45 results on '"Niittylä, Totte"'
Search Results
2. A metabolite roadmap of the wood-forming tissue in Populus tremula
- Author
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Abreu, Ilka N., Johansson, Annika I., Sokołowska, Katarzyna, Niittylä, Totte, Sundberg, Björn, Hvidsten, Torgeir R., Street, Nathaniel R., and Moritz, Thomas
- Published
- 2020
3. Diurnal in vivo xylem sap glucose and sucrose monitoring using implantable organic electrochemical transistor sensors
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Diacci, Chiara, Abedi, Tayebeh, Lee, Jee Woong, Gabrielsson, Erik O., Berggren, Magnus, Simon, Daniel T., Niittylä, Totte, and Stavrinidou, Eleni
- Published
- 2021
- Full Text
- View/download PDF
4. Comparison of tension wood and normal wood for oxidative nanofibrillation and network characteristics
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Jonasson, Simon, Bünder, Anne, Das, Oisik, Niittylä, Totte, and Oksman, Kristiina
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- 2021
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5. Isolation and characterization of cellulose nanofibers from aspen wood using derivatizing and non-derivatizing pretreatments
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Jonasson, Simon, Bünder, Anne, Niittylä, Totte, and Oksman, Kristiina
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- 2020
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6. Corrigendum : Spatially resolved metabolic analysis reveals a central role for transcriptional control in carbon allocation to wood
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Roach, Melissa, Arrivault, Stéphanie, Mahboubi, Amir, Krohn, Nicole, Sulpice, Ronan, Stitt, Mark, and Niittylä, Totte
- Published
- 2018
7. Cellulose Synthase Stoichiometry in Aspen Differs from Arabidopsis and Norway Spruce
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Zhang, Xueyang, Dominguez, Pia Guadalupe, Kumar, Manoj, Bygdell, Joakim, Miroshnichenko, Sergey, Sundberg, Björn, Wingsle, Gunnar, and Niittylä, Totte
- Published
- 2018
8. AspWood : High-Spatial-Resolution Transcriptome Profiles Reveal Uncharacterized Modularity of Wood Formation in Populus tremula
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Sundell, David, Street, Nathaniel R., Kumar, Manoj, Mellerowicz, Ewa J., Kucukoglu, Melis, Johnsson, Christoffer, Kumar, Vikash, Mannapperuma, Chanaka, Delhomme, Nicolas, Nilsson, Ove, Tuominen, Hannele, Pesquet, Edouard, Fischer, Urs, Niittylä, Totte, Sundberg, Björn, and Hvidsten, Torgeir R.
- Published
- 2017
9. Spatially resolved metabolic analysis reveals a central role for transcriptional control in carbon allocation to wood
- Author
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Roach, Melissa, Arrivault, Stéphanie, Mahboubi, Amir, Krohn, Nicole, Sulpice, Ronan, Stitt, Mark, and Niittylä, Totte
- Published
- 2017
10. Two-step derivatization for determination of sugar phosphates in plants by combined reversed phase chromatography/tandem mass spectrometry
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Rende, Umut, Niittylä, Totte, and Moritz, Thomas
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- 2019
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11. Preparation and Characterization of Softwood and Hardwood Nanofibril Hydrogels: Toward Wound Dressing Applications.
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Baş, Yağmur, Berglund, Linn, Niittylä, Totte, Zattarin, Elisa, Aili, Daniel, Sotra, Zeljana, Rinklake, Ivana, Junker, Johan, Rakar, Jonathan, and Oksman, Kristiina
- Published
- 2023
- Full Text
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12. ¹³C Tracking after ¹³CO₂ Supply Revealed Diurnal Patterns of Wood Formation in Aspen
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Mahboubi, Amir, Linden, Pernilla, Hedenström, Mattias, Moritz, Thomas, and Niittylä, Totte
- Published
- 2015
13. A Previously Unknown Maltose Transporter Essential for Starch Degradation in Leaves
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Niittylä, Totte, Messerli, Gaëlle, Trevisan, Martine, Chen, Jychian, Smith, Alison M., and Zeeman, Samuel C.
- Published
- 2004
14. Aspen SUCROSE TRANSPORTER3 Allocates Carbon into Wood Fibers
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Mahboubi, Amir, Ratke, Christine, Gorzsás, András, Kumar, Manoj, Mellerowicz, Ewa J., and Niittylä, Totte
- Published
- 2013
15. Flexible Organic Electronic Ion Pump for Flow‐Free Phytohormone Delivery into Vasculature of Intact Plants.
- Author
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Bernacka‐Wojcik, Iwona, Talide, Loïc, Abdel Aziz, Ilaria, Simura, Jan, Oikonomou, Vasileios K., Rossi, Stefano, Mohammadi, Mohsen, Dar, Abdul Manan, Seitanidou, Maria, Berggren, Magnus, Simon, Daniel T., Tybrandt, Klas, Jonsson, Magnus P., Ljung, Karin, Niittylä, Totte, and Stavrinidou, Eleni
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ABSCISIC acid ,BLOOD vessels ,STOMATA ,PLANT cells & tissues ,BLUE light ,PLANT hormones ,BIOELECTRONICS ,PLANT engineering - Abstract
Plant vasculature transports molecules that play a crucial role in plant signaling including systemic responses and acclimation to diverse environmental conditions. Targeted controlled delivery of molecules to the vascular tissue can be a biomimetic way to induce long distance responses, providing a new tool for the fundamental studies and engineering of stress‐tolerant plants. Here, a flexible organic electronic ion pump, an electrophoretic delivery device, for controlled delivery of phytohormones directly in plant vascular tissue is developed. The c‐OEIP is based on polyimide‐coated glass capillaries that significantly enhance the mechanical robustness of these microscale devices while being minimally disruptive for the plant. The polyelectrolyte channel is based on low‐cost and commercially available precursors that can be photocured with blue light, establishing much cheaper and safer system than the state‐of‐the‐art. To trigger OEIP‐induced plant response, the phytohormone abscisic acid (ABA) in the petiole of intact Arabidopsis plants is delivered. ABA is one of the main phytohormones involved in plant stress responses and induces stomata closure under drought conditions to reduce water loss and prevent wilting. The OEIP‐mediated ABA delivery triggered fast and long‐lasting stomata closure far away from the delivery point demonstrating systemic vascular transport of the delivered ABA, verified delivering deuterium‐labeled ABA. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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16. Aspen growth is not limited by starch reserves
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Wang, Wei, Talide, Loic, Viljamaa, Sonja, and Niittylä, Totte
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- 2022
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17. Characteristics of Cellulose Nanofibrils from Transgenic Trees with Reduced Expression of Cellulose Synthase Interacting 1
- Author
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Jonasson, Simon, Bünder, Anne, Berglund, Linn, Niittylä, Totte, and Oksman, Kristiina
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Wood Science - Abstract
Cellulose nanofibrils can be derived from the native load-bearing cellulose microfibrils in wood. These microfibrils are synthesized by a cellulose synthase enzyme complex that resides in the plasma membrane of developing wood cells. It was previously shown that transgenic hybrid aspen trees with reduced expression of CSI1 have different wood mechanics and cellulose microfibril properties. We hypothesized that these changes in the native cellulose may affect the quality of the corresponding nanofibrils. To test this hypothesis, wood from wild-type and transgenic trees with reduced expression of CSI1 was subjected to oxidative nanofibril isolation. The transgenic wood-extracted nanofibrils exhibited a significantly lower suspension viscosity and estimated surface area than the wild-type nanofibrils. Furthermore, the nanofibril networks manufactured from the transgenics exhibited high stiffness, as well as reduced water uptake, tensile strength, strain-to-break, and degree of polymerization. Presumably, the difference in wood properties caused by the decreased expression of CSI1 resulted in nanofibrils with distinctive qualities. The observed changes in the physicochemical properties suggest that the differences were caused by changes in the apparent nanofibril aspect ratio and surface accessibility. This study demonstrates the possibility of influencing wood-derived nanofibril quality through the genetic engineering of trees.
