scholarly journals Cortical tension overrides geometrical cues to orient microtubules in confined protoplasts

2020 ◽  
Vol 117 (51) ◽  
pp. 32731-32738
Author(s):  
Leia Colin ◽  
Antoine Chevallier ◽  
Satoru Tsugawa ◽  
Florian Gacon ◽  
Christophe Godin ◽  
...  
Keyword(s):  
Plant Cells ◽  
Cell System ◽  
Cellulose Synthesis ◽  
Cortical Microtubules ◽  
In Planta ◽  
Curvature Ratio ◽  
Cortical Tension ◽  
Maximal Tension

In plant cells, cortical microtubules (CMTs) generally control morphogenesis by guiding cellulose synthesis. CMT alignment has been proposed to depend on geometrical cues, with microtubules aligning with the cell long axis in silico and in vitro. Yet, CMTs are usually transverse in vivo, i.e., along predicted maximal tension, which is transverse for cylindrical pressurized vessels. Here, we adapted a microwell setup to test these predictions in a single-cell system. We confined protoplasts laterally to impose a curvature ratio and modulated pressurization through osmotic changes. We find that CMTs can be longitudinal or transverse in wallless protoplasts and that the switch in CMT orientation depends on pressurization. In particular, longitudinal CMTs become transverse when cortical tension increases. This explains the dual behavior of CMTs in planta: CMTs become longitudinal when stress levels become low, while stable transverse CMT alignments in tissues result from their autonomous response to tensile stress fluctuations.

scholarly journals Reappraisal of Spinach-based RNA Visualization in Plants

2020 ◽  
Author(s):  
Zhiming Yu ◽  
Fengling Mei ◽  
Haiting Yan ◽  
Qiyuan Chen ◽  
Mengqin Yao ◽  
...  
Keyword(s):  
Tandem Repeats ◽  
Rna Binding ◽  
Ex Vivo ◽  
Plant Cells ◽  
Quantitative Detection ◽  
Rna Aptamer ◽  
In Planta ◽  
Green Fluorescence

ABSTRACTRNAs can be imaged in living cells using molecular beacons, RNA-binding labeled proteins and RNA aptamer-based approaches. However, Spinach RNA-mimicking GFP (RMG) has not been successfully used to monitor cellular RNAs in plants. In this study, we re-evaluated Spinach-based RNA visualization in different plants via transient, transgenic, and virus-based expression strategies. We found that like bacterial, yeast and human cellular tRNAs, plant tRNAs such as tRNALys (K) can protect and/or stabilize the spinach RNA aptamer interaction with the fluorophore DFHBI enabling detectable levels of green fluorescence to be emitted. The tRNALys-spinach-tRNALys (KSK), once delivered into “chloroplast-free” onion epidermal cells can emit strong green fluorescence in the presence of DFHBI. Transgenic or virus-based expression of monomer KSK, in either stably transformed or virus-infected Nicotinana benthamiana plants, failed to show RMG fluorescence. However, incorporating tandem repeats of KSK into recombinant viral RNAs, enabled qualitative and quantitative detection, both in vitro and ex vivo (ex planta), of KSK-specific green fluorescence, though RMG was less obvious in vivo (in planta). These findings demonstrate Spinach-based RNA visualization has the potential for ex vivo and in vivo monitoring RNAs in plant cells.One sentence summarySpinach-based RMG technology was reevaluated to have potential for ex vivo and in vivo monitoring RNAs in plant cells.

scholarly journals Fitness of Isolates of Phytophthora capsici Resistant to Mefenoxam from Squash and Pepper Fields in North Carolina

Plant Disease ◽  
2008 ◽  
Vol 92 (10) ◽  
pp. 1439-1443 ◽  
Author(s):  
Adalberto C. Café-Filho ◽  
Jean Beagle Ristaino
Keyword(s):  
North Carolina ◽  
Phytophthora Capsici ◽  
Colony Growth ◽  
Relative Fitness ◽  
In Planta ◽  
Phytophthora Blight ◽  
In Vivo Experiments ◽  
First Time

