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  • 1. Barlier, I
    et al.
    Kowalczyk, M
    Marchant, A
    Ljung, K
    Bhalerao, R
    Bennett, M
    Sandberg, G
    Bellini, C
    The SUR2 gene of Arabidopsis thaliana encodes the cytochrome P450 CYP83B1, a modulator of auxin homeostasis.2000In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 97, no 26Article in journal (Refereed)
    Abstract [en]

    Genetic screens have been performed to identify mutants with altered auxin homeostasis in Arabidopsis. A tagged allele of the auxin-overproducing mutant sur2 was identified within a transposon mutagenized population. The SUR2 gene was cloned and shown to encode the CYP83B1 protein, which belongs to the large family of the P450-dependent monooxygenases. SUR2 expression is up-regulated in sur1 mutants and induced by exogenous auxin in the wild type. Analysis of indole-3-acetic acid (IAA) synthesis and metabolism in sur2 plants indicates that the mutation causes a conditional increase in the pool size of IAA through up-regulation of IAA synthesis.

  • 2. Baud, Sébastien
    et al.
    Bellec, Yannick
    Miquel, Martine
    Bellini, Catherine
    Caboche, Michel
    Lepiniec, Loïc
    Faure, Jean-Denis
    Rochat, Christine
    gurke and pasticcino3 mutants affected in embryo development are impaired in acetyl-CoA carboxylase.2004In: EMBO Reports, ISSN 1469-221X, E-ISSN 1469-3178, Vol. 5, no 5Article in journal (Refereed)
    Abstract [en]

    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.

  • 3. Bellec, Y.
    et al.
    Harrar, Y.
    Butaeye, C.
    Darnet, S.
    Bellini, C.
    Faure, J. D.
    Pasticcino2 is a protein tyrosine phosphatase-like involved in cell proliferation and differentiation in Arabidopsis2002In: The Plant Journal, ISSN 0960-7412, E-ISSN 1365-313X, Vol. 32, no 5, 713-722 p.Article in journal (Refereed)
    Abstract [en]

    The pasticcino2 (pas2) mutant shows impaired embryo and seedling development associated with cell dedifferentiation and proliferation. This process is specifically enhanced in presence of cytokinins leading to callus-like structure of the apical part of the seedling. Cell proliferation concerns localized and stochastic nodules of dividing cells. In absence of cytokinins, cell proliferation leads to small calli on stems but, most often, cell proliferation is associated with post-genital organ fusion. The PAS2 gene was identified by positional cloning. PAS2 expression was found in every plant organ and was not regulated by PAS1 and PAS3 genes. PAS2 encodes the Arabidopsis member of the protein tyrosine phosphatase-like (Ptpl) family, a new PTP family originally described in mice and humans and characterized by a mutated PTP active site. This family of proteins has a yeast homolog that is essential for cell viability. The absence of yeast PAS2 homolog can be functionally replaced by the Arabidopsis PAS2 protein, demonstrating that PAS2 function is conserved between higher and lower eukaryotes.

  • 4.
    Bellini, C
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Adventious roots2014In: eLSArticle, review/survey (Other (popular science, discussion, etc.))
  • 5. Bellini, C
    Transformation in Lycopersicon esculentum L. (Tomato).1993In: Plant Protoplasts and Genetic Engineering / [ed] Y. Bajaj, Springer Berlin/Heidelberg, 1993, 265-277 p.Chapter in book (Refereed)
  • 6. Bellini, C.
    et al.
    Chupeau, M. C.
    Gervais, M.
    Vastra, G.
    Chupeau, Y.
    Importance of myo-inositol, calcium and ammonium for the viability and division of tomato (Lycopersicon esculentum) protoplasts.1990In: Plant Cell Tissue and Organ Culture, ISSN 0167-6857, E-ISSN 1573-5044, Vol. 23, no 1, 27-37 p.Article in journal (Refereed)
  • 7. Bellini, C.
    et al.
    Chupeau, M. C.
    Guerche, P.
    Vastra, G.
    Chupeau, Y.
    Transformation of Lycopersicon peruvianum and Lycopersicon esculentum mesophyll protoplasts by electroporation1989In: Plant Science, ISSN 0168-9452, E-ISSN 1873-2259, Vol. 65, no 1, 63-75 p.Article in journal (Refereed)
  • 8. Bellini, C.
    et al.
    Delarue, M.Vittorioso, P.Faure, J. D.Prinsen, E.Van Onckelen, H.Barlier, I.Caboche, M.
    Phytohormones and development of lateral roots in Arabidopsis thaliana1998Conference proceedings (editor) (Other academic)
  • 9. Bellini, C.
    et al.
    Giordani, C.
    Lupotto, E.
    Locatelli, F.
    Cuzzoni, E.
    Avogadro, E.
    Castiglione, S.
    Sala, F.
    Stability of a foreign gene in transgenic Nicotiana tabacum  plants during a cycle of dedifferentiation-differentiation1992In: Plant Science, ISSN 0168-9452, E-ISSN 1873-2259, Vol. 82, no 2, 193-200 p.Article in journal (Refereed)
    Abstract [en]

    Protoplasts of Nicotiana tabacum were transformed with the APH(3’)II gene, which confers kanamycin resistance. Plants resistant to kanamycin were differentiated and 3 of them were chosen at random. These were used to study the stability of the foreign gene after a cycle of dedifferentiation, to produce calli, and differentiation, to produce new plants. The effect of the selective pressure was analyzed by performing dedifferentiation and differentiation in the presence or absence of kanamycin. Inbred plants were also produced from the original transformed plants and used as control. Southern blot analysis of DNA extracted from 66 regenerated plants showed in all cases that no detectable alteration occurred both in gene structure and insertion site. Furthermore the specific activity of the APH(3’)II enzyme was shown to be at high level in all regenerated plants regardless of the fact that they were regenerated in the presence or absence of kanamycin. The results described here are experimental evidence that a hybrid forcing gene is rather stable in a heterologous genome even after dedifferentiation of the transformed plants and differentiation in vitro, i.e. in those conditions known to be correlated with extensive somaclonal variation.

  • 10. Bellini, C.
    et al.
    Guerche, P.
    Spielmann, A.
    Goujaud, J.
    Lesaint, C.
    Caboche, M.
    Genetic analysis of transgenic tobacco plants obtained by liposome-mediated transformation: absence of evidence for the mutagenic effect of inserted sequences in sixty characterized transformants1989In: Journal of Heredity, ISSN 0022-1503, E-ISSN 1465-7333, Vol. 80, no 5, 361-367 p.Article in journal (Refereed)
  • 11. Bellini, C
    et al.
    Pautot, V
    La transgenèse végétale1995In: Larousse Annuel, France: Larousse , 1995, 182-184 p.Chapter in book (Other (popular science, discussion, etc.))
  • 12.
    Bellini, Catherine
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Institut Jean-Pierre Bourgin, UMR 1318 INRA-AgroParisTech, Versailles, France.
    Pacurar, Daniel I
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Perrone, Irene
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Adventitious roots and lateral roots: similarities and differences2014In: Annual Review of Plant Biology, ISSN 1543-5008, E-ISSN 1545-2123, Vol. 65, 639-666 p.Article, book review (Refereed)
    Abstract [en]

    In addition to its role in water and nutrient uptake, the root system is fundamentally important because it anchors a plant to its substrate. Although a wide variety of root systems exist across different species, all plants have a primary root (derived from an embryonic radicle) and different types of lateral roots. Adventitious roots, by comparison, display the same functions as lateral roots but develop from aerial tissues. In addition, they not only develop as an adaptive response to various stresses, such as wounding or flooding, but also are a key limiting component of vegetative propagation. Lateral and adventitious roots share key elements of the genetic and hormonal regulatory networks but are subject to different regulatory mechanisms. In this review, we discuss the developmental processes that give rise to lateral and adventitious roots and highlight knowledge acquired over the past few years about the mechanisms that regulate adventitious root formation.

