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Plant Cell Environ: Salt Glands in mangrove

Plant Cell Environ: Salt Glands in mangrove | Emerging Research in Plant Cell Biology | Scoop.it

Salt glands are fascinating anatomically and physiologically. If you've never read the great SCHMIDT-NIELSEN's work, here's a link to an OA paper on "The salt-secreting glands of marine birds", from 1960. (http://circ.ahajournals.org/content/21/5/955.abstract).

 

Salt glands seem to be an example of convergent evolution. They've arisen repeatedly to deal with the problem salt elimination without too much water loss. They are a terrific tool to help students learn about the movement of ions across membranes. 

 

Here are a few review articles with more information about salt glands and other halophyte adaptations:

Flowers and Colmer, New Phytol 2008 (http://onlinelibrary.wiley.com/doi/10.1111/j.1469-8137.2008.02531.x/full)

Munns and Tester, Annu Rev Plant Biol 2008 (http://www.annualreviews.org/doi/abs/10.1146/annurev.arplant.59.032607.092911?journalCode=arplant)

Flowers et al, Functional Plant Biol. 2010 (http://www.tempoandmode.com/wp-content/uploads/2010/07/flowersevolutionhalophytesfuncplbiol10.pdf)and from

Plants in Action (http://plantsinaction.science.uq.edu.au/edition1/?q=content/17-3-1-devices-manage-leaf-salt).


Via 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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China pulls plug on genetically modified rice and corn

China pulls plug on genetically modified rice and corn | Emerging Research in Plant Cell Biology | Scoop.it
Reasons behind move not clear
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New Phytologist: Hitchhiker's guide to multi-dimensional plant pathology (2014)

New Phytologist: Hitchhiker's guide to multi-dimensional plant pathology (2014) | Emerging Research in Plant Cell Biology | Scoop.it

Filamentous pathogens pose a substantial threat to global food security. One central question in plant pathology is how pathogens cause infection and manage to evade or suppress plant immunity to promote disease. With many technological advances over the past decade, including DNA sequencing technology, an array of new tools has become embedded within the toolbox of next-generation plant pathologists. By employing a multidisciplinary approach plant pathologists can fully leverage these technical advances to answer key questions in plant pathology, aimed at achieving global food security. This review discusses the impact of: cell biology and genetics on progressing our understanding of infection structure formation on the leaf surface; biochemical and molecular analysis to study how pathogens subdue plant immunity and manipulate plant processes through effectors; genomics and DNA sequencing technologies on all areas of plant pathology; and new forms of collaboration on accelerating exploitation of big data. As we embark on the next phase in plant pathology, the integration of systems biology promises to provide a holistic perspective of plant–pathogen interactions from big data and only once we fully appreciate these complexities can we design truly sustainable solutions to preserve our resources.


Via Kamoun Lab @ TSL, Alejandro Rojas, Mary Williams
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Marie Zen Attitude's curator insight, July 26, 8:21 AM

Un petit lien spécial pour Emeric ;)

 

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Induction of Caspase-3-like activity in Rice following release of cytochrome-f from the chloroplast and subsequent interaction with the Ubiquitin-Proteasome System

Induction of Caspase-3-like activity in Rice following release of cytochrome-f from the chloroplast and subsequent interaction with the Ubiquitin-Proteasome System | Emerging Research in Plant Cell Biology | Scoop.it
It has been known that the process of leaf senescence is accompanied by programmed cell death (PCD), and the previous study indicated that dark-induced senescence in detached leaves from rice led to the release of cytochrome f (Cyt f) from chloroplast into the cytoplasm. In this study, the effects of Cyt f on PCD were studied both in vitro and in vivo. In a cell-free system, purified Cyt f activated caspase-3-like protease and endonuclease OsNuc37, and induced DNA fragmentation. Furthermore, Cyt f-induced caspase-3-like activity could be inhibited by MG132, which suggests that the activity was attributed to the 26S proteasome. Conditional expression of Cyt f in the cytoplasm could also activate caspase-3-like activity and DNA fragmentation. Fluorescein diacetate staining and annexin V-FITC/PI double staining demonstrated that Cyt f expression in cytoplasm significantly increased the percentage of PCD protoplasts. Yeast two-hybrid screening showed that Cyt f might interact with E3-ubiquitin ligase and RPN9b, the subunits of the ubiquitin proteasome system (UPS), and other PCD-related proteins. Taken together, these results suggest that the released Cyt f from the chloroplast into the cytoplasm might activate or rescue caspase-3-like activity by interacting with the UPS, ultimately leading to the induction of PCD.

