Plant and Cell Physiology (Plant Cell Physiol )

Publisher: Nihon Shokubutsu Seiri Gakkai; Oxford University Press; HighWire Press, Oxford University Press

Description

Plant and Cell Physiology is an international journal devoted to the publication of original papers in the biological sciences including: physiology biochemistry biophysics chemistry molecular biology cell biology and gene engineering of plants and micro-organisms.

  • Impact factor
    4.98
  • 5-year impact
    4.30
  • Cited half-life
    7.90
  • Immediacy index
    1.07
  • Eigenfactor
    0.02
  • Article influence
    1.35
  • Website
    Plant and Cell Physiology website
  • Other titles
    Plant & cell physiology (Online), Plant and cell physiology
  • ISSN
    1471-9053
  • OCLC
    45088618
  • Material type
    Document, Periodical, Internet resource
  • Document type
    Internet Resource, Computer File, Journal / Magazine / Newspaper

Publisher details

Oxford University Press

  • Pre-print
    • Author can archive a pre-print version
  • Post-print
    • Author cannot archive a post-print version
  • Restrictions
    • 12 months embargo on science, technology, medicine articles
    • 2 years embargo on arts and humanities articles
    • Some titles may have different embargoes
  • Conditions
    • Pre-print can only be posted prior to acceptance
    • Pre-print must be accompanied by set statement (see link)
    • Pre-print must not be replaced with post-print, instead a link to published version with amended set statement should be made
    • Pre-print on author's personal website, employer website, free public server or pre-prints in subject area
    • Post-print in Institutional repositories or Central repositories
    • Publisher version cannot be used except for Nucleic Acids Research articles
    • Published source must be acknowledged
    • Must link to publisher version
    • Set phrase to accompany archived copy (see policy)
    • Articles in some journals can be made Open Access on payment of additional charge
    • Eligible UK authors may deposit in OpenDepot
    • Publisher will deposit on behalf of NIH funded authors to PubMed Central, Nucleic Acids Research authors must pay their fee first
    • Some titles may use different policies
  • Classification
    ​ yellow

Publications in this journal

  • [Show abstract] [Hide abstract]
    ABSTRACT: Plants, which are sessile unlike most animals, have evolved a system to reduce growth under stress; however, the molecular mechanisms of this stress response are not well known. During programmed development, a fraction of the leaf epidermal precursor cells become meristemoid mother cells (MMCs), which are stem cells that produce both stomatal guard cells and epidermal pavement cells. Here we report that Arabidopsis plants, in response to osmotic stress, post-transcriptionally decrease the protein level of SPEECHLESS, the transcription factor promoting MMC identity, through the action of a mitogen-activated protein kinase (MAPK) cascade. The growth reduction under osmotic stress was lessened by inhibition of the MAPK cascade or by a mutation that disrupted the MAPK-target amino acids in SPEECHLESS, indicating that Arabidopsis reduces growth under stress by integrating the osmotic stress signal into the MAPK-SPEECHLESS core developmental pathway.
    Plant and Cell Physiology 11/2014;
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    ABSTRACT: Small molecule demethylation is considered unusual in plants. Of the studied instances, the N-demethylation of nicotine is catalyzed by a cytochrome P450 monooxygenase, while the O-dealkylation of alkaloids in Papaver somniferum is mediated by 2-oxoglutarate-dependent dioxygenases (2-ODDs). This report describes a 2-ODD regiospecifically catalyzing the 7-O-demethylation of methoxylated flavones in peltate trichomes of sweet basil (Ocimum basilicum L.). Three candidate 2-ODDs were identified in basil trichome transcriptome database. Only the candidate designated ObF7ODM1 was found to be active with and highly specific for the proposed natural substrates, gardenin B and 8-hydroxysalvigenin. Of the characterized 2-ODDs, ObF7ODM1 is most closely related to O-demethylases from Papaver. The demethylase activity in trichomes from four basil chemotypes matches well with the abundance of ObF7ODM1 peptides and transcripts in the same trichome preparations. Treatment of basil plants with a 2-ODD inhibitor prohexadione-calcium significantly reduced the accumulation of 7-O-demethylated flavone nevadensin, confirming the involvement of a 2-ODD in its formation. Notably, the full-length open reading frame of ObF7ODM1 contains a second in-frame AUG codon 57 nucleotides downstream of the first translation initiation codon. Both AUG codons are recognized by bacterial translation machinery during heterologous gene expression. The N-truncated ObF7ODM1 is nearly inactive. The N-terminus essential for activity is unique to ObF7ODM1 and does not align with the sequences of other 2-ODDs. Further studies will reveal whether alternative translation initiation plays a role in regulating the O-demethylase activity in planta. Molecular identification of the flavone 7-O-demethylase completes the biochemical elucidation of the lipophilic flavone network in basil.
