genes co-located with a QTL mapped in the RIL population.

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The genome of the stress-tolerant wild tomato species Solanum pennellii

The genome of the stress-tolerant wild tomato species Solanum pennellii | Emerging Research in Plant Cell Biology | Scoop.it

Solanum pennellii is a wild tomato species endemic to Andean regions in South America, where it has evolved to thrive in arid habitats. Because of its extreme stress tolerance and unusual morphology, it is an important donor of germplasm for the cultivated tomatoSolanum lycopersicum1. Introgression lines (ILs) in which large genomic regions of S. lycopersicum are replaced with the corresponding segments from S. pennellii can show remarkably superior agronomic performance2. Here we describe a high-quality genome assembly of the parents of the IL population. By anchoring the S. pennellii genome to the genetic map, we define candidate genes for stress tolerance and provide evidence that transposable elements had a role in the evolution of these traits. Our work paves a path toward further tomato improvement and for deciphering the mechanisms underlying the myriad other agronomic traits that can be improved with S. pennellii germplasm.


Via Pierre-Marc Delaux, Francis Martin
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Comparative Phylogenomics Uncovers the Impact of Symbiotic Associations on Host Genome Evolution

Comparative Phylogenomics Uncovers the Impact of Symbiotic Associations on Host Genome Evolution | Emerging Research in Plant Cell Biology | Scoop.it

Abstract

 

Mutualistic symbioses between eukaryotes and beneficial microorganisms of their microbiome play an essential role in nutrition, protection against disease, and development of the host. However, the impact of beneficial symbionts on the evolution of host genomes remains poorly characterized. Here we used the independent loss of the most widespread plant–microbe symbiosis, arbuscular mycorrhization (AM), as a model to address this question. Using a large phenotypic approach and phylogenetic analyses, we present evidence that loss of AM symbiosis correlates with the loss of many symbiotic genes in the Arabidopsis lineage (Brassicales). Then, by analyzing the genome and/or transcriptomes of nine other phylogenetically divergent non-host plants, we show that this correlation occurred in a convergent manner in four additional plant lineages, demonstrating the existence of an evolutionary pattern specific to symbiotic genes. Finally, we use a global comparative phylogenomic approach to track this evolutionary pattern among land plants. Based on this approach, we identify a set of 174 highly conserved genes and demonstrate enrichment in symbiosis-related genes. Our findings are consistent with the hypothesis that beneficial symbionts maintain purifying selection on host gene networks during the evolution of entire lineages.


Via Pierre-Marc Delaux, Jean-Michel Ané, Mary Williams, Christophe Jacquet
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Pierre-Marc Delaux's curator insight, July 17, 11:57 AM

Yeah!! Online finally :)

Jean-Michel Ané's curator insight, July 17, 12:28 PM

Paper from our lab!

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Nature Biotechnology Cover: Aphid pest control (2013)

Nature Biotechnology Cover: Aphid pest control (2013) | Emerging Research in Plant Cell Biology | Scoop.it

Soybean aphid nymphs (Aphis glycines) navigating trichomes on the underside of a soybean leaf. Bonning et al. use a plant virus coat protein to deliver an insect-specific neurotoxin from the aphid gut into the body cavity, providing a new strategy for managing sap-sucking agricultural pests. Credit: Greg VanNostrand. Article by Bonning et al. at http://www.nature.com/nbt/journal/v32/n1/full/nbt.2753.html


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Rabenstein, Frank's curator insight, January 10, 6:49 AM

this strategy seems to be aplicable also for cereal luteoviruses?