Via Suayib Üstün
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Soil Biology and Biochemistry: Root exudates mediated interactions belowground

Soil Biology and Biochemistry: Root exudates mediated interactions belowground | Emerging Research in Plant Cell Biology | Scoop.it

"The root exudate composition reflects the contradictory-concomitantly attractive and repulsive-behaviour of plants towards soil microorganisms."


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Rare earth elements activate endocytosis in plant cells

It has long been observed that rare earth elements (REEs) regulate multiple facets of plant growth and development. However, the underlying mechanisms remain largely unclear. Here, using electron microscopic autoradiography, we show the life cycle of a light REE (lanthanum) and a heavy REE (terbium) in horseradish leaf cells. Our data indicate that REEs were first anchored on the plasma membrane in the form of nanoscale particles, and then entered the cells by endocytosis. Consistently, REEs activated endocytosis in plant cells, which may be the cellular basis of REE actions in plants. Moreover, we discovered that a portion of REEs was successively released into the cytoplasm, self-assembled to form nanoscale clusters, and finally deposited in horseradish leaf cells. Taken together, our data reveal the life cycle of REEs and their cellular behaviors in plant cells, which shed light on the cellular mechanisms of REE actions in living organisms.

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Looking forward to genetically edited fruit crops: Trends in Biotechnology

The availability of genome sequences for many fruit crops has redefined the boundaries of genetic engineering and genetically modified (GM) crop plants. However commercialization of GM crops is hindered by numerous regulatory and social hurdles. Here, we focus on recently developed genome-editing tools for fruit crop improvement and their importance from the consumer perspective. Challenges and opportunities for the deployment of new genome-editing tools for fruit plants are also discussed.

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Is there an association between root architecture and mycorrhizal growth response?

Is there an association between root architecture and mycorrhizal growth response? | Emerging Research in Plant Cell Biology | Scoop.it
The symbiosis between arbuscular mycorrhizal (AM) fungi and plants is evolutionarily widespread. The response of plant growth to inoculation by these fungi (mycorrhizal growth response; MGR) is highly variable, ranging from positive to negative. Some of this variation is hypothesized to be associated with root structure and function. Specifically, species with a coarse root architecture, and thus a limited intrinsic capacity to absorb soil nutrients, are expected to derive the greatest growth benefit from inoculation with AM fungi.To test this hypothesis, previously published literature and phylogenetic information were combined in a meta-analysis to examine the magnitude and direction of relationships among several root architectural traits and MGR.Published studies differed in the magnitude and direction of relationships between root architecture and MGR. However, when combined, the overall relationship between MGR and allocation to roots, root diameter, root hair length and root hair density did not differ significantly from zero.These findings indicate that possessing coarse roots is not necessarily a predictor of plant growth response to AM fungal colonization. Root architecture is therefore unlikely to limit the evolution of variation in MGR.
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Crossover Localisation Is Regulated by the Neddylation Posttranslational Regulatory Pathway

Crossover Localisation Is Regulated by the Neddylation Posttranslational Regulatory Pathway | Emerging Research in Plant Cell Biology | Scoop.it