  • 13. Bennett, M
    et al.
    Bellini, C
    Van Der Straeten, D
    Integrative biology: dissecting cross talk between plant signaling pathways2005In: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 123, 109- p.Article, review/survey (Other (popular science, discussion, etc.))
  • 14. Boerjan, W.
    et al.
    Cervera, M. T.
    Delarue, M.
    Beeckman, T.
    Dewitte, W.
    Bellini, C.
    Caboche, M.
    Vanonckelen, H.
    Vanmontagu, M.
    Inze, D.
    Superroot, a recessive mutation in Arabidopsis, confers auxin overproduction1995In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 7, no 9, 1405-1419 p.Article in journal (Refereed)
    Abstract [en]

    We have isolated seven allelic recessive Arabidopsis mutants, designated superroot (sur1-1 to sur1-7), displaying several abnormalities reminiscent of auxin effects. These characteristics include small and epinastic cotyledons, an elongated hypocotyl in which the connection between the stele and cortical and epidermal cells disintegrates, the development of excess adventitious and lateral roots, a reduced number of leaves, and the absence of an inflorescence. When germinated in the dark, sur1 mutants did not develop the apical hook characteristic of etiolated seedlings, We were able to phenocopy the Sur1(-) phenotype by supplying auxin to wild-type seedlings, to propagate sur7 explants on phytohormone-deficient medium, and to regenerate shoots from these explants by the addition of cytokinins alone to the culture medium. Analysis by gas chromatography coupled to mass spectrometry indicated increased levels of both free and conjugated indole-3-acetic acid. sur1 was crossed to the mutant axr2 and the altered-auxin response mutant ctr1. The phenotype of both double mutants was additive. The sur1 gene was mapped on chromosome 2 at 0.5 centimorgans from the gene encoding phytochrome B.

  • 15. Bohmert, K.
    et al.
    Camus, I.
    Bellini, C.
    Bouchez, D.
    Caboche, M.
    Benning, C.
    AGO1 defines a novel locus of Arabidopsis controlling leaf development1998In: EMBO Journal, ISSN 0261-4189, E-ISSN 1460-2075, Vol. 17, no 1, 170-180 p.Article in journal (Refereed)
    Abstract [en]

    An allelic series of the novel argonaute mutant (ago1-1 to ago1-6) of the herbaceous plant Arabidopsis thaliana has been isolated, The ago1 mutation pleotropically affects general plant architecture, The apical shoot meristem generates rosette leaves and a single stem, but axillary meristems rarely develop, Rosette leaves lack a leaf blade but still show adaxial/abaxial differentiation, Instead of cauline leaves, filamentous structures without adaxial/abaxial differentiation develop along the stem and an abnormal inflorescence bearing infertile flowers with filamentous organs is produced, Two independent T-DNA insertions into the AGO1 locus led to the isolation of two corresponding genomic sequences as well as a complete cDNA. The AGO1 locus was mapped close to the marker mi291a on chromosome 1. Antisense expression of the cDNA resulted in a partial mutant phenotype, Sense expression caused some transgenic lines to develop goblet-like leaves and petals, The cDNA encodes a putative 115 kDa protein with sequence similarity tea translation products of a novel gene family present in nematodes as,yell as humans, No specific function has been assigned to these genes, Similar proteins are not encoded by the genomes of yeast or bacteria, suggesting that AGOI belongs to a novel class of genes with a function specific to multicellular organisms.

  • 16. Camilleri, Christine
    et al.
    Azimzadeh, Juliette
    Pastuglia, Martine
    Bellini, Catherine
    Grandjean, Olivier
    Bouchez, David
    The Arabidopsis TONNEAU2 gene encodes a putative novel protein phosphatase 2A regulatory subunit essential for the control of the cortical cytoskeleton.2002In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 14, no 4Article in journal (Refereed)
    Abstract [en]

    In Arabidopsis ton2 mutants, abnormalities of the cortical microtubular cytoskeleton, such as disorganization of the interphase microtubule array and lack of the preprophase band before mitosis, markedly affect cell shape and arrangement as well as overall plant morphology. We present the molecular isolation of the TON2 gene, which is highly conserved in higher plants and has a vertebrate homolog of unknown function. It encodes a protein similar in its C-terminal part to B" regulatory subunits of type 2A protein phosphatases (PP2As). We show that the TON2 protein interacts with an Arabidopsis type A subunit of PP2A in the yeast two-hybrid system and thus likely defines a novel subclass of PP2A subunits that are possibly involved in the control of cytoskeletal structures in plants.

  • 17. Carol, R. J.
    et al.
    Breiman, A.
    Erel, N.
    Vittorioso, P.
    Bellini, C.
    PASTICCINO1 (AtFKBP70) is a nuclear-localised immunophilin required during Arabidopsis thaliana embryogenesis2001In: Plant Science, ISSN 0168-9452, E-ISSN 1873-2259, Vol. 161, no 3, 527-535 p.Article in journal (Refereed)
    Abstract [en]

    The PASTICCINO1 (PAS1) gene of Arabidopsis thaliana encodes a protein with homology to the FK506-binding protein (FKBP) class of immunophilins. To begin to understand more about the possible function of PAS1, we tested some properties of recombinant PAS1 protein and analysed the expression of the gene in Arabidopsis embryos and cell cultures and in tobacco cells. In pas1-1/+ heterozygote embryos the pas1-1 allele is expressed at very low levels in all cells, but it is misexpressed in the pas1-1 homozygote mutant at the same stage. Anti-PAS1 affinity-purified antibodies recognise a 70 kDa protein from dividing cell cultures of Arabidopsis. In indirect immunofluorescence, the same antibodies label the nuclei of dividing tobacco BY-2 cells. In a protease-coupled assay, recombinant PAS1 protein has low peptidylprolyl cis-trans isomerase (PPIase) activity, which is inhibited by the immunosuppressive drugs FK506 and rapamycin, but not by cyclosporin. PAS1 also binds calmodulin in vitro. This data suggests the importance of the correctly regulated production of functional PAS1 protein, a likely nuclear-localised FKBP, for the correct development of the plant embryo. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.