    Plant and Cell Physiology 11/2014;
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    ABSTRACT: How do sessile plants cope with irregularities in soil nutrient availability? The uptake of essential minerals from the soil influences plant growth and development. However, most environments do not provide sufficient nutrients; rather nutrient distribution in the soil can be uneven and change temporally according to environmental factors. To maintain mineral nutrient homeostasis in their tissues, plants have evolved sophisticated systems for coping with spatial and temporal variability in soil nutrient concentrations. Among these are mechanisms for modulating root system architectures in response to nutrient availability. This review discusses recent advances in knowledge of the two important strategies for optimizing nutrient uptake and translocation in plants: root architecture modification and transporter expression control in response to nutrient availability. Recent studies have determined (i) nutrient-specific root patterns, (ii) their physiological consequences, and (iii) the molecular mechanisms underlying these modulation systems that operate to facilitate efficient nutrient acquisition. Another mechanism employed by plants in nutrient-heterogeneous soils involves modification of nutrient transport activities in a nutrient-concentration-dependent manner. In recent years, considerable progress has been made in characterizing the diverse functions of transporters for specific nutrients; it is now clear that the expression and activities of nutrient transporters are finely regulated in multiple steps at both the transcriptional and post-transcriptional levels for adaptation to a wide range of nutrient conditions.
    Plant and Cell Physiology 11/2014;
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    ABSTRACT: 4-Aminobutyrate (GABA) accumulates in apple fruit during controlled atmosphere storage. A potential source of GABA is the polyamine putrescine, which can be oxidized via copper containing amine oxidase (CuAO), resulting in the production 4-aminobutanal/Δ(1)-pyrroline, with the consumption of O2 and release of H2O2 and ammonia. Five putative CuAO genes (MdAOs) were cloned from apple (Malus domestica Borkh. cv. Empire) fruit and the deduced amino acid sequences found to contain the active sites typically conserved in CuAOs. Genes encoding two of these enzymes, MdAO1 and MdAO2, were highly expressed in apple fruit and selected for further analysis. Amino acid sequence analysis predicted the presence of a C-terminal peroxisomal targeting signal 1 tripeptide in MdAO1 and an N-terminal signal peptide and N-glycosylation site in MdAO2. Transient expression of green fluorescent protein-fusion proteins in Arabidopsis protoplasts or onion epidermal cells revealed a peroxisomal localization for MdAO1 and an extracellular localization for MdAO2. The enzymatic activity of purified recombinant MdAO1 and MdAO2 was measured continuously as H2O2 production using a coupled reaction. MdAO1 did not use monoamines or polyamines and displayed high catalytic efficiency for 1,3-diaminopropane, putrescine and cadaverine, whereas MdAO2 exclusively utilized aliphatic and aromatic monoamines, including 2-phenylethylamine and tyramine. Together, these results indicate that MdAO1 may contribute to GABA production via putrescine oxidation in the peroxisome of apple fruit under controlled atmosphere conditions. MdAO2 seems to be involved in deamination of 2-phenylethylamine, which is a step in the biosynthesis of 2-phenylethanol, a contributor to fruit flavour and flower fragrance.
