The IBR5 phosphatase promotes Arabidopsis auxin responses through a novel mechanism distinct from TIR1-mediated repressor degradation

<p>Abstract</p> <p>Background</p> <p>In Arabidopsis, INDOLE-3-BUTYRIC ACID RESPONSE5 (IBR5), a putative dual-specificity protein phosphatase, is a positive regulator of auxin response. Mutations in <it>IBR5 </it>result in decreased plant height, defective vascular development, increased leaf serration, fewer lateral roots, and resistance to the phytohormones auxin and abscisic acid. However, the pathways through which IBR5 influences auxin responses are not fully understood.</p> <p>Results</p> <p>We analyzed double mutants of <it>ibr5 </it>with other mutants that dampen auxin responses and found that combining <it>ibr5 </it>with an auxin receptor mutant, <it>tir1</it>, enhanced auxin resistance relative to either parent. Like other auxin-response mutants, auxin-responsive reporter accumulation was reduced in <it>ibr5</it>. Unlike other auxin-resistant mutants, the Aux/IAA repressor reporter protein AXR3NT-GUS was not stabilized in <it>ibr5</it>. Similarly, the Aux/IAA repressor IAA28 was less abundant in <it>ibr5 </it>than in wild type. <it>ibr5 </it>defects were not fully rescued by overexpression of a mutant form of IBR5 lacking the catalytic cysteine residue.</p> <p>Conclusion</p> <p>Our genetic and molecular evidence suggests that IBR5 is a phosphatase that promotes auxin responses, including auxin-inducible transcription, differently than the TIR1 auxin receptor and without destabilizing Aux/IAA repressor proteins. Our data are consistent with the possibility that auxin-responsive transcription can be modulated downstream of TIR1-mediated repressor degradation.</p

Componentes del amor y bienestar psicológico en estudiantes de una Universidad Privada de Trujillo

RESUMEN En la presente investigación se exploró la relación entre Componentes del amor y el Bienestar psicológico, llevándose a cabo un Diseño de estudio Correlacional, cuya muestra de tipo probabilística estuvo conformada por 125 estudiantes universitarios entre 20 y 24 años de edad de la ciudad de Trujillo y se utilizaron para su medición La Escala Triangular del amor de Sternberg y la Escala de Bienestar Psicológico de Ryff, adaptado por Van Dierendonck. Los resultados evidencian que se encuentra correlación negativa y significativa (r=-.17, p<.05) entre el componente Intimidad y la dimensión autonomía, asimismo se correlaciona positiva y altamente significativa el mismo componente con la dimensión crecimiento personal (r=.28, p<.01); en lo que respecta al segundo componente (Pasión) se correlaciona de manera negativa y significativamente (r=-.19, p<.05) con la dimensión dominio del entorno, empero se correlaciona de forma positiva y altamente significativa (r=.25, p<.01)con la dimensión crecimiento personal; además en lo que respecta al tercer componente (Compromiso) se evidencia correlación positiva y significativa (r=.20, p<.05) con la dimensión dominio del entorno, no obstante correlación negativa y altamente significativa (r=-.24, p<01) con la dimensión crecimiento personal. En lo concerniente a los resultados descriptivos se observa que el componente de amor con tendencia de medio a alto en la muestra de estudio es Intimidad (52.8% y 29.6%); y finalmente en lo concerniente a bienestar psicológico todas las dimensiones presentan una tendencia de nivel medio; excepto Propósito en la vida, cuyo puntaje se ubicó en un nivel de medio a bajo (60.0% y 26.4%). PALABRAS CLAVE: componentes del amor, bienestar psicológico, relación de pareja.ABSTRACT The present research explored the relationship between Components of Love and Psychological Well-Being, carrying out a correlational study design, whose sample of probabilistic type was formed by 125 university students between 20 and 24 years old from Trujillo city and were used for measurement of Sternberg’s Triangular Scale of Love and the Ryff Psychological Well-Being Scale adapted by Van Dierendonck. The results show that there is a negative and significant correlation (r=-.17, p<.05) between the Intimacy component and the Autonomy dimension, and the same component is correlated positively and highly significant with the Personal Growth dimension (r=.28, p<.01), with respect to the second component Passion is negatively and significantly correlated (r=-.19, p<.05) with the dimension Domain of the Environment, however is correlated in a positive way and highly significant (r=.25, p<.01) with the Personal Growth dimension. In addition to the third component (Commitment) evidence positive and significant correlation (r=.20, p<01) with the dimension Domain of the Environment, however negative and highly significant correlation (r=-.24, p<01) with the Personal Growth dimension. Regarding to the descriptive results it is observed that the love component with tendency medium to high in the study sample is Intimacy (52.8% and 29.6%); and finally with respect to Psychological Well-Being all the dimensions present a mediumlevel tendency, except Purpose in life whose score was placed in a level of medium to low (60.0% and 26.4%). KEYWORDS: components of love, psychological wellbeing, relationship

