Time Course and Polarity of Primary Phloem Fibre Differentiation in Pisum sativum

Low, static concentrations of ammonium have less negative effects on nodulation of pea ( Pisum sativum L.) than nitrate and in some cases may actually stimulate nodulation. Two experiments were carried out to assess the effects of supplying both forms of mineral N, separately and in combination, on nodule initiation, nodule development, nodule distribution between primary and lateral (secondary) roots, tertiary root development, and N2 fixation in pea. Pea plants were grown for up to 24 d after inoculation in hydroponic culture with no mineral N (zero N), NO3– (0.5 mmol·L–1), NH4+ (0.5 mmol·L–1), or NO3– (0.25 mmol·L–1) plus NH4+ (0.25 mmol·L–1). Concentrations of nitrate and ammonium were monitored on a daily basis and held relatively constant by continuous, automatic additions of stock solutions. Pea plants accumulated the most total dry mass (DM) and total N when supplied with the combination of nitrate plus ammonium but had the lowest nodule DM and percentage of nitrogen derived from the atmosphere. Whole-plant nodulation (nodules per plant) and DM-specific nodulation (nodules·g–1 root DM) were 2.3- and 2.4-fold greater, respectively, in pea plants receiving NH4+ at 0.5 mmol·L–1 than in those supplied with NO3– at 0.5 mmol·L–1. The nodulation responses of plants receiving NO3– at 0.25 mmol·L–1 plus NH4+ at 0.25 mmol·L–1 were more similar to those of plants receiving only nitrate than only ammonium, indicating that when both forms of mineral N are available to plants, nitrate has a predominant effect on the nodulation response. Assessment of the stage of development of nodule primordia and nodules during the time course of the experiments indicated that nitrate not only decreased the degree of nodule initiation but also the rate at which those nodules developed. Microscopic observations indicated that the more negative effects of the nitrate treatment on DM-specific nodulation as compared with the ammonium treatment were consistent on both the primary and lateral roots. Quantification of nodulation and tertiary root development on lateral roots indicated that the stimulating effects of ammonium were specific to nodulation; the effects on tertiary root development were different. The study demonstrates for the first time that when both forms of mineral N are available at equal concentrations, the nodulation response in pea is influenced more by nitrate than by ammonium and that the effects of nitrate and ammonium on tertiary root initiation and development are unlike those on nodulation.

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The effect of nitrate on the time course of nitrogen fixation and growth in Pisum sativum and Vicia faba

Plant and Soil ◽

10.1007/bf00010848 ◽

1990 ◽

Vol 127 (1) ◽

pp. 143-146 ◽

Cited By ~ 9

Author(s):

B. R. Buttery ◽

A. H. Gibson

Keyword(s):

Nitrogen Fixation ◽

Pisum Sativum ◽

Vicia Faba ◽

Time Course

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Unequal Growth Rate of Pollen Tubes from Normal and Stringless Pea Genotypes

HortScience ◽

10.21273/hortsci.27.7.833 ◽

1992 ◽

Vol 27 (7) ◽

pp. 833-834 ◽

Cited By ~ 4

Author(s):

Rebecca J. McGee ◽

James R. Baggett

Keyword(s):

Growth Rate ◽

Pisum Sativum ◽

Pollen Tube ◽

Time Course ◽

Pollen Tubes ◽

In Vitro Germination ◽

Pollen Tube Growth Rate ◽

Germination Of Pollen

There was no difference in percentage in vitro germination of pollen from stringless pea (Pisum sativum L.) cv. Sugar Daddy and stringy `Oregon Sugarpod II' (OSP) and `OSU 705' (705). However, pollen tubes of `Sugar Daddy' grew more slowly in vitro than those of OSP or 705. Differences in pollen tube growth rate were demonstrated in vivo following time-course pollinations involving reciprocal crosses of `Sugar Daddy' with OSP and 705, along with the selfed parents. After 8 hours, pollen tubes from stringless peas (“stringless” pollen) had entered 13% of the ovules compared with 51% for those from stringy peas (“stringy” pollen). Stringless pollen tubes entered 29% and stringy pollen tubes 66% of the ovules after 10 hours. The slower growth of stringless compared with stringy pollen tubes is a plausible explanation for previously observed deficiencies of stringless plants in segregating populations.

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Identification of Fusarium solani f. sp. pisi (Fsp) responsive genes in Pisum sativum

10.1101/2020.05.12.091892 ◽

2020 ◽

Cited By ~ 1

Author(s):

Bruce A. Williamson-Benavides ◽

Richard Sharpe ◽

Grant Nelson ◽

Eliane T. Bodah ◽

Lyndon D. Porter ◽

...