    Plant and Cell Physiology 11/2014;
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    ABSTRACT: Potassium (K(+)) is an essential mineral nutrient for plant growth and development, with numerous membrane transporters and channels having been implicated in the maintenance and regulation of its homeostasis. The cation cesium (Cs(+)) is toxic for plants but shares similar chemical properties to the K(+) ion and hence competes with its transport. Here, we report that K(+) and Cs(+) homeostasis in Arabidopsis thaliana also requires the action of ZIFL2 (Zinc-Induced Facilitator-Like 2), a member of the Major Facilitator Superfamily (MFS) of membrane transporters. We show that the Arabidopsis ZIFL2 is a functional transporter able to mediate K(+) and Cs(+) influx when heterologously expressed in yeast. Promoter-reporter, RT-PCR and fluorescent protein fusion experiments indicate that the predominant ZIFL2.1 isoform is targeted to the plasma-membrane of endodermal and pericyle root cells. ZIFL2 loss of function and overexpression respectively exacerbate and alleviate plant sensitivity upon Cs(+) and excess K(+) supply, also influencing Cs(+) whole-plant partitioning. We propose that the activity of this Arabidopsis MFS carrier promotes cellular K(+) efflux in the root, thereby restricting Cs(+)/K(+) xylem loading and subsequent root-to-shoot translocation under conditions of Cs(+) or high K(+) external supply.
    Plant and Cell Physiology 11/2014;
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    ABSTRACT: Gene targeting (GT) is a technique used to modify endogenous genes in target genomes precisely via homologous recombination (HR). Although GT plants are produced using genetic transformation techniques, if the difference between the endogenous and the modified gene is limited to point mutations, GT crops can be considered equivalent to non-genetically-modified mutant crops generated by conventional mutagenesis techniques. However, it is difficult to guarantee the non-incorporation of DNA fragments from Agrobacterium in GT plants created by Agrobacterium-mediated GT despite screening with conventional Southern blot and/or PCR techniques. Here, we report a comprehensive analysis of herbicide-tolerant rice plants generated by inducing point mutations in the rice ALS gene via Agrobacterium-mediated GT. We performed genome comparative genomic hybridization (CGH) array analysis and whole genome sequencing to evaluate the molecular composition of GT rice plants. Thus far, no integration of Agrobacterium-derived DNA fragments has been detected in GT rice plants. However, more than 1,000 single nucleotide polymorphisms (SNPs) and insertion/deletion (InDels) were found in GT plants. Among these mutations, 20-100 variants might have some effect on expression levels and/or protein function. Information about additive mutations should be useful in clearing out uninvited mutations by backcrossing.
    Plant and Cell Physiology 11/2014;
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    ABSTRACT: Jasmonic acid and its derivatives (jasmonates: JAs) are phytohormones with essential roles in plant defense against pathogenesis and herbivorous arthropods. Both the up- and down-regulation of defense responses are dependent on signaling pathways mediated by JAs as well as other stress hormones (for example, salicylic acid), generally those involving the transcriptional and post-transcriptional regulation of transcription factors via protein modification and epigenetic regulation. In addition to the typical model plant Arabidopsis (a dicotyledon), advances in genetics research have made rice a model monocot in which innovative pest control traits can be introduced and whose JA signaling pathway can be studied. In this review, we introduce the dynamic functions of JAs in plant defense strategy using defensive substances (e.g., indole alkaloids and terpenoid phytoalexins) and airborne signals (e.g., green leaf volatiles and volatile terpenes) in response to biotrophic and necrotrophic pathogens as well as aboveground and belowground herbivores. We then discuss the important issue of how the mutualism of herbivorous arthropods with viruses or bacteria can cause cross-talk between JA and other phytohormones to counter the defense systems.