Genetic approaches to elucidating the mechanisms of indole-3-acetic acid and indole-3-butyric acid function in Arabidopsis thaliana

Auxin is an important plant hormone that plays significant roles in plant growth and development, influencing apical dominance, hypocotyl elongation, lateral root initiation, gravitropism, and phototropism. There are two forms of endogenous auxin, indole-3-butyric acid (IBA) and the more abundant indole-3-acetic acid (IAA). Auxin signal transduction pathways remain to be fully elucidated, though numerous auxin-response mutants have been identified. IBR5 is a gene potentially involved in auxin signal transduction. The ibr5 mutant has pleiotropic defects including decreased sensitivity to the inhibitory effects of auxin, synthetic auxins, auxin transport inhibitors, and the phytohormone abscisic acid. Like certain other auxin-response mutants, ibr5 has a long root and short hypocotyl when grown in the light. Additionally, ibr5 displays aberrant vascular patterning, increased leaf serration, and reduced accumulation of an auxin-inducible reporter. Positional information was used to determine that the gene defective in ibr5 encodes an apparent dual-specificity phosphatase. Using immunoblot and promoter-reporter gene analyses, we found that IBR5 is expressed throughout the plant. The identification of IBR5 relatives in other flowering plants suggests that IBR5 function is conserved throughout angiosperms. The results suggest that IBR5 is a phosphatase modulating phytohormone signal transduction and support a link between auxin and abscisic acid signaling pathways. Less is known concerning IBA function, though this auxin is widely used for rooting in commercial and agricultural settings. IBA functions primarily via its conversion to IAA by a process similar to fatty acid beta-oxidation in the peroxisomes. Additionally, IBA may act via its own signaling pathway, separate from IAA. Screens for mutants resistant to the inhibitory effects of IBA that remain sensitive to IAA have revealed 32 mutants to date. These IBA-response mutants have been placed into five distinct classes based on phenotypic analyses of root and hypocotyl elongation following growth on various hormones and unsupplemented medium. Here I characterize eight IBA-response mutants and use positional information to localize the genes defective in these mutants. Analyzing genes involved in IAA and IBA responses will provide a better understanding of the function of auxin in Arabidopsis thaliana and may eventually allow manipulation of the pathways involved to enhance agricultural production

[Accepted Article Manuscript Version (Postprint)] Identification and Functional Characterization of Arabidopsis PEROXIN4 and the Interacting Protein PEROXIN22

Peroxins are genetically defined as proteins necessary for peroxisome biogenesis. By screening for reduced response to indole-3-butyric acid, which is metabolized to active auxin in peroxisomes, we isolated an Arabidopsis thaliana peroxin4 (pex4) mutant. This mutant displays sucrose-dependent seedling development and reduced lateral root production, characteristics of plant peroxisome malfunction. We used yeast two-hybrid analysis to determine that PEX4, an apparent ubiquitinconjugating enzyme, interacts with a previously unidentified Arabidopsis protein, PEX22. A pex4 pex22 double mutant enhanced pex4 defects, confirming that PEX22 is a peroxin. Expression of both Arabidopsis genes together complemented yeast pex4 or pex22 mutant defects, whereas expression of either gene individually failed to rescue the corresponding yeast mutant. Therefore, it is likely that the Arabidopsis proteins can function similarly to the yeast PEX4–PEX22 complex, with PEX4 ubiquitinating substrates and PEX22 tethering PEX4 to the peroxisome. However, the severe sucrose dependence of the pex4 pex22 mutant is not accompanied by correspondingly strong defects in peroxisomal matrix protein import, suggesting that this peroxin pair may have novel plant targets in addition to those important in fungi. Isocitrate lyase is stabilized in pex4 pex22, indicating that PEX4 and PEX22 may be important during the remodeling of peroxisome matrix contents as glyoxysomes transition to leaf peroxisomes

The IBR5 phosphatase promotes Arabidopsis auxin responses through a novel mechanism distinct from TIR1-mediated repressor degradation-5