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Variation in allelic expression associated with a recombination hotspot in Zea mays

Variation in allelic expression associated with a recombination hotspot in Zea mays | Emerging Research in Plant Cell Biology | Scoop.it

Gene expression is a complex process, requiring precise spatial and temporal regulation of transcription factor activity; however, modifications of individual cis- and trans-acting modules can be molded by natural selection to create a sizeable number of novel phenotypes. Results from decades of research indicate that developmental and phenotypic divergence among eukaryotic organisms is driven primarily by variation in levels of gene expression that are dictated by mutations, either in structural or regulatory regions, of genes. The relative contributions and interplay of cis- and trans-acting regulatory factors to this evolutionary process, however, remain poorly understood. Analysis of eight genes in the Bz1–Sh1 interval of Zea mays (maize) indicates significant allele-specific expression biases in at least one tissue for all genes, ranging from 1.3-fold to 36-fold. All detected effects were cis-regulatory in nature, although genetic background may also influence the level of expression bias and tissue specificity for some allelic combinations. Most allelic pairs exhibited the same direction and approximate intensity of bias across all four tissues; however, a subset of allelic pairs show alternating dominance across different tissue types or variation in the degree of bias in different tissues. In addition, the genes showing the most striking levels of allelic bias co-localize with a previously described recombination hotspot in this region, suggesting a naturally occurring genetic mechanism for creating regulatory variability for a subset of plant genes that may ultimately lead to evolutionary diversification.

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Dt2 Is a Gain-of-Function MADS-Domain Factor Gene That Specifies Semideterminacy in Soybean

Dt2 Is a Gain-of-Function MADS-Domain Factor Gene That Specifies Semideterminacy in Soybean | Emerging Research in Plant Cell Biology | Scoop.it

Similar to Arabidopsis thaliana, the wild soybeans (Glycine soja) and many cultivars exhibit indeterminate stem growth specified by the shoot identity gene Dt1, the functional counterpart of Arabidopsis TERMINAL FLOWER1 (TFL1). Mutations inTFL1 and Dt1 both result in the shoot apical meristem (SAM) switching from vegetative to reproductive state to initiate terminal flowering and thus produce determinate stems. A second soybean gene (Dt2) regulating stem growth was identified, which, in the presence of Dt1, produces semideterminate plants with terminal racemes similar to those observed in determinate plants. Here, we report positional cloning and characterization of Dt2, a dominant MADS domain factor gene classified into the APETALA1/SQUAMOSA (AP1/SQUA) subfamily that includes floral meristem (FM) identity genes AP1, FUL, and CAL in Arabidopsis. Unlike AP1, whose expression is limited to FMs in which the expression of TFL1 is repressed,Dt2 appears to repress the expression of Dt1 in the SAMs to promote early conversion of the SAMs into reproductive inflorescences. Given that Dt2 is not the gene most closely related to AP1 and that semideterminacy is rarely seen in wild soybeans, Dt2 appears to be a recent gain-of-function mutation, which has modified the genetic pathways determining the stem growth habit in soybean.

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Bonus content: In Brief 

http://www.plantcell.org/content/early/2014/07/08/tpc.114.129056.full.pdf+html

and profile of lead author: 

http://www.plantcell.org/content/early/2014/07/08/tpc.114.126938/suppl/DC2

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Host-induced bacterial cell wall decomposition mediates pattern-triggered immunity in Arabidopsis

Host-induced bacterial cell wall decomposition mediates pattern-triggered immunity in Arabidopsis | Emerging Research in Plant Cell Biology | Scoop.it

Peptidoglycans (PGNs) are immunogenic bacterial surface patterns that trigger immune activation in metazoans and plants. It is generally unknown how complex bacterial structures such as PGNs are perceived by plant pattern recognition receptors (PRRs) and whether host hydrolytic activities facilitate decomposition of bacterial matrices and generation of soluble PRR ligands. Here we show that Arabidopsis thaliana, upon bacterial infection or exposure to microbial patterns, produces a metazoan lysozyme-like hydrolase (lysozyme 1, LYS1). LYS1 activity releases soluble PGN fragments from insoluble bacterial cell walls and cleavage products are able to trigger responses typically associated with plant immunity. Importantly, LYS1 mutant genotypes exhibit super-susceptibility to bacterial infections similar to that observed on PGN receptor mutants. We propose that plants employ hydrolytic activities for the decomposition of complex bacterial structures, and that soluble pattern generation might aid PRR-mediated immune activation in cell layers adjacent to infection sites.

