scholarly journals Analysis of Arabidopsis glucose insensitive mutants, gin5 and gin6, reveals a central role of the plant hormone ABA in the regulation of plant vegetative development by sugar

2000 ◽  
Vol 14 (16) ◽  
pp. 2085-2096 ◽  
Author(s):  
Francisco Arenas-Huertero ◽  
Analilia Arroyo ◽  
Li Zhou ◽  
Jen Sheen ◽  
Patricia León
Keyword(s):  
Aba Signaling ◽  
Vegetative Development ◽  
Glucose Signaling ◽  
Putative Transcription Factor ◽  
Normal Glucose ◽  
Specific Accumulation ◽  
Early Seedling ◽  
Aba Insensitive

Sugars have signaling roles in a wide variety of developmental processes in plants. To elucidate the regulatory components that constitute the glucose signaling network governing plant growth and development, we have isolated and characterized two Arabidopsisglucose insensitive mutants, gin5 and gin6, based on a glucose-induced developmental arrest during early seedling morphogenesis. The T-DNA-tagged gin6 mutant abrogates the glucose-induced expression of a putative transcription factor, ABI4, previously shown to be involved in seed-specific abscisic acid (ABA) responses. Thus, ABI4 might be a regulator involved in both glucose- and seed-specific ABA signaling. The characterization of thegin5 mutant, on the other hand, reveals that glucose-specific accumulation of ABA is essential for hexokinase-mediated glucose responses. Consistent with this result, we show that three ABA-deficient mutants (aba1-1, aba2-1, andaba3-2) are also glucose insensitive. Exogenous ABA can restore normal glucose responses in gin5 and aba mutants but not in gin6 plants. Surprisingly, only abi4 andabi5-1 but not other ABA-insensitive signaling mutants (abi1-1, abi2-1, and abi3-1) exhibit glucose insensitivity, indicating the involvement of a distinct ABA signaling pathway in glucose responses. These results provide the first direct evidence to support a novel and central role of ABA in plant glucose responses mediated through glucose regulation of both ABA levels by GIN5 and ABA signaling by GIN6/ABI4.

scholarly journals Interplay between positive and negative regulation by B3-type transcription factors is critical for the accurate expression of the ABA INSENSITIVE 4 gene.

2021 ◽  
Author(s):  
Alma Fabiola Hernández-Bernal ◽  
Elizabeth Cordoba ◽  
Mónica Santos Mendoza ◽  
Kenny Alejandra Agreda-Laguna ◽  
Alejandra Dagmara Rivera ◽  
...  
Keyword(s):  
Vegetative Development ◽  
Cis Acting ◽  
Molecular Approaches ◽  
Developing Seed ◽  
Regulatory Circuit ◽  
Accurate Expression ◽  
Early Seedling ◽  
Environmental Responses ◽  
Aba Insensitive ◽  
Precise Expression

The ABA-INSENSITIVE 4 transcription factor is key for the regulation of diverse aspects of plant development and environmental responses, including proper perception of hormonal and nutritional signals. ABI4 activity is highly regulated at the transcriptional and post-transcriptional levels leading to precise expression mainly in the developing seed and early seedling development. Based on genetic and molecular approaches in the current study we provide new insights into the central mechanism underpinning the transcriptional regulation of ABI4 during both seed and vegetative development. We identified a complex interplay between the LEC2 and ABI3 transcriptional activators and the HSI/VAL repressors that is critical for proper ABI4 expression. Interestingly, the regulation by these proteins relies on the two RY cis-acting motifs present two kb upstream of the ABI4 gene. Our analysis also shows that the chromatin landscape of the ABI4 loci is highly dependent on the LEC2 and HSI2/VAL proteins. LEC2 regulation extends to the vegetative development and the absence of this factor results in ABA- and sugar-insensitive signaling in the developing plant. This regulatory circuit functions as a major control module for the correct spatial-temporal expression of ABI4 and prevents its ectopic accumulation that is harmful to the plant.

scholarly journals O-fucosylation of CPN20 by SPINDLY Derepresses Abscisic Acid Signaling During Seed Germination and Seedling Development

2021 ◽  
Vol 12 ◽  
Author(s):  
Lin Liang ◽  
Qi Wang ◽  
Zihao Song ◽  
Yaxin Wu ◽  
Qing Liang ◽  
...  
Keyword(s):  
Seed Germination ◽  
Mammalian Cells ◽  
Electron Transfer Dissociation ◽  
Seedling Development ◽  
Aba Signaling ◽  
Early Seedling ◽  
Aba Insensitive ◽  
Early Seedling Development