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- 2022
18. Sucrose synthase activity is not required for cellulose biosynthesis in Arabidopsis.
- Author
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Wang, Wei, Viljamaa, Sonja, Hodek, Ondrej, Moritz, Thomas, and Niittylä, Totte
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CELLULOSE synthase ,CELLULOSE ,SUCROSE ,BIOSYNTHESIS ,PLANT cell walls ,ARABIDOPSIS - Abstract
SUMMARY: Biosynthesis of plant cell walls requires UDP‐glucose as the substrate for cellulose biosynthesis, and as an intermediate for the synthesis of other matrix polysaccharides. The sucrose cleaving enzyme sucrose synthase (SUS) is thought to have a central role in UDP‐glucose biosynthesis, and a long‐held and much debated hypothesis postulates that SUS is required to supply UDP‐glucose to cellulose biosynthesis. To investigate the role of SUS in cellulose biosynthesis of Arabidopsis thaliana we characterized mutants in which four or all six Arabidopsis SUS genes were disrupted. These sus mutants showed no growth phenotypes, vascular tissue cell wall defects, or changes in cellulose content. Moreover, the UDP‐glucose content of rosette leaves of the sextuple sus mutants was increased by approximately 20% compared with wild type. It can thus be concluded that cellulose biosynthesis is able to employ alternative UDP‐glucose biosynthesis pathway(s), and thereby the model of SUS requirements for cellulose biosynthesis in Arabidopsis can be refuted. Significance Statement: Many models of cellulose biosynthesis in plants imply that sucrose synthase channels the substrate UDP‐glucose to the plasma membrane localized cellulose synthase complex. Here we used sextuple Arabidopsis mutants devoid of sucrose synthase activity to test this hypothesis directly. The results show that sucrose synthase is not required for cellulose biosynthesis in Arabidopsis. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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19. CAGEs are Golgi‐localized GT31 enzymes involved in cellulose biosynthesis in Arabidopsis.
- Author
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Nibbering, Pieter, Castilleux, Romain, Wingsle, Gunnar, and Niittylä, Totte
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CELLULOSE synthase ,XYLEM ,PLANT cell walls ,CELLULOSE ,BIOSYNTHESIS ,ENZYMES ,GOLGI apparatus ,CARRIER proteins - Abstract
SUMMARY: Cellulose is the main structural component in the plant cell walls. We show that two glycosyltransferase family 31 (GT31) enzymes of Arabidopsis thaliana, here named cellulose synthesis associated glycosyltransferases 1 and 2 (CAGE1 and 2), influence both primary and secondary cell wall cellulose biosynthesis. cage1cage2 mutants show primary cell wall defects manifesting as impaired growth and cell expansion in seedlings and etiolated hypocotyls, along with secondary cell wall defects, apparent as collapsed xylem vessels and reduced xylem wall thickness in the inflorescence stem. Single and double cage mutants also show increased sensitivity to the cellulose biosynthesis inhibitor isoxaben. The cage1cage2 phenotypes were associated with an approximately 30% reduction in cellulose content, an approximately 50% reduction in secondary cell wall CELLULOSE SYNTHASE (CESA) protein levels in stems and reduced cellulose biosynthesis rate in seedlings. CESA transcript levels were not significantly altered in cage1cage2 mutants, suggesting that the reduction in CESA levels was caused by a post‐transcriptional mechanism. Both CAGE1 and 2 localize to the Golgi apparatus and are predicted to synthesize β‐1,3‐galactans on arabinogalactan proteins. In line with this, the cage1cage2 mutants exhibit reduced levels of β‐Yariv binding to arabinogalactan protein linked β‐1,3‐galactan. This leads us to hypothesize that defects in arabinogalactan biosynthesis underlie the cellulose deficiency of the mutants. Significance Statement: Cellulose, the main component of plant cell walls, is synthesized at the plasma membrane by a multiprotein complex with cellulose synthase enzymes at its core. Here, we show that two Golgi localized glycosyltransferase enzymes are indirectly involved in cellulose biosynthesis, likely by acting on the synthesis of glycans on arabinogalactan proteins. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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20. The Norway spruce genome sequence and conifer genome evolution
- Author
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Nystedt, Björn, Street, Nathaniel R., Wetterbom, Anna, Zuccolo, Andrea, Lin, Yao-Cheng, Scofield, Douglas G., Vezzi, Francesco, Delhomme, Nicolas, Giacomello, Stefania, Alexeyenko, Andrey, Vicedomini, Riccardo, Sahlin, Kristoffer, Sherwood, Ellen, Elfstrand, Malin, Gramzow, Lydia, Holmberg, Kristina, Hällman, Jimmie, Keech, Olivier, Klasson, Lisa, Koriabine, Maxim, Kucukoglu, Melis, Käller, Max, Luthman, Johannes, Lysholm, Fredrik, Niittylä, Totte, Olson, Åke, Rilakovic, Nemanja, Ritland, Carol, Rosselló, Josep A., Sena, Juliana, Svensson, Thomas, Talavera-López, Carlos, Theien, Günter, Tuominen, Hannele, Vanneste, Kevin, Wu, Zhi-Qiang, Zhang, Bo, Zerbe, Philipp, Arvestad, Lars, Bhalerao, Rishikesh, Bohlmann, Joerg, Bousquet, Jean, Gil, Rosario Garcia, Hvidsten, Torgeir R., de Jong, Pieter, MacKay, John, Morgante, Michele, Ritland, Kermit, Sundberg, Björn, Lee Thompson, Stacey, Van de Peer, Yves, Andersson, Björn, Nilsson, Ove, Ingvarsson, Pär K., Lundeberg, Joakim, and Jansson, Stefan
- Published
- 2013
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21. Mobile forms of carbon in trees: metabolism and transport.