Keyword(s):

Gene Expression ◽

Pisum Sativum ◽

Fusarium Solani ◽

Root Rot ◽

Time Course ◽

Acid Synthesis ◽

Anthocyanin Synthesis ◽

Transcriptomic Response ◽

Sugar Transporters ◽

Go Enrichment

AbstractPisum sativum (pea) is rapidly emerging as an inexpensive and major contributor to the plant-derived protein market. Due to its nitrogen-fixation capability, short life cycle, and low water usage, pea is a useful cover-and-break crop that requires minimal external inputs. It is critical for sustainable agriculture and indispensable for future food security. Root rot in pea, caused by the fungal pathogen Fusarium solani f. sp. pisi (Fsp), can result in a 15-60% reduction in yield. It is urgent to understand the molecular basis of Fsp interaction in pea to develop root rot tolerant cultivars. A complementary genetics and gene expression approach was undertaken in this study to identify Fsp-responsive genes in four tolerant and four susceptible pea genotypes. Time course RNAseq was performed on both sets of genotypes after Fsp challenge. Analysis of the transcriptome data resulted in the identification of 42,905 differentially expressed contigs (DECs). Interestingly, the vast majority of DECs were overexpressed in the susceptible genotypes at all sampling time points, rather than in the tolerant genotypes. Gene expression and GO enrichment analyses revealed genes coding for receptor-mediated endocytosis, sugar transporters, salicylic acid synthesis and signaling, and cell death were overexpressed in the susceptible genotypes. In the tolerant genotypes, genes involved in exocytosis, and secretion by cell, the anthocyanin synthesis pathway, as well as the DRR230 gene, a pathogenesis-related (PR) gene, were overexpressed. The complementary genetic and RNAseq approach has yielded a set of potential genes that could be targeted for improved tolerance against root rot in P. sativum. Fsp challenge produced a futile transcriptomic response in the susceptible genotypes. This type of response is hypothesized to be related to the speed at which the pathogen infestation advances in the susceptible genotypes, and the preexisting level of disease-preparedness in the tolerant genotypes.

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Ultrastructural Changes of the Symbiotic Chlorella-Like Alga Isolated from Hydra Viridis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100054212 ◽

1982 ◽

Vol 40 ◽

pp. 320-321

Author(s):

K.W. Lee ◽

R.H. Meints ◽

D. Kuczmarski ◽

J.L. Van Etten

Keyword(s):

Time Course ◽

Reciprocal Cross ◽

Ultrastructural Level ◽

Ultrastructural Changes ◽

Symbiotic Relationship ◽

Cell Recognition ◽

Green Hydra ◽

Different Strains ◽

Hydra Viridis

The physiological, biochemical, and ultrastructural aspects of the symbiotic relationship between the Chlorella-like algae and the hydra have been intensively investigated. Reciprocal cross-transfer of the Chlorellalike algae between different strains of green hydra provide a system for the study of cell recognition. However, our attempts to culture the algae free of the host hydra of the Florida strain, Hydra viridis, have been consistently unsuccessful. We were, therefore, prompted to examine the isolated algae at the ultrastructural level on a time course.

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Destruction of Actin Filaments by Osmium Tetroxide

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100079772 ◽

1977 ◽

Vol 35 ◽

pp. 466-467

Author(s):

P. Maupin-Szamier ◽

T. D. Pollard

Keyword(s):

Actin Filaments ◽

Time Course ◽

Osmium Tetroxide ◽

Rabbit Muscle ◽

Muscle Actin ◽

Sodium Phosphate Buffer ◽

Transmission Electron ◽

The Difference ◽

Rates Of Decay ◽

Short Time

We have studied the destruction of rabbit muscle actin filaments by osmium tetroxide (OSO4) to develop methods which will preserve the structure of actin filaments during preparation for transmission electron microscopy.Negatively stained F-actin, which appears as smooth, gently curved filaments in control samples (Fig. 1a), acquire an angular, distorted profile and break into progressively shorter pieces after exposure to OSO4 (Fig. 1b,c). We followed the time course of the reaction with viscometry since it is a simple, quantitative method to assess filament integrity. The difference in rates of decay in viscosity of polymerized actin solutions after the addition of four concentrations of OSO4 is illustrated in Fig. 2. Viscometry indicated that the rate of actin filament destruction is also dependent upon temperature, buffer type, buffer concentration, and pH, and requires the continued presence of OSO4. The conditions most favorable to filament preservation are fixation in a low concentration of OSO4 for a short time at 0°C in 100mM sodium phosphate buffer, pH 6.0.

