scholarly journals Cytokinins in the Bryophyte Physcomitrella patens: Analyses of Activity, Distribution, and Cytokinin Oxidase/Dehydrogenase Overexpression Reveal the Role of Extracellular Cytokinins

2007 ◽  
Vol 145 (3) ◽  
pp. 786-800 ◽  
Author(s):  
Klaus von Schwartzenberg ◽  
Marta Fernández Núñez ◽  
Hanna Blaschke ◽  
Petre I. Dobrev ◽  
Ondrej Novák ◽  
...  
Keyword(s):  
Physcomitrella Patens ◽  
Cytokinin Oxidase ◽  
Activity Distribution

Computational approach towards understanding structural and functional role of cytokinin oxidase/dehydrogenase 2 (CKX2) in enhancing grain yield in rice plant

2019 ◽  
Vol 38 (4) ◽  
pp. 1158-1167 ◽  
Author(s):  
Gayatri Gouda ◽  
Manoj Kumar Gupta ◽  
Ravindra Donde ◽  
Jitendra Kumar ◽  
Ramakrishna Vadde ◽  
...  
Keyword(s):  
Grain Yield ◽  
Rice Plant ◽  
Functional Role ◽  
Computational Approach ◽  
Cytokinin Oxidase

Role of catalyst pellet activity distribution in catalyst poisoning

1994 ◽  
Vol 108 (2) ◽  
pp. 141-156
Author(s):  
Alena Brunovská ◽  
Bibiána Remiarová ◽  
Pavol Pranda
Keyword(s):  
Catalyst Poisoning ◽  
Activity Distribution ◽  
Catalyst Pellet

scholarly journals Physcomitrella patens: a model to investigate the role of RAC/ROP GTPase signalling in tip growth

2010 ◽  
Vol 61 (7) ◽  
pp. 1917-1937 ◽  
Author(s):  
D. Magnus Eklund ◽  
Emma M. Svensson ◽  
Benedikt Kost
Keyword(s):  
Tip Growth ◽  
Physcomitrella Patens ◽  
Rop Gtpase

scholarly journals Diversified Regulation of Cytokinin Levels and Signaling During Botrytis cinerea Infection in Arabidopsis

2021 ◽  
Vol 12 ◽  
Author(s):  
Beibei Li ◽  
Ruolin Wang ◽  
Shiya Wang ◽  
Jiang Zhang ◽  
Ling Chang
Keyword(s):  
Botrytis Cinerea ◽  
Response Regulator ◽  
Plant Immunity ◽  
Defense Responses ◽  
Cytokinin Oxidase ◽  
Plant Defense Responses ◽  
Necrotrophic Pathogen ◽  
Transcriptional Changes ◽  
Complex Regulation

Cytokinins (CKs) can modulate plant immunity to various pathogens, but how CKs are involved in plant defense responses to the necrotrophic pathogen Botrytis cinerea is still unknown. Here, we found that B. cinerea infection induced transcriptional changes in multiple genes involved in the biosynthesis, degradation, and signaling of CKs, as well as their contents, in pathogen-infected Arabidopsis leaves. Among the CKs, the gene expression of CYTOKININ OXIDASE/DEHYDROGENASE 5 (CKX5) was remarkably induced in the local infected leaves and the distant leaves of the same plant without pathogen inoculation. Cis-zeatin (cZ) and its riboside (cZR) accumulated considerably in infected leaves, suggesting an important role of the cis-zeatin type of CKs in the plant response to B. cinerea. Cytokinin double-receptor mutants were more susceptible to B. cinerea infection, whereas an exogenous CK treatment enhanced the expression levels of defense-related genes and of jasmonic acid (JA) and ethylene (ET), but not salicylic acid (SA), resulting in higher resistance of Arabidopsis to B. cinerea. Investigation of CK responses to B. cinerea infection in the JA biosynthesis mutant, jar1-1, and ET-insensitive mutant, ein2-1, showed that CK signaling and levels of CKs, namely, those of isopentenyladenine (iP), isopentenyladenine riboside (iPR), and trans-zeatin (tZ), were enhanced in jar1-1-infected leaves. By contrast, reductions in iP, iPR, tZ, and tZ riboside (tZR) as well as cZR contents occurred in ein2-1-infected leaves, whose transcript levels of CK signaling genes were likewise differentially regulated. The Arabidopsis Response Regulator 5 (ARR5) gene was upregulated in infected leaves of ein2-1 whereas another type-A response regulator, ARR16, was significantly downregulated, suggesting the existence of a complex regulation of CK signaling via the ET pathway. Accumulation of the cis-zeatin type of CKs in B. cinerea-infected leaves depended on ET but not JA pathways. Collectively, our findings provide evidence that CK responds to B. cinerea infection in a variety of ways that are differently modulated by JA and ET pathways in Arabidopsis.