SPINDLY is involved in some aspects of plant development. However, the nature of this protein as an O-fucosyltransferase was recently discovered. In this study, we show that SPINDLY (SPY) interacts with CPN20 in yeast two-hybrid and split-luc assays, and the interaction is promoted by ABA. CPN20 is a chloroplast-localized co-chaperonin that negatively regulates ABAR-mediated ABA signaling. By using Electron Transfer Dissociation-MS/MS analysis, two O-fucosylation sites, e.g., 116th and 119th threonines, were detected in ectopically expressed CPN20 in mammalian cells and in Arabidopsis. The O-fucosylation at both threonine residues was confirmed by in vitro peptide O-fucosylation assay. We further show that CPN20 accumulates in the chloroplast of spy mutants, suggesting that SPY negatively regulates CPN20 localization in the chloroplast. In vivo protein degradation assay along with CPN20 localization behavior suggest that import of CPN20 into the chloroplast is negatively regulated by SPY. Genetic analysis shows that ABA insensitive phenotypes of spy-3 in terms of seed germination and early seedling development are partially suppressed by the cpn20 mutation, suggesting that CPN20 acts downstream of SPY in this ABA signaling pathway and that there may exist other pathways in parallel with CPN20. Collectively, the above data support the notion that the O-fucosylation of CPN20 by SPY fine-tunes ABA signaling in Arabidopsis.

Salt stress in Arabidopsis thaliana seedlings: Role of indoleamines in stress alleviation

2021 ◽  
Vol 4 (1) ◽  
pp. 70-83
Author(s):  
Mukund R. Shukla ◽  
Vikramjit S. Bajwa ◽  
Jose A. Freixas-Coutin ◽  
Praveen K Saxena
Keyword(s):  
Salt Stress ◽  
Stress Tolerance ◽  
Antioxidant Defense ◽  
Ion Homeostasis ◽  
Nacl Stress ◽  
Aba Signaling ◽  
Antioxidant Defense Systems ◽  
Pre Treatment ◽  
Aba Insensitive

Salinity is a major environmental stress in agriculture with significantly detrimental effects on crop productivity. The development of strategies to enhance salinity stress tolerance in plants is essential to ensure crop production in saline environments. Melatonin (Mel) and serotonin (Ser) accumulate in response to environmental stresses and are presumed to play protective roles and improve growth of tissues during recovery. In this study, the effects of Mel and Ser were investigated in Arabidopsis under NaCl stress. Exogenous Mel (10 µM) and Ser (10 µM) treatment significantly increased fresh weight, lateral root number, and shoot height in A. thaliana seedlings exposed to NaCl stress (25 mM and 50 mM) compared to the non-treated control seedlings. In order to understand the role of these indoleamines in alleviating salt stress, we investigated the effects of Mel and Ser treatments on the expression of salt stress responsive genes including, transcription factors involved in abscisic acid (ABA) signaling pathway, ABA-INSENSITIVE 3 (ABI3)and ABA-INSENSITIVE 5 (ABI5); ABA responsive gene, RESPONSIVE TO DESSICATION 29B (RD29B), ABA-independent gene, RESPONSIVE TO DESSICATION 29A (RD29A) and Arabidopsis trithorax-like gene (ATX1) which function in stress responses via ABA-dependent and ABA-independent manner. Other genes included, ROS-signaling transcription factor ZAT10 and ZAT12, and the genes encoding ion transporters crucial for maintaining ion homeostasis, HIGH AFFINITY K+ TRANSPORTER 5 (HAK5) and SALT OVERLY SENSITIVE 1 (SOS1). Mel (10 µM) pre-treatment for 24 hrs followed by 50 mM salt treatment up-regulated ABI3, RD29B, ZAT12 and HAK5. The Ser (10 µM) pre-treatment significantly up-regulated ZAT12.These results indicate that indoleamine pre-treatment improved plant growth under salt stress with Mel facilitating salt tolerance via upregulation of ABA responsive genes, mediation of antioxidant defense systems to counteract the salt-induced ROS overproduction as well as controlling ion homeostasis. Although Ser displayed no significant effects on ABA signaling, it was found to increase the expression of antioxidant defense gene, ZAT12. This study demonstrates the importance of indoleamine pathway in mediation of salt stress response and provides the first indication of the involvement of Ser in salt stress tolerance. 

scholarly journals Arabidopsis LSH8 Positively Regulates ABA Signaling by Changing the Expression Pattern of ABA-Responsive Proteins

2021 ◽  
Vol 22 (19) ◽  
pp. 10314
Author(s):  
Jinpeng Zou ◽  
Zhifang Li ◽  
Haohao Tang ◽  
Li Zhang ◽  
Jingdu Li ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Seed Germination ◽  
Signaling Pathway ◽  
Expression Pattern ◽  
Large Scale ◽  
Aba Signaling ◽  
Wild Type ◽  
Floral Organogenesis ◽  
Early Seedling ◽  
Aba Insensitive