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Dominguez, Pia Guadalupe and Niittylä, Totte
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CARBON metabolism , *XYLEM , *WOOD , *CARDIOVASCULAR system , *RAFFINOSE , *PHYSIOLOGY - Abstract
Plants constitute 80% of the biomass on earth, and almost two-thirds of this biomass is found in wood. Wood formation is a carbon (C)-demanding process and relies on C transport from photosynthetic tissues. Thus, understanding the transport process is of major interest for understanding terrestrial biomass formation. Here, we review the molecules and mechanisms used to transport and allocate C in trees. Sucrose is the major form in which C is transported in plants, and it is found in the phloem sap of all tree species investigated so far. However, in several tree species, sucrose is accompanied by other molecules, notably polyols and the raffinose family of oligosaccharides. We describe the molecules that constitute each of these transport groups, and their distribution across different tree species. Furthermore, we detail the metabolic reactions for their synthesis, the mechanisms by which trees load and unload these compounds in and out of the vascular system, and how they are radially transported in the trunk and finally catabolized during wood formation. We also address a particular C recirculation process between phloem and xylem that occurs in trees during the annual cycle of growth and dormancy. A search of possible evolutionary drivers behind the diversity of C-carrying molecules in trees reveals no consistent differences in C transport mechanisms between angiosperm and gymnosperm trees. Furthermore, the distribution of C forms across species suggests that climate-related environmental factors will not explain the diversity of C transport forms. However, the consideration of C-transport mechanisms in relation to tree–rhizosphere coevolution deserves further attention. To conclude the review, we identify possible future lines of research in this field. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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22. Fructokinase is required for carbon partitioning to cellulose in aspen wood
- Author
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Roach, Melissa, Gerber, Lorenz, Sandquist, David, Gorzsás, András, Hedenström, Mattias, Kumar, Manoj, Steinhauser, Marie Caroline, Feil, Regina, Daniel, Geoffrey, Stitt, Mark, Sundberg, Björn, and Niittylä, Totte
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- 2012
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23. Fluorescence Lifetime Imaging as an In Situ and Label-Free Readout for the Chemical Composition of Lignin.
- Author
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Escamez, Sacha, Terryn, Christine, Gandla, Madhavi Latha, Yassin, Zakiya, Scheepers, Gerhard, Näsholm, Torgny, Sundman, Ola, Jönsson, Leif J., Lundberg-Felten, Judith, Tuominen, Hannele, Niittylä, Totte, and Paës, Gabriel
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- 2021
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24. Sucrose synthase determines carbon allocation in developing wood and alters carbon flow at the whole tree level in aspen.
- Author
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Dominguez, Pia Guadalupe, Donev, Evgeniy, Derba‐Maceluch, Marta, Bünder, Anne, Hedenström, Mattias, Tomášková, Ivana, Mellerowicz, Ewa J., and Niittylä, Totte
- Subjects
ASPEN (Trees) ,EUROPEAN aspen ,SUCROSE ,BIOMASS ,CARBON - Abstract
Summary: Despite the ecological and industrial importance of biomass accumulation in wood, the control of carbon (C) allocation to this tissue and to other tree tissues remain poorly understood.We studied sucrose synthase (SUS) to clarify its role in biomass formation and C metabolism at the whole tree level in hybrid aspen (Populus tremula × tremuloides). To this end, we analysed source leaves, phloem, developing wood, and roots of SUSRNAi trees using a combination of metabolite profiling, 13CO2 pulse labelling experiments, and long‐term field experiments.The glasshouse grown SUSRNAi trees exhibited a mild stem phenotype together with a reduction in wood total C. The 13CO2 pulse labelling experiments showed an alteration in the C flow in all the analysed tissues, indicating that SUS affects C metabolism at the whole tree level. This was confirmed when the SUSRNAi trees were grown in the field over a 5‐yr period; their stem height, diameter and biomass were substantially reduced.These results establish that SUS influences C allocation to developing wood, and that it affects C metabolism at the whole tree level. See also the Commentary on this article by Gessler, 229: 8–10. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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25. The Spatio-Temporal Distribution of Cell Wall-Associated Glycoproteins During Wood Formation in Populus.
- Author
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Abedi, Tayebeh, Castilleux, Romain, Nibbering, Pieter, and Niittylä, Totte
- Subjects
GLYCOPROTEINS ,WOOD chemistry ,PLANT cell walls ,PLANT cell development ,PROLINE ,GLYCAN structure - Abstract
Plant cell wall associated hydroxyproline-rich glycoproteins (HRGPs) are involved in several aspects of plant growth and development, including wood formation in trees. HRGPs such as arabinogalactan-proteins (AGPs), extensins (EXTs), and proline rich proteins (PRPs) are important for the development and architecture of plant cell walls. Analysis of publicly available gene expression data revealed that many HRGP encoding genes show tight spatio-temporal expression patterns in the developing wood of Populus that are indicative of specific functions during wood formation. Similar results were obtained for the expression of glycosyl transferases putatively involved in HRGP glycosylation. In situ immunolabelling of transverse wood sections using AGP and EXT antibodies revealed the cell type specificity of different epitopes. In mature wood AGP epitopes were located in xylem ray cell walls, whereas EXT epitopes were specifically observed between neighboring xylem vessels, and on the ray cell side of the vessel walls, likely in association with pits. Molecular mass and glycan analysis of AGPs and EXTs in phloem/cambium, developing xylem, and mature xylem revealed clear differences in glycan structures and size between the tissues. Separation of AGPs by agarose gel electrophoresis and staining with β-D-glucosyl Yariv confirmed the presence of different AGP populations in phloem/cambium and xylem. These results reveal the diverse changes in HRGP-related processes that occur during wood formation at the gene expression and HRGP glycan biosynthesis levels, and relate HRGPs and glycosylation processes to the developmental processes of wood formation. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
