| 1. |
- Mounet, Fabien, et al.
(författare)
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Down-regulation of a single auxin efflux transport protein in tomato induces precocious fruit development
- 2012
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Ingår i: Journal of Experimental Botany. - Oxford : Oxford University Press. - 0022-0957 .- 1460-2431. ; 63:13, s. 4901-4917
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Tidskriftsartikel (refereegranskat)abstract
- The PIN-FORMED (PIN) auxin efflux transport protein family has been well characterized in the model plant Arabidopsis thaliana, where these proteins are crucial for auxin regulation of various aspects of plant development. Recent evidence indicates that PIN proteins may play a role in fruit set and early fruit development in tomato (Solanum lycopersicum), but functional analyses of PIN-silenced plants failed to corroborate this hypothesis. Here it is demonstrated that silencing specifically the tomato SlPIN4 gene, which is predominantly expressed in tomato flower bud and young developing fruit, leads to parthenocarpic fruits due to precocious fruit development before fertilization. This phenotype was associated with only slight modifications of auxin homeostasis at early stages of flower bud development and with minor alterations of ARF and Aux/IAA gene expression. However, microarray transcriptome analysis and large-scale quantitative RT-PCR profiling of transcription factors in developing flower bud and fruit highlighted differentially expressed regulatory genes, which are potential targets for auxin control of fruit set and development in tomato. In conclusion, this work provides clear evidence that the tomato PIN protein SlPIN4 plays a major role in auxin regulation of tomato fruit set, possibly by preventing precocious fruit development in the absence of pollination, and further gives new insights into the target genes involved in fruit set.
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| 2. |
- Abelev, Betty, et al.
(författare)
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Long-range angular correlations on the near and away side in p-Pb collisions at root S-NN=5.02 TeV
- 2013
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Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 719:1-3, s. 29-41
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Tidskriftsartikel (refereegranskat)abstract
- Angular correlations between charged trigger and associated particles are measured by the ALICE detector in p-Pb collisions at a nucleon-nucleon centre-of-mass energy of 5.02 TeV for transverse momentum ranges within 0.5 < P-T,P-assoc < P-T,P-trig < 4 GeV/c. The correlations are measured over two units of pseudorapidity and full azimuthal angle in different intervals of event multiplicity, and expressed as associated yield per trigger particle. Two long-range ridge-like structures, one on the near side and one on the away side, are observed when the per-trigger yield obtained in low-multiplicity events is subtracted from the one in high-multiplicity events. The excess on the near-side is qualitatively similar to that recently reported by the CMS Collaboration, while the excess on the away-side is reported for the first time. The two-ridge structure projected onto azimuthal angle is quantified with the second and third Fourier coefficients as well as by near-side and away-side yields and widths. The yields on the near side and on the away side are equal within the uncertainties for all studied event multiplicity and p(T) bins, and the widths show no significant evolution with event multiplicity or p(T). These findings suggest that the near-side ridge is accompanied by an essentially identical away-side ridge. (c) 2013 CERN. Published by Elsevier B.V. All rights reserved.
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| 3. |
- Abelev, Betty, et al.
(författare)
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Measurement of prompt J/psi and beauty hadron production cross sections at mid-rapidity in pp collisions at root s=7 TeV
- 2012
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; :11
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Tidskriftsartikel (refereegranskat)abstract
- The ALICE experiment at the LHC has studied J/psi production at mid-rapidity in pp collisions at root s = 7 TeV through its electron pair decay on a data sample corresponding to an integrated luminosity L-int = 5.6 nb(-1). The fraction of J/psi from the decay of long-lived beauty hadrons was determined for J/psi candidates with transverse momentum p(t) > 1,3 GeV/c and rapidity vertical bar y vertical bar < 0.9. The cross section for prompt J/psi mesons, i.e. directly produced J/psi and prompt decays of heavier charmonium states such as the psi(2S) and chi(c) resonances, is sigma(prompt J/psi) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 8.3 +/- 0.8(stat.) +/- 1.1 (syst.)(-1.4)(+1.5) (syst. pol.) mu b. The cross section for the production of b-hadrons decaying to J/psi with p(t) > 1.3 GeV/c and vertical bar y vertical bar < 0.9 is a sigma(J/psi <- hB) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 1.46 +/- 0.38 (stat.)(-0.32)(+0.26) (syst.) mu b. The results are compared to QCD model predictions. The shape of the p(t) and y distributions of b-quarks predicted by perturbative QCD model calculations are used to extrapolate the measured cross section to derive the b (b) over bar pair total cross section and d sigma/dy at mid-rapidity.