scholarly journals The distribution of ribosomes between different functional states in livers of fed and starved mice

1973 ◽  
Vol 134 (2) ◽  
pp. 387-398 ◽  
Author(s):  
Michael Norman ◽  
Stjepan Gamulin ◽  
Kay Clark
Keyword(s):  
Protein Synthesis ◽  
Orotic Acid ◽  
Specific Radioactivity ◽  
Negligible Effect ◽  
Quantitative Distribution ◽  
Activity Distribution ◽  
Ad Libitum ◽  
Functional States ◽  
Radioactive Labelling

1. To investigate the role of ribosome function in regulating protein synthesis, the activity, distribution and functional states of ribosomal particles were investigated in livers of mice fed ad libitum or starved overnight. 2. The distribution of protein-synthesizing activity between polyribosomes of different sizes was analysed after incorporation of radioactive leucine, and the quantitative distribution of ribosomes as native subunits, monomers and polyribosomes was analysed after incorporation of orotic acid. Precursors labelled with 3H or 14C were given separately to fed and starved mice, so that livers from the two groups of animals were processed together. 3. The former experiments showed that starvation has little effect on the distribution of protein-synthesizing activity across polyribosome sedimentation patterns, though the latter experiments showed that the proportion of ribosomes existing as monomers increased from 9.5% to 15.2%, whereas the proportion existing as polyribosomes decreased from 81.4% to 75.6%. Starvation had a negligible effect on the proportion of native subunits, which accounted for 9.1% and 9.2% of the ribosomes in fed and starved mice respectively. 4. The monomeric ribosome fraction was isolated and subjected to ionic conditions which selectively dissociate single ribosomes. Starvation increased the proportion of monomers that dissociated from 59% to 72%, so the monomers that accumulate in livers of starved animals are single ribosomes and not monoribosomes resulting from degradation of polyribosomes. 5. The fate of newly formed ribosomal particles was studied by measuring the specific radioactivity of native subunits, monomers and polyribosomes at different times after injection of radioactively labelled orotic acid. Starvation did not appear to affect equilibration between newly formed particles and polyribosomes, and the radioactivity of polyribosomes in both groups of mice reached about 90% of that in native subunits after 4h. The radioactive labelling of monomers proceeded at a slower rate, especially after starvation. At 4h, the radioactivity of monomers was 64% and 55% that of native subunits in fed and starved mice respectively.

scholarly journals Mutations in Glucan, Water Dikinase Affect Starch Degradation and Gametophore Development in the Moss Physcomitrella patens

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Ntombizanele T. Mdodana ◽  
Jonathan F. Jewell ◽  
Ethel E. Phiri ◽  
Marthinus L. Smith ◽  
Kenneth Oberlander ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Growth Medium ◽  
Vascular Plants ◽  
Physcomitrella Patens ◽  
Early Stage ◽  
Plant Evolution ◽  
The Other ◽  
Starch Degradation ◽  
Glucose Supplementation

