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1.
Decoding ABA and osmostress signalling in plants from an evolutionary point of view.
Komatsu, K, Takezawa, D, Sakata, Y
Plant, cell & environment. 2020;(12):2894-2911
Abstract
The plant hormone abscisic acid (ABA) is fundamental for land plant adaptation to water-limited conditions. Osmostress, such as drought, induces ABA accumulation in angiosperms, triggering physiological responses such as stomata closure. The core components of angiosperm ABA signalling are soluble ABA receptors, group A protein phosphatase type 2C and SNF1-related protein kinase2 (SnRK2). ABA also has various functions in non-angiosperms, however, suggesting that its role in adaptation to land may not have been angiosperm-specific. Indeed, among land plants, the core ABA signalling components are evolutionarily conserved, implying their presence in a common ancestor. Results of ongoing functional genomics studies of ABA signalling components in bryophytes and algae have expanded our understanding of the evolutionary role of ABA signalling, with genome sequencing uncovering the ABA core module even in algae. In this review, we describe recent discoveries involving the ABA core module in non-angiosperms, tracing the footprints of how ABA evolved as a phytohormone. We also cover the latest findings on Raf-like kinases as upstream regulators of the core ABA module component SnRK2. Finally, we discuss the origin of ABA signalling from an evolutionary perspective.
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2.
Fusarium oxysporum infection activates the plastidial branch of the terpenoid biosynthesis pathway in flax, leading to increased ABA synthesis.
Boba, A, Kostyn, K, Kozak, B, Wojtasik, W, Preisner, M, Prescha, A, Gola, EM, Lysh, D, Dudek, B, Szopa, J, et al
Planta. 2020;(2):50
Abstract
Upregulation of the terpenoid pathway and increased ABA content in flax upon Fusarium infection leads to activation of the early plant's response (PR genes, cell wall remodeling, and redox status). Plants have developed a number of defense strategies against the adverse effects of fungi such as Fusarium oxysporum. One such defense is the production of antioxidant secondary metabolites, which fall into two main groups: the phenylpropanoids and the terpenoids. While functions and biosynthesis of phenylpropanoids have been extensively studied, very little is known about the genes controlling the terpenoid synthesis pathway in flax. They can serve as antioxidants, but are also substrates for a plethora of different compounds, including those of regulatory functions, like ABA. ABA's function during pathogen attack remains obscure and often depends on the specific plant-pathogen interactions. In our study we showed that in flax the non-mevalonate pathway is strongly activated in the early hours of pathogen infection and that there is a redirection of metabolites towards ABA synthesis. The elevated synthesis of ABA correlates with flax resistance to F. oxysporum, thus we suggest ABA to be a positive regulator of the plant's early response to the infection.
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3.
A selective autophagy cargo receptor NBR1 modulates abscisic acid signalling in Arabidopsis thaliana.
Tarnowski, L, Rodriguez, MC, Brzywczy, J, Piecho-Kabacik, M, Krčkova, Z, Martinec, J, Wawrzynska, A, Sirko, A
Scientific reports. 2020;(1):7778
Abstract
The plant selective autophagy cargo receptor neighbour of breast cancer 1 gene (NBR1) has been scarcely studied in the context of abiotic stress. We wanted to expand this knowledge by using Arabidopsis thaliana lines with constitutive ectopic overexpression of the AtNBR1 gene (OX lines) and the AtNBR1 Knock-Out (KO lines). Transcriptomic analysis of the shoots and roots of one representative OX line indicated differences in gene expression relative to the parental (WT) line. In shoots, many differentially expressed genes, either up- or down-regulated, were involved in responses to stimuli and stress. In roots the most significant difference was observed in a set of downregulated genes that is mainly related to translation and formation of ribonucleoprotein complexes. The link between AtNBR1 overexpression and abscisic acid (ABA) signalling was suggested by an interaction network analysis of these differentially expressed genes. Most hubs of this network were associated with ABA signalling. Although transcriptomic analysis suggested enhancement of ABA responses, ABA levels were unchanged in the OX shoots. Moreover, some of the phenotypes of the OX (delayed germination, increased number of closed stomata) and the KO lines (increased number of lateral root initiation sites) indicate that AtNBR1 is essential for fine-tuning of the ABA signalling pathway. The interaction of AtNBR1 with three regulatory proteins of ABA pathway (ABI3, ABI4 and ABI5) was observed in planta. It suggests that AtNBR1 might play role in maintaining the balance of ABA signalling by controlling their level and/or activity.