26. CELLULOSE SYNTHASE INTERACTING 1 is required for wood mechanics and leaf morphology in aspen.
- Author
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Bünder, Anne, Sundman, Ola, Mahboubi, Amir, Persson, Staffan, Mansfield, Shawn D., Rüggeberg, Markus, and Niittylä, Totte
- Subjects
WOOD chemistry ,CELLULOSE synthase ,LEAF morphology ,EUROPEAN aspen ,CELL morphology ,X-ray diffraction measurement ,FLEXURAL strength - Abstract
SUMMARY: Cellulose microfibrils synthesized by CELLULOSE SYNTHASE COMPLEXES (CSCs) are the main load‐bearing polymers in wood. CELLULOSE SYNTHASE INTERACTING1 (CSI1) connects CSCs with cortical microtubules, which align with cellulose microfibrils. Mechanical properties of wood are dependent on cellulose microfibril alignment and structure in the cell walls, but the molecular mechanism(s) defining these features is unknown. Herein, we investigated the role of CSI1 in hybrid aspen (Populus tremula × Populus tremuloides) by characterizing transgenic lines with significantly reduced CSI1 transcript abundance. Reduction in leaves (50–80%) caused leaf twisting and misshaped pavement cells, while reduction (70–90%) in developing xylem led to impaired mechanical wood properties evident as a decrease in the elastic modulus and rupture. X‐ray diffraction measurements indicate that microfibril angle was not impacted by the altered CSI1 abundance in developing wood fibres. Instead, the augmented wood phenotype of the transgenic trees was associated with a reduced cellulose degree of polymerization. These findings establish a function for CSI1 in wood mechanics and in defining leaf cell shape. Furthermore, the results imply that the microfibril angle in wood is defined by CSI1 independent mechanism(s). [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
27. Genome‐wide association study identified novel candidate loci affecting wood formation in Norway spruce.
- Author
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Baison, John, Vidalis, Amaryllis, Zhou, Linghua, Chen, Zhi‐Qiang, Li, Zitong, Sillanpää, Mikko J., Bernhardsson, Carolina, Scofield, Douglas, Forsberg, Nils, Grahn, Thomas, Olsson, Lars, Karlsson, Bo, Wu, Harry, Ingvarsson, Pär K., Lundqvist, Sven‐Olof, Niittylä, Totte, and García‐Gil, M Rosario
- Subjects
LOCUS (Genetics) ,NORWAY spruce ,SINGLE nucleotide polymorphisms ,BOTANY ,FORESTS & forestry ,TREE growth ,WOOD quality - Abstract
Summary: Norway spruce is a boreal forest tree species of significant ecological and economic importance. Hence there is a strong imperative to dissect the genetics underlying important wood quality traits in the species. We performed a functional genome‐wide association study (GWAS) of 17 wood traits in Norway spruce using 178 101 single nucleotide polymorphisms (SNPs) generated from exome genotyping of 517 mother trees. The wood traits were defined using functional modelling of wood properties across annual growth rings. We applied a Least Absolute Shrinkage and Selection Operator (LASSO‐based) association mapping method using a functional multilocus mapping approach that utilizes latent traits, with a stability selection probability method as the hypothesis testing approach to determine a significant quantitative trait locus. The analysis provided 52 significant SNPs from 39 candidate genes, including genes previously implicated in wood formation and tree growth in spruce and other species. Our study represents a multilocus GWAS for complex wood traits in Norway spruce. The results advance our understanding of the genetics influencing wood traits and identifies candidate genes for future functional studies. Significance Statement: Wood provides both structural support and a transport route for water and solutes in trees. Our work provides a framework to dissect the genetic nature of wood formation and adds to our understanding of tree growth and development. With the current research focus on wood cell wall biosynthesis in general, and lignocellulose feedstock for biorefineries, we believe that this contribution will be of wide interest for the plant science community. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
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28. 13C Tracking after 13CO2 Supply Revealed Diurnal Patterns of Wood Formation in Aspen1
- Author
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Mahboubi, Amir, Linden, Pernilla, Hedenström, Mattias, Moritz, Thomas, and Niittylä, Totte
- Subjects
Analysis of Variance ,Carbon Isotopes ,Principal Component Analysis ,Sucrose ,Magnetic Resonance Spectroscopy ,Articles ,Carbon Dioxide ,Phloem ,Models, Biological ,Wood ,Circadian Rhythm ,Plant Leaves ,Populus ,Cell Wall ,Metabolome ,Cellulose ,Metabolic Networks and Pathways - Abstract
Wood of trees is formed from carbon assimilated in the photosynthetic tissues. Determining the temporal dynamics of carbon assimilation, subsequent transport into developing wood, and incorporation to cell walls would further our understanding of wood formation in particular and tree growth in general. To investigate these questions, we designed a (13)CO2 labeling system to study carbon transport and incorporation to developing wood of hybrid aspen (Populus tremula × tremuloides). Tracking of (13)C incorporation to wood over a time course using nuclear magnetic resonance spectroscopy revealed diurnal patterns in wood cell wall biosynthesis. The dark period had a differential effect on (13)C incorporation to lignin and cell wall carbohydrates. No (13)C was incorporated into aromatic amino acids of cell wall proteins in the dark, suggesting that cell wall protein biosynthesis ceased during the night. The results show previously unrecognized temporal patterns in wood cell wall biosynthesis, suggest diurnal cycle as a possible cue in the regulation of carbon incorporation to wood, and establish a unique (13)C labeling method for the analysis of wood formation and secondary growth in trees.