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The time course of calcium deposition in shells of the barnacle (Balanus amphititre amphititre) during cyprid-juvenile metamorphosis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100168621 ◽

1994 ◽

Vol 52 ◽

pp. 178-179

Author(s):

Nancy R. Wallace ◽

Craig C. Freudenrich ◽

Karl Wilbur ◽

Peter Ingram ◽

Ann LeFurgey

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Time Course ◽

Vertical Plane ◽

Mantle Cavity ◽

Qualitative Assessment ◽

Calcium Deposition ◽

Free Swimming ◽

Freeze Dried ◽

Scanning Electron

The morphology of balanomorph barnacles during metamorphosis from the cyprid larval stage to the juvenile has been examined by light microscopy and scanning electron microscopy (SEM). The free-swimming cyprid attaches to a substrate, rotates 90° in the vertical plane, molts, and assumes the adult shape. The resulting metamorph is clad in soft cuticle and has an adult-like appearance with a mantle cavity, thorax with cirri, and incipient shell plates. At some time during the development from cyprid to juvenile, the barnacle begins to mineralize its shell, but it is not known whether calcification occurs before, during, or after ecdysis. To examine this issue, electron probe x-ray microanalysis (EPXMA) was used to detect calcium in cyprids and juveniles at various times during metamorphosis.Laboratory-raised, free-swimming cyprid larvae were allowed to settle on plastic coverslips in culture dishes of seawater. The cyprids were observed with a dissecting microscope, cryopreserved in liquid nitrogen-cooled liquid propane at various times (0-24 h) during metamorphosis, freeze dried, rotary carbon-coated, and examined with scanning electron microscopy (SEM). EPXMA dot maps were obtained in parallel for qualitative assessment of calcium and other elements in the carapace, wall, and opercular plates.

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Arabidopsis 4-COUMAROYL-COA LIGASE 8 contributes to the biosynthesis of the benzenoid ring of coenzyme Q in peroxisomes

Biochemical Journal ◽

10.1042/bcj20190688 ◽

2019 ◽

Vol 476 (22) ◽

pp. 3521-3532

Author(s):

Eric Soubeyrand ◽

Megan Kelly ◽

Shea A. Keene ◽

Ann C. Bernert ◽

Scott Latimer ◽

...

Keyword(s):

Oxidative Metabolism ◽

Time Course ◽

Reverse Genetics ◽

De Novo ◽

Coenzyme Q ◽

Control Level ◽

Wild Type ◽

Fluorescent Reporters ◽

Coa Ligase ◽

Peroxisomal Targeting

Plants have evolved the ability to derive the benzenoid moiety of the respiratory cofactor and antioxidant, ubiquinone (coenzyme Q), either from the β-oxidative metabolism of p-coumarate or from the peroxidative cleavage of kaempferol. Here, isotopic feeding assays, gene co-expression analysis and reverse genetics identified Arabidopsis 4-COUMARATE-COA LIGASE 8 (4-CL8; At5g38120) as a contributor to the β-oxidation of p-coumarate for ubiquinone biosynthesis. The enzyme is part of the same clade (V) of acyl-activating enzymes than At4g19010, a p-coumarate CoA ligase known to play a central role in the conversion of p-coumarate into 4-hydroxybenzoate. A 4-cl8 T-DNA knockout displayed a 20% decrease in ubiquinone content compared with wild-type plants, while 4-CL8 overexpression boosted ubiquinone content up to 150% of the control level. Similarly, the isotopic enrichment of ubiquinone's ring was decreased by 28% in the 4-cl8 knockout as compared with wild-type controls when Phe-[Ring-13C6] was fed to the plants. This metabolic blockage could be bypassed via the exogenous supply of 4-hydroxybenzoate, the product of p-coumarate β-oxidation. Arabidopsis 4-CL8 displays a canonical peroxisomal targeting sequence type 1, and confocal microscopy experiments using fused fluorescent reporters demonstrated that this enzyme is imported into peroxisomes. Time course feeding assays using Phe-[Ring-13C6] in a series of Arabidopsis single and double knockouts blocked in the β-oxidative metabolism of p-coumarate (4-cl8; at4g19010; at4g19010 × 4-cl8), flavonol biosynthesis (flavanone-3-hydroxylase), or both (at4g19010 × flavanone-3-hydroxylase) indicated that continuous high light treatments (500 µE m−2 s−1; 24 h) markedly stimulated the de novo biosynthesis of ubiquinone independently of kaempferol catabolism.

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