scholarly journals Exogenous steroid hormones stimulate full development of autonomous endosperm in Arabidopsis thaliana

2015 ◽  
Vol 84 (2) ◽  
pp. 287-301 ◽  
Author(s):  
Joanna Rojek ◽  
Łukasz Pawełko ◽  
Małgorzata Kapusta ◽  
Aleksandra Naczk ◽  
Jerzy Bohdanowicz
Keyword(s):  
Arabidopsis Thaliana ◽  
Steroid Hormones ◽  
Restriction Analysis ◽  
Endosperm Development ◽  
Central Cell ◽  
Wild Type ◽  
Cell Divisions ◽  
Development And Differentiation ◽  
Autonomous Endosperm

<p>Most flowering plants, including important crops, require double fertilization to form an embryo and endosperm, which nourishes it. Independence from fertilization is a feature of apomictic plants that produce seeds, from which the plants that are clones of the mother plant arise. The phenomenon of apomixis occurs in some sexual plants under specific circumstances. Since the launch of a fertilization-independent mechanism is considered a useful tool for plant breeding, there have been efforts to artificially induce apomixis. We have been able to produce fertilization-independent endosperm in vitro in <em>Arabidopsis</em> over the last few years. This paper demonstrates the methods of improving the quality of the endosperm obtained using plant and mammalian steroid hormones. Additionally, it shows the study on the autonomous endosperm (AE) formation mechanism in vitro.</p><p>This paper examines the effect of exogenous steroid hormones on unfertilized egg and central cell divisions in culture of unpollinated pistils of <em>Arabidopsis</em> Col-0 wild-type and <em>fie-1</em> mutant. All media with hormones used (estrone, androsterone, progesterone, and epibrassinolide) stimulated central cell divisions and fertilization-independent endosperm development. The stages of AE development followed the pattern of <em>Arabidopsis thaliana</em> wild type after fertilization. Subsequent stages of AE were observed from 2-nuclear up to cellular with the most advanced occurring on medium with 24-epibrassinolide and progesterone. The significant influence of mammalian sex hormones on speed of AE development and differentiation was noticed. Using restriction analysis, the changes in methylation of <em>FIE</em> gene was established under in vitro condition. The authors of this paper showed that <em>Arabidopsis thaliana</em> has a high potency to fertilization-independent development.</p>

scholarly journals Agrobacterium tumefaciens Transformation of the Radiation Hypersensitive Arabidopsis thaliana Mutants uvh1 and rad5

1998 ◽  
Vol 11 (11) ◽  
pp. 1136-1141 ◽  
Author(s):  
Jaesung Nam ◽  
Kirankumar S. Mysore ◽  
Stanton B. Gelvin
Keyword(s):  
Arabidopsis Thaliana ◽  
Agrobacterium Tumefaciens ◽  
Transformation Process ◽  
Stable Transformation ◽  
Wild Type ◽  
Dna Integration ◽  
Agrobacterium Tumefaciens Transformation ◽  
Inoculation Assay

The Arabidopsis thaliana mutants uvh1 and rad5, originally identified as radiation hypersensitive, were reported to be deficient in T-DNA integration based on the relative efficiencies of stable transformation and T-DNA transfer. We reassessed these mutants for susceptibility to transformation by Agrobacterium tumefaciens. The mutant rad5 showed a significant reduction in the efficiency of transient as well as stable transformation, compared with its wild-type progenitor. These data indicate that rad5 is blocked at a step in the transformation process prior to T-DNA integration. We additionally found, using both an in vitro root inoculation and an in vivo flower bolt inoculation assay, that the mutant uvh1 is as susceptible to A. tumefaciens-mediated transformation as is its wild-type progenitor, C10.

scholarly journals Fusion of a Flavin-Based Fluorescent Protein to Hydroxynitrile Lyase from Arabidopsis thaliana Improves Enzyme Stability

2013 ◽  
Vol 79 (15) ◽  
pp. 4727-4733 ◽  
Author(s):  
Kathrin Emmi Scholz ◽  
Benita Kopka ◽  
Astrid Wirtz ◽  
Martina Pohl ◽  
Karl-Erich Jaeger ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Fusion Proteins ◽  
Enzyme Stability ◽  
Enzyme Analysis ◽  
Phase System ◽  
Wild Type ◽  
Hydroxynitrile Lyase ◽  
Fluorescent Reporter