- Published
- 2015
29. Sucrose transport and carbon fluxes during wood formation.
- Author
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Mahboubi, Amir and Niittylä, Totte
- Subjects
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BIOSYNTHESIS , *WOOD , *XYLEM , *METABOLISM , *SUCROSE - Abstract
Wood biosynthesis defines the chemical and structural properties of wood. The metabolic pathways that produce the precursors of wood cell wall polymers have a central role in defining wood properties. To make rational design of wood properties feasible, we need not only to understand the cell wall biosynthetic machinery, but also how sucrose transport and metabolism in developing wood connect to cell wall biosynthesis and how they respond to genetic and environmental cues. Here, we review the current understanding of the sucrose transport and primary metabolism pathways leading to the precursors of cell wall biosynthesis in woody plant tissues. We present both old, persistent questions and new emerging themes with a focus on wood formation in trees and draw upon evidence from the xylem tissues of herbaceous plants when it is relevant. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
30. Cellulose Synthase Stoichiometry in Aspen Differs from Arabidopsis and Norway Spruce.
- Author
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Xueyang Zhang, Dominguez, Pia Guadalupe, Kumar, Manoj, Bygdell, Joakim, Miroshnichenko, Sergey, Sundberg, Björn, Wingsle, Gunnar, and Niittylä, Totte
- Published
- 2018
- Full Text
- View/download PDF
31. Cytosolic invertase contributes to the supply of substrate for cellulose biosynthesis in developing wood.
- Author
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Rende, Umut, Wang, Wei, Gandla, Madhavi Latha, Jönsson, Leif J., and Niittylä, Totte
- Subjects
INVERTASE ,CELLULOSE synthase ,BIOSYNTHESIS ,PHENOTYPES ,MICROFIBRILS - Abstract
Carbon for cellulose biosynthesis is derived from sucrose. Cellulose is synthesized from uridine 5′-diphosphoglucose ( UDP-glucose), but the enzyme(s) responsible for the initial sucrose cleavage and the source of UDP-glucose for cellulose biosynthesis in developing wood have not been defined., We investigated the role of CYTOSOLIC INVERTASEs ( CINs) during wood formation in hybrid aspen ( Populus tremula × tremuloides) and characterized transgenic lines with reduced CIN activity during secondary cell wall biosynthesis., Suppression of CIN activity by 38-55% led to a 9-13% reduction in crystalline cellulose. The changes in cellulose were reflected in reduced diameter of acid-insoluble cellulose microfibrils and increased glucose release from wood upon enzymatic digestion of cellulose. Reduced CIN activity decreased the amount of the cellulose biosynthesis precursor UDP-glucose in developing wood, pointing to the likely cause of the cellulose phenotype., The findings suggest that CIN activity has an important role in the cellulose biosynthesis of trees, and indicate that cellulose biosynthesis in wood relies on a quantifiable UDP-glucose pool. The results also introduce a concept of altering cellulose microfibril properties by modifying substrate supply to cellulose biosynthesis. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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32. Laser Capture Microdissection Protocol for Xylem Tissues of Woody Plan.
- Author
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Blokhina, Olga, Valerio, Concetta, Sokołowska, Katarzyna, Lei Zhao, Kärkönen, Anna, Niittylä, Totte, and Fagerstedt, Kurt
- Subjects
MICRODISSECTION ,XYLEM ,WOODY plants - Abstract
Laser capture microdissection (LCM) enables precise dissection and collection of individual cell types from complex tissues. When applied to plant cells, and especially to woody tissues, LCM requires extensive optimization to overcome such factors as rigid cell walls, large central vacuoles, intercellular spaces, and technical issues with thickness and flatness of the sections. Here we present an optimized protocol for the laser-assisted microdissection of developing xylem from mature trees: a gymnosperm (Norway spruce, Picea abies) and an angiosperm (aspen, Populus tremula) tree. Different cell types of spruce and aspen wood (i.e., ray cells, tracheary elements, and fibers) were successfully microdissected from tangential, cross and radial cryosections of the current year's growth ring. Two approaches were applied to achieve satisfactory flatness and anatomical integrity of the spruce and aspen specimens. The commonly used membrane slides were ineffective as a mounting surface for the wood cryosections. Instead, in the present protocol we use glass slides, and introduce a glass slide sandwich assembly for the preparation of aspen sections. To ascertain that not only the anatomical integrity of the plant tissue, but also the molecular features were not compromised during the whole LCM procedure, good quality total RNA could be extracted from the microdissected cells. This showed the efficiency of the protocol and established that our methodology can be integrated in transcriptome analyses to elucidate cell-specific molecular events regulating wood formation in trees. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
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33. 13C Tracking after 13CO2 Supply Revealed Diurnal Patterns of Wood Formation in Aspen.
- Author
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Mahboubi, Amir, Linden, Pernilla, Hedenström, Mattias, Moritz, Thomas, and Niittylä, Totte
- Subjects
CARBON dioxide ,ASPEN (Trees) ,PHOTOSYNTHESIS ,WOOD ,PLANT cell walls ,BIOSYNTHESIS - Abstract
Wood of trees is formed from carbon assimilated in the photosynthetic tissues. Determining the temporal dynamics of carbon assimilation, subsequent transport into developing wood, and incorporation to cell walls would further our understanding of wood formation in particular and tree growth in general. To investigate these questions, we designed a
13 CO2 labeling system to study carbon transport and incorporation to developing wood of hybrid aspen (Populus tremula x tremuloides). Tracking of13 C incorporation to wood over a time course using nuclear magnetic resonance spectroscopy revealed diurnal patterns in wood cell wall biosynthesis. The dark period had a differential effect on13 C incorporation to lignin and cell wall carbohydrates. No13 C was incorporated into aromatic amino acids of cell wall proteins in the dark, suggesting that cell wall protein biosynthesis ceased during the night. The results show previously unrecognized temporal patterns in wood cell wall biosynthesis, suggest diurnal cycle as a possible cue in the regulation of carbon incorporation to wood, and establish a unique13 C labeling method for the analysis of wood formation and secondary growth in trees. [ABSTRACT FROM AUTHOR]- Published
- 2015
- Full Text
- View/download PDF
34. Deficient sucrose synthase activity in developing wood does not specifically affect cellulose biosynthesis, but causes an overall decrease in cell wall polymers.