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Nature: The long-term maintenance of a resistance polymorphism through diffuse interactions (2014)

Nature: The long-term maintenance of a resistance polymorphism through diffuse interactions (2014) | Emerging Research in Plant Cell Biology | Scoop.it

Plant resistance (R) genes are a crucial component in plant defence against pathogens1. Although R genes often fail to provide durable resistance in an agricultural context, they frequently persist as long-lived balanced polymorphisms in nature2, 3, 4. Standard theory explains the maintenance of such polymorphisms through a balance of the costs and benefits of resistance and virulence in a tightly coevolving host–pathogen pair5, 6. However, many plant–pathogen interactions lack such specificity7. Whether, and how, balanced polymorphisms are maintained in diffusely interacting species8 is unknown. Here we identify a naturally interacting R gene and effector pair in Arabidopsis thaliana and its facultative plant pathogen, Pseudomonas syringae. The protein encoded by the R gene RPS5 recognizes an AvrPphB homologue (AvrPphB2) and exhibits a balanced polymorphism that has been maintained for over 2 million years (ref. 3). Consistent with the presence of an ancient balanced polymorphism, the R gene confers a benefit when plants are infected with P. syringae carrying avrPphB2 but also incurs a large cost in the absence of infection. RPS5alleles are maintained at intermediate frequencies in populations globally, suggesting ubiquitous selection for resistance. However, the presence of P. syringae carrying avrPphB is probably insufficient to explain the RPS5 polymorphism. First, avrPphB homologues occur at very low frequencies in P. syringae populations on A. thaliana. Second, AvrPphB only rarely confers a virulence benefit to P. syringae on A. thaliana. Instead, we find evidence that selection for RPS5 involves multiple non-homologous effectors and multiple pathogen species. These results and an associated model suggest that the R gene polymorphism in A. thaliana may not be maintained through a tightly coupled interaction involving a single coevolved R gene and effector pair. More likely, the stable polymorphism is maintained through complex and diffuse community-wide interactions.


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Epigenetic reprogramming in plant sexual reproduction

Epigenetic reprogramming in plant sexual reproduction | Emerging Research in Plant Cell Biology | Scoop.it

Epigenetic reprogramming consists of global changes in DNA methylation and histone modifications. In mammals, epigenetic reprogramming is primarily associated with sexual reproduction and occurs during both gametogenesis and early embryonic development. Such reprogramming is crucial not only to maintain genomic integrity through silencing transposable elements but also to reset the silenced status of imprinted genes. In plants, observations of stable transgenerational inheritance of epialleles have argued against reprogramming. However, emerging evidence supports that epigenetic reprogramming indeed occurs during sexual reproduction in plants and that it has a major role in maintaining genome integrity and a potential contribution to epiallelic variation.

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Molecular genetic framework for protophloem formation

The phloem performs essential systemic functions in tracheophytes, yet little is known about its molecular genetic specification. Here we show that application of the peptide ligand CLAVATA3/EMBRYO SURROUNDING REGION 45 (CLE45) specifically inhibits specification of protophloem in Arabidopsis roots by locking the sieve element precursor cell in its preceding developmental state. CLE45 treatment, as well as viable transgenic expression of a weak CLE45G6T variant, interferes not only with commitment to sieve element fate but also with the formative sieve element precursor cell division that creates protophloem and metaphloem cell files. However, the absence of this division appears to be a secondary effect of discontinuous sieve element files and subsequent systemically reduced auxin signaling in the root meristem. In the absence of the formative sieve element precursor cell division, metaphloem identity is seemingly adopted by the normally procambial cell file instead, pointing to possibly independent positional cues for metaphloem formation. The protophloem formation and differentiation defects in brevis radix (brx) andoctopus (ops) mutants are similar to those observed in transgenic seedlings with increased CLE45 activity and can be rescued by loss of function of a putative CLE45 receptor, BARELY ANY MERISTEM 3 (BAM3). Conversely, a dominant gain-of-function ops allele or mild OPS dosage increase suppresses brx defects and confers CLE45 resistance. Thus, our data suggest that delicate quantitative interplay between the opposing activities of BAM3-mediated CLE45 signals and OPS-dependent signals determines cellular commitment to protophloem sieve element fate, with OPS acting as a positive, quantitative master regulator of phloem fate.