Crossovers (COs) are at the origin of genetic variability, occurring across successive generations, and they are also essential for the correct segregation of chromosomes during meiosis. Their number and position are precisely controlled, however the mechanisms underlying these controls are poorly understood. Neddylation/rubylation is a regulatory pathway of posttranslational protein modification that is required for numerous cellular processes in eukaryotes, but has not yet been linked to homologous recombination. In a screen for meiotic recombination-defective mutants, we identified several axr1 alleles, disrupting the gene encoding the E1 enzyme of the neddylation complex in Arabidopsis. Using genetic and cytological approaches we found that axr1 mutants are characterised by a shortage in bivalent formation correlated with strong synapsis defects. We determined that the bivalent shortage inaxr1 is not due to a general decrease in CO formation but rather due to a mislocalisation of class I COs. In axr1, as in wild type, COs are still under the control of the ZMM group of proteins. However, in contrast to wild type, they tend to cluster together and no longer follow the obligatory CO rule. Lastly, we showed that this deregulation of CO localisation is likely to be mediated by the activity of a cullin 4 RING ligase, known to be involved in DNA damage sensing during somatic DNA repair and mouse spermatogenesis. In conclusion, we provide evidence that the neddylation/rubylation pathway of protein modification is a key regulator of meiotic recombination. We propose that rather than regulating the number of recombination events, this pathway regulates their localisation, through the activation of cullin 4 RING ligase complexes. Possible targets for these ligases are discussed.

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DNA Topoisomerase I Affects Polycomb Group Protein-Mediated Epigenetic Regulation and Plant Development by Altering Nucleosome Distribution in Arabidopsis

DNA Topoisomerase I Affects Polycomb Group Protein-Mediated Epigenetic Regulation and Plant Development by Altering Nucleosome Distribution in Arabidopsis | Emerging Research in Plant Cell Biology | Scoop.it

It has been perplexing that DNA topoisomerases, enzymes that release DNA supercoils, play specific roles in development. In this study, using a floral stem cell model in Arabidopsis thaliana, we uncovered a role for TOPOISOMERASE1α(TOP1α) in Polycomb Group (PcG) protein-mediated histone 3 lysine 27 trimethylation (H3K27me3) at, and transcriptional repression of, the stem cell maintenance gene WUSCHEL (WUS). We demonstrated that H3K27me3 deposition at other PcG targets also requires TOP1α. Intriguingly, the repression of some, as well as the expression of many, PcG target genes requires TOP1α. The mechanism that unifies the opposing effects of TOP1α appears to lie in its role in decreasing nucleosome density, which probably allows the binding of factors that either recruit PcG, as we demonstrated for AGAMOUS at the WUS locus, or counteract PcG-mediated regulation. Although TOP1α reduces nucleosome density at all genes, the lack of a 5′ nucleosome-free region is a feature that distinguishes PcG targets from nontargets and may condition the requirement for TOP1α for their expression. This study uncovers a connection between TOP1α and PcG, which explains the specific developmental functions of TOP1α.

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Detection of Parasitic Plant Suicide Germination Compounds Using a High-Throughput Arabidopsis HTL/KAI2 Strigolactone Perception System

Detection of Parasitic Plant Suicide Germination Compounds Using a High-Throughput Arabidopsis HTL/KAI2 Strigolactone Perception System | Emerging Research in Plant Cell Biology | Scoop.it

Strigolactones are terpenoid-based plant hormones that act as communication signals within a plant, between plants and fungi, and between parasitic plants and their hosts. Here we show that an active enantiomer form of the strigolactone GR24, the germination stimulant karrikin, and a number of structurally related small molecules called cotylimides all bind the HTL/KAI2 α/β hydrolase in Arabidopsis. Strigolactones and cotylimides also promoted an interaction between HTL/KAI2 and the F-box protein MAX2 in yeast. Identification of this chemically dependent protein-protein interaction prompted the development of a yeast-based, high-throughput chemical screen for potential strigolactone mimics. Of the 40 lead compounds identified, three were found to have in planta strigolactone activity using Arabidopsis-based assays. More importantly, these three compounds were all found to stimulate suicide germination of the obligate parasitic plant Striga hermonthica. These results suggest that screening strategies involving yeast/Arabidopsis models may be useful in combating parasitic plant infestations.

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JExBot Special Issue on Fruit Ripening: August 2014, 65 (16)

JExBot Special Issue on Fruit Ripening: August 2014, 65 (16) | Emerging Research in Plant Cell Biology | Scoop.it

It has been 12 years since publication of the last Journal of Experimental Botany Special Issue on Fruit Development and Ripening (Vol. 53, No 377, October 2002). At that time the biosynthesis and mode of action of ethylene in fruit ripening had already been established, and advances in genetics were revealing links between genes and phenotypes, especially noteworthy was the map-based cloning of genes underlying tomato non-ripening loci such as ripening inhibitor (rin). Since then there have been substantial advances in our understanding of ripening in tomato and many other dry and fleshy fruits. This has been accelerated by the delivery of genome sequences for a wide range of plants including fleshy fruit bearing species and the development of systems biology approaches to understanding regulatory networks.