Abstract The role of starch degradation in non-vascular plants is poorly understood. To expand our knowledge of this area, we have studied this process in Physcomitrella patens. This has been achieved through examination of the step known to initiate starch degradation in angiosperms, glucan phosphorylation, catalysed by glucan, water dikinase (GWD) enzymes. Phylogenetic analysis indicates that GWD isoforms can be divided into two clades, one of which contains GWD1/GWD2 and the other GWD3 isoforms. These clades split at a very early stage within plant evolution, as distinct sequences that cluster within each were identified in all major plant lineages. Of the five genes we identified within the Physcomitrella genome that encode GWD-like enzymes, two group within the GWD1/GWD2 clade and the others within the GWD3 clade. Proteins encoded by both loci in the GWD1/GWD2 clade, named PpGWDa and PpGWDb, are localised in plastids. Mutations of either PpGWDa or PpGWDb reduce starch phosphate abundance, however, a mutation at the PpGWDa locus had a much greater influence than one at PpGWDb. Only mutations affecting PpGWDa inhibited starch degradation. Mutants lacking this enzyme also failed to develop gametophores, a phenotype that could be chemically complemented using glucose supplementation within the growth medium.

scholarly journals Caulonema differentiation in Funaria protonema

2020 ◽  
Vol 64 (1-2-3) ◽  
pp. 21-28 ◽  
Author(s):  
Man-Mohan Johri
Keyword(s):  
Physcomitrella Patens ◽  
Auxin Level ◽  
Helix Loop Helix ◽  
Transcription Factor Genes ◽  
The Status ◽  
Level 3 ◽  
Experimental Approaches ◽  
Cell Densities ◽  
Work Done

The strategies and experimental approaches that led the author to demonstrate the role of auxin in caulonema differentiation in the protonema of the moss Funaria hygrometrica are discussed. In stationary suspension cultures, the status of cell differentiation is regulated by inoculum cell density and auxin level. At low inoculum cell densities, 2-5 µM indole acetic acid (IAA) led to the differentiation of 65-70% caulonema filaments in 5-6 days. Caulonema can also differentiate in auxin-free medium if buffered at pH 5.0 after a lag of 6±1 days. The duration of lag can be manipulated and the cells are capable of responding to auxin at a higher level (3-10 µM) and produce about 20% caulonema after 3 days. This responsiveness or sensitivity to auxin can be enhanced further by growing cells in a nutrient-limited medium buffered at pH 5.0. In this medium, addition of 3 µM IAA led to the differentiation of 75-80% caulonema and rhizoids within 3 to 4 days. Work done in other laboratories has shown that auxin promotes caulonema differentiation in the moss Physcomitrella patens by positively regulating two basic helix-loop-helix type of transcription factor genes namely root hair defective six-like1 (PpRSL1) and PpRSL2 (Jang and Dolan 2011, New Phytologist 192: 319-327).

scholarly journals An evolutionary conserved lysine acetylation hotspot regulates plant mitochondrial malate dehydrogenase activity

2020 ◽  
Author(s):  
Manuel Balparda ◽  
Marlene Elsässer ◽  
Mariana Badia ◽  
Jonas Giese ◽  
Meike Hüdig ◽  
...  
Keyword(s):  
Malate Dehydrogenase ◽  
Physcomitrella Patens ◽  
Homology Modelling ◽  
Land Plant ◽  
Land Plants ◽  
Lysine Acetylation ◽  
Reduction Activity ◽  
Plant Acclimation ◽  
Mitochondrial Malate Dehydrogenase