  • 18. Castelain, Mathieu
    et al.
    Le Hir, Rozenn
    Bellini, Catherine
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    The non-DNA-binding bHLH transcription factor PRE3/bHLH135/ATBS1/TMO7 is involved in the regulation of light signaling pathway in Arabidopsis2012In: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 145, no 3, 450-460 p.Article in journal (Refereed)
    Abstract [en]

    Plant basic Helix-loop-helix (bHLH) proteins are transcription factors that are involved in many developmental mechanisms, including light signaling and hormone homeostasis. Some of them are non-DNA-binding proteins and could act as dominant negative regulators of other bHLH proteins by forming heterodimers, in a similar way to animal inhibitor of DNA-binding proteins. It has been recently reported that several non-DNA-binding bHLHs are involved in light signaling (KDR/PRE6), gibberellic acid signaling (PRE1/BNQ1/bHLH136) or brassinosteroid signaling (ATBS1). Here we report that Arabidopsis lines overexpressing the PRE3/bHLH135/ATBS1/TMO7 gene are less responsive to red, far-red and blue light than wild-type which is likely to explain the light hyposensitive phenotype displayed when grown under white light conditions. Using quantitative polymerase chain reaction, we show that the expression of PRE3 and KDR/PRE6 genes is regulated by light and that light-related genes are deregulated in the PRE3-ox lines. We show that PRE3 is expressed in the shoot and root meristems and that PRE3-ox lines also have a defect in lateral root development. Our results not only suggest that PRE3 is involved in the regulation of light signaling, but also support the hypothesis that non-DNA-binding bHLH genes are promiscuous genes regulating a wide range of both overlapping and specific regulatory pathways.

  • 19. Chardon, Fabien
    et al.
    Bedu, Magali
    Calenge, Fanny
    Klemens, Patrick A. W.
    Spinner, Lara
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Clement, Gilles
    Chietera, Giorgiana
    Leran, Sophie
    Ferrand, Marina
    Lacombe, Benoit
    Loudet, Olivier
    Dinant, Sylvie
    Bellini, Catherine
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Neuhaus, H. Ekkehard
    Daniel-Vedele, Francoise
    Krapp, Anne
    Leaf Fructose Content Is Controlled by the Vacuolar Transporter SWEET17 in Arabidopsis2013In: Current Biology, ISSN 0960-9822, E-ISSN 1879-0445, Vol. 23, no 8, 697-702 p.Article in journal (Refereed)
    Abstract [en]

    In higher plants, soluble sugars are mainly present as sucrose, glucose, and fructose [1]. Sugar allocation is based on both source-to-sink transport and intracellular transport between the different organelles [2,3] and depends on actual plant requirements [4]. Under abiotic stress conditions, such as nitrogen limitation, carbohydrates accumulate in plant cells [5]. Despite an increasing number of genetic studies [6, 7], the genetic architecture determining carbohydrate composition is poorly known. Using a quantitative genetics approach, we determined that the carrier protein SWEET17 is a major factor controlling fructose content in Arabidopsis leaves. We observed that when SWEET17 expression is reduced, either by induced or natural variation, fructose accumulates in leaves, suggesting an enhanced storage capacity. Subcellular localization of SWEET17-GFP to the tonoplast and functional expression in Xenopus oocytes showed that SWEET17 is the first vacuolar fructose transporter to be characterized in plants. Physiological studies in planta provide evidence that SWEET17 acts to export fructose out of the vacuole. Overall, our results suggest that natural variation in leaf fructose levels is controlled by the vacuolar fructose transporter SWEET17. SWEET17 is highly conserved across the plant kingdom; thus, these findings offer future possibilities to modify carbohydrate partitioning in crops.

  • 20. Chupeau, MC
    et al.
    Bellini, C.
    Guerche, P.
    Maisonneuve, B.
    Vastra, G.
    Chupeau, Y.
    Transgenic plants of lettuce (Lactuca sativa) obtained through electroporation of protoplasts1989In: Nature Biotechnology 1989, Vol. 7, no 5, 503-508 p.Article in journal (Refereed)
  • 21. Contesto, Celine
    et al.
    Milesi, Sandrine
    Mantelin, Sophie
    Zancarini, Anouk
    Desbrosses, Guilhem
    Varoquaux, Fabrice
    Bellini, Catherine
    Kowalczyk, Mariusz
    Touraine, Bruno
    The auxin-signaling pathway is required for the lateral root response of Arabidopsis to the rhizobacterium Phyllobacterium brassicacearum2010In: Planta, ISSN 0032-0935, E-ISSN 1432-2048, Vol. 232, no 6, 1455-1470 p.Article in journal (Refereed)
    Abstract [en]

    Plant root development is highly responsive both to changes in nitrate availability and beneficial microorganisms in the rhizosphere. We previously showed that Phyllobacterium brassicacearum STM196, a plant growth-promoting rhizobacteria strain isolated from rapeseed roots, alleviates the inhibition exerted by high nitrate supply on lateral root growth. Since soil-borne bacteria can produce IAA and since this plant hormone may be implicated in the high nitrate-dependent control of lateral root development, we investigated its role in the root development response of Arabidopsis thaliana to STM196. Inoculation with STM196 resulted in a 50% increase of lateral root growth in Arabidopsis wild-type seedlings. This effect was completely abolished in aux1 and axr1 mutants, altered in IAA transport and signaling, respectively, indicating that these pathways are required. The STM196 strain, however, appeared to be a very low IAA producer when compared with the high-IAA-producing Azospirillum brasilense sp245 strain and its low-IAA-producing ipdc mutant. Consistent with the hypothesis that STM196 does not release significant amounts of IAA to the host roots, inoculation with this strain failed to increase root IAA content. Inoculation with STM196 led to increased expression levels of several IAA biosynthesis genes in shoots, increased Trp concentration in shoots, and increased auxin-dependent GUS staining in the root apices of DR5::GUS transgenic plants. All together, our results suggest that STM196 inoculation triggers changes in IAA distribution and homeostasis independently from IAA release by the bacteria.

  • 22. Cowling, R. J.
    et al.
    Vittorioso, P.
    Faure, J. D.
    Caboche, M.
    Bellini, C.
    The role of PASTICCINO1, an FKBP-like protein, in plant development1999Book (Other academic)
    Abstract [en]

    The pasticcino (pas) mutants of Arabidopsis thaliana were identified due to their abnormal response to cytokinins. These mutants fall into 3 complementation groups: pas1 (2 alleles), pas2 (1 allele) and pas3 (4 alleles). The mutants all have excessive and disorganised cell divisions leading to extra cell layers in the hypocotyl, abnormal apical meristems, and rosettes with fused vitreous leaves. This cell proliferation effect is exaggerated in the presence of cytokinins. The PAS1 gene was cloned via a T-DNA insertion; it encodes for a protein with similarities to FK506-binding proteins (FKBPs), a class of immunophilins. Like other large FKBPs the PAS1 protein has several putative FKBP domains, a tetratricopeptide repeat domain and a calmodulin binding motif. PAS1 also has conserved nuclear localisation signals. Although the presence of immunophilins has been demonstrated in plants, their functions are unknown. PAS1 is the first plant immunophilin-like gene to be disrupted and suggests a role for PAS 1 in the control of plant cell division.