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Mating system shifts and transposable element evolution in the plant genus Capsella

Mating system shifts and transposable element evolution in the plant genus Capsella | Emerging Research in Plant Cell Biology | Scoop.it
Despite having predominately deleterious fitness effects, transposable elements (TEs) are major constituents of eukaryote genomes in general and of plant genomes in particular. Although the proportion of the genome made up of TEs varies at least four-fold across plants, the relative importance of the evolutionary forces shaping variation in TE abundance and distributions across taxa remains unclear. Under several theoretical models, mating system plays an important role in governing the evolutionary dynamics of TEs. Here, we use the recently sequenced Capsella rubella reference genome and short-read whole genome sequencing of multiple individuals to quantify abundance, genome distributions, and population frequencies of TEs in three recently diverged species of differing mating system, two self-compatible species (C. rubella and C. orientalis) and their self-incompatible outcrossing relative, C. grandiflora.
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Exploring the functional soil-microbe interface and exoenzymes through soil metaexoproteomics

Exploring the functional soil-microbe interface and exoenzymes through soil metaexoproteomics | Emerging Research in Plant Cell Biology | Scoop.it

Functionally important proteins at the interface of cell and soil are of potentially low abundance when compared with commonly recovered intracellular proteins. A novel approach was developed and used to extract the metaexoproteome, the subset of proteins found outside the cell, in the context of a soil enriched with the nitrogen-containing recalcitrant polymer chitin. The majority of proteins recovered was of bacterial origin and localized to the outer membrane or extracellular milieu. A wide variety of transporter proteins were identified, particularly those associated with amino-acid and phosphate uptake. The metaexoproteome extract retained chitinolytic activity and we were successful in detecting Nocardiopsis-like chitinases that correlated with the glycoside hydrolase family 18 (GH18)chi gene data and metataxonomic analysis. Nocardiopsis-like chitinases appeared to be solely responsible for chitinolytic activity in soil. This is the first study to detect and sequence bacterial exoenzymes with proven activity in the soil enzyme pool.


Via Jean-Michel Ané, Francis Martin, Christophe Jacquet
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Jean-Michel Ané's curator insight, July 18, 9:28 AM

After metaproteomics, here is metaexoproteomics!

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The impact of widespread regulatory neofunctionalization on homeolog gene evolution following whole-genome duplication in maize

Whole-genome duplications are a widespread feature of plant genome evolution, having been detected in all flowering plant lineages. Despite the prevalence of these events, the extent to which duplicated genes (homeolog gene pairs) functionally diverge (neofunctionalization) is unclear. We present a genome-wide analysis of molecular evolution and regulatory neofunctionalization in maize (Zea mays L.). We demonstrate that 13% of all homeolog gene pairs in maize are regulatory neofunctionalized in leaves, and that regulatory neofunctionalized genes experience enhanced purifying selection. We show that significantly more genes have been regulatory neofunctionalized in foliar leaves than in husk leaves and that both leaf types have experienced selection for distinct functional roles. Furthermore, we demonstrate that biased subgenome expression dominance occurs only in the presence of regulatory neofunctionalization and that in nonregulatory neofunctionalized genes subgenome dominance is progressively acquired during development. Taken together, our study reveals several novel insights into the evolution of maize, genes, and gene expression, and provides a general model for gene evolution following whole-genome duplication in plants.An international, peer-reviewed genome sciences journal featuring outstanding original research that offers novel insights into the biology of all organisms

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The genome sequence of African rice (Oryza glaberrima) and evidence for independent domestication

The genome sequence of African rice (Oryza glaberrima) and evidence for independent domestication | Emerging Research in Plant Cell Biology | Scoop.it
Mingsheng Chen, Klaus Mayer, Steve Rounsley, Rod Wing and colleagues report the genome sequence of African rice (Oryza glaberrima), a different species than Asian rice. The authors resequenced 20 O. glaberrima accessions and 94 Oryza barthii accessions (the putative progenitor species of O. glaberrima), and their analyses support the hypothesis that O. glaberrima was domesticated in a single region along the upper Niger river.