Despite the wide adoption of mefenoxam (Ridomil Gold EC) for vegetables in North Carolina, the incidence of Phytophthora blight on pepper (Capsicum annuum) and squash (Cucurbita pepo) is high. Seventy-five isolates of Phytophthora capsici were collected in five pepper and one squash field in order to assess mefenoxam sensitivity. The relative fitness of resistant and sensitive isolates was contrasted in vitro by their respective rates of colony growth and their ability to produce sporangia in unamended V8 juice agar medium. In in vivo experiments, the aggressiveness of isolates on pepper was evaluated. The frequency of resistant isolates in North Carolina populations was 63%, considerably higher than resistance levels in areas where mefenoxam is not widely adopted. Resistant isolates grew on amended media at rates >80 to 90% and >100% of the nonamended control at 100 μg ml-1 and 5 μg ml-1, respectively. Sensitive isolates did not growth at 5 or 100 μg ml-1. All isolates from three fields, including two pepper and a squash field, were resistant to mefenoxam. Populations from other fields were composed of either mixes of sensitive and resistant isolates or only sensitive isolates. Response to mefenoxam remained stable during the course of in vitro and in planta experiments. Occurrence of a mefenoxam-resistant population of P. capsici on squash is reported here for the first time in North Carolina. When measured by rate of colony growth, sporulation in vitro, or aggressiveness in planta, fitness of resistant isolates was not reduced. Mefenoxam-resistant isolates from squash were as aggressive on pepper as sensitive or resistant pepper isolates. These results suggest that mefenoxam-resistant populations of P. capsici are as virulent and fit as sensitive populations.

scholarly journals A Selective TSH Receptor Antagonist Inhibits Stimulation of Thyroid Function in Female Mice

Endocrinology ◽  
2014 ◽  
Vol 155 (1) ◽  
pp. 310-314 ◽  
Author(s):  
Susanne Neumann ◽  
Eshel A. Nir ◽  
Elena Eliseeva ◽  
Wenwei Huang ◽  
Juan Marugan ◽  
...  
Keyword(s):  
Small Molecule ◽  
Sodium Iodide ◽  
Cell System ◽  
Tsh Receptor ◽  
Free T4 ◽  
Serum Free ◽  
Stimulation Of ◽  
Lowered Serum

Because the TSH receptor (TSHR) plays an important role in the pathogenesis of thyroid disease, a TSHR antagonist could be a novel treatment. We attempted to develop a small molecule, drug-like antagonist of TSHR signaling that is selective and active in vivo. We synthesized NCGC00242364 (ANTAG3) by chemical modification of a previously reported TSHR antagonist. We tested its potency, efficacy, and selectivity in a model cell system in vitro by measuring its activity to inhibit stimulation of cAMP production stimulated by TSH, LH, or FSH. We tested the in vivo activity of ANTAG3 by measuring its effects to lower serum free T4 and thyroid gene expression in female BALB/c mice continuously treated with ANTAG3 for 3 days and given low doses of TRH continuously or stimulated by a single administration of a monoclonal thyroid-stimulating antibody M22. ANTAG3 was selective for TSHR inhibition; half-maximal inhibitory doses were 2.1 μM for TSHR and greater than 30 μM for LH and FSH receptors. In mice treated with TRH, ANTAG3 lowered serum free T4 by 44% and lowered mRNAs for sodium-iodide cotransporter and thyroperoxidase by 75% and 83%, respectively. In mice given M22, ANTAG3 lowered serum free T4 by 38% and lowered mRNAs for sodium-iodide cotransporter and thyroperoxidase by 73% and 40%, respectively. In conclusion, we developed a selective TSHR antagonist that is effective in vivo in mice. This is the first report of a small-molecule TSHR antagonist active in vivo and may lead to a drug to treat Graves' disease.

scholarly journals PHIALOMYCES MACROSPORUS REDUCES CERCOSPORA COFFEICOLA SURVIVAL ON SYMPTOMATIC COFFEE LEAVES

2019 ◽  
Vol 14 (1) ◽  
pp. 1
Author(s):  
Marie Caroline Ferreira Laborde ◽  
Deila Magna dos Santos Botelho ◽  
Gabriel Alfonso Alvarez Rodriguez ◽  
Mário Lúcio Vilela de Resende ◽  
Marisa Vieira de Queiroz ◽  
...  
Keyword(s):  
Plant Pathogens ◽  
Disease Rate ◽  
In Planta ◽  
Necrotrophic Pathogen ◽  
Initial Inoculum ◽  
Saprobe Fungi ◽  
Cercospora Coffeicola ◽  
Brown Eye Spot