  • 23. Creusot, F.
    et al.
    Fouilloux, E.
    Dron, M.
    Lafleuriel, J.
    Picard, G.
    Billault, A.
    Lepaslier, D.
    Cohen, D.
    Chaboute, M. E.
    Durr, A.
    Fleck, J.
    Gigot, C.
    Camilleri, C.
    Bellini, C.
    Caboche, M.
    Bouchez, D.
    The CIC YAC library: Sizing of the clones and determination of clones carrying repeated DNA sequences.1995In: The Plant Journal, ISSN 0960-7412, E-ISSN 1365-313X, Vol. 8, no 5, 763-770 p.Article in journal (Refereed)
    Abstract [en]

    A new Arabidopsis thaliana (ecotype Columbia) genomic library has been constructed in Yeast Artificial Chromosomes: the CIC library (for CEPH, INRA and CNRS). Optimization of plant culture conditions and protoplast preparation allowed the recovery of large amounts of viable protoplasts. Mechanical shearing of DNA was minimized by isolation of DNA from protoplasts embedded in agarose. Cloning of large inserts was favored by including two successive size fractionation steps (after partial EcoRI digestion and after ligation with the vector arms), which selected DNA fragments larger than 350 kb. The library consists of 1152 clones with an average insert size of 420 kb. Clones carrying chloroplast DNA and various nuclear repeated sequences have been identified. Twenty-one per cent of the clones are found to contain chloroplast DNA. Therefore, the library represents around four nuclear genome equivalents. The clones containing 5S rDNA genes, 18S-25S rDNA sequences and the 180 bp paracentromeric repeated element account for 3.6%, 8.9% and 5.8%, respectively. Only one clone was found to carry the 160 bp paracentromeric repeated element. Given the smaller size of clones carrying Arabidopsis repeated DNA, the average size of remaining clones is around 480 kb. The library was screened by PCR amplification using pairs of primers corresponding to sequences dispersed in the genome. Seventy out of 76 pairs of primers identified from one to seven YAC clones. Thus at least 92% of the genome is represented in the CIC library. The survey of the library for clones containing unlinked DNA sequences indicates that the proportion of chimeric clones is lower than 10%.

  • 24. Cuzzoni, E
    et al.
    Locatelli, F
    Bellini, C
    Giordani, C
    Lupotto, E
    Sala, F
    A study on the stability of the NPTII gene during a cycle of dedifferentiation / differentiation in N. tabacum1990In: Giornale Botanico Italiano, ISSN 0017-0070, Vol. 124, no 4, 136-137 p.Article in journal (Refereed)
  • 25. Delarue, M.
    et al.
    Muller, P.
    Bellini, C.
    Delbarre, A.
    Increased auxin efflux in the IAA-overproducing sur1 mutant of Arabidopsis thaliana: A mechanism for reducing auxin levels?1999In: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 107, no 1, 120-127 p.Article in journal (Refereed)
    Abstract [en]

    With the aim of investigating the mechanisms that maintain auxin homeostasis in plants, we have monitored the net uptake and metabolism of exogenously supplied indole-3-acetic acid (IAA) and naphthalene-1-acetic acid (NAA) in seedlings of wild type and the IAA-overproducing mutant sur1 of Arabidopsis thaliana. Tritiated IAA and NAA entered the seedling tissues within minutes and were mostly accumulated as metabolites, probably amino acid and sugar conjugates, The mutant seedlings were marked by a strong increase of [H-3]IAA metabolism and a reduction of the accumulation levels of both free [H-3]IAA and [H-3]NAA. The same characteristics were observed in wild-type seedlings grown on 5 mu M picloram. We measured [H-3]NAA uptake in the presence of high concentrations of unlabeled NAA or the auxin efflux carrier inhibitor naphthylphthalamic acid (NPA). This abolished the difference in free [H-3]NAA accumulation between the mutant or picloram-treated seedlings and wild-type seedlings. These data indicated that active auxin efflux carriers were present in Arabidopsis seedling tissues. Picloram-treated seedlings and seedlings of the IAA-overproducing mutant sur1 displayed increased auxin efflux carrier activity as well as elevated conjugation of IAA. There is previous evidence to suggest that conjugation is a means to remove excess IAA in plant cells. Here, we discuss the possibility of efflux constituting an additional mechanism for regulating free IAA levels in the face of an excess auxin supply.

  • 26. Delarue, M.
    et al.
    Prinsen, E.
    Van Onckelen, H.
    Caboche, M.
    Bellini, C.
    Sur2 mutations of Arabidopsis thaliana define a new locus involved in the control of auxin homeostasis1998In: The Plant Journal, ISSN 0960-7412, E-ISSN 1365-313X, Vol. 14, no 5, 603-611 p.Article in journal (Refereed)
    Abstract [en]

    A new auxin homeostasis gene in Arabidopsis called SUR2 has been identified. This gene, mapped to the bottom of chromosome 4, is defined by two recessive nuclear mutants designated superroot2 (sur2), which display several abnormalities reminiscent of auxin effects. A number of these characteristics are similar to the phenotype of the previously described auxin-overproducing mutant superroot1 (sur1); however, several lines of evidences reveal that the SUR2 gene defines a new key point in the regulation of endogenous auxin concentrations. The phenotype of the sur1 sur2 double mutant is additive. Analysis by gas chromatography coupled to mass spectrometry indicated increased levels of free indole-3-acetic acid correlated with a decreased level of bound auxin in the sur2 mutant. These results suggest that SUR2 may be involved in the control of auxin conjugation.

  • 27. Delarue, M.
    et al.
    Santoni, V.
    Caboche, M.
    Bellini, C.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    cristal mutations in Arabidopsis confer a genetically heritable, recessive, hyperhydric phenotype1997In: Planta, ISSN 0032-0935, E-ISSN 1432-2048, Vol. 202, no 1, 51-61 p.Article in journal (Refereed)
    Abstract [en]

    A new class of recessive Arabidopsis mutants, designated cristal (cii) has been isolated which display several abnormalities reminiscent of hyperhydric symptoms. These characteristics include translucent and wrinkled cotyledons and leaves, abnormal chloroplast organization, a reduced amount of chlorophyll, a reduced dry weight and a decreased number of palisade cells in the leaves accompanied by an increase of intercellular space, and therefore give a vitreous appearance to the aerial part. The phenotype is also dependent on the culture medium water potential. The cril gene was mapped on chromosome 4 close to the DHS1 marker.

  • 28. Desnos, T.
    et al.
    Orbovic, V.
    Bellini, C.
    Kronenberger, J.
    Caboche, M.
    Traas, J.
    Hofte, H.
    Procuste1 mutants identify two distinct genetic pathways controlling hypocotyl cell elongation, respectively in dark and light-grown Arabidopsis seedlings1996In: Development, ISSN 0950-1991, E-ISSN 1477-9129, Vol. 122, no 2, 683-693 p.Article in journal (Refereed)
    Abstract [en]

    Plant morphogenesis is dependent on a tight control of cell division and expansion. Cell elongation during postembryonic hypocotyl growth is under the control of a light-regulated developmental switch. Light is generally believed to exert its effects on hypocotyl elongation through a phytochrome- and blue-light receptor- mediated inhibitory action on a so far unknown cell elongation mechanism. We describe here a new class of allelic mutants in Arabidopsis, at the locus PROCUSTE1 (prc1-1 to -4), which have a hypocotyl elongation defect specifically associated with the dark-grown developmental program. Normal hypocotyl elongation is restored in plants grown in white, blue or red light. In agreement with this, the constitutive photomorphogenic mutation cop1-6, which induces a deetiolated phenotype in the dark, is epistatic to prc1-2 for the hypocotyl phenotype. Epistasis analyses in red and blue light respectively, indicate that phytochrome B but not the blue light receptor HY4, is required for the switch from PRC1-dependent to PRC1-independent elongation. The conditional hypocotyl growth defect is associated with a deformation of the hypocotyl surface due to an uncontrolled swelling of epidermal, cortical or endodermal cells, suggesting a defect in the structure of the expanding cell wall, A similar phenotype was observed in elongating roots, which was however, independent of the light conditions. The aerial part of mature mutant plants grown in the light was indistinguishable from the wild type. prc1 mutants provide a means of distinguishing, for the first time, two genetic pathways regulating hypocotyl cell elongation respectively in dark- and light-grown seedlings, whereby light not only inhibits hypocotyl growth, but also activates a PRC1-independent cell elongation program.