Via Francis Martin
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A review of the effects of soil organisms on plant hormone signalling pathways

A review of the effects of soil organisms on plant hormone signalling pathways | Emerging Research in Plant Cell Biology | Scoop.it

Plants interact with a large number of soil organisms. For a long time, these interactions have been the research area of soil ecologists and trophic relationships and physico-chemical modifications of the soil matrix were generally proposed as mechanisms underlying plant-soil organism interactions. However, some specific symbioses and diseases have been well characterized at the molecular level by plant biologists and microbiologists. These interactions involve a physical contact between soil organism and plant. They are mediated through signal molecules that play upon the different plant hormonal signalling pathways, leading to modifications in plant development and defence. Nowadays, the role of signal molecules emerges as an important feature of interactions between plants and free-living soil organisms. In this review we discuss genetic and physiological evidences of hormone signalling involvement in plant response to physically associated but also free-living soil organisms, for very different taxa ranging from the micrometer to the centimetre scales. The same hormone signalling pathways seems to be activated by very different kinds of soil organisms such as bacteria, nematodes, collembola and even earthworms, with common consequences on plant growth, development and defence. Plant hormonal homeostasis appears to be the corner stone to understand and predict the issue of the multiple interactions that plants entertain with the community of soil organisms.


Via Jean-Michel Ané, Mary Williams
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Strigolactones regulate rice tiller angle by attenuating shoot gravitropism through inhibiting auxin biosynthesis

Strigolactones regulate rice tiller angle by attenuating shoot gravitropism through inhibiting auxin biosynthesis | Emerging Research in Plant Cell Biology | Scoop.it

Tiller angle, a key agronomic trait for achieving ideal plant architecture and increasing grain yield, is regulated mainly by shoot gravitropism. Strigolactones (SLs) are a group of newly identified plant hormones that are essential for shoot branching/rice tillering and have further biological functions as yet undetermined. Through screening for suppressors of lazy1 (sols), a classic rice mutant exhibiting large tiller angle and defective shoot gravitropism, we identified multiple SOLS that are involved in the SL biosynthetic or signaling pathway. We show that SL biosynthetic or signaling mutants can rescue the spreading phenotype of lazy1 (la1) and that SLs can inhibit auxin biosynthesis and attenuate rice shoot gravitropism, mainly by decreasing the local indoleacetic acid content. Although both SLs and LA1 are negative regulators of polar auxin transport, SLs do not alter the lateral auxin transport of shoot base, unlike LA1, which is a positive regulator of lateral auxin transport in rice. Genetic evidence demonstrates that SLs and LA1 participate in regulating shoot gravitropism and tiller angle in distinct genetic pathways. In addition, the SL-mediated shoot gravitropism is conserved in Arabidopsis. Our results disclose a new role of SLs and shed light on a previously unidentified mechanism underlying shoot gravitropism. Our study indicates that SLs could be considered as an important tool to achieve ideal plant architecture in the future.

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Transcriptomic and physiological characterization of the fefe mutant of melon (Cucumis melo) reveals new aspects of iron–copper crosstalk

Transcriptomic and physiological characterization of the fefe mutant of melon (Cucumis melo) reveals new aspects of iron–copper crosstalk | Emerging Research in Plant Cell Biology | Scoop.it
Iron (Fe) and copper (Cu) homeostasis are tightly linked across biology. In previous work, Fe deficiency interacted with Cu-regulated genes and stimulated Cu accumulation.The C940-fe (fefe) Fe-uptake mutant of melon (Cucumis melo) was characterized, and the fefe mutant was used to test whether Cu deficiency could stimulate Fe uptake. Wild-type and fefe mutant transcriptomes were determined by RNA-seq under Fe and Cu deficiency.FeFe-regulated genes included core Fe uptake, metal homeostasis, and transcription factor genes. Numerous genes were regulated by both Fe and Cu. The fefe mutant was rescued by high Fe or by Cu deficiency, which stimulated ferric-chelate reductase activity,FRO2 expression, and Fe accumulation. Accumulation of Fe in Cu-deficient plants was independent of the normal Fe-uptake system. One of the four FRO genes in the melon and cucumber (Cucumis sativus) genomes was Fe-regulated, and one was Cu-regulated. Simultaneous Fe and Cu deficiency synergistically up-regulated Fe-uptake gene expression.Overlap in Fe and Cu deficiency transcriptomes highlights the importance of Fe–Cu crosstalk in metal homeostasis. The fefe gene is not orthologous to FIT, and thus identification of this gene will provide clues to help understand regulation of Fe uptake in plants.
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Plant, Cell & Environment - Volume 37, Issue 8 - Plant Volatiles

