TMK1-based auxin signaling regulates abscisic acid responses via phosphorylating ABI1/2 in Arabidopsis

Differential concentrations of phytohormone trigger distinct outputs, which provides a mechanism for the plasticity of plant development and an adaptation strategy among plants to changing environments. However, the underlying mechanisms of the differential responses remain unclear. Here we report that a high concentration of auxin, distinct from the effect of low auxin concentration, enhances abscisic acid (ABA) responses in Arabidopsis thaliana, which partially relies on TRANS-MEMBERANE KINASE 1 (TMK1), a key regulator in auxin signaling. We show that high auxin and TMK1 play essential and positive roles in ABA signaling through regulating ABA INSENSITIVE 1 and 2 (ABI1/2), two negative regulators of the ABA pathway. TMK1 inhibits the phosphatase activity of ABI2 by direct phosphorylation of threonine 321 (T321), a conserved phosphorylation site in ABI2 proteins, whose phosphorylation status is important for both auxin and ABA responses. This TMK1-dependent auxin signaling in the regulation of ABA responses provides a possible mechanism underlying the high auxin responses in plants and an alternative mechanism involved in the coordination between auxin and ABA signaling.

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A Screen for Genes That Function in Abscisic Acid Signaling in Arabidopsis thaliana

Genetics ◽

10.1093/genetics/161.3.1247 ◽

2002 ◽

Vol 161 (3) ◽

pp. 1247-1255 ◽

Cited By ~ 1

Author(s):

Eiji Nambara ◽

Masaharu Suzuki ◽

Suzanne Abrams ◽

Donald R McCarty ◽

Yuji Kamiya ◽

...

Keyword(s):

Abscisic Acid ◽

Growth And Development ◽

Plant Hormone ◽

The Other ◽

Aba Signaling ◽

Wild Type ◽

Plant Growth And Development ◽

Diverse Range ◽

Abscisic Acid Signaling ◽

Aba Insensitive

Abstract The plant hormone abscisic acid (ABA) controls many aspects of plant growth and development under a diverse range of environmental conditions. To identify genes functioning in ABA signaling, we have carried out a screen for mutants that takes advantage of the ability of wild-type Arabidopsis seeds to respond to (−)-(R)-ABA, an enantiomer of the natural (+)-(S)-ABA. The premise of the screen was to identify mutations that preferentially alter their germination response in the presence of one stereoisomer vs. the other. Twenty-six mutants were identified and genetic analysis on 23 lines defines two new loci, designated CHOTTO1 and CHOTTO2, and a collection of new mutant alleles of the ABA-insensitive genes, ABI3, ABI4, and ABI5. The abi5 alleles are less sensitive to (+)-ABA than to (−)-ABA. In contrast, the abi3 alleles exhibit a variety of differences in response to the ABA isomers. Genetic and molecular analysis of these alleles suggests that the ABI3 transcription factor may perceive multiple ABA signals.

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Brassinosteroids repress the seed maturation program during the seed-to-seedling transition

Plant Physiology ◽

10.1093/plphys/kiab089 ◽

2021 ◽

Author(s):

Jiuxiao Ruan ◽

Huhui Chen ◽

Tao Zhu ◽

Yaoguang Yu ◽

Yawen Lei ◽

...

Keyword(s):

Arabidopsis Thaliana ◽

Transcription Factor ◽

Abscisic Acid ◽

Plant Hormone ◽

Flowering Plants ◽

Seed Maturation ◽

Domain Protein ◽

Abscisic Acid Insensitive3 ◽

Underlying Mechanisms ◽

Embryonic Structure

Abstract In flowering plants, repression of the seed maturation program is essential for the transition from the seed to the vegetative phase, but the underlying mechanisms remain poorly understood. The B3-domain protein VIVIPAROUS1/ABSCISIC ACID-INSENSITIVE3-LIKE 1 (VAL1) is involved in repressing the seed maturation program. Here we uncovered a molecular network triggered by the plant hormone brassinosteroid (BR) that inhibits the seed maturation program during the seed-to-seedling transition in Arabidopsis (Arabidopsis thaliana). val1-2 mutant seedlings treated with a BR biosynthesis inhibitor form embryonic structures, whereas BR signaling gain-of-function mutations rescue the embryonic structure trait. Furthermore, the BR-activated transcription factors BRI1-EMS-SUPPRESSOR 1 and BRASSINAZOLE-RESISTANT 1 bind directly to the promoter of AGAMOUS-LIKE15 (AGL15), which encodes a transcription factor involved in activating the seed maturation program, and suppress its expression. Genetic analysis indicated that BR signaling is epistatic to AGL15 and represses the seed maturation program by downregulating AGL15. Finally, we showed that the BR-mediated pathway functions synergistically with the VAL1/2-mediated pathway to ensure the full repression of the seed maturation program. Together, our work uncovered a mechanism underlying the suppression of the seed maturation program, shedding light on how BR promotes seedling growth.

