Auxin represents a key signal in plants, regulating almost every aspect of their growth and development. Major breakthroughs have been made dissecting the molecular basis of auxin transport, perception, and response. In contrast, how plants control the metabolism and homeostasis of the major form of auxin in plants, indole-3-acetic acid (IAA), remains unclear. In this paper, we initially describe the function of the Arabidopsis thaliana gene DIOXYGENASE FOR AUXIN OXIDATION 1 (AtDAO1). Transcriptional and translational reporter lines revealed that AtDAO1 encodes a highly root-expressed, cytoplasmically localized IAA oxidase. Stable isotope-labeled IAA feeding studies of loss and gain of function AtDAO1 lines showed that this oxidase represents the major regulator of auxin degradation to 2-oxoindole-3-acetic acid (oxIAA) in Arabidopsis Surprisingly, AtDAO1 loss and gain of function lines exhibited relatively subtle auxin-related phenotypes, such as altered root hair length. Metabolite profiling of mutant lines revealed that disrupting AtDAO1 regulation resulted in major changes in steady-state levels of oxIAA and IAA conjugates but not IAA. Hence, IAA conjugation and catabolism seem to regulate auxin levels in Arabidopsis in a highly redundant manner. We observed that transcripts of AtDOA1 IAA oxidase and GH3 IAA-conjugating enzymes are auxin-inducible, providing a molecular basis for their observed functional redundancy. We conclude that the AtDAO1 gene plays a key role regulating auxin homeostasis in Arabidopsis, acting in concert with GH3 genes, to maintain auxin concentration at optimal levels for plant growth and development.
- MeSH
- Arabidopsis enzymologie genetika MeSH
- biologické modely MeSH
- dioxygenasy metabolismus MeSH
- fenotyp MeSH
- fylogeneze MeSH
- homeostáza * MeSH
- kořeny rostlin metabolismus MeSH
- kyseliny indoloctové metabolismus MeSH
- messenger RNA genetika metabolismus MeSH
- metabolomika MeSH
- mutace genetika MeSH
- oxidace-redukce MeSH
- promotorové oblasti (genetika) genetika MeSH
- proteiny huseníčku chemie genetika metabolismus MeSH
- regulace genové exprese u rostlin MeSH
- rostlinné geny * MeSH
- sekvence aminokyselin MeSH
- semenáček metabolismus MeSH
- výhonky rostlin metabolismus MeSH
- zelené fluorescenční proteiny metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Auxin phytohormones control most aspects of plant development through a complex and interconnected signaling network. In the presence of auxin, AUXIN/INDOLE-3-ACETIC ACID (AUX/IAA) transcriptional repressors are targeted for degradation by the SKP1-CULLIN1-F-BOX (SCF) ubiquitin-protein ligases containing TRANSPORT INHIBITOR RESISTANT 1/AUXIN SIGNALING F-BOX (TIR1/AFB). CULLIN1-neddylation is required for SCFTIR1/AFB functionality, as exemplified by mutants deficient in the NEDD8-activating enzyme subunit AUXIN-RESISTANT 1 (AXR1). Here, we report a chemical biology screen that identifies small molecules requiring AXR1 to modulate plant development. We selected four molecules of interest, RubNeddin 1 to 4 (RN1 to -4), among which RN3 and RN4 trigger selective auxin responses at transcriptional, biochemical, and morphological levels. This selective activity is explained by their ability to consistently promote the interaction between TIR1 and a specific subset of AUX/IAA proteins, stimulating the degradation of particular AUX/IAA combinations. Finally, we performed a genetic screen using RN4, the RN with the greatest potential for dissecting auxin perception, which revealed that the chromatin remodeling ATPase BRAHMA is implicated in auxin-mediated apical hook development. These results demonstrate the power of selective auxin agonists to dissect auxin perception for plant developmental functions, as well as offering opportunities to discover new molecular players involved in auxin responses.