<p>Saprobe fungi and necrotrophic pathogens share the same niche within crop stubble and the search for fungi non-pathogenic to plants that are able to displace the plant pathogens from its overwintering substrate contributes to the disease management. Brown eye spot (<em>Cercospora coffeicola</em>) is among the most important coffee diseases, it is caused by a necrotrophic pathogen that has decaying leaves as its major source of inoculum. We have screened saprobe fungi for the ability to reduce <em>C. coffeicola</em> sporulation and viability and determined the possible mechanisms involved in the observed biocontrol. A selected saprobe fungus, <em>Phialomyces macrosporus</em>, reduced the pathogen’s viability by 40% both <em>in vitro</em> and <em>in vivo</em>. The fungus acts through antibiosis and competition for nutrients. It produced both volatile and non-volatile compounds that inhibited <em>C. coffeicola</em> growth, sporulation, and viability. It also produced the tissue maceration enzyme (polygalacturonase), which reduces the pathogen both in detached leaves or in planta. The reduction in the fungal viability either by the saprobe fungus or its polygalacturonase-fraction supernatant resulted in the reduction of the disease rate. Therefore, <em>P. macrosporus </em>is a potential microbial agent that can be used in an integrated management of brown eye spot through the reduction of the initial inoculum of the pathogen that survives and builds up in infected leaves.</p><p> </p>

scholarly journals Biochemistry of postharvest spoilage of sweet potato (Ipomoea batatas L.). 2. Comparison of cellulolytic enzyme production in cultures and fungi-infected sweet potato tubers

2006 ◽  
pp. 48-57
Author(s):  
R. C. Ray
Keyword(s):  
Sweet Potato ◽  
Enzyme Production ◽  
Ipomoea Batatas ◽  
Rhizopus Oryzae ◽  
Cellulose Synthesis ◽  
Cellulolytic Enzyme ◽  
Optimum Temperature ◽  
Potato Tubers

The study was conducted to determine the production in vitro and in vivo of cellulases by Botrydiplodia theobromae and Rhizopus oryzae. Isolates of these organisms were obtained from the postharvest decay of sweetpotato tubers. Results revealed that B. theobrornae and R. oryzae which were isolated from postharvest spoilage of sweetpotato tubers produced endo-13-1,4-glucanase and exo-V-1 ,4-glucanase in culture and in fungi-infected tissues of sweetpotato tubers. The optimum temperature and pH for cellulose synthesis and activity were 30°C and pH 6.5, respectively.

scholarly journals Distinct Peculiarities of In Planta Synthesis of Isoprenoid and Aromatic Cytokinins

Biomolecules ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 86
Author(s):  
Vladimir Oslovsky ◽  
Ekaterina Savelieva ◽  
Mikhail Drenichev ◽  
Georgy Romanov ◽  
Sergey Mikhailov
Keyword(s):  
Arabidopsis Thaliana ◽  
Plant Cells ◽  
Cytokinin Activity ◽  
Hormonal Activity ◽  
In Planta ◽  
Significant Difference ◽  
Aromatic Cytokinins ◽  
Derivatives Of ◽  
Ribose Moiety

The biosynthesis of aromatic cytokinins in planta, unlike isoprenoid cytokinins, is still unknown. To compare the final steps of biosynthesis pathways of aromatic and isoprenoid cytokinins, we synthesized a series of nucleoside derivatives of natural cytokinins starting from acyl-protected ribofuranosyl-, 2′-deoxyribofuranosyl- and 5′-deoxyribofuranosyladenine derivatives using stereoselective alkylation with further deblocking. Their cytokinin activity was determined in two bioassays based on model plants Arabidopsis thaliana and Amaranthus caudatus. Unlike active cytokinins-bases, cytokinin nucleosides lack the hormonal activity until the ribose moiety is removed. According to our experiments, ribo-, 2′-deoxyribo- and 5′-deoxyribo-derivatives of isoprenoid cytokinin N6-isopentenyladenine turned in planta into active cytokinins with clear hormonal activity. As for aromatic cytokinins, both 2′-deoxyribo- and 5′-deoxyribo-derivatives did not exhibit analogous activity in Arabidopsis. The 5′-deoxyribo-derivatives cannot be phosphorylated enzymatically in vivo; therefore, they cannot be “activated” by the direct LOG-mediated cleavage, largely occurring with cytokinin ribonucleotides in plant cells. The contrasting effects exerted by deoxyribonucleosides of isoprenoid (true hormonal activity) and aromatic (almost no activity) cytokinins indicates a significant difference in the biosynthesis of these compounds.