- Author
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Gerber, Lorenz, Zhang, Bo, Roach, Melissa, Rende, Umut, Gorzsás, András, Kumar, Manoj, Burgert, Ingo, Niittylä, Totte, and Sundberg, Björn
- Subjects
SUCROSE synthase ,BIOSYNTHESIS ,ASPEN (Trees) ,WOOD ,PLANT cell walls ,CHEMICAL synthesis ,GLUCOSE - Abstract
• The biosynthesis of wood in aspen (Populus) depends on the metabolism of sucrose, which is the main transported form of carbon from source tissues. The largest fraction of the wood biomass is cellulose, which is synthesized from UDP-glucose. Sucrose synthase (SUS) has been proposed previously to interact directly with cellulose synthase complexes and specifically supply UDP-glucose for cellulose biosynthesis. • To investigate the role of SUS in wood biosynthesis, we characterized transgenic lines of hybrid aspen with strongly reduced SUS activity in developing wood. • No dramatic growth phenotypes in glasshouse-grown trees were observed, but chemical fingerprinting with pyrolysis-GC/MS, together with micromechanical analysis, showed notable changes in chemistry and ultrastructure of the wood in the transgenic lines. Wet chemical analysis showed that the dry weight percentage composition of wood polymers was not changed significantly. However, a decrease in wood density was observed and, consequently, the content of lignin, hemicellulose and cellulose was decreased per wood volume. The decrease in density was explained by a looser structure of fibre cell walls as shown by increased wall shrinkage on drying. • The results show that SUS is not essential for cellulose biosynthesis, but plays a role in defining the total carbon incorporation to wood cell walls. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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35. Paramutation-Like Interaction of T-DNA Loci in Arabidopsis.
- Author
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Xue, Weiya, Ruprecht, Colin, Street, Nathaniel, Hematy, Kian, Chang, Christine, Frommer, Wolf B., Persson, Staffan, and Niittylä, Totte
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NUCLEIC acids ,BRASSICACEAE ,ARABIDOPSIS ,GENETIC regulation ,GENE expression - Abstract
In paramutation, epigenetic information is transferred from one allele to another to create a gene expression state which is stably inherited over generations. Typically, paramutation describes a phenomenon where one allele of a gene downregulates the expression of another allele. Paramutation has been described in several eukaryotes and is best understood in plants. Here we describe an unexpected paramutation-like trans SALK T-DNA interaction in Arabidopsis. Unlike most of the previously described paramutations, which led to gene silencing, the trans SALK T-DNA interaction caused an increase in the transcript levels of the endogenous gene (COBRA) where the T-DNA was inserted. This increased COBRA expression state was stably inherited for several generations and led to the partial suppression of the cobra phenotype. DNA methylation was implicated in this trans SALK T-DNA interaction since mutation of the DNA methyltransferase 1 in the suppressed cobra caused a reversal of the suppression. In addition, null mutants of the DNA demethylase ROS1 caused a similar COBRA transcript increase in the cobra SALK T-DNA mutant as the trans T-DNA interaction. Our results provide a new example of a paramutation-like trans T-DNA interaction in Arabidopsis, and establish a convenient hypocotyl elongation assay to study this phenomenon. The results also alert to the possibility of unexpected endogenous transcript increase when two T-DNAs are combined in the same genetic background. [ABSTRACT FROM AUTHOR]
- Published
- 2012
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36. Similar Protein Phosphatases Control Starch Metabolism in Plants and Glycogen Metabolism in Mammals.
- Author
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Niittylä, Totte, Comparot-Moss, Sylviane, Wei-Ling Lue, Messerli, Gaëlie, Trevisanm, Martine, Seymour, Michael D. J., Gatehouse, John A., Villadsen, Dorthe, Smith, Steven M., Jychian Chen, Zeeman, Samuel C., and Smith, Alison M.
- Subjects
- *
PROTEINS , *PHOSPHORYLATION , *STARCH , *ARABIDOPSIS , *PHOSPHATASES , *GLYCOGEN - Abstract
We report that protein phosphorylation is involved in the control of starch metabolism in Arabidopsis leaves at night. sex4 (starch excess 4) mutants, which have strongly reduced rates of starch metabolism, lack a protein predicted to be a dual specificity protein phosphatase. We have shown that this protein is chloroplastic and can bind to glucans and have presented evidence that it acts to regulate the initial steps of starch degradation at the granule surface. Remarkably, the most closely related protein to SEX4 outside the plant kingdom is laforin, a glucan-binding protein phosphatase required for the metabolism of the mammalian storage carbohydrate glycogen and implicated in a severe form of epilepsy (Lafora disease) in humans. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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37. The Effect of High Lignin Content on Oxidative Nanofibrillation of Wood Cell Wall.
- Author
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Jonasson, Simon, Bünder, Anne, Berglund, Linn, Hertzberg, Magnus, Niittylä, Totte, Oksman, Kristiina, and Vilela, Carla
- Subjects
LIGNINS ,LIGNIN structure ,ATOMIC force microscopy ,WOOD - Abstract
Wood from field-grown poplars with different genotypes and varying lignin content (17.4 wt % to 30.0 wt %) were subjected to one-pot 2,2,6,6-Tetramethylpiperidin-1-yl)oxyl catalyzed oxidation and high-pressure homogenization in order to investigate nanofibrillation following simultaneous delignification and cellulose oxidation. When comparing low and high lignin wood it was found that the high lignin wood was more easily fibrillated as indicated by a higher nanofibril yield (68% and 45%) and suspension viscosity (27 and 15 mPa·s). The nanofibrils were monodisperse with diameter ranging between 1.2 and 2.0 nm as measured using atomic force microscopy. Slightly less cellulose oxidation (0.44 and 0.68 mmol·g
−1 ) together with a reduced process yield (36% and 44%) was also found which showed that the removal of a larger amount of lignin increased the efficiency of the homogenization step despite slightly reduced oxidation of the nanofibril surfaces. The surface area of oxidized high lignin wood was also higher than low lignin wood (114 m2 ·g−1 and 76 m2 ·g−1 ) which implicates porosity as a factor that can influence cellulose nanofibril isolation from wood in a beneficial manner. [ABSTRACT FROM AUTHOR]- Published
- 2021
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38. A Previously Unknown Maltose Transporter Essential forStarch Degradation in Leaves.
- Author
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Niittylä, Totte, Messerli, Gaëlle, Trevisan, Martine, Chen, Jychian, Smith, Alison M., and Zeeman, Samuel C.