    Plant and Cell Physiology 11/2014;
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    ABSTRACT: The decapping enzymes DCP1 and DCP2 are components of a decapping complex that degrades mRNAs. DCP2 is the catalytic core and DCP1 is an auxiliary subunit. It has been assumed that DCP1 and DCP2 are consistently co-localized in cytoplasmic RNA granules called processing bodies (P-bodies). However, it has not been confirmed whether DCP1 and DCP2 co-localize in Arabidopsis thaliana. In this study, we generated DCP1-GFP and DCP2-GFP transgenic plants that complemented dcp1 and dcp2 mutants, respectively, to see whether localization of DCP2 is identical to that of DCP1. DCP2 was present throughout the cytoplasm, whereas DCP1 formed P-body-like foci. Use of DCP1-GFP/DCP2-RFP or DCP1-RFP/DCP2-GFP plants showed that heat treatment induced DCP2 assembly into DCP1 foci. In contrast, cold treatment did not induce DCP2 assembly while the number of DCP1 foci increased. These changes in DCP1 and DCP2 localization during heat and cold treatments occurred without changes in DCP1 and DCP2 protein abundance. Our results show that DCP1 and DCP2 respond differently to environmental changes, indicating that P-bodies have diverse DCP1 and DCP2 proportions depending on environmental conditions. The localization changes of DCP1 and DCP2 may explain how specific mRNAs are degraded during changes in environmental conditions.
    Plant and Cell Physiology 10/2014;
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    ABSTRACT: During the last decade, significant research progress in Arabidopsis thaliana has been made in defining the molecular mechanisms behind the plant circadian clock. The circadian clock must have the ability to integrate both external light and ambient temperature signals into its transcriptional circuitry to properly regulate its function. We previously showed that transcription of a set of clock genes including LUX (LUX ARRHYTHMO), GI (GIGANTEA), LNK1 (NIGHT LIGHT-INDUCIBLE AND CLOCK-REGULATED GENE 1), PRR9 (PSEUDO-RESPONSE REGULATOR 9) and PRR7 is commonly regulated through the evening complex (EC) nighttime repressor in response to both moderate changes in temperature (Δ6°C) and differences in steady-state growth-compatible temperature (16°C to 28°C). Here, we further show that a nighttime-light signal also feeds into the circadian clock transcriptional circuitry through the EC nighttime repressor, so that the same set of EC target genes is upregulated in response to a nighttime-light pulse. This light-induced event is dependent on phytochromes, but not cryptochromes. Interestingly, both the warm-night and nighttime-light signals negatively modulate the activity of the EC nighttime repressor in a synergistic manner. In other words, an exponential burst of transcription of the EC target genes is observed only when these signals are simultaneously fed into the repressor. Taken together, we propose that the EC nighttime repressor plays a crucial role in modulating the clock transcriptional circuitry to properly keep track of seasonal changes in photo- and thermal-cycles by conservatively double-checking the external light and ambient temperature signals.
    Plant and Cell Physiology 10/2014;
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    ABSTRACT: Plants share photosynthetically fixed carbon with arbuscular mycorrhizal (AM) fungi to maintain their growth and nutrition. AM fungi are oleogenic fungi that contain numerous lipid droplets in their syncytial mycelia during most of their life cycle. These lipid droplets are probably used for supporting growth of extraradical mycelia and propagation; however, when and where the lipid droplets are produced remains unclear. To address these issues, we investigated the correlation between intracellular colonization stages and the appearance of fungal lipid droplets in roots by a combination of vital staining of fungal structures, selective staining of lipids and live imaging. We discovered that a surge of lipid droplets coincided with the collapse of arbuscular branches, indicating that arbuscule collapse and the emergence of lipid droplets may be associated processes. This phenomenon was observed in the model AM fungus Rhizophagus irregularis and the ancestral member of AM fungi Paraglomus occultum. Because the collapsing arbuscules were metabolically inactive, the emerged lipid droplets are probably derived from preformed lipids but not de novo synthesized. Our observations highlight a novel mode of lipid release by AM fungi.