Or the indicated time, then stained for GUS activity. (B) Auxin-response defects of lines. Lengths of primary roots of 8-day-old seedlings grown under yellow-filtered light at 22°C on medium supplemented with various concentrations of 2,4-D are shown. Error bars represent standard errors of the means (= 20). (C) 8-day-old Col-0 (Wt) and carrying [16] were heat-shocked for 2 hours, mock (ethanol) treated or treated with 10 μM IBA for 40 minutes, then stained for GUS activity. (D) 8-day-old Col-0 (Wt), , , and carrying [16] were heat shocked for 2 hours. Midway through a 2-hour heat shock, DMSO (mock) or 50 μM MG132 treatment was initiated. Seedlings were stained for GUS activity 2 hours after return to room temperature. Separate experiments revealed that inclusion of DMSO during the heat shock (included as an MG132 carrier in panel D) resulted in more intense AXR3NT-GUS staining (L.C.S., unpublished), which could account for the higher apparent GUS activity in panel D when compared to panel A.<p><b>Copyright information:</b></p><p>Taken from "The IBR5 phosphatase promotes Arabidopsis auxin responses through a novel mechanism distinct from TIR1-mediated repressor degradation"</p><p>http://www.biomedcentral.com/1471-2229/8/41</p><p>BMC Plant Biology 2008;8():41-41.</p><p>Published online 18 Apr 2008</p><p>PMCID:PMC2374786.</p><p></p

The IBR5 phosphatase promotes Arabidopsis auxin responses through a novel mechanism distinct from TIR1-mediated repressor degradation-9

Ings to medium supplemented with either 0 (ethanol control) or 10 μM IBA. Primordia emerged from the main root were counted as lateral roots. Error bars represent standard errors of the means (≥ 14). had significantly fewer lateral roots in response to IBA than either or (≤ 0.001 in two-tailed -tests assuming unequal variance). (B) Lengths of hypocotyls were measured 4 days after transfer of 1-day-old seedlings to the dark. Error bars represent standard errors of the means (= 20). hypocotyls were significantly longer than and hypocotyls on 20 or 40 μM IBA (≤ 0.0001 in two-tailed -tests assuming unequal variance). hypocotyls were significantly longer than and on 20 (≤ 0.01) or 40 μM IBA (≤ 0.001) in two-tailed -tests assuming unequal variance. (C) Length of primary roots 4 days after transfer of 4-day-old seedlings to medium supplemented with either 0 (ethanol control) or 10 μM ABA. roots were significantly longer than and roots on ABA (≤ 0.001) in two-tailed -tests assuming unequal variance. roots were significantly longer than and roots following control (≤ 0.001) or ABA (≤ 0.01) treatments in two-tailed -tests assuming unequal variance. Error bars represent standard errors of the means (≥ 14).<p><b>Copyright information:</b></p><p>Taken from "The IBR5 phosphatase promotes Arabidopsis auxin responses through a novel mechanism distinct from TIR1-mediated repressor degradation"</p><p>http://www.biomedcentral.com/1471-2229/8/41</p><p>BMC Plant Biology 2008;8():41-41.</p><p>Published online 18 Apr 2008</p><p>PMCID:PMC2374786.</p><p></p

The IBR5 phosphatase promotes Arabidopsis auxin responses through a novel mechanism distinct from TIR1-mediated repressor degradation-8

R patterning defects. Cleared cotyledons of 8-day-old Col-0 (Wt), , , and seedlings are shown. Scale bar = 1 mm. (C, D) auxin-response defects. Lengths of primary roots of 8-day-old seedlings grown under yellow-filtered light at 22°C on medium supplemented with various concentrations of IBA (C) or 2,4-D (D) are shown. roots were significantly longer than and roots on control media and on all auxins tested (≤ 0.001) in -tests assuming unequal variance. Error bars represent standard errors of the means (≥ 18).<p><b>Copyright information:</b></p><p>Taken from "The IBR5 phosphatase promotes Arabidopsis auxin responses through a novel mechanism distinct from TIR1-mediated repressor degradation"</p><p>http://www.biomedcentral.com/1471-2229/8/41</p><p>BMC Plant Biology 2008;8():41-41.</p><p>Published online 18 Apr 2008</p><p>PMCID:PMC2374786.</p><p></p

The IBR5 phosphatase promotes Arabidopsis auxin responses through a novel mechanism distinct from TIR1-mediated repressor degradation-3