- MeSH
- Arabidopsis genetika metabolismus MeSH
- F-box proteiny metabolismus MeSH
- genetická transkripce účinky léků MeSH
- geneticky modifikované rostliny genetika MeSH
- kyseliny indoloctové metabolismus MeSH
- protein NEDD8 genetika MeSH
- proteinligasy komplexu SCF metabolismus MeSH
- proteiny huseníčku genetika metabolismus MeSH
- proteolýza * MeSH
- receptory buněčného povrchu metabolismus MeSH
- regulace genové exprese u rostlin MeSH
- regulátory růstu rostlin genetika metabolismus MeSH
- semenáček metabolismus MeSH
- signální transdukce MeSH
- transkripční faktory metabolismus MeSH
- vývoj rostlin genetika fyziologie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, N.I.H., Extramural MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
Root-hair growth and development regulated by soil microbes is associated with auxin. In this background, we hypothesized that mycorrhizal fungal inoculation induces greater root-hair growth through stimulated auxin synthesis and transport under water stress conditions. Trifoliate orange (Poncirus trifoliata) was inoculated with an arbuscular mycorrhizal (AM) fungus (Funneliformis mosseae) under well-watered (WW) and drought stress (DS) for 9 weeks. Compared with non-AM seedlings, AM seedlings displayed significantly higher density, length, and diameter of root hairs and root indoleacetic acid (IAA) level, whereas lower total root IAA efflux, regardless of soil moisture status. Root PtYUC3 and PtYUC8 involved in IAA biosynthesis were up-regulated by mycorrhization under WW and DS, whereas AM-modulated expression in PtTAA1, PtTAR2, PtYUC4, and PtYUC6 depended on status of soil moisture. Mycorrhizal inoculation down-regulated the transcript level of root auxin efflux carriers like PtPIN1 and PtPIN3, whereas significantly up-regulated the expression of root auxin-species influx carriers like PtABCB19 and PtLAX2 under DS. These results indicated that AMF-stimulated greater root-hair growth of trifoliate orange under DS that is independent on AMF species is related with mycorrhiza-modulated auxin synthesis and transport, which benefits the host plant to enhance drought tolerance.
- MeSH
- biologický transport MeSH
- fyziologický stres * MeSH
- Glomeromycota růst a vývoj fyziologie MeSH
- kyseliny indoloctové metabolismus MeSH
- messenger RNA genetika metabolismus MeSH
- mykorhiza růst a vývoj fyziologie MeSH
- období sucha * MeSH
- počet mikrobiálních kolonií MeSH
- Poncirus genetika růst a vývoj mikrobiologie fyziologie MeSH
- regulace genové exprese u rostlin MeSH
- rostlinné geny MeSH
- rostlinné proteiny genetika metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
In Arabidopsis thaliana, canonical auxin-dependent gene regulation is mediated by 23 transcription factors from the AUXIN RESPONSE FACTOR (ARF) family that interact with auxin/indole acetic acid repressors (Aux/IAAs), which themselves form co-receptor complexes with one of six TRANSPORT INHIBITOR1/AUXIN-SIGNALLING F-BOX (TIR1/AFB) proteins. Different combinations of co-receptors drive specific sensing outputs, allowing auxin to control a myriad of processes. ARF6 and ARF8 are positive regulators of adventitious root initiation upstream of jasmonate, but the exact auxin co-receptor complexes controlling the transcriptional activity of these proteins has remained unknown. Here, using loss-of-function mutants we show that three Aux/IAA genes, IAA6, IAA9, and IAA17, act additively in the control of adventitious root (AR) initiation. These three IAA proteins interact with ARF6 and/or ARF8 and likely repress their activity in AR development. We show that TIR1 and AFB2 are positive regulators of AR formation and TIR1 plays a dual role in the control of jasmonic acid (JA) biosynthesis and conjugation, as several JA biosynthesis genes are up-regulated in the tir1-1 mutant. These results lead us to propose that in the presence of auxin, TIR1 and AFB2 form specific sensing complexes with IAA6, IAA9, and/or IAA17 to modulate JA homeostasis and control AR initiation.
- MeSH
- Arabidopsis cytologie genetika růst a vývoj metabolismus MeSH
- F-box proteiny metabolismus MeSH
- hypokotyl metabolismus MeSH
- kořeny rostlin růst a vývoj MeSH
- kyseliny indoloctové metabolismus MeSH
- proteiny huseníčku metabolismus MeSH
- receptory buněčného povrchu metabolismus MeSH
- regulace genové exprese u rostlin MeSH
- signální transdukce * MeSH
- stabilita proteinů MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Peptides derived from non-functional precursors play important roles in various developmental processes, but also in (a)biotic stress signaling. Our (phospho)proteome-wide analyses of C-TERMINALLY ENCODED PEPTIDE 5 (CEP5)-mediated changes revealed an impact on abiotic stress-related processes. Drought has a dramatic impact on plant growth, development and reproduction, and the plant hormone auxin plays a role in drought responses. Our genetic, physiological, biochemical, and pharmacological results demonstrated that CEP5-mediated signaling is relevant for osmotic and drought stress tolerance in Arabidopsis, and that CEP5 specifically counteracts auxin effects. Specifically, we found that CEP5 signaling stabilizes AUX/IAA transcriptional repressors, suggesting the existence of a novel peptide-dependent control mechanism that tunes auxin signaling. These observations align with the recently described role of AUX/IAAs in stress tolerance and provide a novel role for CEP5 in osmotic and drought stress tolerance.