ABSTRACTHydroxynitrile lyase fromArabidopsis thaliana(AtHNL) was fused to different fluorescent reporter proteins. Whereas all fusion constructs retained enzymatic activity and fluorescencein vivoandin vitro, significant differences in activity and pH stability were observed. In particular, flavin-based fluorescent reporter (FbFP) fusions showed almost 2 orders of magnitude-increased half-lives in the weakly acidic pH range compared to findings for the wild-type enzyme. Analysis of the quaternary structure of the respective FbFP-AtHNL fusion proteins suggested that this increased stability is apparently caused by oligomerization mediated via the FbFP tag. Moreover, the increased stability of the fusion proteins enabled the efficient synthesis of (R)-mandelonitrile in an aqueous-organic two-phase system at a pH of <5. Remarkably, (R)-mandelonitrile synthesis is not possible using wild-typeAtHNL under the same conditions due to the inherent instability of this enzyme below pH 5. The fusion strategy presented here reveals a surprising means for the stabilization of enzymes and stresses the importance of a thoroughin vitrocharacterization ofin vivo-employed fluorescent fusion proteins.

scholarly journals The ASYMMETRIC LEAVES2 gene of Arabidopsis thaliana regulates formation of a symmetric lamina, establishment of venation and repression of meristem-related homeobox genes in leaves

Development ◽  
2001 ◽  
Vol 128 (10) ◽  
pp. 1771-1783 ◽  
Author(s):  
E. Semiarti ◽  
Y. Ueno ◽  
H. Tsukaya ◽  
H. Iwakawa ◽  
C. Machida ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Apical Meristem ◽  
Homeobox Genes ◽  
Free Medium ◽  
Wild Type ◽  
Leaf Lamina ◽  
Chain Reaction ◽  
Class 1 ◽  
Polymerase Chain

The asymmetric leaves2 (as2) mutant of Arabidopsis thaliana generated leaf lobes and leaflet-like structures from the petioles of leaves in a bilaterally asymmetric manner. Both the delayed formation of the primary vein and the asymmetric formation of secondary veins were apparent in leaf primordia of as2 plants. A distinct midvein, which is the thickest vein and is located in the longitudinal center of the leaf lamina of wild-type plants, was often rudimentary even in mature as2 leaves. However, several parallel veins of very similar thickness were evident in such leaves. The complexity of venation patterns in all leaf-like organs of as2 plants was reduced. The malformed veins were visible before the development of asymmetry of the leaf lamina and were maintained in mature as2 leaves. In vitro culture on phytohormone-free medium of leaf sections from as2 mutants and from the asymmetric leaves1 (as1) mutant, which has a phenotype similar to that of as2, revealed an elevated potential in both cases for regeneration of shoots from leaf cells. Analysis by the reverse transcription-polymerase chain reaction showed that transcripts of the KNAT1, KNAT2 and KNAT6 (a recently identified member of the class 1 knox family) genes accumulated in the leaves of both as2 and as1 plants but not of wild type. Transcripts of the STM gene also accumulated in as1 leaves. These findings suggest that, in leaves, the AS2 and AS1 genes repress the expression of these homeobox genes, which are thought to maintain the indeterminate cell state in the shoot apical meristem. Taken together, our results suggest that AS2 and AS1 might be involved in establishment of a prominent midvein and of networks of other veins as well as in the formation of the symmetric leaf lamina, which might be related to repression of class 1 knox homeobox genes in leaves.

scholarly journals Chlorinated Auxins—How Does Arabidopsis Thaliana Deal with Them?

2020 ◽  
Vol 21 (7) ◽  
pp. 2567 ◽  
Author(s):  
Antje Walter ◽  
Lorenzo Caputi ◽  
Sarah O’Connor ◽  
Karl-Heinz van Pée ◽  
Jutta Ludwig-Müller
Keyword(s):  
Arabidopsis Thaliana ◽  
Acetic Acid ◽  
Model Organism ◽  
Wild Type ◽  
In Planta ◽  
Bacteria And Fungi ◽  
Tryptophan Derivatives ◽  
Indole 3 Acetic Acid ◽  
Iaa Conjugates