R patterning defects. Cleared cotyledons of 8-day-old Col-0 (Wt), , , and seedlings are shown. Scale bar = 1 mm. (C, D) auxin-response defects. Lengths of primary roots of 8-day-old seedlings grown under yellow-filtered light at 22°C on medium supplemented with various concentrations of IBA (C) or 2,4-D (D) are shown. roots were significantly longer than and roots in the absence of hormone and on 5, 10, and 20 μM IBA (≤ 0.001) in two-tailed -tests assuming unequal variance. roots were significantly longer than and roots on 20 (≤ 0.01), 40 (≤ 0.01), 80 (≤ 0.0001), and 120 (≤ 0.001) nM 2,4-D in two-tailed -tests assuming unequal variance. Error bars represent standard errors of the means (≥ 16).<p><b>Copyright information:</b></p><p>Taken from "The IBR5 phosphatase promotes Arabidopsis auxin responses through a novel mechanism distinct from TIR1-mediated repressor degradation"</p><p>http://www.biomedcentral.com/1471-2229/8/41</p><p>BMC Plant Biology 2008;8():41-41.</p><p>Published online 18 Apr 2008</p><p>PMCID:PMC2374786.</p><p></p

The IBR5 phosphatase promotes Arabidopsis auxin responses through a novel mechanism distinct from TIR1-mediated repressor degradation-7

F part of the phosphatase catalytic domains of Arabidopsis IBR5 and several putative and confirmed DSP proteins. Sequences shown are the closest IBR5 homologs from rice (Os06g0308100 and Os02g0720300), an IBR5 relative from Arabidopsis with demonstrated DSP activity (At3g23610/DsPTP1; [52]) and three human (Hs) DSP enzymes. Sequences were aligned with the MegAlign program (DNAStar, Madison, WI) using the CLUSTAL W method. Catalytic residues are shaded in purple, conserved DSP signature residues are shaded in blue, residues identical in at least four sequences are shaded in black, similar residues are shaded in gray, and dashes indicate gaps introduced to maximize alignment. (B) Six-week-old Col-0 (Wt), Wt (), Wt (), , (), () line A, and () line B grown in continuous light are shown. (C) Immunoblot analysis with an anti-IBR5 antibody [37]; top panel) and anti-HSC70 antibody (Stressgen Bioreagents) of protein prepared from 2-day-old seedlings of the lines shown in panel B. Positions of IBR5 and HSC70 are indicated at left. (D) Wt () and Wt () display similar 2,4-D response as Wt. Lengths of primary roots of 8-day-old seedlings grown under yellow-filtered light at 22°C on medium supplemented with various concentrations of 2,4-D are shown. Error bars represent standard errors of the means (≥ 18). (E) () line A, and () line B fail to fully rescue 2,4-D resistance. Seedlings were measured as in (D). Error bars represent standard errors of the means (≥ 17). (F) Length of primary roots 4 days after transfer of 4-day-old seedlings to either 0 (ethanol control) or 10 μM ABA medium. Error bars represent standard errors of the means (≥ 8).<p><b>Copyright information:</b></p><p>Taken from "The IBR5 phosphatase promotes Arabidopsis auxin responses through a novel mechanism distinct from TIR1-mediated repressor degradation"</p><p>http://www.biomedcentral.com/1471-2229/8/41</p><p>BMC Plant Biology 2008;8():41-41.</p><p>Published online 18 Apr 2008</p><p>PMCID:PMC2374786.</p><p></p

The IBR5 phosphatase promotes Arabidopsis auxin responses through a novel mechanism distinct from TIR1-mediated repressor degradation-4

IAA, 10 μM NAA, or 10 μM 2,4-D for 2 hours, then stained for GUS activity. Scale bar = 0.5 mm. (B) 5-day-old dark-grown Col-0 (Wt) and seedlings carrying the construct [13, 37] were mock treated or treated with 1 μM IAA, 10 μM IAA, 10 μM NAA, or 10 μM 2,4-D for 2 hours, then stained for GUS activity. Scale bar = 1 mm.<p><b>Copyright information:</b></p><p>Taken from "The IBR5 phosphatase promotes Arabidopsis auxin responses through a novel mechanism distinct from TIR1-mediated repressor degradation"</p><p>http://www.biomedcentral.com/1471-2229/8/41</p><p>BMC Plant Biology 2008;8():41-41.</p><p>Published online 18 Apr 2008</p><p>PMCID:PMC2374786.</p><p></p