Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This review represents the first effort ever to survey the entire literature on auxin (indole-3-acetic acid, IAA) action in all plants, with special emphasis on the green plant lineage, including charophytes (the green alga group closest to the land plants), bryophytes (the most basal land plants), pteridophytes (vascular non-seed plants), and seed plants. What emerges from this survey is the surprising perspective that the physiological mechanisms for regulating IAA levels and many IAA-mediated responses found in seed plants are also present in charophytes and bryophytes, at least in nascent forms. For example, the available evidence suggests that the apical regions of both charophytes and liverworts synthesize IAA via a tryptophan-independent pathway, with IAA levels being regulated via the balance between the rates of IAA biosynthesis and IAA degradation. The apical regions of all the other land plants utilize the same class of biosynthetic pathway, but they have the potential to utilize IAA conjugation and conjugate hydrolysis reactions to achieve more precise spatial and temporal control of IAA levels. The thallus tips of charophytes exhibit saturable IAA influx and efflux carriers, which are apparently not sensitive to polar IAA transport inhibitors. By contrast, two divisions of bryophyte gametophytes and moss sporophytes are reported to carry out polar IAA transport, but these groups exhibit differing sensitivities to those inhibitors. Although the IAA regulation of charophyte development has received almost no research attention, the bryophytes manifest a wide range of developmental responses, including tropisms, apical dominance, and rhizoid initiation, which are subject to IAA regulation that resembles the hormonal control over corresponding responses in seed plants. In pteridophytes, IAA regulates root initiation and vascular tissue differentiation in a manner also very similar to its effects on those processes in seed plants. Thus, it is concluded that the seed plants did not evolve de novo mechanisms for mediating IAA responses, but have rather modified pre-existing mechanisms already operating in the early land plants. Finally, this paper discusses the encouraging prospects for investigating the molecular evolution of auxin action.
Plant Mol Biol
PMID:Evolutionary patterns in auxin action. 1203 57

Despite recent progress auxin signal transduction remains largely scetchy and enigmatic. A good body of evidence supports the notion that the ABP1 could be a functional receptor or part of a receptor, respectively, but this is not generally accepted. Evidence for other functional receptors is lacking, as is any clearcut evidence for a function of G proteins. Protons may serve as second messengers in guard cells but the existing evidence for a role of calcium remains to be clearified. Phospholipases C and D seem not to have a function in auxin signal transduction whereas the indications for a role of phospholipase A2 in auxin signal transduction accumulated recently. Mitogen-activated protein kinase (MAPK) is modulated by auxin and the protein kinase PINOID has a role in auxin transport modulation even though their functional linkage to other signalling molecules is ill-defined. It is hypothesized that signal transduction precedes activation of early genes such as IAA genes and that ubiquitination and the proteasome are a mechanism to integrate signal duration and signal strength in plants and act as major regulators of hormone sensitivity.
Plant Mol Biol
PMID:Secondary messengers and phospholipase A2 in auxin signal transduction. 1203 60

A molecular approach to investigate auxin signaling in plants has led to the identification of several classes of early/primary auxin response genes. Within the promoters of these genes, cis elements that confer auxin responsiveness (referred to as auxin-response elements or AuxREs) have been defined, and a family of trans-acting transcription factors (auxin-response factors or ARFs) that bind with specificity to AuxREs has been characterized. A family of auxin regulated proteins referred to as Aux/IAA proteins also play a key role in regulating these auxin-response genes. Auxin may regulate transcription on early response genes by influencing the types of interactions between ARFs and Aux/IAAs.
Plant Mol Biol
PMID:Auxin-responsive gene expression: genes, promoters and regulatory factors. 1203 61