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Molecular genetic framework for protophloem formation

Molecular genetic framework for protophloem formation | Emerging Research in Plant Cell Biology | Scoop.it

ABSTRACT:

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) and octopus (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.


Via fundoshi, Christophe Jacquet
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To grow or defend? Low red : far-red ratios reduce jasmonate sensitivity in Arabidopsis seedlings by promoting DELLA degradation and increasing JAZ10 stability -

To grow or defend? Low red : far-red ratios reduce jasmonate sensitivity in Arabidopsis seedlings by promoting DELLA degradation and increasing JAZ10 stability - | Emerging Research in Plant Cell Biology | Scoop.it

How plants balance resource allocation between growth and defense under conditions of competitive stress is a key question in plant biology. Low red : far-red (R : FR) ratios, which signal a high risk of competition in plant canopies, repress jasmonate-induced defense responses. The mechanism of this repression is not well understood. We addressed this problem in Arabidopsis by investigating the role of DELLA and JASMONATE ZIM domain (JAZ) proteins.We showed that a quintuple della mutant and a phyB mutant were insensitive to jasmonate for several physiological readouts. Inactivation of the photoreceptor phyB by low R : FR ratios rapidly reduced DELLA protein abundance, and the inhibitory effect of FR on jasmonate signaling was missing in the gai-1 mutant, which encodes a stable version of the GAI DELLA protein.We also demonstrated that low R : FR ratios and the phyB mutation stabilized the protein JAZ10. Furthermore, we demonstrated that JAZ10 was required for the inhibitory effect of low R : FR on jasmonate responses, and that the jaz10 mutation restored jasmonate sensitivity to the phyB mutant.We conclude that, under conditions of competition for light, plants redirect resource allocation from defense to rapid elongation by promoting DELLA degradation and enhancing JAZ10 stability.


Via Christophe Jacquet, Suayib Üstün
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Considerations when investigating lncRNA function in vivo

Although a small number of the vast array of animal long non-coding RNAs (lncRNAs) have known effects on cellular processes examined in vitro, the extent of their contributions to normal cell processes throughout development, differentiation and disease for the most part remains less clear. Phenotypes arising from deletion of an entire genomic locus cannot be unequivocally attributed either to the loss of the lncRNA per se or to the associated loss of other overlapping DNA regulatory elements. The distinction between cis- or trans-effects is also often problematic. We discuss the advantages and challenges associated with the current techniques for studying the in vivo function of lncRNAs in the light of different models of lncRNA molecular mechanism, and reflect on the design of experiments to mutate lncRNA loci. These considerations should assist in the further investigation of these transcriptional products of the genome. - See more at: http://elifesciences.org/content/3/e03058#sthash.Aw8kY4dB.dpuf

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Frontiers: RNA trafficking in parasitic plant systems (2012)

Frontiers: RNA trafficking in parasitic plant systems (2012) | Emerging Research in Plant Cell Biology | Scoop.it

RNA trafficking in plants contributes to local and long-distance coordination of plant development and response to the environment. However, investigations of mobile RNA identity and function are hindered by the inherent difficulty of tracing a given molecule of RNA from its cell of origin to its destination. Several methods have been used to address this problem, but all are limited to some extent by constraints associated with accurately sampling phloem sap or detecting trafficked RNA. Certain parasitic plant species form symplastic connections to their hosts and thereby provide an additional system for studying RNA trafficking. The haustorial connections of Cuscuta andPhelipanche species are similar to graft junctions in that they are able to transmit mRNAs, viral RNAs, siRNAs, and proteins from the host plants to the parasite. In contrast to other graft systems, these parasites form connections with host species that span a wide phylogenetic range, such that a high degree of nucleotide sequence divergence may exist between host and parasites and allow confident identification of most host RNAs in the parasite system. The ability to identify host RNAs in parasites, and vice versa, will facilitate genomics approaches to understanding RNA trafficking. This review discusses the nature of host–parasite connections and the potential significance of host RNAs for the parasite. Additional research on host–parasite interactions is needed to interpret results of RNA trafficking studies, but parasitic plants may provide a fascinating new perspective on RNA trafficking.