  • 29. Fagard, M
    et al.
    Boutet, S
    Morel, J B
    Bellini, C
    Vaucheret, H
    AGO1, QDE-2, and RDE-1 are related proteins required for post-transcriptional gene silencing in plants, quelling in fungi, and RNA interference in animals.2000In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 97, no 21Article in journal (Refereed)
    Abstract [en]

    Introduction of transgene DNA may lead to specific degradation of RNAs that are homologous to the transgene transcribed sequence through phenomena named post-transcriptional gene silencing (PTGS) in plants, quelling in fungi, and RNA interference (RNAi) in animals. It was shown previously that PTGS, quelling, and RNAi require a set of related proteins (SGS2, QDE-1, and EGO-1, respectively). Here we report the isolation of Arabidopsis mutants impaired in PTGS which are affected at the Argonaute1 (AGO1) locus. AGO1 is similar to QDE-2 required for quelling and RDE-1 required for RNAi. Sequencing of ago1 mutants revealed one amino acid essential for PTGS that is also present in QDE-2 and RDE-1 in a highly conserved motif. Taken together, these results confirm the hypothesis that these processes derive from a common ancestral mechanism that controls expression of invading nucleic acid molecules at the post-transcriptional level. As opposed to rde-1 and qde-2 mutants, which are viable, ago1 mutants display several developmental abnormalities, including sterility. These results raise the possibility that PTGS, or at least some of its elements, could participate in the regulation of gene expression during development in plants.

  • 30. Faivre-Rampant, O.
    et al.
    Kevers, C.
    Bellini, C.
    Gaspar, T.
    Peroxidase activity, ethylene production, lignification and growth limitation in shoots of a nonrooting mutant of tobacco1998In: Plant physiology and biochemistry (Paris), ISSN 0981-9428, E-ISSN 1873-2690, Vol. 36, no 12, 873-877 p.Article in journal (Refereed)
    Abstract [en]

    The rooting recalcitrant rac Nicotiana tabacum cv Xanthi mutant has been multiplied in vitro under the form of shoots in parallel to wild-type. rac Shoots grew at a lower rate and did not root whatever the treatments when compared to those of wild-type shoots. They were characterized by a higher lignin level, a higher total specific peroxidase activity with higher activity of both acidic and basic isoperoxidases (although missing and supernumerary isoenzymes were observed), and higher ethylene production. These observations might be causally related to growth inhibitions as similar incidences have been noted in different stress-induced growth limitation, through cell wall rigidification and auxin catabolism. The relationship between these aspects and rooting recalcitrance remains to be explored. (C) Elsevier, Paris.

  • 31. Faure, J. D.
    et al.
    Vittorioso, P.
    Santoni, V.
    Fraisier, V.
    Prinsen, E.
    Barlier, I.
    Van Onckelen, H.
    Caboche, M.
    Bellini, C.
    The PASTICCINO genes of Arabidopsis thaliana are involved in the control of cell division and differentiation1998In: Development, ISSN 0950-1991, E-ISSN 1477-9129, Vol. 125, no 5, 909-918 p.Article in journal (Refereed)
    Abstract [en]

    The control of cell division by growth regulators is critical to proper plant development. The isolation of single-gene mutants altered in the response to plant hormones should permit the identification of essential genes controlling the growth and development of plants. We have isolated mutants pasticcino belonging to 3 complementation groups (pas1, pas2, pas3) in the progeny of independent ethyl methane sulfonate and T-DNA mutagenized Arabidopsis thaliana plants. The screen was performed in the presence or absence of cytokinin. The mutants isolated were those that showed a significant hypertrophy of their apical parts when grown on cytokinin-containing medium. The pas mutants have altered embryo, leaf and root development. They display uncoordinated cell divisions which are enhanced by cytokinin. Physiological and biochemical analyses show that cytokinins are probably involved in pas phenotypes. The PAS genes have been mapped respectively to chromosomes 3, 5 and 1 and represent new plant genes involved in the control of cell division and plant development.

  • 32. Geiss, G
    et al.
    Gutierrez, L
    Bellini, C
    Adventitious root formation: new insights and perspective2009In: Root Development / [ed] Beeckman T, Blackwell Publishing, 2009, 127-156 p.Chapter in book (Other academic)
  • 33. Geiss, G.
    et al.
    Gutierrez, L.
    Bellini, C.
    Adventitious root formation new insights and perspectives2010In: Root Development / [ed] Tom Beeckman, Wiley-Blackwell, 2010Chapter in book (Other academic)
  • 34. Guenin, Stephanie
    et al.
    Mauriat, Melanie
    Pelloux, Jerome
    Van Wuytswinkel, Olivier
    Bellini, Catherine
    Gutierrez, Laurent
    Normalization of qRT-PCR data: the necessity of adopting a systematic, experimental conditions-specific, validation of references2009In: Journal of Experimental Botany, ISSN 0022-0957, E-ISSN 1460-2431, Vol. 60, no 2, 487-493 p.Article in journal (Refereed)
    Abstract [en]

    Quantitative RT-PCR (reverse transcription polymerase chain reaction, also known as qRT-PCR or real-time RT-PCR) has been used in large proportions of transcriptome analyses published to date. The accuracy of the results obtained by this method strongly depends on accurate transcript normalization using stably expressed genes, known as references. Statistical algorithms have been developed recently to help validate reference genes but, surprisingly, this robust approach is under-utilized in plants. Instead, putative ’housekeeping’ genes tend to be used as references without any proper validation. The concept of normalization in transcript quantification is introduced here and the factors affecting its reliability in qRT-PCR are discussed in an attempt to convince molecular biologists, and non-specialists, that systematic validation of reference genes is essential for producing accurate, reliable data in qRT-PCR analyses, and thus should be an integral component of them.