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Low ABA concentration promotes root growth and hydrotropism through relief of ABA INSENSITIVE 1-mediated inhibition of plasma membrane H+-ATPase 2

Science Advances ◽

10.1126/sciadv.abd4113 ◽

2021 ◽

Vol 7 (12) ◽

pp. eabd4113

Author(s):

Rui Miao ◽

Wei Yuan ◽

Yue Wang ◽

Irene Garcia-Maquilon ◽

Xiaolin Dang ◽

...

Keyword(s):

Plasma Membrane ◽

Root Growth ◽

Experimental System ◽

Aba Signaling ◽

Wild Type ◽

Normal Medium ◽

C Terminus ◽

Quadruple Mutant ◽

Aba Insensitive ◽

Aba Receptors

The hab1-1abi1-2abi2-2pp2ca-1 quadruple mutant (Qabi2-2) seedlings lacking key negative regulators of ABA signaling, namely, clade A protein phosphatases type 2C (PP2Cs), show more apoplastic H+ efflux in roots and display an enhanced root growth under normal medium or water stress medium compared to the wild type. The presence of low ABA concentration (0.1 micromolar), inhibiting PP2C activity via monomeric ABA receptors, enhances root apoplastic H+ efflux and growth of the wild type, resembling the Qabi2-2 phenotype in normal medium. Qabi2-2 seedlings also demonstrate increased hydrotropism compared to the wild type in obliquely-oriented hydrotropic experimental system, and asymmetric H+ efflux in root elongation zone is crucial for root hydrotropism. Moreover, we reveal that Arabidopsis ABA-insensitive 1, a key PP2C in ABA signaling, interacts directly with the C terminus of Arabidopsis plasma membrane H+-dependent adenosine triphosphatase 2 (AHA2) and dephosphorylates its penultimate threonine residue (Thr947), whose dephosphorylation negatively regulates AHA2.

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Under salt stress guard cells rewire ion transport and abscisic acid (ABA) signaling

New Phytologist ◽

10.1111/nph.17376 ◽

2021 ◽

Author(s):

Sohail M. Karimi ◽

Matthias Freund ◽

Brittney M. Wager ◽

Michael Knoblauch ◽

Jörg Fromm ◽

...

Keyword(s):

Abscisic Acid ◽

Salt Stress ◽

Ion Transport ◽

Guard Cells ◽

Aba Signaling

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Influence of Abscisic Acid and Sucrose on Somatic Embryogenesis in CactusCopiapoa tenuissimaRitt. formamostruosa

The Scientific World JOURNAL ◽

10.1155/2013/513985 ◽

2013 ◽

Vol 2013 ◽

pp. 1-7 ◽

Cited By ~ 13

Author(s):

J. Lema-Rumińska ◽

K. Goncerzewicz ◽

M. Gabriel

Keyword(s):

Somatic Embryogenesis ◽

Abscisic Acid ◽

Somatic Embryos ◽

Sucrose Concentration ◽

Turgor Pressure ◽

Direct Somatic Embryogenesis ◽

Fresh Weight ◽

High Concentration ◽

Globular Stage ◽

Indirect Somatic Embryogenesis

Having produced the embryos of cactusCopiapoa tenuissimaRitt. formamonstruosaat the globular stage and callus, we investigated the effect of abscisic acid (ABA) in the following concentrations: 0, 0.1, 1, 10, and 100 μM on successive stages of direct (DSE) and indirect somatic embryogenesis (ISE). In the indirect somatic embryogenesis process we also investigated a combined effect of ABA (0, 0.1, 1 μM) and sucrose (1, 3, 5%). The results showed that a low concentration of ABA (0-1 μM) stimulates the elongation of embryos at the globular stage and the number of correct embryos in direct somatic embryogenesis, while a high ABA concentration (10–100 μM) results in growth inhibition and turgor pressure loss of somatic embryos. The indirect somatic embryogenesis study in this cactus suggests that lower ABA concentrations enhance the increase in calli fresh weight, while a high concentration of 10 μM ABA or more changes calli color and decreases its proliferation rate. However, in the case of indirect somatic embryogenesis, ABA had no effect on the number of somatic embryos and their maturation. Nevertheless, we found a positive effect of sucrose concentration for both the number of somatic embryos and the increase in calli fresh weight.

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AtMybL-O modulates abscisic acid biosynthesis to optimize plant growth and ABA signaling in response to drought stress

Applied Biological Chemistry ◽

10.1007/s13765-018-0376-2 ◽

2018 ◽

Vol 61 (4) ◽

pp. 473-477 ◽

Cited By ~ 6

Author(s):

Chan Young Jeong ◽

Won Je Lee ◽

Hai An Truong ◽

Cao Sơn Trịnh ◽

Suk-Whan Hong ◽

...