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| 4. |
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| 5. |
- Alallaq, Sanaria, 1976-
(författare)
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Characterization of adventitious root formation in Populus species and Norway spruce
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Adventitious root (AR) formation is a form of post-embryonic development and is a key adaptive trait in plants. De novo adventitious root regeneration represents an elegant evolutionary innovation that allows many plant species to multiply through vegetative propagation; it is widely used in forestry and horticulture to multiply elite genotypes. However, several tree species with high economic and ecological value are difficult to root, and the genetic and molecular bases underlying AR regeneration remain largely elusive. Recently our laboratory showed that jasmonate (JA) and cytokinins (CK) act cooperatively to repress AR initiation (ARI) in Arabidopsishypocotyls, while auxin positively controls ARI by repressing this negative effect. With the recent availability of the reference genomes of Populus spp. and Norway spruce (Picea abies), the aim of this thesis is to explore the molecular and mechanistic foundations of AR formation in woody species and check whether or not there is conservation of the molecular mechanisms identified in Arabidopsis. First, physiological, molecular and hormonic approaches coupled with extensive anatomical analysis were combined to explore the role of light spectral quality in the control of ARI in P. abies de-rooted seedlings. We showed that constant red light (cRL) promotes ARI by reducing the content of the wound-induced phytohormones JA and JA-isoleucine and repressing the accumulation of the isopentyl-adenine-type cytokinins. These results suggest that the cooperative role of JA and CK signaling in the repression of ARI is evolutionarily conserved.Next we compared transcriptomic data from the cambium tissue of woody stem cuttings of the hybrid aspen T89, which is difficult-to-root, and from the hybrid poplar OP42, which is easy-to-root, under hydroponic conditions. The analyses revealed high transcriptional activity in OP42, with twice as many transcription factors differentially expressed in OP42 24 hours after cutting compared to T89. Although we did not observe significant differences in the expression of Auxin response factor (ARF) genes between the two genotypes, the production of transgenic plants downregulating or over-expressing ARF6, 8 or 17 confirmed that PtARF6 and PtARF8 positively and PtARF17 negatively regulate AR development in transgenic hybrid aspen T89. Interestingly, the expression of MYC2 orthologs as well as the expression of several genes involved in JA signaling increased more in T89 than in OP42, suggesting that JA could be a negative regulator of ARI in Populus spp. We also showed that overexpressing PtMYC2 led to a reduced number of ARs in hybrid aspen T89 cuttings. In addition, many genes encoding ROS scavenging proteins such as peroxidases or GSTs were significantly differentially expressed in OP42 24 h after cutting but not in T89, which is interesting since peroxidase activity has often been positively correlated with ARI. In parallel to this research, we characterized the rooting phenotype of clones from the Swedish Aspen (SwAsp) collection usingin vitro cuttings. We observed a significant variation in the rooting ability as well as different root system establishment between the clones. We analyzed the expression of some genes known to be involved in AR development in selected clones with contrasting AR phenotypes but could not identify any correlation between gene expression and rooting phenotype. A transcriptomic analysis of selected clones, with contrasting AR phenotypes, could be a useful tool in the identification of marker genes, which can be used for future selection of the best rooting clones of Populus or other economically important trees in breeding programs.
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| 6. |
- Alallaq, Sanaria, et al.
(författare)
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Red Light Controls Adventitious Root Regeneration by Modulating Hormone Homeostasis in Picea abies Seedlings
- 2020
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Ingår i: Frontiers in Plant Science. - : Frontiers Media S.A.. - 1664-462X. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Vegetative propagation relies on the capacity of plants to regeneratede novoadventitious roots (ARs), a quantitative trait controlled by the interaction of endogenous factors, such as hormones and environmental cues among which light plays a central role. However, the physiological and molecular components mediating light cues during AR initiation (ARI) remain largely elusive. Here, we explored the role of red light (RL) on ARI in de-rooted Norway spruce seedlings. We combined investigation of hormone metabolism and gene expression analysis to identify potential signaling pathways. We also performed extensive anatomical characterization to investigate ARI at the cellular level. We showed that in contrast to white light, red light promoted ARI likely by reducing jasmonate (JA) and JA-isoleucine biosynthesis and repressing the accumulation of isopentyl-adenine-type cytokinins. We demonstrated that exogenously applied JA and/or CK inhibit ARI in a dose-dependent manner and found that they possibly act in the same pathway. The negative effect of JA on ARI was confirmed at the histological level. We showed that JA represses the early events of ARI. In conclusion, RL promotes ARI by repressing the accumulation of the wound-induced phytohormones JA and CK.