    Plant and Cell Physiology 09/2014;
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    ABSTRACT: Lunularia cruciata occupies a very basal position in the phylogenetic tree of liverworts, which in turn have been recognized as a very early clade of land plants. It would therefore seem appropriate to take L. cruciata as the starting point for investigating character evolution in the metal(loid) response of land plants. One of the strongest evolutionary pressures for land colonization by plants has come from potential access to much greater amounts of nutritive ions from surface rocks. This might have resulted in the need to precisely regulate trace element homeostasis and to minimize the risk of exposure to toxic concentrations of certain metals, prompting the evolution of a number of response mechanisms, such as synthesis of phytochelatins, metal(loid)-binding thiol-peptides. Accordingly, if the ability to synthesize phytochelatins and the occurrence of an active phytochelatin synthase are traits present in a basal liverwort, and have been even reinforced in “modern” tracheophytes, e.g. Arabidopsis thaliana, then such traits would presumably have played an essential role in plant fitness over time. Hence, we demonstrated here that: 1) L. cruciata compartmentalizes cadmium in the vacuoles of the phototosynthetic parenchyma by means of a phytochelatin-mediated detoxification strategy, and possesses a phytochelatin synthase that is activated by cadmium and homeostatic concentrations of iron(II) and zinc; 2) A. thaliana phytochelatin synthase displays a higher and broader response to several metal(loid)s [namely: cadmium, iron(II), zinc, copper, mercury, lead, arsenic(III)] than the phytochelatin synthase of L. cruciata.
    Plant and Cell Physiology 09/2014;
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    ABSTRACT: Our previous findings showed that the expression of RhVI1 was tightly correlated with the ability of bud to grow out and was under sugar, gibberellins and light control. Here, we aimed to give an insight into the mechanistic basis of this regulation. In situ hybridization showed that RhVI1 expression was localized in epidermal cells of young leaf of bursting bud. Thereafter, we isolated a 895bp fragment of the promoter of RhVI1. In silico analysis identified putative cis-elements involved in the response to sugars, light and gibberellins on its proximal part (595bp). To carry out functional analysis of the RhVI1 promoter in a homologous system, we developed a direct method for stable transformation of rose cells. 5' deletions of the proximal promoter fused to the uidA reporter gene were inserted into the rose cell genome to study cells response to exogenous and endogenous stimuli. Deletion analysis revealed that the 468bp promoter fragment is sufficient to trigger reporter gene activity in response to light, sugars and gibberellins. This region confers sucrose and fructose, but not glucose, responsive-activation in the dark. Inversely, the -595bp to -468bp region that carries the sugar-repressive element (SRE) is required to down-regulate the RhVI1 promoter in response to sucrose and fructose in the dark. We also demonstrate that sugar/light and gibberellin/light act synergistically to sharply upregulate GUS activity under the control of the 595bp pRhVI1 region. These results reveal that the 127bp promoter fragment located between -595pb and -468pb is critical for light-and-sugar and light-and-gibberellins to act synergistically.
    Plant and Cell Physiology 08/2014;
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    ABSTRACT: We found that the transient freezing behavior in photophobic responses of Euglena gracilis is a good indicator for the metabolic status of the cells. The transient blue-light photophobic responses of Euglena gracilis cells were investigated on-chip using a new measurement, 'trace momentum' (TM), to quantitatively evaluate their swimming activity in real time. When blue light of intensity >30 mW/cm(2) was repeatedly switched on and off, a large negative spike in the TM was observed at the onset of the 'blue-light-off' phase. Single-cell trace analysis at a blue light intensity of 40 mW/cm(2) showed that 48% (on average, N = 15) of tumbling Euglena cells ceased activity ('freezing') for 2-30s at the onset of blue-light-off before commencing straightforward swimming, while 45% smoothly commenced straightforward swimming without delay. The proportion of freezing Euglena cells depended on the blue light intensity (only 20% at 20 mW/cm(2)). When the cells were stimulated by four blue light pulses at the higher intensity, without pre-exposure, the transient freezing behavior was more prominent but, on repeating the stimuli after an 80 min interval in red light, the same cells did not freeze. This shows that the metabolism of the cells had changed to anti-freezing during the interval. The relation between the interval time with/without light irradiation and the blue-light adaptation was elucidated experimentally. The origin of the freezing behavior is considered to be a shortage of a metabolic substance that promotes smooth switching of flagellum movement from on-site rotation mode to straightforward swimming mode.