  • 35. Guerche, P.
    et al.
    Bellini, C.
    Lemoullec, J. M.
    Caboche, M.
    Use Of Transient Expression For The Optimization Of Direct Gene Transfer Into Tobacco Mesophyll Protoplasts By Electroporation1987In: Biochimie, ISSN 0300-9084, E-ISSN 1638-6183, Vol. 69, no 6-7, 621-628 p.Article in journal (Refereed)
  • 36.
    Gutierrez, Laurent
    et al.
    Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-90183 Umeå, Sweden.
    Bussell, John D
    Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-90183 Umeå, Sweden.
    Pacurar, Daniel I
    Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-90183 Umeå, Sweden.
    Schwambach, Josèli
    Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-90183 Umeå, Sweden.
    Pacurar, Monica
    Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-90183 Umeå, Sweden.
    Bellini, Catherine
    Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-90183 Umeå, Sweden.
    Phenotypic plasticity of adventitious rooting in Arabidopsis is controlled by complex regulation of Auxin response factor transcripts and microRNA abundance2009In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 21, no 10, 3119-3132 p.Article in journal (Refereed)
    Abstract [en]

    The development of shoot-borne roots, or adventitious roots, is indispensable for mass propagation of elite genotypes. It is a complex genetic trait with a high phenotypic plasticity due to multiple endogenous and environmental regulatory factors. We demonstrate here that a subtle balance of activator and repressor AUXIN RESPONSE FACTOR (ARF) transcripts controls adventitious root initiation. Moreover, microRNA activity appears to be required for fine-tuning of this process. Thus, ARF17, a target of miR160, is a negative regulator, and ARF6 and ARF8, targets of miR167, are positive regulators of adventitious rooting. The three ARFs display overlapping expression domains, interact genetically, and regulate each other's expression at both transcriptional and posttranscriptional levels by modulating miR160 and miR167 availability. This complex regulatory network includes an unexpected feedback regulation of microRNA homeostasis by direct and nondirect target transcription factors. These results provide evidence of microRNA control of phenotypic variability and are a significant step forward in understanding the molecular mechanisms regulating adventitious rooting.

  • 37. Gutierrez, Laurent
    et al.
    Mauriat, Melanie
    Pelloux, Jerome
    Bellini, Catherine
    van Wuytswinkel, Olivier
    Towards a systematic validation of references in real-time RT-PCR2008In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 20, no 7, 1734-1735 p.Article in journal (Refereed)
  • 38. Gutierrez, Laurent
    et al.
    Mauriat, Mélanie
    Guénin, Stéphanie
    Pelloux, Jérôme
    Lefebvre, Jean-François
    Louvet, Romain
    Rusterucci, Christine
    Moritz, Thomas
    Guerineau, François
    Bellini, Catherine
    Van Wuytswinkel, Olivier
    The lack of a systematic validation of reference genes: a serious pitfall undervalued in reverse transcription-polymerase chain reaction (RT-PCR) analysis in plants.2008In: Plant Biotechnology Journal, ISSN 1467-7644, E-ISSN 1467-7652, Vol. 6, no 6Article in journal (Refereed)
    Abstract [en]

    Reverse transcription-polymerase chain reaction (RT-PCR) approaches have been used in a large proportion of transcriptome analyses published to date. The accuracy of the results obtained by this method strongly depends on accurate transcript normalization using stably expressed genes, known as references. Statistical algorithms have been developed recently to help validate reference genes, and most studies of gene expression in mammals, yeast and bacteria now include such validation. Surprisingly, this important approach is under-utilized in plant studies, where putative housekeeping genes tend to be used as references without any appropriate validation. Using quantitative RT-PCR, the expression stability of several genes commonly used as references was tested in various tissues of Arabidopsis thaliana and hybrid aspen (Populus tremula x Populus tremuloides). It was found that the expression of most of these genes was unstable, indicating that their use as references is inappropriate. The major impact of the use of such inappropriate references on the results obtained by RT-PCR is demonstrated in this study. Using aspen as a model, evidence is presented indicating that no gene can act as a universal reference, implying the need for a systematic validation of reference genes. For the first time, the extent to which the lack of a systematic validation of reference genes is a stumbling block to the reliability of results obtained by RT-PCR in plants is clearly shown.

  • 39. Gutierrez, Laurent
    et al.
    Mongelard, Gaelle
    Flokova, Kristyna
    Pacurar, Daniel I.
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Novak, Ondrej
    Staswick, Paul
    Kowalczyk, Mariusz
    Pacurar, Monica
    Demailly, Herve
    Geiss, Gaia
    Bellini, Catherine
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Auxin Controls Arabidopsis Adventitious Root Initiation by Regulating Jasmonic Acid Homeostasis2012In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 24, no 6, 2515-2527 p.Article in journal (Refereed)
    Abstract [en]

    Vegetative shoot-based propagation of plants, including mass propagation of elite genotypes, is dependent on the development of shoot-borne roots, which are also called adventitious roots. Multiple endogenous and environmental factors control the complex process of adventitious rooting. In the past few years, we have shown that the auxin response factors ARF6 and ARF8, targets of the microRNA miR167, are positive regulators of adventitious rooting, whereas ARF17, a target of miR160, is a negative regulator. We showed that these genes have overlapping expression profiles during adventitious rooting and that they regulate each other's expression at the transcriptional and posttranscriptional levels by modulating the homeostasis of miR160 and miR167. We demonstrate here that this complex network of transcription factors regulates the expression of three auxin-inducible Gretchen Hagen3 (GH3) genes, GH3.3, GH3.5, and GH3.6, encoding acyl-acid-amido synthetases. We show that these three GH3 genes are required for fine-tuning adventitious root initiation in the Arabidopsis thaliana hypocotyl, and we demonstrate that they act by modulating jasmonic acid homeostasis. We propose a model in which adventitious rooting is an adaptive developmental response involving crosstalk between the auxin and jasmonate regulatory pathways.

  • 40. Gutierrez, Laurent
    et al.
    Van Wuytswinkel, Olivier
    Castelain, Mathieu
    Bellini, Catherine
    Combined networks regulating seed maturation2007In: Trends in Plant Science, ISSN 1360-1385, E-ISSN 1878-4372, Vol. 12, no 7, 294-300 p.Article, review/survey (Refereed)
    Abstract [en]

    Seed maturation is an important phase of seed development during which embryo growth ceases, storage products accumulate, the protective tegument differentiates and tolerance to desiccation develops, leading to seed dormancy. The spatial and temporal regulation of all these processes requires the concerted action of several signaling pathways that integrate information from genetic programs, and both hormonal and metabolic signals. Recent genetic studies have identified some of the interactions that occur between four master regulators in Arabidopsis, increasing our knowledge of the control of the transcriptional program involved in seed maturation. Moreover, several recent breakthroughs have led to a better understanding of the role of abscisic acid signal modulation and the importance of metabolic regulation in the maternal to filial switch leading to the maturation phase.

  • 41. Harrar, Y.
    et al.
    Bellec, Y.
    Bellini, C.
    Faure, J. D.
    Hormonal control of cell proliferation requires PASTICCINO genes2003In: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 132, no 3, 1217-1227 p.Article in journal (Refereed)
    Abstract [en]

    PASTICCINO (PAS) genes are required for coordinated cell division and differentiation during plant development. In loss-of-function pas mutants, plant aerial tissues showed ectopic cell division that was specifically enhanced by cytokinins, leading to disorganized tumor-like tissue. To determine the role of the PAS genes in controlling cell proliferation, we first analyzed the expression profiles of several genes involved in cell division and meristem function. Differentiated and meristematic cells of the pas mutants were more competent for cell division as illustrated by the ectopic and enlarged expression profiles of CYCLIN-DEPENDENT KINASE A and CYCLIN B1. The expression of meristematic homeobox genes KNOTTED-LIKE IN ARABIDOPSIS (KNAT2, KNAT6), and SHOOT MERISTEMLESS was also increased in pas mutants. Moreover, the loss of meristem function caused by shoot meristemless mutation can be suppressed by pas2. The KNAT2 expression pattern defines an enlarged meristematic zone in pas mutants that can be mimicked in wild type by cytokinin treatment. Cytokinin induction of the primary cytokinin response markers, ARABIDOPSIS RESPONSE REGULATOR (ARR5 and ARR6), was enhanced and lasted longer in pas mutants, suggesting that PAS genes in wild type repress cytokinin responses. The expression of the cytokinin-regulated cyclin D, cyclin D3.1, was nonetheless not modified in pas mutants. However, primary auxin response genes were down-regulated in pas mutants, as shown by a lower auxin induction of IAA4 and IAA1 genes, demonstrating that the auxin response was also modified. Altogether, our results suggest that PAS genes are involved in the hormonal control of cell division and differentiation.