Via Kamoun Lab @ TSL
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The movement of the non-cell-autonomous transcription factor, SHORT-ROOT relies on endomembrane system

The movement of the non-cell-autonomous transcription factor, SHORT-ROOT relies on endomembrane system | Emerging Research in Plant Cell Biology | Scoop.it

Plant cells are able to convey positional and developmental information between cells through the direct transfer of transcription factors. One well-studied example of this is the SHORT-ROOT protein, which moves from the stele into the neighboring ground tissue layer to specify endodermis. While it has been shown that SHR trafficking relies on plasmodesmata (PD), and interaction with the SHR INTERACTING EMBRYONIC LETHAL (SIEL) protein, little is known about how SHR trafficking is controlled or how SIEL promotes the movement of SHR. Here we show that SHR can move from multiple different cell types in the root. Analysis of subcellular localization indicates that in the cytoplasm of root or leaf cells, SHR localizes to endosomes in a SIEL dependent manner. Interference of early and late endosomes disrupts intercellular movement of SHR. Our findings reveal an essential role for the plant endomembrane, independent of secretion, in the intercellular trafficking of SHR.


Via Christophe Jacquet
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Strigolactones and the control of plant development: lessons from shoot branching

Strigolactones and the control of plant development: lessons from shoot branching | Emerging Research in Plant Cell Biology | Scoop.it

Strigolactones (SLs) were originally identified through their activities as root exudates in the rhizosphere; however, it is now clear that they have many endogenous signalling roles in plants. In this review we discuss recent progress in understanding SL action in planta, particularly in the context of the regulation of shoot branching, one of the best-characterized endogenous roles for SLs. Rapid progress has been made in understanding SL biosynthesis, but many questions remain unanswered. There are hints of as yet unidentified sources of SL, as well as unknown SL–like molecules with important signalling functions. SL signalling is even more enigmatic. Although a likely receptor has been identified, along with some candidate immediate downstream targets, our understanding of how these targets mediate SL signalling is limited. There is still considerable uncertainty about whether the targets of SL signalling are primarily transcriptional or not. There is at least one non-transcriptional target, because a rapid primary response to SL is the removal of PIN1 auxin exporter proteins from the plasma membrane in vascular-associated cells of the stem. We discuss how the various early events in SL signalling could result in the observed changes in shoot branching.


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Differential Activity of Striga hermonthica Seed Germination Stimulants and Gigaspora rosea Hyphal Branching Factors in Rice and Their Contribution to Underground Communication

Differential Activity of Striga hermonthica Seed Germination Stimulants and Gigaspora rosea Hyphal Branching Factors in Rice and Their Contribution to Underground Communication | Emerging Research in Plant Cell Biology | Scoop.it

Abstract

 

Strigolactones (SLs) trigger germination of parasitic plant seeds and hyphal branching of symbiotic arbuscular mycorrhizal (AM) fungi. There is extensive structural variation in SLs and plants usually produce blends of different SLs. The structural variation among natural SLs has been shown to impact their biological activity as hyphal branching and parasitic plant seed germination stimulants. In this study, rice root exudates were fractioned by HPLC. The resulting fractions were analyzed by MRM-LC-MS to investigate the presence of SLs and tested using bioassays to assess their Striga hermonthica seed germination and Gigaspora rosea hyphal branching stimulatory activities. A substantial number of active fractions were revealed often with very different effect on seed germination and hyphal branching. Fractions containing (−)−orobanchol and ent-2'-epi-5-deoxystrigol contributed little to the induction of S. hermonthicaseed germination but strongly stimulated AM fungal hyphal branching. Three SLs in one fraction, putative methoxy-5-deoxystrigol isomers, had moderate seed germination and hyphal branching inducing activity. Two fractions contained strong germination stimulants but displayed only modest hyphal branching activity. We provide evidence that these stimulants are likely SLs although no SL-representative masses could be detected using MRM-LC-MS. Our results show that seed germination and hyphal branching are induced to very different extents by the various SLs (or other stimulants) present in rice root exudates. We propose that the development of rice varieties with different SL composition is a promising strategy to reduce parasitic plant infestation while maintaining symbiosis with AM fungi.