Dramatic advances in our understanding of auxin signal-response pathways have been made in recent years. Much of this new knowledge has come through the study of mutants in Arabidopsis thaliana. Mutations have been identified in a wide variety of auxin-response components, including auxin transporters, protein kinases and phosphatases, components of a ubiquitin-proteosome pathway, and transcriptional regulators. This review focuses on mutations that affect auxin-modulated transcription factors, in particular those in the Aux/IAA and AUXIN RESPONSE FACTOR (ARF) genes. Mutants in members of these related gene families exhibit phenotypes that indicate both unique localized functions, as well as overlapping redundant functions, throughout plant development - from embryogenesis to flowering. Effects of specific mutations on Aux/IAA and ARF protein functions at the biochemical and physiological levels will be discussed. We will also discuss potential mechanisms for interactions between auxin and light response pathways that are suggested by these mutants.
Plant Mol Biol
PMID:Genetics of Aux/IAA and ARF action in plant growth and development. 1203 62

Auxin-regulated gene expression is mediated by two families of transcription factors. The ARF proteins bind to a conserved DNA sequence called the AuxRE and activate transcription. The Aux/IAA proteins repress ARF function, presumably by forming dimers with ARF proteins. Recent genetic studies in Arabidopsis indicate that auxin regulates this system by promoting the ubiquitin-mediated degradation of the Aux/IAA proteins, thus permitting ARF function. Mutations in components of SCF(TIR1), a ubiquitin protein ligase (E3) result in stabilization of Aux/IAA proteins and decreased auxin response. Further, recent biochemical experiments indicate that the Aux/IAA proteins bind SCF(TIR1) in an auxin-dependent manner.
Plant Mol Biol
PMID:The role of regulated protein degradation in auxin response. 1203 63

Prosopis chilensis (Mol.) Stuntz (Algarrobo de Chile) is an important native tree species that can be grown in arid and semiarid regions for wood and forage production and environmental protection. Developing a simple and reliable in vitro protocol for cloning it would enable to improve it genetically. Explants of P. chilensis were taken from 4 months-old plants grown in the greenhouse or from adult trees grown in a natural environment. Nodal segments 1-2 cm long containing an axillary bud were selected from elongating shoots. These cuttings were aseptically cultured on two agar-solid basal media, MS or BTMm, and treated with 0.05 mg L-1 BA and 3 mg L-1 of either IAA, IBA or NAA. Sucrose (3% w/v) was used as carbon source. The percentage of sprouted cuttings and whole plant regeneration as well as its shoot and root length were recorded. Number, length and dry weight of shoots and roots were also measured. Rooting was successful with cuttings taken from young or adult plants, but explants from young plants showed a better response. Culturing in BTMm resulted in significantly greater shoot and root biomass than culturing in MS. Moreover, this response was higher in young explants when IBA was used as growth regulator. This paper reports a simple and effective method to micropropagate P. chilensis from young and adult plants.
 ...
PMID:Micropropagation of Prosopis chilensis (Mol.) Stuntz from young and mature plants. 1205 79

During early pea fruit growth, the physiological roles of 4-chloroindole-3-acetic acid (4-Cl-IAA) and IAA, natural pea auxins, in regulating gibberellin (GA) 20-oxidase gene expression (PsGA20ox1) were tested with 4-position, ring-substituted auxins that have a range of biological activities (fruit growth). The effect of seeds, and natural and synthetic auxins (4-Cl-IAA, and IAA; 4-Me-IAA, 4-Et-IAA and 4-F-IAA, respectively), and auxin concentration (4-Cl-IAA) on PsGA20ox1 mRNA levels in pea pericarp were investigated over a 24 h treatment period. The ability of the 4-substituted auxins to increase PsGA20ox1 mRNA levels in deseeded pericarp was correlated with their ability to stimulate pericarp growth. The greatest increase in pericarp PsGA20ox1 mRNA levels and growth was observed when deseeded pericarps were treated with the naturally occurring pea auxin, 4-Cl-IAA; however, IAA was not effective. Silver thiosulfate, an ethylene action antagonist, did not reverse IAA's lack of stimulation of PsGA20ox1 over the control treatment. 4-Me-IAA was the second most active auxin in stimulating PsGA20ox1 and was the second most biologically active auxin. Application of the 4-substituted IAA analogs, 4-Et-IAA and 4-F-IAA, to deseeded pericarps resulted in minimal or no increase in PsGA20ox1 transcript levels or pericarp growth. Pericarp PsGA20ox1 mRNA levels increased with increasing 4-Cl-IAA concentration and showed transitory increases at low 4-Cl-IAA treatments (30 to 300 pmol). These results support a unique physiological role for the auxin 4-Cl-IAA in the regulation of GA metabolism by effecting PsGA20ox1 expression during early pea fruit growth.
Plant Mol Biol 2002 Jul
PMID:Specificity of auxin regulation of gibberellin 20-oxidase gene expression in pea pericarp. 1209 Jun 20