  • 42. Harrar, Y.
    et al.
    Bellini, C.
    Faure, J. D.
    FKBPs: at the crossroads of folding and transduction2001In: Trends in Plant Science, ISSN 1360-1385, E-ISSN 1878-4372, Vol. 6, no 9, 426-431 p.Article, review/survey (Refereed)
    Abstract [en]

    FK506-binding proteins (FKBPs) belong to the large family of peptidyl-prolyl cis-trans isomerases, which are known to be involved in many cellular processes, such as cell signalling, protein trafficking and transcription. FKBPs associate into protein complexes, although the involvement and precise role of their foldase activity remain to be elucidated. FKBPs represent a large gene family in plants that is involved in growth and development. Disruption of genes encoding FKBPs in plants and animals has underlined the importance of this family of proteins in the regulation of cell division and differentiation.

  • 43. Harrar, Yaël
    et al.
    Bellec, Yannick
    Bellini, Catherine
    Faure, Jean-Denis
    Hormonal control of cell proliferation requires PASTICCINO genes.2003In: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 132, no 3Article in journal (Refereed)
    Abstract [en]

    PASTICCINO (PAS) genes are required for coordinated cell division and differentiation during plant development. In loss-of-function pas mutants, plant aerial tissues showed ectopic cell division that was specifically enhanced by cytokinins, leading to disorganized tumor-like tissue. To determine the role of the PAS genes in controlling cell proliferation, we first analyzed the expression profiles of several genes involved in cell division and meristem function. Differentiated and meristematic cells of the pas mutants were more competent for cell division as illustrated by the ectopic and enlarged expression profiles of CYCLIN-DEPENDENT KINASE A and CYCLIN B1. The expression of meristematic homeobox genes KNOTTED-LIKE IN ARABIDOPSIS (KNAT2, KNAT6), and SHOOT MERISTEMLESS was also increased in pas mutants. Moreover, the loss of meristem function caused by shoot meristemless mutation can be suppressed by pas2. The KNAT2 expression pattern defines an enlarged meristematic zone in pas mutants that can be mimicked in wild type by cytokinin treatment. Cytokinin induction of the primary cytokinin response markers, ARABIDOPSIS RESPONSE REGULATOR (ARR5 and ARR6), was enhanced and lasted longer in pas mutants, suggesting that PAS genes in wild type repress cytokinin responses. The expression of the cytokinin-regulated cyclin D, cyclin D3.1, was nonetheless not modified in pas mutants. However, primary auxin response genes were down-regulated in pas mutants, as shown by a lower auxin induction of IAA4 and IAA1 genes, demonstrating that the auxin response was also modified. Altogether, our results suggest that PAS genes are involved in the hormonal control of cell division and differentiation.

  • 44.
    Keech, Olivier
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Pesquet, Edouard
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Gutierrez, Laurent
    Ahad, Abdul
    Bellini, Catherine
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Smith, Steven M
    Gardeström, Per
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Leaf senescence is accompanied by an early disruption of the microtubule network in Arabidopsis.2010In: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 154, no 4, 1710-1720 p.Article in journal (Refereed)
    Abstract [en]

    The dynamic assembly and disassembly of microtubules (MTs) is essential for cell function. Although leaf senescence is a well-documented process, the role of the MT cytoskeleton during senescence in plants remains unknown. Here, we show that both natural leaf senescence and senescence of individually darkened Arabidopsis (Arabidopsis thaliana) leaves are accompanied by early degradation of the MT network in epidermis and mesophyll cells, whereas guard cells, which do not senesce, retain their MT network. Similarly, entirely darkened plants, which do not senesce, retain their MT network. While genes encoding the tubulin subunits and the bundling/stabilizing MT-associated proteins (MAPs) MAP65 and MAP70-1 were repressed in both natural senescence and dark-induced senescence, we found strong induction of the gene encoding the MT-destabilizing protein MAP18. However, induction of MAP18 gene expression was also observed in leaves from entirely darkened plants, showing that its expression is not sufficient to induce MT disassembly and is more likely to be part of a Ca(2+)-dependent signaling mechanism. Similarly, genes encoding the MT-severing protein katanin p60 and two of the four putative regulatory katanin p80s were repressed in the dark, but their expression did not correlate with degradation of the MT network during leaf senescence. Taken together, these results highlight the earliness of the degradation of the cortical MT array during leaf senescence and lead us to propose a model in which suppression of tubulin and MAP genes together with induction of MAP18 play key roles in MT disassembly during senescence.

  • 45. Klemens, Patrick A. W.
    et al.
    Patzke, Kathrin
    Deitmer, Joachim
    Spinner, Lara
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Institut National de la Research Agronomic, UMR1318, Institut Jean-Pierre Bourgin, Saclay Plant Sciences, Versailles, France.
    Le Hir, Rozenn
    Bellini, Catherine
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Institut National de la Research Agronomic, UMR1318, Institut Jean-Pierre Bourgin, Saclay Plant Sciences, Versailles, France.
    Bedu, Magali
    Chardon, Fabien
    Krapp, Anne
    Neuhaus, H. Ekkehard
    Overexpression of the Vacuolar Sugar Carrier AtSWEET16 Modifies Germination, Growth, and Stress Tolerance in Arabidopsis2013In: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 163, no 3, 1338-1352 p.Article in journal (Refereed)
    Abstract [en]

    Here, we report that SUGARS WILL EVENTUALLY BE EXPORTED TRANSPORTER (SWEET16) from Arabidopsis (Arabidopsis thaliana) is a vacuole-located carrier, transporting glucose (Glc), fructose (Fru), and sucrose (Suc) after heterologous expression in Xenopus laevis oocytes. The SWEET16 gene, similar to the homologs gene SWEET17, is mainly expressed in vascular parenchyma cells. Application of Glc, Fru, or Suc, as well as cold, osmotic stress, or low nitrogen, provoke the down-regulation of SWEET16 messenger RNA accumulation. SWEET16 overexpressors (35S(Pro):SWEET16) showed a number of peculiarities related to differences in sugar accumulation, such as less Glc, Fru, and Suc at the end of the night. Under cold stress, 35S(Pro):SWEET16 plants are unable to accumulate Fru, while under nitrogen starvation, both Glc and Fru, but not Suc, were less abundant. These changes of individual sugars indicate that the consequences of an increased SWEET16 activity are dependent upon the type of external stimulus. Remarkably, 35S(Pro):SWEET16 lines showed improved germination and increased freezing tolerance. The latter observation, in combination with the modified sugar levels, points to a superior function of Glc and Suc for frost tolerance. 35S(Pro):SWEET16 plants exhibited increased growth efficiency when cultivated on soil and showed improved nitrogen use efficiency when nitrate was sufficiently available, while under conditions of limiting nitrogen, wild-type biomasses were higher than those of 35S(Pro):SWEET16 plants. Our results identify SWEET16 as a vacuolar sugar facilitator, demonstrate the substantial impact of SWEET16 overexpression on various critical plant traits, and imply that SWEET16 activity must be tightly regulated to allow optimal Arabidopsis development under nonfavorable conditions.