Plant hormones have various functions in plants and play crucial roles in all developmental and differentiation stages. Auxins constitute one of the most important groups with the major representative indole-3-acetic acid (IAA). A halogenated derivate of IAA, 4-chloro-indole-3-acetic acid (4-Cl-IAA), has previously been identified in Pisum sativum and other legumes. While the enzymes responsible for the halogenation of compounds in bacteria and fungi are well studied, the metabolic pathways leading to the production of 4-Cl-IAA in plants, especially the halogenating reaction, are still unknown. Therefore, bacterial flavin-dependent tryptophan-halogenase genes were transformed into the model organism Arabidopsis thaliana. The type of chlorinated indole derivatives that could be expected was determined by incubating wild type A. thaliana with different Cl-tryptophan derivatives. We showed that, in addition to chlorinated IAA, chlorinated IAA conjugates were synthesized. Concomitantly, we found that an auxin conjugate synthetase (GH3.3 protein) from A. thaliana was able to convert chlorinated IAAs to amino acid conjugates in vitro. In addition, we showed that the production of halogenated tryptophan (Trp), indole-3-acetonitrile (IAN) and IAA is possible in transgenic A. thaliana in planta with the help of the bacterial halogenating enzymes. Furthermore, it was investigated if there is an effect (i) of exogenously applied Cl-IAA and Cl-Trp and (ii) of endogenously chlorinated substances on the growth phenotype of the plants.

scholarly journals Differential Contribution of Plant-Beneficial Functions from Pseudomonas kilonensis F113 to Root System Architecture Alterations in Arabidopsis thaliana and Zea mays

2018 ◽  
Vol 31 (2) ◽  
pp. 212-223 ◽  
Author(s):  
Jordan Vacheron ◽  
Guilhem Desbrosses ◽  
Sébastien Renoud ◽  
Rosa Padilla ◽  
Vincent Walker ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Type Strain ◽  
Wild Type Strain ◽  
Phosphate Solubilization ◽  
Glucose Dehydrogenase ◽  
Root System Architecture ◽  
Deletion Mutants ◽  
Wild Type ◽  
Relative Contribution

Fluorescent pseudomonads are playing key roles in plant-bacteria symbiotic interactions due to the multiple plant-beneficial functions (PBFs) they are harboring. The relative contributions of PBFs to plant-stimulatory effects of the well-known plant growth-promoting rhizobacteria Pseudomonas kilonensis F113 (formerly P. fluorescens F113) were investigated using a genetic approach. To this end, several deletion mutants were constructed, simple mutants ΔphlD (impaired in the biosynthesis of 2,4-diacetylphloroglucinol [DAPG]), ΔacdS (deficient in 1-aminocyclopropane-1-carboxylate deaminase activity), Δgcd (glucose dehydrogenase deficient, impaired in phosphate solubilization), and ΔnirS (nitrite reductase deficient), and a quadruple mutant (deficient in the four PBFs mentioned above). Every PBF activity was quantified in the wild-type strain and the five deletion mutants. This approach revealed few functional interactions between PBFs in vitro. In particular, biosynthesis of glucose dehydrogenase severely reduced the production of DAPG. Contrariwise, the DAPG production impacted positively, but to a lesser extent, phosphate solubilization. Inoculation of the F113 wild-type strain on Arabidopsis thaliana Col-0 and maize seedlings modified the root architecture of both plants. Mutant strain inoculations revealed that the relative contribution of each PBF differed according to the measured plant traits and that F113 plant-stimulatory effects did not correspond to the sum of each PBF relative contribution. Indeed, two PBF genes (ΔacdS and ΔnirS) had a significant impact on root-system architecture from both model plants, in in vitro and in vivo conditions. The current work underscored that few F113 PBFs seem to interact between each other in the free-living bacterial cells, whereas they control in concert Arabidopsis thaliana and maize growth and development.

scholarly journals Knockout of Arabidopsis Serotonin N-Acetyltransferase-2 Reduces Melatonin Levels and Delays Flowering

Biomolecules ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 712 ◽  
Author(s):  
Hyoung Yool Lee ◽  
Kyungjin Lee ◽  
Kyoungwhan Back
Keyword(s):  
Arabidopsis Thaliana ◽  
Enzyme Activity ◽  
Amino Acid ◽  
Plant Growth ◽  
Wild Type ◽  
Knockout Mutant ◽  
Flowering Locus T ◽  
Amino Acid Homology ◽  
Delayed Flowering