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4.
Auxin-Abscisic Acid Interactions in Plant Growth and Development.
Emenecker, RJ, Strader, LC
Biomolecules. 2020;(2)
Abstract
Plant hormones regulate many aspects of plant growth, development, and response to biotic and abiotic stress. Much research has gone into our understanding of individual plant hormones, focusing primarily on their mechanisms of action and the processes that they regulate. However, recent research has begun to focus on a more complex problem; how various plant hormones work together to regulate growth and developmental processes. In this review, we focus on two phytohormones, abscisic acid (ABA) and auxin. We begin with brief overviews of the hormones individually, followed by in depth analyses of interactions between auxin and ABA, focusing on interactions in individual tissues and how these interactions are occurring where possible. Finally, we end with a brief discussion and future prospects for the field.
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5.
Abscisic Acid Treatment in Patients with Prediabetes.
Derosa, G, Maffioli, P, D'Angelo, A, Preti, PS, Tenore, G, Novellino, E
Nutrients. 2020;(10)
Abstract
AIM: to evaluate the effects of abscisic acid (ABA), contained in dwarf peaches, on the regression of impaired fasting glucose (IFG) or impaired glucose tolerance (IGT) conditions. MATERIALS AND METHODS sixty-five patients with IFG or IGT were randomized to take ABA or placebo for 3 months. We evaluated: fasting plasma glucose (FPG), postprandial plasma glucose (PPG), glycated hemoglobin (HbA1c), fasting plasma insulin (FPI), homeostatic model assessment of insulin resistance (HOMA-IR), lipid profile and high sensitivity C-reactive protein (Hs-CRP). At baseline, and after 3 months, all patients underwent an oral glucose tolerance test (OGTT), an euglycemic hyperinsulinemic clamp, and a glucagon test. RESULTS a significant reduction of HbA1c, FPG, PPG, FPI and HOMA-IR was observed in the ABA group. After 3 months, 26.7% of patients returned to a normal glycemic status in the ABA group versus zero patients in placebo group; 20.0% were classified as IFG and 53.3% as IGT in the nutraceutical group versus 33.3% and 63.3% in the placebo group. The M value was higher in the ABA group at the end of the treatment. Finally, Hs-CRP was reduced after 3 months of ABA consumption. CONCLUSIONS abscisic acid can be effective in ameliorating glyco-metabolic compensation and in reducing inflammatory status in patients with IFG or IGT.
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6.
Balancing growth and adaptation to stress: Crosstalk between brassinosteroid and abscisic acid signaling.
Wang, Q, Yu, F, Xie, Q
Plant, cell & environment. 2020;(10):2325-2335
Abstract
Plant growth and development are plastic and canadapt to environmental changes. In this process different plant hormones coordinate to modulate plant growth and environmental interactions. In this article, we describe the individual brassinosteroid (BR) and abscisic acid (ABA) signaling pathways, emphasize the specific regulatory mechanisms between ABA and BR responses and discuss how both phytohormones coordinate growth, development and stress responses in plants. BR signaling is essential for plant development, while ABA signaling is activated to ensure plants survive stress. The crosstalk between BR and ABA, especially protein phosphorylation, protein stability control and downstream transcription control of key components of both pathways are discussed in terms of modulating plant development and stress adaptation.
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7.
Abscisic Acid and Jasmonate Metabolisms Are Jointly Regulated During Senescence in Roots and Leaves of Populus trichocarpa.
Wojciechowska, N, Wilmowicz, E, Marzec-Schmidt, K, Ludwików, A, Bagniewska-Zadworna, A
International journal of molecular sciences. 2020;(6)
Abstract
Plant senescence is a highly regulated process that allows nutrients to be mobilized from dying tissues to other organs. Despite that senescence has been extensively studied in leaves, the senescence of ephemeral organs located underground is still poorly understood, especially in the context of phytohormone engagement. The present study focused on filling this knowledge gap by examining the roles of abscisic acid (ABA) and jasmonate in the regulation of senescence of fine, absorptive roots and leaves of Populus trichocarpa. Immunohistochemical (IHC), chromatographic, and molecular methods were utilized to achieve this objective. A transcriptomic analysis identified significant changes in gene expression that were associated with the metabolism and signal transduction of phytohormones, especially ABA and jasmonate. The increased level of these phytohormones during senescence was detected in both organs and was confirmed by IHC. Based on the obtained data, we suggest that phytohormonal regulation of senescence in roots and leaves is organ-specific. We have shown that the regulation of ABA and JA metabolism is tightly regulated during senescence processes in both leaves and roots. The results were discussed with respect to the role of ABA in cold tolerance and the role of JA in resistance to pathogens.