Via Pierre-Marc Delaux, Francis Martin
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Epigenetic reprogramming in plant sexual reproduction : Nature Reviews Genetics

Epigenetic reprogramming in plant sexual reproduction : Nature Reviews Genetics | 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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Genomic-scale exchange of mRNA between a parasitic plant and its hosts

Movement of RNAs between cells of a single plant is well documented, but cross-species RNA transfer is largely unexplored. Cuscuta pentagona (dodder) is a parasitic plant that forms symplastic connections with its hosts and takes up host messenger RNAs (mRNAs). We sequenced transcriptomes of Cuscuta growing on Arabidopsis and tomato hosts to characterize mRNA transfer between species and found that mRNAs move in high numbers and in a bidirectional manner. The mobile transcripts represented thousands of different genes, and nearly half the expressed transcriptome of Arabidopsis was identified in Cuscuta. These findings demonstrate that parasitic plants can exchange large proportions of their transcriptomes with hosts, providing potential mechanisms for RNA-based interactions between species and horizontal gene transfer.

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IN BRIEF: When to Hold Them: Retention of Duplicate Genes in Poplar

IN BRIEF: When to Hold Them: Retention of Duplicate Genes in Poplar | Emerging Research in Plant Cell Biology | Scoop.it

In some ways, your genes resemble playing cards: you work with the hand you’re dealt. Sometimes, during the course of evolution, the dealer throws a species an unusual hand that includes duplicates of a few, or all, of its genes. Indeed, in plants, single-gene and whole-genome duplications have played a major role in evolution. For cards and genes, holding too many can prove a burden, and genes can be discarded over evolutionary time by deletion or inactivation through the accumulation of mutations. The mechanisms that retain genes in the genome remain a subject of ongoing study (reviewed in Conant and Wolfe, 2008). Duplicate genes can diverge in function, as if you could turn one of your two copies of the queen of hearts into a queen of diamonds, or even into a novel card—say the princess of stars—that could be a game-changer. However, such neofunctionalization occurs as a race against the accumulation of deleterious mutations, which inactivate the gene.....

Jennifer Mach's insight:

Mini-review of http://www.plantcell.org/content/26/6/2404.abstract

 

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The monolignol pathway contributes to the biosynthesis of volatile phenylpropenes in flowers

The monolignol pathway contributes to the biosynthesis of volatile phenylpropenes in flowers | Emerging Research in Plant Cell Biology | Scoop.it
Volatile phenylpropenes play important roles in the mediation of interactions between plants and their biotic environments. Their biosynthesis involves the elimination of the oxygen functionality at the side-chain of monolignols and competes with lignin formation for monolignol utilization. We hypothesized that biochemical steps before the monolignol branch point are shared between phenylpropene and lignin biosynthesis; however, genetic evidence for this shared pathway has been missing until now.Our hypothesis was tested by RNAi suppression of the petunia (Petunia hybrida) cinnamoyl-CoA reductase 1 (PhCCR1), which catalyzes the first committed step in monolignol biosynthesis. Detailed metabolic profiling and isotopic labeling experiments were performed in petunia transgenic lines.Downregulation of PhCCR1 resulted in reduced amounts of total lignin and decreased flux towards phenylpropenes, whereas internal and emitted pools of phenylpropenes remained unaffected. Surprisingly, PhCCR1 silencing increased fluxes through the general phenylpropanoid pathway by upregulating the expression of cinnamate-4-hydroxylase (C4H), which catalyzes the second reaction in the phenylpropanoid pathway.In conclusion, our results show that PhCCR1 is involved in both the biosynthesis of phenylpropenes and lignin production. However, PhCCR1 does not perform a rate-limiting step in the biosynthesis of phenylpropenes, suggesting that scent biosynthesis is prioritized over lignin formation in petals.
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Rapid identification of angulata leaf mutations using next-generation sequencing