  • 46.
    Le Hir, Rozenn
    et al.
    UMR1318 Institut Jean-Pierre Bourgin, INRA-AgroParisTech, INRA Centre de Versailles, Versailles, France.
    Bellini, Catherine
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). UMR1318 Institut Jean-Pierre Bourgin, INRA-AgroParisTech, INRA Centre de Versailles, Versailles, France.
    The plant-specific Dof transcription factors family: new players involved in vascular system development and functioning in Arabidopsis2013In: Frontiers in Plant Science, ISSN 1664-462X, Vol. 4, Article Number: 164- p.Article, review/survey (Refereed)
    Abstract [en]

    In higher plants phloem and xylem are responsible for long-distance transport of water, nutrients, and signals that act systemically at short or long-distance to coordinate developmental processes. The formation of the plant vascular system is a complex process that integrates signaling events and gene regulation at transcriptional and posttranscriptional levels. Thanks to transcriptomic and proteomic analysis we start to better understand the mechanisms underlying the formation and the functioning of the vascular system. The role of the DNA-binding with one finger (Dof TFs), a group of plant-specific transcription factors, recently emerged as part of the transcriptional regulatory networks acting on the formation and functioning of the vascular tissues. More than half of the members of this TF family are expressed in the vascular system. In addition some of them have been proposed to be mobile proteins, suggesting a possible role in the control of short- or long-distance signaling as well. This review summarizes the current knowledge on Dof TFs family in Arabidopsis with a special focus on their role in vascular development and functioning.

  • 47. Le Hir, Rozenn
    et al.
    Beneteau, Julie
    Bellini, Catherine
    Vilaine, Francoise
    Dinant, Sylvie
    Gene expression profiling: keys for investigating phloem functions2008In: Trends in Plant Science, ISSN 1360-1385, E-ISSN 1878-4372, Vol. 13, no 6, 273-280 p.Article, review/survey (Refereed)
    Abstract [en]

    Phloem is the major route for transport of carbohydrates, amino acids, and other nutrients from source to sink tissues. Hormones, mRNAs, small RNAs and proteins also are transported by the phloem, and potentially play pivotal roles in communication between organs to coordinate plant development and physiology. A comprehensive understanding of the mechanisms involved in phloem transport and signalling is still lacking. Recent transcript profiling in several plant species has provided new insights to phloem-specialized functions. Here, we review conclusions regarding the unique functions of the phloem and discuss putative roles for mRNAs and small RNA species in long-distance signalling.

  • 48. Le Hir, Rozenn
    et al.
    Castelain, Mathieu
    Chakraborti, Dipankar
    Moritz, Thomas
    Dinant, Sylvie
    Bellini, Catherine
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, Versailles, France.
    AtbHLH68 transcription factor contributes to the regulation of ABA homeostasis and drought stress tolerance in Arabidopsis thaliana2017In: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 160, no 3, 312-327 p.Article in journal (Refereed)
    Abstract [en]

    Basic helix-loop-helix (bHLH) transcription factors are involved in a wide range of developmental processes and in response to biotic and abiotic stresses. They represent one of the biggest families of transcription factors but only few of them have been functionally characterized. Here we report the characterization of AtbHLH68 and show that, although the knock out mutant did not have an obvious development phenotype, it was slightly more sensitive to drought stress than the Col-0, and AtbHLH68 overexpressing lines displayed defects in lateral root (LR) formation and a significant increased tolerance to drought stress, likely related to an enhanced sensitivity to abscisic acid (ABA) and/or increased ABA content. AtbHLH68 was expressed in the vascular system of Arabidopsis and its expression was modulated by exogenously applied ABA in an organ-specific manner. We showed that the expression of genes involved in ABA metabolism [AtAAO3 (AtALDEHYDE OXIDASE 3) and AtCYP707A3 (AtABSCISIC ACID 8HYDROXYLASE 3)], in ABA-related response to drought-stress (AtMYC2, AtbHLH122 and AtRD29A) or during LRs development (AtMYC2 and AtABI3) was de-regulated in the overexpressing lines. We propose that AtbHLH68 has a function in the regulation of LR elongation, and in the response to drought stress, likely through an ABA-dependent pathway by regulating directly or indirectly components of ABA signaling and/or metabolism.

  • 49.
    Le Hir, Rozenn
    et al.
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Swedish University of Agricultural Sciences, Umeå and AgroParisTech, Versailles Cedex, France.
    Sorin, Clement
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Chakraborti, Dipankar
    Moritz, Thomas
    Schaller, Hubert
    Tellier, Frederique
    Robert, Stephanie
    Morin, Halima
    Bako, Laszlo
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Bellini, Catherine
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Swedish University of Agricultural Sciences, Umeå and AgroParisTech, Versailles Cedex, France.
    ABCG9, ABCG11 and ABCG14 ABC transporters are required for vascular development in Arabidopsis2013In: The Plant Journal, ISSN 0960-7412, E-ISSN 1365-313X, Vol. 76, no 5, 811-824 p.Article in journal (Refereed)
    Abstract [en]

    In order to obtain insights into the regulatory pathways controlling phloem development, we characterized three genes encoding membrane proteins from the G sub-family of ABC transporters (ABCG9, ABCG11 and ABCG14), whose expression in the phloem has been confirmed. Mutations in the genes encoding these dimerizing half transporters' are semi-dominant and result in vascular patterning defects in cotyledons and the floral stem. Co-immunoprecipitation and bimolecular fluorescence complementation experiments demonstrated that these proteins dimerize, either by flexible pairing (ABCG11 and ABCG9) or by forming strict heterodimers (ABCG14). In addition, metabolome analyses and measurement of sterol ester contents in the mutants suggested that ABCG9, ABCG11 and ABCG14 are involved in lipid/sterol homeostasis regulation. Our results show that these three ABCG genes are required for proper vascular development in Arabidopsis thaliana.

  • 50. Le Hir, Rozenn
    et al.
    Spinner, Lara
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Institut National de la Research Agronomic, UMR1318 INRA-AgroParisTech, Institut Jean-Pierre Bourgin, Univ. Paris-Sud.
    Klemens, Patrick A. W.
    Chakraborti, Dipankar
    de Marco, Federica
    Vilaine, Francoise
    Wolff, Nelly
    Lemoine, Remi
    Porcheron, Benoit
    Gery, Carine
    Teoule, Evelyne
    Chabout, Salem
    Mouille, Gregory
    Neuhaus, H. Ekkehard
    Dinant, Sylvie
    Bellini, Catherine
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Institut National de la Research Agronomic, UMR1318 INRA-AgroParisTech, Institut Jean-Pierre Bourgin, Univ. Paris-Sud.
    Disruption of the Sugar Transporters AtSWEET11 and AtSWEET12 Affects Vascular Development and Freezing Tolerance in Arabidopsis2015In: Molecular Plant, ISSN 1674-2052, E-ISSN 1752-9867, Vol. 8, no 11, 1687-1690 p.Article in journal (Refereed)
12 1 - 50 of 75
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