Keyword(s):

Abscisic Acid ◽

Drought Stress ◽

Plant Growth ◽

Aba Signaling ◽

Acid Biosynthesis ◽

Abscisic Acid Biosynthesis

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Abscisic Acid and Flowering Regulation: Many Targets, Different Places

International Journal of Molecular Sciences ◽

10.3390/ijms21249700 ◽

2020 ◽

Vol 21 (24) ◽

pp. 9700

Author(s):

Damiano Martignago ◽

Beata Siemiatkowska ◽

Alessandra Lombardi ◽

Lucio Conti

Keyword(s):

Abscisic Acid ◽

Adaptive Strategy ◽

Spatial Context ◽

Central Question ◽

Aba Signaling ◽

Flowering Locus T ◽

Flowering Genes ◽

Potential Benefits ◽

Dry Climates ◽

Flowering Regulation

Plants can react to drought stress by anticipating flowering, an adaptive strategy for plant survival in dry climates known as drought escape (DE). In Arabidopsis, the study of DE brought to surface the involvement of abscisic acid (ABA) in controlling the floral transition. A central question concerns how and in what spatial context can ABA signals affect the floral network. In the leaf, ABA signaling affects flowering genes responsible for the production of the main florigen FLOWERING LOCUS T (FT). At the shoot apex, FD and FD-like transcription factors interact with FT and FT-like proteins to regulate ABA responses. This knowledge will help separate general and specific roles of ABA signaling with potential benefits to both biology and agriculture.

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ABI5 regulates ABA-induced anthocyanin biosynthesis by modulating the MYB1-bHLH3 complex in apple

Journal of Experimental Botany ◽

10.1093/jxb/eraa525 ◽

2020 ◽

Author(s):

Jian-Ping An ◽

Xiao-Wei Zhang ◽

Ya-Jing Liu ◽

Xiao-Fei Wang ◽

Chun-Xiang You ◽

...

Keyword(s):

Abscisic Acid ◽

Target Genes ◽

Anthocyanin Biosynthesis ◽

Aba Signaling ◽

Plant Growth And Development ◽

Biochemical Tests ◽

Positive Role ◽

Helix Loop Helix ◽

Transcriptional Regulatory ◽

Transcriptional Regulatory Mechanisms

Abstract Abscisic acid (ABA) induces anthocyanin biosynthesis in many plant species. However, the molecular mechanism of ABA-regulated anthocyanin biosynthesis remains unclear. As a crucial regulator of ABA signaling, ABSCISIC ACID-INSENSITIVE5 (ABI5) is involved in many aspects of plant growth and development, yet its regulation of anthocyanin biosynthesis has not been elucidated. In this study, we found that MdABI5, the apple homolog of Arabidopsis ABI5, positively regulated ABA-induced anthocyanin biosynthesis. A series of biochemical tests showed that MdABI5 specifically interacts with basic helix-loop-helix 3 (MdbHLH3), a positive regulator of anthocyanin biosynthesis. MdABI5 enhanced the binding of MdbHLH3 to its target genes dihydroflavonol 4-reductase (MdDFR) and UDP flavonoid glucosyl transferase (MdUF3GT). In addition, MdABI5 directly bound to the promoter of MdbHLH3 to activate its expression. Moreover, MdABI5 enhanced ABA-promoted interaction between MdMYB1 and MdbHLH3. Finally, antisense suppression of MdbHLH3 significantly reduced anthocyanin biosynthesis promoted by MdABI5, indicating that MdABI5-promoted anthocyanin biosynthesis was dependent on MdbHLH3. Taken together, our data suggest that MdABI5 plays a positive role in ABA-induced anthocyanin biosynthesis by modulating the MdbHLH3-MdMYB1 complex. Our work broadens the regulatory network of ABA-mediated anthocyanin biosynthesis, providing new insights to further study the transcriptional regulatory mechanisms behind this process.

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Arabidopsis exoribonuclease USB1 interacts with the PPR-domain protein SOAR1 to negatively regulate abscisic acid signaling

Journal of Experimental Botany ◽

10.1093/jxb/eraa315 ◽

2020 ◽

Vol 71 (19) ◽

pp. 5837-5851

Author(s):

Yu Ma ◽

Shang Zhang ◽

Chao Bi ◽

Chao Mei ◽

Shang-Chuan Jiang ◽

...

Keyword(s):

Abscisic Acid ◽

Regulation Of Gene Expression ◽

Mrna Splicing ◽

Plant Responses ◽

Aba Signaling ◽

Pentatricopeptide Repeat ◽

Spliceosome Assembly ◽

Early Seedling ◽

Post Transcriptional Regulation ◽

Early Seedling Development

Abstract Signaling by the phytohormone abscisic acid (ABA) involves pre-mRNA splicing, a key process of post-transcriptional regulation of gene expression. However, the regulatory mechanism of alternative pre-mRNA splicing in ABA signaling remains largely unknown. We previously identified a pentatricopeptide repeat protein SOAR1 (suppressor of the ABAR-overexpressor 1) as a crucial player downstream of ABAR (putative ABA receptor) in ABA signaling. In this study, we identified a SOAR1 interaction partner USB1, which is an exoribonuclease catalyzing U6 production for spliceosome assembly. We reveal that together USB1 and SOAR1 negatively regulate ABA signaling in early seedling development. USB1 and SOAR1 are both required for the splicing of transcripts of numerous genes, including those involved in ABA signaling pathways, suggesting that USB1 and SOAR1 collaborate to regulate ABA signaling by affecting spliceosome assembly. These findings provide important new insights into the mechanistic control of alternative pre-mRNA splicing in the regulation of ABA-mediated plant responses to environmental cues.

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