Rapid identification of angulata leaf mutations using next-generation sequencing | Emerging Research in Plant Cell Biology | Scoop.it

Map-based (positional) cloning has traditionally been the preferred strategy for identifying the causal genes underlying the phenotypes of mutants isolated in forward genetic screens. Massively parallel sequencing technologies are enabling the rapid cloning of genes identified in such screens. We have used a combination of linkage mapping and whole-genome re-sequencing to identify the causal mutations in four loss-of-function angulata (anu) mutants. These mutants were isolated in a screen for mutants with defects in leaf shape and leaf pigmentation. Our results show that theanu1-1, anu4-1, anu9-1 and anu12-1 mutants carry new alleles of the previously characterizedSECA2, TRANSLOCON AT THE OUTER MEMBRANE OF CHLOROPLASTS 33 (TOC33), NON-INTRINSIC ABC PROTEIN 14 (NAP14) and CLP PROTEASE PROTEOLYTIC SUBUNIT 1 (CLPR1) genes. Re-sequencing the genomes of fine mapped mutants is a feasible approach that has allowed us to identify a moderate number of candidate mutations, including the one that causes the mutant phenotype, in a nonstandard genetic background. Our results indicate that anumutations specifically affect plastid-localized proteins involved in diverse processes, such as the movement of peptides through chloroplast membranes (ANU1 and ANU4), metal homeostasis (ANU9) and protein degradation (ANU12).

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Epiphytic leafy liverworts diversified in angiosperm-dominated forests

Epiphytic leafy liverworts diversified in angiosperm-dominated forests | Emerging Research in Plant Cell Biology | Scoop.it
Recent studies have provided evidence for pulses in the diversification of angiosperms, ferns, gymnosperms, and mosses as well as various groups of animals during the Cretaceous revolution of terrestrial ecosystems. However, evidence for such pulses has not been reported so far for liverworts. Here we provide new insight into liverwort evolution by integrating a comprehensive molecular dataset with a set of 20 fossil age constraints. We found evidence for a relative constant diversification rate of generalistic liverworts (Jungermanniales) since the Palaeozoic, whereas epiphytic liverworts (Porellales) show a sudden increase of lineage accumulation in the Cretaceous. This difference is likely caused by the pronounced response of Porellales to the ecological opportunities provided by humid, megathermal forests, which were increasingly available as a result of the rise of the angiosperms.

Via Francis Martin
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The innermost secrets of root development

The innermost secrets of root development | Emerging Research in Plant Cell Biology | Scoop.it

For a plant embryo to grow from a single fertilized egg cell to a complex multicellular structure, it must undergo a highly ordered sequence of cell divisions, during which the emerging tissues are patterned and ultimately differentiate. In vascular plants, the vascular tissues lie deep within roots and shoots, where they provide the main mechanism for transporting water and nutrients between organs. The specification of root vascular tissues provides an elegant system to investigate tissue patterning. It had previously been shown that two plant hormones cross regulate each other's activity and transport to control vascular patterning (1). However, on page 636 of this issue, De Rybel et al. (2) identify a new interaction between these hormones through the regulation of their local synthesis, such that collectively these hormonal interactions coordinate the processes of both cell division and tissue patterning to specify the stereotypical vascular pattern in Arabidopsis embryos.


Via Francis Martin, Christophe Jacquet
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Mario Sergio Nicolodi's curator insight, August 8, 4:34 PM

Compartilhando: "Para um embrião de planta de crescer a partir de uma única célula de ovo fertilizado de uma estrutura multicelular complexo, devem ser submetidos a uma sequência altamente ordenada de divisões celulares, durante o qual os tecidos são emergentes modelado e, finalmente diferenciar."

Mario Sergio Nicolodi's curator insight, August 8, 4:39 PM

Compratilhando: "Para um embrião de planta crescer a partir de uma única célula [...]"

Mario Sergio Nicolodi's curator insight, August 8, 5:08 PM

Compratilhando: "Para um embrião de planta crescer a partir de uma única célula [...]"