    Plant and Cell Physiology 07/2014;
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    ABSTRACT: Genetic engineering of roses and other plants of floricultural importance to give them a truly blue petal color is arguably one of the holy grails of plant biotechnology. Toward this goal, bluish carnations and roses were previously engineered by establishing an exclusive accumulation of delphinidin (Dp)-type anthocyanins in their petals via the heterologous expression of a flavonoid 3',5'-hydroxylase gene. Very recently, purple-blue varieties of chrysanthemums were also genetically engineered via a similar biochemical strategy. Although the floral colors of these transgenic plants still lack a true blue color, the basis for the future molecular breeding of truly blue flowers is via the engineering of anthocyanin pathways. Anthocyanins with multiple aromatic acyl groups (often referred to as polyacylated anthocyanins) in the 3' or 7-position tend to display a more stable blue color than non-acylated anthocyanins. The 7-polyacylation process during the biosynthesis of purple-blue anthocyanins in delphinium (Delphinium grandiflorum) was found to occur in vacuoles using acyl-glucose as both the glucosyl and acyl donor. Glucosyltransferases and acyltransferases involved in anthocyanin 7-polyacylation in delphinium are vacuolar acyl-glucose-dependent enzymes belonging to the glycoside hydrolase family 1 and serine carboxypeptidae-like protein family, respectively. The 7-polyacylation proceeds through the alternate glucosylation and p-hydroxybenzoylation catalyzed by these enzymes. p-Hydroxybenzoyl-glucose serves as the p-hydroxybenzoyl and glucosyl donor to produce anthocyanins modified with a p-hydroxybenzoyl-glucose concatemer at the 7-position. This novel finding has provided a potential breakthrough for the genetic engineering of truly blue flowers, where polyacylated Dp-type anthocyanins are accumulated exclusively in the petals.
    Plant and Cell Physiology 07/2014;
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    ABSTRACT: Among secondary metabolites, flavonoids are particularly important for plant life cycle and could be beneficial for human health. The study of Arabidopsis thaliana transparent testa mutants showed that seed flavonoids are important for environmental adaptation, ROS homeostasis, dormancy and longevity. Compared with Arabidopsis and maize (Zea mays L.), far less has been done on rice (Oryza sativa L.) particularly for cultivars with non-pigmented seeds. In this study, we describe the localization, nature and relative abundance of flavonoids in the mature and germinated non-pigmented Nipponbare seeds using a combination of confocal microscopy, mass spectrometry and gene expression analysis. The mature seed exclusively accumulates flavones mostly in the embryo and to a lesser extent in the pericarp/testa. Due to the variety of flavone conjugation patterns, 21 different flavones were identified including sulfated flavones never mentioned before in cereals. Schaftoside (Apigenin-6-C-glucoside-8-C-arabinoside) and its two isomers represent nearly 50% of all rice seed flavones and are the only flavonoids accumulated in the pericarp/testa seed compartment. These 21 conjugated flavones showed a very stable profile during rice seed germination sensu stricto while expression of key flavone synthesis genes strongly increase before the completion of germination. We discuss the potential roles of these rice seed flavones in a seed biology context.