AbstractPlants need to be able to rapidly and flexibly adjust their metabolism to changes their immediate environment. Since this necessity results from the sessile lifestyle of land plants, key mechanisms of orchestrating central metabolic acclimation are likely to have evolved early. Here we explore the role of lysine acetylation as a posttranslational modification to directly modulate metabolic function. First, we generate a lysine acetylome of the early divergent land plant Physcomitrium (Physcomitrella) patens. We identify 638 lysine acetylation sites, which were predominant in the mitochondria and plastids. A comparison with different angiosperms, including Arabidopsis thaliana, pinpoints lysine acetylation as conserved strategy in land plants. We focus on modified enzymes involved in mitochondrial central metabolism and select the mitochondrial malate dehydrogenase (mMDH), which acts as a hub of plant metabolic flexibility. In P. patens we detected a unique lysine acetylated site located next to one of the four acetylation sites detected in A. thaliana mMDH1. We assessed the kinetic behavior of recombinant A. thaliana and P. patens mMDHs with site-specifically incorporated acetyllysines. While the sites K325, K329 and K334 do not show any changes in the catalytic properties as assessed by oxaloacetate reduction activity, acetylation of A. thaliana mMDH1 at K170 markedly decreases its activity and acetylation of P. patens mMDH1 at K172 increases it. In both cases, acetylation induces modifications of the turnover number of the enzymes, without modifying the affinity for the substrates. Homology modelling of the mMDH1 proteins reveals a hotspot of lysine acetylation that is distant from the active site and homomerisation interfaces but conserved in land plants. The data reveal lysine acetylation as a strategy to tune the enzymatic properties of central metabolic enzymes with likely impact on metabolic capacity and flexibility to underpin plant acclimation.

ABA mediation of shoot cytokinin oxidase activity: assessing its impacts on cytokinin status and biomass allocation of nutrient-deprived durum wheat

2009 ◽  
Vol 36 (1) ◽  
pp. 66 ◽  
Author(s):  
Lidia B. Vysotskaya ◽  
Alla V. Korobova ◽  
Stanislav Y. Veselov ◽  
Ian C. Dodd ◽  
Guzel R. Kudoyarova
Keyword(s):  
Root Growth ◽  
Durum Wheat ◽  
Nutrient Solution ◽  
Oxidase Activity ◽  
Shoot Growth ◽  
Xylem Sap ◽  
Nutrient Deprivation ◽  
Cytokinin Oxidase ◽  
Shoot To Root Ratio

Although nutrient deprivation alters the concentrations of several plant hormones, the role of each in decreasing shoot-to-root ratio is not clear. A 10-fold dilution of the nutrient concentration supplied to hydroponically-grown 7-day-old durum wheat (Triticum turgidum L. ssp. durum Desf.) plants decreased shoot growth, shoot-to-root ratio and shoot and root cytokinin concentrations, increased shoot ABA concentration and shoot cytokinin oxidase activity, but had no effect on xylem sap ABA and cytokinin concentrations. Nutrient deprivation also increased xylem concentrations of conjugated ABA. The role of ABA in these responses was addressed by adding 11.4 µm ABA to the nutrient solution of well fertilised plants, or 1.2 mm fluridone (an inhibitor of ABA biosynthesis) to the nutrient solution of nutrient-deprived plants. The former induced similar changes in shoot-to-root ratio (by inhibiting shoot growth), shoot ABA concentration, shoot and root cytokinin concentrations and shoot cytokinin oxidase activity as nutrient deprivation. Conversely, fluridone addition to nutrient-deprived plants restored shoot-to-root ratio (by inhibiting root growth), shoot ABA concentration, shoot and root cytokinin concentrations to levels similar to well fertilised plants. Although root growth maintenance during nutrient deprivation depends on a threshold ABA concentration, shoot growth inhibition is independent of shoot ABA status. Although fluridone decreased shoot cytokinin oxidase activity of nutrient-deprived plants, it was still 1.7-fold greater than well fertilised plants, implying that nutrient deprivation could also activate shoot cytokinin oxidase independently of ABA. These data question the root signal basis of cytokinin action, but demonstrate that changes in ABA status can regulate shoot cytokinin concentrations via altering their metabolism.

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