Plant, Cell & Environment - Volume 37, Issue 8 - Plant Volatiles | Emerging Research in Plant Cell Biology | Scoop.it

Special Issue on plant volatiles!

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Auxin transport sites are visualized in planta using fluorescent auxin analogs

The plant hormone auxin is a key morphogenetic signal that controls many aspects of plant growth and development. Cellular auxin levels are coordinately regulated by multiple processes, including auxin biosynthesis and the polar transport and metabolic pathways. The auxin concentration gradient determines plant organ positioning and growth responses to environmental cues. Auxin transport systems play crucial roles in the spatiotemporal regulation of the auxin gradient. This auxin gradient has been analyzed using SCF-type E3 ubiquitin-ligase complex-based auxin biosensors in synthetic auxin-responsive reporter lines. However, the contributions of auxin biosynthesis and metabolism to the auxin gradient have been largely elusive. Additionally, the available information on subcellular auxin localization is still limited. Here we designed fluorescently labeled auxin analogs that remain active for auxin transport but are inactive for auxin signaling and metabolism. Fluorescent auxin analogs enable the selective visualization of the distribution of auxin by the auxin transport system. Together with auxin biosynthesis inhibitors and an auxin biosensor, these analogs indicated a substantial contribution of local auxin biosynthesis to the formation of auxin maxima at the root apex. Moreover, fluorescent auxin analogs mainly localized to the endoplasmic reticulum in cultured cells and roots, implying the presence of a subcellular auxin gradient in the cells. Our work not only provides a useful tool for the plant chemical biology field but also demonstrates a new strategy for imaging the distribution of small-molecule hormones.

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The role of photorespiration during the evolution of C4 photosynthesis in the genus Flaveria

The role of photorespiration during the evolution of C4 photosynthesis in the genus Flaveria | Emerging Research in Plant Cell Biology | Scoop.it

C4 photosynthesis represents a most remarkable case of convergent evolution of a complex trait, which includes the reprogramming of the expression patterns of thousands of genes. Anatomical, physiological, and phylogenetic and analyses as well as computational modeling indicate that the establishment of a photorespiratory carbon pump (termed C2 photosynthesis) is a prerequisite for the evolution of C4. However, a mechanistic model explaining the tight connection between the evolution of C4 and C2 photosynthesis is currently lacking. Here we address this question through comparative transcriptomic and biochemical analyses of closely related C3, C3–C4, and C4 species, combined with Flux Balance Analysis constrained through a mechanistic model of carbon fixation. We show that C2 photosynthesis creates a misbalance in nitrogen metabolism between bundle sheath and mesophyll cells. Rebalancing nitrogen metabolism requires anaplerotic reactions that resemble at least parts of a basic C4 cycle. Our findings thus show how C2 photosynthesis represents a pre-adaptation for the C4 system, where the evolution of the C2 system establishes important C4 components as a side effect.

Jennifer Mach's insight:

Also Insight from eLife:

http://elifesciences.org/content/3/e03702

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TAA1-Regulated Local Auxin Biosynthesis in the Root-Apex Transition Zone Mediates the Aluminum-Induced Inhibition of Root Growth in Arabidopsis

TAA1-Regulated Local Auxin Biosynthesis in the Root-Apex Transition Zone Mediates the Aluminum-Induced Inhibition of Root Growth in Arabidopsis | Emerging Research in Plant Cell Biology | Scoop.it