Melatonin plays roles in both plant growth and defense. Serotonin N-acetyltransferase (SNAT) catalyzes formation of N-acetylserotonin (NAS) from serotonin. Plants contain two SNAT isogenes, which exhibit low-level amino acid homology. We studied the Arabidopsis thaliana SNAT2 (AtSNAT2) gene; we prepared recombinant SNAT2 protein and characterized a snat2 knockout mutant. The SNAT2 protein exhibited 27% amino acid homology with SNAT1; the Km was 232 μM and the Vmax was 2160 pmol/min/mg protein. Melatonin inhibited SNAT enzyme activity in vitro. SNAT2 mRNA was abundantly expressed in flowers; the melatonin content of flowers of the snat2 mutant was significantly less than that of wild-type flowers. The mutant exhibited delayed flowering and reductions in leaf area and biomass compared to the wild type. Delayed flowering was attributable to reductions in the expression levels of the gibberellin biosynthetic genes ent-kaurene synthase (KS) and FLOWERING LOCUS T (FT).

Perturbation Of Gpsm2/Lgn Enhances Haematopoietic Stem Cell Function

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1176-1176
Author(s):  
Stephen Ting ◽  
Nicole Lee ◽  
Ming Li ◽  
Sarah Russell ◽  
Nathan Godde ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Stem Cell ◽  
Fold Increase ◽  
Haematopoietic Stem Cell ◽  
Wild Type ◽  
Cell Divisions ◽  
Terminal Domain ◽  
Limiting Dilution

Abstract A gain of function screen of candidate cell polarity genes identified the gene, Gpsm2 (G protein signaling modulator 2) also known as LGN or Pins, as an enhancer of haematopoietic stem cell (HSC) function. Mammalian Gpsm2 comprises an N-terminal domain composed of ten Leucine–Glycine–Asparagine (LGN) repeats within seven to eight tetratricopeptide motifs, which functions to bind NuMA (Nuclear Mitotic Apparatus) and a C-terminal domain containing four GoLoco repeats that modulates guanine nucleotide exchange via Gai interaction. In effect, Gpsm2 is an integral component that coordinates G protein signalling to mitotic spindle orientation during cell division. In multiple independent experiments, Gpsm2-transduced HSCs and cultured for 7 days in vitro compared to vector-transduced HSCs showed enhanced HSC repopulation out to 20 weeks-plus post transplant. At these time points, bone marrow and thymic DNA from multiple recipient mice were analysed via Southern blots with a GFP probe. This showed Gpsm2-transduced HSCs retained multipotency but that only one out of a minimum of 12 clones had undergone in vitro symmetrical expansion. Current limiting dilution assay will assess quantitatively this relative absence of HSC expansion. Although in vitro assays with Gpsm2-transduced bone marrow cells showed reduced colony formation and slightly attenuated cell proliferation, limiting dilution assays in secondary transplants showed Gpsm2-transduced HSCs maintained self-renewal ability together with a significant (p=0.009) 4-fold increase in HSC frequency compared to vector-transduced HSCs. This presumably reflects the importance of the interaction between Gpsm2-transduced HSCs within the niche in vivo. A mouse mutant lacking all GoLoco repeats of the C-terminal domain (LGN deltaC) is viable, where analyses of the neuroprogenitors of this mouse revealed altered asymmetrical versus symmetrical cell divisions without a detrimental effect on neuronal production (Konno et al. Nat Cell Biol 2008). A subsequent study of the role of LGN in epidermal development identified that a significant (>80%) knockdown of LGN via shRNA also altered asymmetrical cell divisions of epidermal stem-progenitor cells, however with a functional loss of skin barrier (Williams et al. Nature 2011). This defect could be partially rescued by the LGN N-terminal protein suggesting the LGN deltaC mouse still has functional, albeit, incomplete LGN/Gpsm2 function. We have analysed haematopoiesis in the LGN deltaC mouse. There were no significant differences in wild-type versus homozygous LGN deltaC LSK numbers, in vitro colony formation or in vivo CFU-spleen assays. However, limiting dilution assays showed a 7-fold increase (p=0.02) in HSC frequency in the LGN deltaC mouse, and competitive CD45.2/CD45.1 transplantations analysed at 16 weeks post transplant showed CD45.2 LGN deltaC HSCs reconstituted significantly (p=0.015) better compared to CD45.2 wild-type HSCs. On the premise that the Gpsm2 function of controlling somatic stem cell fate is conserved, we are investigating the hypothesise that the mechanism of perturbation of Gpsm2 enhancement of HSC function is through altered HSC asymmetric and symmetric divisional fate. Disclosures: No relevant conflicts of interest to declare.

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