- Subjects
- *
ARABIDOPSIS , *MALTOSE , *DISACCHARIDES , *STARCH , *SUCROSE , *PLANT mutation - Abstract
A previously unknown maltose transporter is essential for the conversion of starch to sucrose in Arabidopsis leaves at night. The transporter was identified by isolating two allelic mutants with high starch levels and very high maltose, an intermediate of starch breakdown. The mutations affect a gene of previously unknown function, MEX1. We show that MEX1 is a maltose transporter that is unrelated to other sugar transporters. The severe mex1 phenotype demonstrates that MEX1 is the predominant route of carbohydrate export from chloroplasts at night. Homologous genes in plants including rice and potato indicate that maltose export is of widespread significance. [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
39. Golgi-localized exo-β1,3-galactosidases involved in cell expansion and root growth in Arabidopsis.
- Author
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Nibbering, Pieter, Petersen, Bent L., Motawia, Mohammed Saddik, Jørgensen, Bodil, Ulvskov, Peter, and Niittylä, Totte
- Subjects
- *
GOLGI apparatus , *ROOT growth , *PLANT proteins , *STERIC hindrance , *ARABIDOPSIS , *ARABIDOPSIS thaliana - Abstract
Plant arabinogalactan proteins (AGPs) are a diverse group of cell surface--and wall--associated glycoproteins. Functionally important AGP glycans are synthesized in the Golgi apparatus, but the relationships among their glycosylation levels, processing, and functionalities are poorly understood. Here, we report the identification and functional characterization of two Golgilocalized exo-β-1,3-galactosidases from the glycosyl hydrolase 43 (GH43) family in Arabidopsis thaliana. GH43 loss-of-function mutants exhibited root cell expansion defects in sugar-containing growth media. This root phenotype was associated with an increase in the extent of AGP cell wall association, as demonstrated by Yariv phenylglycoside dye quantification and comprehensive microarray polymer profiling of sequentially extracted cell walls. Characterization of recombinant GH43 variants revealed that the exo-β-1,3-galactosidase activity of GH43 enzymes is hindered by β-1,6 branches on β-1,3-galactans. In line with this steric hindrance, the recombinant GH43 variants did not release galactose from cell wall--extracted glycoproteins or AGP-rich gumarabic. These results indicate that the lack of exoβ-1,3-galactosidase activity alters cell wall extensibility in roots, a phenotype that could be explained by the involvement of galactosidases in AGP glycan biosynthesis. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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40. Characteristics of Cellulose Nanofibrils from Transgenic Trees with Reduced Expression of Cellulose Synthase Interacting 1.
- Author
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Jonasson S, Bünder A, Berglund L, Niittylä T, and Oksman K
- Abstract
Cellulose nanofibrils can be derived from the native load-bearing cellulose microfibrils in wood. These microfibrils are synthesized by a cellulose synthase enzyme complex that resides in the plasma membrane of developing wood cells. It was previously shown that transgenic hybrid aspen trees with reduced expression of CSI1 have different wood mechanics and cellulose microfibril properties. We hypothesized that these changes in the native cellulose may affect the quality of the corresponding nanofibrils. To test this hypothesis, wood from wild-type and transgenic trees with reduced expression of CSI1 was subjected to oxidative nanofibril isolation. The transgenic wood-extracted nanofibrils exhibited a significantly lower suspension viscosity and estimated surface area than the wild-type nanofibrils. Furthermore, the nanofibril networks manufactured from the transgenics exhibited high stiffness, as well as reduced water uptake, tensile strength, strain-to-break, and degree of polymerization. Presumably, the difference in wood properties caused by the decreased expression of CSI1 resulted in nanofibrils with distinctive qualities. The observed changes in the physicochemical properties suggest that the differences were caused by changes in the apparent nanofibril aspect ratio and surface accessibility. This study demonstrates the possibility of influencing wood-derived nanofibril quality through the genetic engineering of trees.
- Published
- 2022
- Full Text
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41. Diurnal in vivo xylem sap glucose and sucrose monitoring using implantable organic electrochemical transistor sensors.
- Author
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Diacci C, Abedi T, Lee JW, Gabrielsson EO, Berggren M, Simon DT, Niittylä T, and Stavrinidou E
- Abstract
Bioelectronic devices that convert biochemical signals to electronic readout enable biosensing with high spatiotemporal resolution. These technologies have been primarily applied in biomedicine while in plants sensing is mainly based on invasive methods that require tissue sampling, hindering in-vivo detection and having poor spatiotemporal resolution. Here, we developed enzymatic biosensors based on organic electrochemical transistors (OECTs) for in-vivo and real-time monitoring of sugar fluctuations in the vascular tissue of trees. The glucose and sucrose OECT-biosensors were implanted into the vascular tissue of trees and were operated through a low-cost portable unit for 48hr. Our work consists a proof-of-concept study where implantable OECT-biosensors not only allow real-time monitoring of metabolites in plants but also reveal new insights into diurnal sugar homeostasis. We anticipate that this work will contribute to establishing bioelectronic technologies as powerful minimally invasive tools in plant science, agriculture and forestry., Competing Interests: The authors declare no competing interests., (© 2020 The Authors.)
- Published
- 2020
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42. OPENER Is a Nuclear Envelope and Mitochondria Localized Protein Required for Cell Cycle Progression in Arabidopsis.
- Author
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Wang W, Zhang X, and Niittylä T
- Subjects
- Alleles, Arabidopsis embryology, Arabidopsis genetics, Cell Proliferation, Conserved Sequence genetics, DNA, Bacterial genetics, Endosperm metabolism, Gene Dosage, Gene Expression Regulation, Plant, Genes, Essential, Genetic Testing, Membrane Proteins metabolism, Mitochondria ultrastructure, Mitochondrial Size, Mutagenesis, Insertional genetics, Mutation genetics, Phenotype, Plant Roots cytology, Protein Transport, Arabidopsis cytology, Arabidopsis metabolism, Arabidopsis Proteins metabolism, Cell Cycle, Mitochondria metabolism, Mitochondrial Proteins metabolism, Nuclear Envelope metabolism, Nuclear Proteins metabolism
- Abstract
Currently one-third of the proteins encoded by the Arabidopsis ( Arabidopsis thaliana ) genome are of unknown function. Some of these unknown proteins are likely to be involved in uncharacterized vital biological processes. Evolutionarily conserved single copy genes in flowering plants have been shown to be enriched in essential housekeeping functions. This together with publicly available gene expression data allows for a focused search for uncharacterized essential genes. Here we identify an essential single copy gene called OPENER ( OPNR ) in Arabidopsis. We show that OPNR is predominantly expressed in actively dividing cells and performs essential functions in seed development and root meristem maintenance. Cell cycle tracking using 5-ethynyl-2'-deoxyuridine staining and fluorescent cell cycle markers together with the increased size of nucleolus and nucleus in opnr mutants indicate that OPNR is required for cell cycle progression through the S or G2 phases. Intriguingly, OPNR localizes to the nuclear envelope and mitochondria. Furthermore, the nuclear envelope localization of OPNR is dependent on its interaction with nuclear inner membrane Sad1/UNC-84 (SUN) domain proteins SUN1 and SUN2. Taken together our results open a line of investigation into an evolutionarily conserved essential cellular process occurring in both the nuclear envelopes and mitochondria of dividing cells., (© 2019 American Society of Plant Biologists. All rights reserved.)