The transition zone (TZ) of the root apex is the perception site of Al toxicity. Here, we show that exposure of Arabidopsis thaliana roots to Al induces a localized enhancement of auxin signaling in the root-apex TZ that is dependent on TAA1, which encodes a Trp aminotransferase and regulates auxin biosynthesis. TAA1 is specifically upregulated in the root-apex TZ in response to Al treatment, thus mediating local auxin biosynthesis and inhibition of root growth. The TAA1-regulated local auxin biosynthesis in the root-apex TZ in response to Al stress is dependent on ethylene, as revealed by manipulating ethylene homeostasis via the precursor of ethylene biosynthesis 1-aminocyclopropane-1-carboxylic acid, the inhibitor of ethylene biosynthesis aminoethoxyvinylglycine, or mutant analysis. In response to Al stress, ethylene signaling locally upregulates TAA1 expression and thus auxin responses in the TZ and results in auxin-regulated root growth inhibition through a number of auxin response factors (ARFs). In particular, ARF10 and ARF16 are important in the regulation of cell wall modification–related genes. Our study suggests a mechanism underlying how environmental cues affect root growth plasticity through influencing local auxin biosynthesis and signaling.

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Plant biology informs drug discovery

In times of tight budgets, researchers are frequently asked to focus on 'translational science', although paradigm-shifting breakthroughs often emerge from basic research that is conducted without aiming for therapeutically relevant applications. An unconventional marriage between plant biology and embryology provides a striking example.

Auxins are a class of phytohormones that regulate…

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A link between auxin functions and the birth defects caused by thalidomide? 

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Simultaneous editing of three homoeoalleles in hexaploid bread wheat confers heritable resistance to powdery mildew

Simultaneous editing of three homoeoalleles in hexaploid bread wheat confers heritable resistance to powdery mildew | Emerging Research in Plant Cell Biology | Scoop.it

Sequence-specific nucleases have been applied to engineer targeted modifications in polyploid genomes1, but simultaneous modification of multiple homoeoalleles has not been reported. Here we use transcription activator–like effector nuclease (TALEN)2, 3 and clustered, regularly interspaced, short palindromic repeats (CRISPR)-Cas9 (refs. 4,5) technologies in hexaploid bread wheat to introduce targeted mutations in the three homoeoalleles that encode MILDEW-RESISTANCE LOCUS (MLO) proteins6. Genetic redundancy has prevented evaluation of whether mutation of all three MLO alleles in bread wheat might confer resistance to powdery mildew, a trait not found in natural populations7. We show that TALEN-induced mutation of all three TaMLOhomoeologs in the same plant confers heritable broad-spectrum resistance to powdery mildew. We further use CRISPR-Cas9 technology to generate transgenic wheat plants that carry mutations in the TaMLO-A1 allele. We also demonstrate the feasibility of engineering targeted DNA insertion in bread wheat through nonhomologous end joining of the double-strand breaks caused by TALENs. Our findings provide a methodological framework to improve polyploid crops.

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Control of phosphate homeostasis through gene regulation in crops

Control of phosphate homeostasis through gene regulation in crops | Emerging Research in Plant Cell Biology | Scoop.it

Phosphorus (P) is an essential yet frequently deficient element in plants. Maintenance of phosphate (Pi) homeostasis is crucial for crop production. In comparison with the model plant Arabidopsis, crops face wider ranges and larger fluctuations in P supply from the soil environment, and thus develop more complicated strategies to improve Pi acquisition and utilization efficiency. Undergirding these strategies, there are numerous genes involved in alternative metabolism pathways that are regulated by complex Pi signaling networks. In this review, we intend to summarize the recent advances in crops on control of Pi homeostasis through gene regulation from Pi acquisition and mobilization within plants, as well as activation of rhizosphere P and P uptake through symbiotic associations.


Via Christophe Jacquet
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Rescooped by Jennifer Mach from Plant evolution
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A global database of C4 photosynthesis in grasses

A global database of C4 photosynthesis in grasses | Emerging Research in Plant Cell Biology | Scoop.it

C3, C4 or Crassulacean acid metabolism (CAM) photosynthetic
pathways represent a fundamental axis of trait variation in plants,
with importance at scales from genome to biome. Knowing the
distribution of these pathways among wild species is a crucial first
step in understanding the patterns and processes of photosynthetic
evolution and its role in ecological processes at large scales.


Via Pierre-Marc Delaux
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