Phytohormone ABA regulates the expression of numerous genes to significantly affect seed dormancy, seed germination and early seedling responses to biotic and abiotic stresses. However, the function of many ABA-responsive genes remains largely unknown. In order to improve the ABA-related signaling network, we conducted a large-scale ABA phenotype screening. LSH, an important transcription factor family, extensively participates in seedling development and floral organogenesis in plants, but whether its family genes are involved in the ABA signaling pathway has not been reported. Here we describe a new function of the transcription factor LSH8 in an ABA signaling pathway. In this study, we found that LSH8 was localized in the nucleus, and the expression level of LSH8 was significantly induced by exogenous ABA at the transcription level and protein level. Meanwhile, seed germination and root length measurements revealed that lsh8 mutant lines were ABA insensitive, whereas LSH8 overexpression lines showed an ABA-hypersensitive phenotype. With further TMT labeling quantitative proteomic analysis, we found that under ABA treatment, ABA-responsive proteins (ARPs) in the lsh8 mutant presented different changing patterns with those in wild-type Col4. Additionally, the number of ARPs contained in the lsh8 mutant was 397, six times the number in wild-type Col4. In addition, qPCR analysis found that under ABA treatment, LSH8 positively mediated the expression of downstream ABA-related genes of ABI3, ABI5, RD29B and RAB18. These results indicate that in Arabidopsis, LSH8 is a novel ABA regulator that could specifically change the expression pattern of APRs to positively mediate ABA responses.

Digital x-ray mapping of nanometer-size supported bimetallic catalysts

1988 ◽  
Vol 46 ◽  
pp. 530-531
Author(s):  
L. T. Germinario
Keyword(s):  
Background Radiation ◽  
Metal Cluster ◽  
Single Element ◽  
Beam Diameter ◽  
X Rays ◽  
X Ray ◽  
Major Interest ◽  
Induced Changes

Understanding the role of metal cluster composition in determining catalytic selectivity and activity is of major interest in heterogeneous catalysis. The electron microscope is well established as a powerful tool for ultrastructural and compositional characterization of support and catalyst. Because the spatial resolution of x-ray microanalysis is defined by the smallest beam diameter into which the required number of electrons can be focused, the dedicated STEM with FEG is the instrument of choice. The main sources of errors in energy dispersive x-ray analysis (EDS) are: (1) beam-induced changes in specimen composition, (2) specimen drift, (3) instrumental factors which produce background radiation, and (4) basic statistical limitations which result in the detection of a finite number of x-ray photons. Digital beam techniques have been described for supported single-element metal clusters with spatial resolutions of about 10 nm. However, the detection of spurious characteristic x-rays away from catalyst particles produced images requiring several image processing steps.

Consideraciones en torno a la reducción solipsista

1970 ◽  
Vol 11 ◽  
Author(s):  
Natalia Carolina Petrillo

ResumenEn el presente trabajo se intentará mostrar que la fenomenología no conduce a una postura solipsista. Para ello, se caracterizará en qué consiste el solipsismo. Luego, se intentará refutar a lo que se ha de llamar “solipsismo metafísico” y “solipsismo gnoseológico”, con el objetivo principal de poner de manifiesto el fundamento de motivación para la salida de la ficción solipsista.Palabras claves:Phenomenology – solipsim – empatía - HusserlAbstractWith the aim of showing that phenomenology does not lead in solipsism, I will first attempt a characterization of it. Then, I will attempt a refutation of the so-called “metaphysical” and “epistemological” solipsisms. Finally, the nature and role of Husserl´s solipsistic fiction is examined, and the grounds that motivate the overcoming of this standpoint are disclosed.key wordsFenomenología – solipsismo - empathy – Husserl

ART STUDIOS – A WAY TO DEVELOPE CHILDREN’S IMAGINATION

2020 ◽  
Vol 11 (1) ◽  
pp. 144-148
Author(s):  
Liuba Zlatkova ◽  
Keyword(s):  
Fairy Tale ◽  
Psychological Effects ◽  
Complete Product ◽  
The Arts ◽  
The Creation ◽  
Role Of Parents

The report describes the steps for creating a musical tale by children in the art studios of „Art Workshop“, Shumen. These studios are led by students volunteers related to the arts from pedagogical department of Shumen University, and are realized in time for optional activities in the school where the child studies. The stages of creating a complete product with the help of different arts are traced – from the birth of the idea; the creation of a fairy tale plot by the children; the characterization of the fairy-tale characters; dressing them in movement, song and speech; creating sets and costumes and creating a finished product to present on stage. The role of parents as a link and a necessary helper for children and leaders is also considered, as well as the positive psychological effects that this cooperation creates.

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