- Published
- 2019
- Full Text
- View/download PDF
43. 13C Tracking after 13CO2 Supply Revealed Diurnal Patterns of Wood Formation in Aspen.
- Author
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Mahboubi A, Linden P, Hedenström M, Moritz T, and Niittylä T
- Subjects
- Analysis of Variance, Carbon Isotopes, Cell Wall metabolism, Cellulose metabolism, Magnetic Resonance Spectroscopy, Metabolic Networks and Pathways, Metabolome, Models, Biological, Phloem metabolism, Plant Leaves metabolism, Principal Component Analysis, Sucrose metabolism, Carbon Dioxide metabolism, Circadian Rhythm, Populus physiology, Wood growth & development
- Abstract
Wood of trees is formed from carbon assimilated in the photosynthetic tissues. Determining the temporal dynamics of carbon assimilation, subsequent transport into developing wood, and incorporation to cell walls would further our understanding of wood formation in particular and tree growth in general. To investigate these questions, we designed a (13)CO2 labeling system to study carbon transport and incorporation to developing wood of hybrid aspen (Populus tremula × tremuloides). Tracking of (13)C incorporation to wood over a time course using nuclear magnetic resonance spectroscopy revealed diurnal patterns in wood cell wall biosynthesis. The dark period had a differential effect on (13)C incorporation to lignin and cell wall carbohydrates. No (13)C was incorporated into aromatic amino acids of cell wall proteins in the dark, suggesting that cell wall protein biosynthesis ceased during the night. The results show previously unrecognized temporal patterns in wood cell wall biosynthesis, suggest diurnal cycle as a possible cue in the regulation of carbon incorporation to wood, and establish a unique (13)C labeling method for the analysis of wood formation and secondary growth in trees., (© 2015 American Society of Plant Biologists. All Rights Reserved.)
- Published
- 2015
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44. Temporal analysis of sucrose-induced phosphorylation changes in plasma membrane proteins of Arabidopsis.
- Author
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Niittylä T, Fuglsang AT, Palmgren MG, Frommer WB, and Schulze WX
- Subjects
- Amino Acid Sequence, Aquaporins metabolism, Arabidopsis cytology, Arabidopsis enzymology, Arabidopsis Proteins chemistry, Arabidopsis Proteins isolation & purification, Cell Membrane enzymology, Cluster Analysis, Mass Spectrometry, Membrane Transport Proteins metabolism, Molecular Sequence Data, Phosphopeptides chemistry, Phosphopeptides isolation & purification, Phosphopeptides metabolism, Phosphorylation drug effects, Plant Proteins metabolism, Plasma Membrane Calcium-Transporting ATPases metabolism, Protein Kinases metabolism, Proton-Translocating ATPases metabolism, Seedlings drug effects, Seedlings metabolism, Substrate Specificity drug effects, Time Factors, Arabidopsis drug effects, Arabidopsis metabolism, Arabidopsis Proteins metabolism, Cell Membrane drug effects, Cell Membrane metabolism, Sucrose pharmacology
- Abstract
Sucrose is the main product of photosynthesis and the most common transport form of carbon in plants. In addition, sucrose is a compound that serves as a signal affecting metabolic flux and development. Here we provide first results of externally induced phosphorylation changes of plasma membrane proteins in Arabidopsis. In an unbiased approach, seedlings were grown in liquid medium with sucrose and then depleted of carbon before sucrose was resupplied. Plasma membranes were purified, and phosphopeptides were enriched and subsequently analyzed quantitatively by mass spectrometry. In total, 67 phosphopeptides were identified, most of which were quantified over five time points of sucrose resupply. Among the identified phosphorylation sites, the well described phosphorylation site at the C terminus of plasma membrane H(+)-ATPases showed a relative increase in phosphorylation level in response to sucrose. This corresponded to a significant increase of proton pumping activity of plasma membrane vesicles from sucrose-supplied seedlings. A new phosphorylation site was identified in the plasma membrane H(+)-ATPase AHA1 and/or AHA2. This phosphorylation site was shown to be crucial for ATPase activity and overrode regulation via the well known C-terminal phosphorylation site. Novel phosphorylation sites were identified for both receptor kinases and cytosolic kinases that showed rapid increases in relative intensities after short times of sucrose treatment. Seven response classes were identified including non-responsive, rapid increase (within 3 min), slow increase, and rapid decrease. Relative quantification of phosphorylation changes by phosphoproteomics provides a means for identification of fast responses to external stimuli in plants as a basis for further functional characterization.
- Published
- 2007
- Full Text
- View/download PDF
45. Fluxomics with ratiometric metabolite dyes.
- Author
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Chaudhuri B, Niittylä T, Hörmann F, and Frommer WB
- Abstract
Today's major excitement in biology centers on signaling: How can a cell or organism measure the myriad of environmental cues, integrate it, and acclimate to the new conditions? Hormonal signals and second messengers are in the focus of most of these studies, e.g., regulation of glucose transporter GLUT4 cycling by insulin, or regulation of plant growth by auxin or brassinosteroids.1-3 In comparison, we generally assume that we know almost everything about basic metabolism since it has been studied for many decades; for example we know since the early 80s that allosteric regulation by fructose-2,6-bisphophate plays an important role in regulating glycolysis in plants and animals.4 This may be the reason why studies of metabolism appear to be a bit out of fashion. But if we look to other organisms such as E. coli or yeast, we rapidly realize that metabolism is controlled by complex interconnected signaling networks, and that we understand little of these signaling networks in humans and plants.5,6 As it turns out, the cell registers many metabolites, and flux through the pathways is regulated using complex signaling networks that involve calcium as well as hormones.
- Published
- 2007
- Full Text
- View/download PDF
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