Recent advances in understanding cotton fibre and seed development

2005 ◽  
Vol 15 (4) ◽  
pp. 269-280 ◽  
Author(s):  
Yong-Ling Ruan
Keyword(s):  
Candidate Genes ◽  
Cotton Seed ◽  
Economic Value ◽  
Cell System ◽  
Cotton Fibre ◽  
Cellulose Synthesis ◽  
Tetraploid Cotton ◽  
Cellular Processes ◽  
Fibre Development

The unique feature of the seed of tetraploid cotton (Gossypium hirsutum and Gossypium barbadense) is that about 30% of the seed coat epidermal cells develop into cellulose-enriched fibres, while the embryos synthesize oils and proteins. Hence, both the maternal and filial tissues of the cotton seed are of significant economic value. After initiation from the ovule epidermis at or just before anthesis, the single-celled fibres elongate to 2.5–6.0 cm long in the tetraploid species before they switch to intensive secondary cell wall cellulose synthesis. Thus, apart from its agronomic importance, the cotton fibre represents a model single-cell system to study the control of cell differentiation and elongation, carbon partitioning to cellulose synthesis and also the interaction between maternal (fibre) and embryonic tissues in seeds. Over the past decade or so, significant effort has been made to understand the cellular and molecular basis of cotton fibre development and oil biosynthesis in the embryo. Metabolic engineering of the oil biosynthetic pathway in cotton seed has successfully produced healthier and stable oils. A number of candidate genes and cellular processes that potentially regulate various aspects of fibre development have been identified. Further elucidation of the in vivo functions of those candidate genes could significantly deepen our understanding of fibre development and offer potential for improvement of fibre quality through genetic engineering or marker-assisted breeding approaches.

scholarly journals Distribution of Fitness and Virulence Effects Caused by Single-Nucleotide Substitutions in Tobacco Etch Virus

2007 ◽  
Vol 81 (23) ◽  
pp. 12979-12984 ◽  
Author(s):  
Purificación Carrasco ◽  
Francisca de la Iglesia ◽  
Santiago F. Elena
Keyword(s):  
Single Case ◽  
Site Directed Mutagenesis ◽  
Relative Fitness ◽  
In Planta ◽  
Nucleotide Substitutions ◽  
Phenotypic Effect ◽  
Single Nucleotide ◽  
Mutant Genotype

ABSTRACT Little is known about the fitness and virulence consequences of single-nucleotide substitutions in RNA viral genomes, and most information comes from the analysis of nonrandom sets of mutations with strong phenotypic effect or which have been assessed in vitro, with their relevance in vivo being unclear. Here we used site-directed mutagenesis to create a collection of 66 clones of Tobacco etch potyvirus, each carrying a different, randomly chosen, single-nucleotide substitution. Competition experiments between each mutant and the ancestral nonmutated clone were performed in planta to quantitatively assess the relative fitness of each mutant genotype. Among all mutations, 40.9% were lethal, and among the viable ones, 36.4% were significantly deleterious and 22.7% neutral. Not a single case of beneficial effects was observed within the level of resolution of our measures. On average, the fitness of a genotype carrying a deleterious but viable mutation was 49% smaller than that for its unmutated progenitor. Deleterious mutational effects conformed to a beta probability distribution. The virulence of a subset of viable mutants was assessed as the reduction in the number of viable seeds produced by infected plants. Mutational effects on virulence ranged between 17% reductions and 24.4% increases. Interestingly, the only mutations showing a significant effect on virulence were hypervirulent. Competitive fitness and virulence were uncorrelated traits.

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