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8.
Linking Brassinosteroid and ABA Signaling in the Context of Stress Acclimation.
Bulgakov, VP, Avramenko, TV
International journal of molecular sciences. 2020;(14)
Abstract
The important regulatory role of brassinosteroids (BRs) in the mechanisms of tolerance to multiple stresses is well known. Growing data indicate that the phenomenon of BR-mediated drought stress tolerance can be explained by the generation of stress memory (the process known as 'priming' or 'acclimation'). In this review, we summarize the data on BR and abscisic acid (ABA) signaling to show the interconnection between the pathways in the stress memory acquisition. Starting from brassinosteroid receptors brassinosteroid insensitive 1 (BRI1) and receptor-like protein kinase BRI1-like 3 (BRL3) and propagating through BR-signaling kinases 1 and 3 (BSK1/3) → BRI1 suppressor 1 (BSU1) -‖ brassinosteroid insensitive 2 (BIN2) pathway, BR and ABA signaling are linked through BIN2 kinase. Bioinformatics data suggest possible modules by which BRs can affect the memory to drought or cold stresses. These are the BIN2 → SNF1-related protein kinases (SnRK2s) → abscisic acid responsive elements-binding factor 2 (ABF2) module; BRI1-EMS-supressor 1 (BES1) or brassinazole-resistant 1 protein (BZR1)-TOPLESS (TPL)-histone deacetylase 19 (HDA19) repressor complexes, and the BZR1/BES1 → flowering locus C (FLC)/flowering time control protein FCA (FCA) pathway. Acclimation processes can be also regulated by BR signaling associated with stress reactions caused by an accumulation of misfolded proteins in the endoplasmic reticulum.
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9.
Abscisic acid dynamics, signaling, and functions in plants.
Chen, K, Li, GJ, Bressan, RA, Song, CP, Zhu, JK, Zhao, Y
Journal of integrative plant biology. 2020;(1):25-54
Abstract
Abscisic acid (ABA) is an important phytohormone regulating plant growth, development, and stress responses. It has an essential role in multiple physiological processes of plants, such as stomatal closure, cuticular wax accumulation, leaf senescence, bud dormancy, seed germination, osmotic regulation, and growth inhibition among many others. Abscisic acid controls downstream responses to abiotic and biotic environmental changes through both transcriptional and posttranscriptional mechanisms. During the past 20 years, ABA biosynthesis and many of its signaling pathways have been well characterized. Here we review the dynamics of ABA metabolic pools and signaling that affects many of its physiological functions.
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10.
Abscisic Acid-Triggered Persulfidation of the Cys Protease ATG4 Mediates Regulation of Autophagy by Sulfide.
Laureano-Marín, AM, Aroca, Á, Pérez-Pérez, ME, Yruela, I, Jurado-Flores, A, Moreno, I, Crespo, JL, Romero, LC, Gotor, C
The Plant cell. 2020;(12):3902-3920
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Abstract
Hydrogen sulfide is a signaling molecule that regulates essential processes in plants, such as autophagy. In Arabidopsis (Arabidopsis thaliana), hydrogen sulfide negatively regulates autophagy independently of reactive oxygen species via an unknown mechanism. Comparative and quantitative proteomic analysis was used to detect abscisic acid-triggered persulfidation that reveals a main role in the control of autophagy mediated by the autophagy-related (ATG) Cys protease AtATG4a. This protease undergoes specific persulfidation of Cys170 that is a part of the characteristic catalytic Cys-His-Asp triad of Cys proteases. Regulation of the ATG4 activity by persulfidation was tested in a heterologous assay using the Chlamydomonas reinhardtii CrATG8 protein as a substrate. Sulfide significantly and reversibly inactivates AtATG4a. The biological significance of the reversible inhibition of the ATG4 by sulfide is supported by the results obtained in Arabidopsis leaves under basal and autophagy-activating conditions. A significant increase in the overall ATG4 proteolytic activity in Arabidopsis was detected under nitrogen starvation and osmotic stress and can be inhibited by sulfide. Therefore, the data strongly suggest that the negative regulation of autophagy by sulfide is mediated by specific persulfidation of the ATG4 protease.