    Plant and Cell Physiology 07/2014;
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    ABSTRACT: Although a large number of microRNAs (miRNAs) have been identified in different plant species, the functional roles and targets of the majority of miRNAs have not yet been determined. Here, Arabidopsis thaliana miRNA400 (miR400) was investigated for its functional role in the defense response to diverse pathogens. Transgenic Arabidopsis plants that overexpress MIR400 (35S::MIR400) displayed much more severe disease symptoms than the wild-type plants when infected with the bacterium Pseudomonas syringae pv. tomato DC3000 or the fungus Botrytis cinerea. MiR400 guided the cleavage of two genes (At1g06580 and At1g62720) encoding pentatricopeptide repeat (PPR) proteins. To further confirm that the miR400-mediated defense response was due to the cleavage of PPR mRNAs, loss-of-function mutant and artificial miRNA-mediated knockdown mutants of PPR were generated, and their disease responses were analyzed upon pathogen challenge. Similar to the 35S::MIR400 plants, the ppr mutants displayed much more severe disease symptoms than the wild-type plants when challenged with the pathogens, indicating that miR400 affects the defense response by cleaving PPR mRNAs. Expression of miR400 was downregulated, whereas the PPR1 and PPR2 transcripts increased upon pathogen challenge. Collectively, the present study reveals that miR400-mediated dysfunction of PPR proteins renders Arabidopsis more susceptible to pathogenic bacteria and fungi, which emphasizes the importance of PPR proteins in plant defense against diverse pathogens.
    Plant and Cell Physiology 07/2014;
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    ABSTRACT: During mRNA translation, nascent peptides with certain specific sequences cause arrest of ribosomes that have synthesized themselves. In some cases, such ribosomal arrest is coupled with mRNA decay. In yeast, mRNA quality control systems have been shown to be involved in mRNA decay associated with ribosomal arrest. However, a link between ribosomal arrest and mRNA quality control systems has not been found in multicellular organisms. In this study, we aimed to explore the relationship between ribosomal arrest and mRNA decay in plants. For this purpose, we used an upstream open reading frame (uORF) of the Arabidopsis thaliana AdoMetDC1 gene, in which the uORF-encoded peptide is involved in polyamine-responsive translational repression of the main coding sequence. Our in vitro analyses revealed that the AdoMetDC1 uORF encoded-peptide caused ribosomal arrest at the uORF stop codon in response to polyamine. Using transgenic calli harboring an AdoMetDC1 uORF-containing reporter gene, we showed that polyamine promoted mRNA decay in a uORF sequence-dependent manner. These results suggest that the polyamine-responsive ribosomal arrest mediated by the uORF-encoded peptide is coupled with mRNA decay. Our results also showed that the polyamine-responsive acceleration of mRNA decay was compromised by defects in factors that are essential for the nonsense-mediated mRNA decay (NMD), an mRNA quality control system that degrades mRNAs with premature stop codons, suggesting that NMD is involved in AdoMetDC1 uORF peptide-mediated mRNA decay. Collectively, these findings suggest that AdoMetDC1 uORF peptide-mediated ribosomal arrest at the uORF stop codon induces NMD.
    Plant and Cell Physiology 06/2014;
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    ABSTRACT: Rapid growth of plant cells by cell division and expansion requires an endomembrane trafficking system. The endomembrane compartments, such as the Golgi stacks, endosome, and vesicles, are important in the synthesis and trafficking of cell wall materials during cell elongation. However, changes in the morphology, distribution, and number of these compartments during the different stages of cell proliferation and differentiation have not yet been clarified. In this study, we examined these changes at the ultrastructural level in tobacco BY-2 cells during the log and stationary phases of growth. We analyzed images of the BY-2 cells prepared by the high-pressure freezing/freeze substitution technique with the aid of an auto-acquisition transmission electron microscope system. We quantified the distribution of secretory and endosomal compartments in longitudinal sections of whole cells by using wide-ranged gigapixel-class images obtained by merging thousands of transmission electron micrographs. During the log phase, all Golgi stacks were composed of several thick cisternae. Approximately 20 vesicle clusters (VCs), including the trans-Golgi network and secretory vesicle cluster, were observed throughout the cell. In the stationary-phase cells, Golgi stacks were thin with small cisternae, and only a few VCs were observed. Nearly the same number of multi-vesicular body and small high-density vesicles were observed in both the stationary and log phases. Results from electron microscopy and live fluorescence imaging indicate that the morphology and distribution of secretory-related compartments dramatically change when cells transition from log to stationary phases of growth.
    Plant and Cell Physiology 06/2014;