- MeSH
- Arabidopsis genetika metabolismus fyziologie MeSH
- biologický transport genetika MeSH
- fosfoproteiny metabolismus MeSH
- fyziologická adaptace * genetika MeSH
- fyziologický stres * genetika MeSH
- genetická transkripce MeSH
- kyseliny indoloctové metabolismus MeSH
- období sucha MeSH
- osmóza MeSH
- peptidy metabolismus MeSH
- proteasomový endopeptidasový komplex metabolismus MeSH
- proteiny huseníčku metabolismus MeSH
- proteom metabolismus MeSH
- proteomika * MeSH
- regulace genové exprese u rostlin MeSH
- semenáček růst a vývoj MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, N.I.H., Extramural MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
The herbicide 2,4-D exhibits an auxinic activity and therefore can be used as a synthetic and traceable analog to study auxin-related responses. Here we identified that not only exogenous 2,4-D but also its amide-linked metabolite 2,4-D-Glu displayed an inhibitory effect on plant growth via the TIR1/AFB auxin-mediated signaling pathway. To further investigate 2,4-D metabolite conversion, identity and activity, we have developed a novel purification procedure based on the combination of ion exchange and immuno-specific sorbents combined with a sensitive liquid chromatography-mass spectrometry method. In 2,4-D treated samples, 2,4-D-Glu and 2,4-D-Asp were detected at 100-fold lower concentrations compared to 2,4-D levels, showing that 2,4-D can be metabolized in the plant. Moreover, 2,4-D-Asp and 2,4-D-Glu were identified as reversible forms of 2,4-D homeostasis that can be converted to free 2,4-D. This work paves the way to new studies of auxin action in plant development.
- MeSH
- Arabidopsis účinky léků růst a vývoj metabolismus MeSH
- F-box proteiny genetika metabolismus MeSH
- herbicidy farmakologie MeSH
- homeostáza MeSH
- kořeny rostlin účinky léků růst a vývoj metabolismus MeSH
- kyselina 2,4-dichlorfenoxyoctová farmakologie MeSH
- kyseliny indoloctové metabolismus MeSH
- proteiny huseníčku genetika metabolismus MeSH
- receptory buněčného povrchu genetika metabolismus MeSH
- regulace genové exprese u rostlin MeSH
- regulátory růstu rostlin farmakologie MeSH
- semenáček účinky léků růst a vývoj metabolismus MeSH
- signální transdukce účinky léků MeSH
- Publikační typ
- časopisecké články MeSH
Plants form associations with different microbes; some promote their growth and protect from biotic and abiotic stresses in different ways. However, the biological role of fungi associated with the rhizosphere of medicinal plants is not well explored. In the present study, Colletotrichum gloeosporioides, and Aspergillus fumigatus isolated from the rhizosphere of Dillenia indica were screened for their phosphate solubilization and indole-3-acetic acid (IAA) production potential. The selected fungal strains were identified by macroscopic, microscopic, and molecular characteristics. Phosphate solubilization was qualitatively and quantitatively evaluated using Pikovskaya's (PVK) agar and PVK broth medium using different substrates such as AlPO4, Ca3(PO4)2, and FePO4. Colletotrichum gloeosporioides and Aspergillus fumigatus with respect to the phosphate source showed solubilization index (SI) of 1.7 ± 0.03 and 2.1 ± 0.04, and solubilized phosphate up to 138.8 ± 0.058 μg/mL and 121.6 ± 0.062 μg/mL. These fungal strains are also good producers of IAA and significantly enhance the growth of Vigna radiata and Cicer arietinum seedlings. This is the first report on A. fumigatus and C. gloeosporioides from the rhizosphere of Dillenia indica and their phosphate solubilization and IAA production ability.
- MeSH
- diabetes mellitus 2. typu komplikace metabolismus patofyziologie MeSH
- dospělí MeSH
- inzulin krev MeSH
- inzulinová rezistence MeSH
- kardiovaskulární nemoci komplikace metabolismus patofyziologie MeSH
- krevní glukóza metabolismus MeSH
- lidé středního věku MeSH
- lidé MeSH
- metabolický syndrom komplikace metabolismus patofyziologie MeSH
- nitrobřišní tuk metabolismus patofyziologie MeSH
- průřezové studie MeSH
- riziko MeSH
- senioři MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- souhrny MeSH