We report the characterization of a member of the auxin-induced IAA gene family from zinnia, designated zIAA8, which is expressed by mesophyll cells differentiating as tracheary elements in vitro. Transcription of zIAA8 is up-regulated within 3 h after cell isolation in inductive medium, indicating that cells perceive and respond to growth factor stimulus early in culture. Transcript levels of zIAA8 remain high through 72 h of culture in medium containing auxin and cytokinin or auxin alone, but low in medium containing only cytokinin or control medium lacking growth factors, demonstrating auxin-specific induction and consistent with lack of desensitization to prolonged auxin stimulation. In situ localization shows zIAA8 is localized to primary vasculature, root tips, and nascent leaves in zinnia seedlings. The observation that zIAA8 is expressed during vascular development in planta supports the hypothesis that expression early in culture reflects early events during normal vascular differentiation. The promoter of Arabidopsis IAA8 drives expression of the GUS reporter in a pattern in Arabidopsis similar to that for zIAA8 in zinnia, suggesting conservation of cis regulatory elements between the species and confirming the results from in situ localization. The vascular expression pattern of the IAA8 promoter in leaves mirrors the developmentally regulated auxin gradient in expanding leaf blades. The expression patterns of zIAA8 and IAA8 yield new insight into vascular development in vitro and in planta, and provide much needed markers for early vascular differentiation.
Plant Mol Biol 2003 Feb
PMID:IAA8 expression during vascular cell differentiation. 1260 72

In this study, we examined the relationship between the accumulation of NaHSeO3, the plant hormone (IAA), and some nutrient elements (K(+), Na(+), Ca(2+)) in the tissues of the roots, mesocotyls and leaves of Zea mays L. plants. Our experiments were carried out with eight- to nine-day old maize plants (Zea mays L. var K33xF2) grown on Hoagland's medium containing the standard macro- and microelements, IAA and NaHSeO(3). The accumulation of selenium, potassium, sodium and calcium in the seedlings was measured by emission spectroscopy using a spectrometer with excitation by the argon inductively coupled plasma technique (ICP-AES). We observed that when selenite and phytohormone (IAA) are present in the external medium of growing plants, they change the uptake and accumulation of some cations (K(+), Na(+), Ca(2+)) in the leaf, mesocotyl and root tissues. The change of transport of some nutrient elements is probably one of the first observed symptoms of selenium's effects on plants.
Cell Mol Biol Lett 2003
PMID:The effect of selenium on the accumulation of some metals in Zea mays L. plants treated with indole-3-acetic acid. 1265 62

A cDNA clone for a mitochondrial MnSOD was isolated from a cDNA library derived from seedlings of the small radish (Raphanus sativus L.). The cDNA clone, RsMnSOD, encoded a polypeptide with a predicted molecular mass of 25.4 kDa and calculated pI of 8.77. Its deduced amino acid sequence was 93% homologous with MnSOD of Arabidopsis. RNA gel blot analysis showed that RsMnSOD transcripts were most abundant in leaves, followed by roots and hypocotyls, whereas transcripts of RsFeSOD and RsCu/ZnSOD were not detected in roots. The hypocotyls of germinated seedlings turned green and finally red in response to white light. These color changes were accompanied by increases in RsMnSOD and RsCu/ZnSOD mRNA. In addition, RsMnSOD expression was strongly induced by osmotic stress, moderately induced by phytohormones such as ABA and IAA, and not induced by xenobiotics other than cercosporin.
Mol Cells 2003 Oct 31
PMID:Cloning and expression of mitochondrial MnSOD from the small radish (Raphanus sativus L.). 1465 Dec 61


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>