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| 7. |
- Aubry, Emilie, et al.
(författare)
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A vacuolar hexose transport is required for xylem development in the inflorescence stem
- 2022
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Ingår i: Plant Physiology. - : Oxford University Press. - 0032-0889 .- 1532-2548. ; 188:2, s. 1229-1247
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Tidskriftsartikel (refereegranskat)abstract
- In Angiosperms, the development of the vascular system is controlled by a complex network of transcription factors. However, how nutrient availability in the vascular cells affects their development remains to be addressed. At the cellular level, cytosolic sugar availability is regulated mainly by sugar exchanges at the tonoplast through active and/or facilitated transport. In Arabidopsis (Arabidopsis thaliana), among the genes encoding tonoplastic transporters, SUGAR WILL EVENTUALLY BE EXPORTED TRANSPORTER 16 (SWEET16) and SWEET17 expression has been previously detected in the vascular system. Here, using a reverse genetics approach, we propose that sugar exchanges at the tonoplast, regulated by SWEET16, are important for xylem cell division as revealed in particular by the decreased number of xylem cells in the swt16 mutant and the accumulation of SWEET16 at the procambium-xylem boundary. In addition, we demonstrate that transport of hexoses mediated by SWEET16 and/or SWEET17 is required to sustain the formation of the xylem secondary cell wall. This result is in line with a defect in the xylem cell wall composition as measured by Fourier-transformed infrared spectroscopy in the swt16swt17 double mutant and by upregulation of several genes involved in secondary cell wall synthesis. Our work therefore supports a model in which xylem development partially depends on the exchange of hexoses at the tonoplast of xylem-forming cells.
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| 8. |
- Bannoud, Florencia, et al.
(författare)
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Adventitious Rooting in Populus Species : Update and Perspectives
- 2021
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Ingår i: Frontiers in Plant Science. - : Frontiers Media S.A.. - 1664-462X. ; 12
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Forskningsöversikt (refereegranskat)abstract
- Populus spp. are among the most economically important species worldwide. These trees are used not only for wood and fiber production, but also in the rehabilitation of degraded lands. Since they are clonally propagated, the ability of stem cuttings to form adventitious roots is a critical point for plant establishment and survival in the field, and consequently for the forest industry. Adventitious rooting in different Populus clones has been an agronomic trait targeted in breeding programs for many years, and many factors have been identified that affect this quantitative trait. A huge variation in the rooting capacity has been observed among the species in the Populus genus, and the responses to some of the factors affecting this trait have been shown to be genotype-dependent. This review analyses similarities and differences between results obtained from studies examining the role of internal and external factors affecting rooting of Populus species cuttings. Since rooting is the most important requirement for stand establishment in clonally propagated species, understanding the physiological and genetic mechanisms that promote this trait is essential for successful commercial deployment.
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| 9. |
- Baud, Sébastien, et al.
(författare)
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gurke and pasticcino3 mutants affected in embryo development are impaired in acetyl-CoA carboxylase.
- 2004
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Ingår i: EMBO Reports. - : EMBO. - 1469-221X .- 1469-3178. ; 5:5
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Tidskriftsartikel (refereegranskat)abstract
- Normal embryo development is required for correct seedling formation. The Arabidopsis gurke and pasticcino3 mutants were isolated from different developmental screens and the corresponding embryos exhibit severe defects in their apical region, affecting bilateral symmetry. We have recently identified lethal acc1 mutants affected in acetyl-CoA carboxylase 1 (ACCase 1) that display a similar embryo phenotype. A series of crosses showed that gk and pas3 are allelic to acc1 mutants, and direct sequencing of the ACC1 gene revealed point mutations in these new alleles. The isolation of leaky acc1 alleles demonstrated that ACCase 1 is essential for correct plant development and that mutations in ACCase affect cellular division in plants, as is the case in yeast. Interestingly, significant metabolic complementation of the mutant phenotype was obtained by exogenous supply of malonate, suggesting that the lack of cytosolic malonyl-CoA is likely to be the initial factor leading to abnormal development in the acc1 mutants.
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| 10. |
- Bellini, Catherine, 1962-
(författare)
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A synthetic auxin for cloning mature trees
- 2024
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Ingår i: Nature Biotechnology. - : Springer Nature. - 1087-0156 .- 1546-1696.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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