Doctor of Philosophy, University of Potsdam (2012)
Diplom, University of Potsdam (2008)
Dominique Bergmann, Postdoctoral Faculty Sponsor
Current Research and Scholarly Interests
My research interest involves the development of plant leaves. Like animals, plants form complex multicellular organs, such as leaves, out of individual stem cell populations. These stem cells need to make fate decisions in order to attain a specialized shape and function. I use molecular genetics and microscopy- based methods to investigate how individual stem cells make the decision to commit to a certain fate. In particular, I am interested in the development of stomatal pores which decorate the leaf surface of land plants and allow them to exchange water vapor and carbon dioxide with the atmosphere.
In the long run, I hope through my science i can contribute to questions regarding global climate change and water availability. Since stomatal pores are the direkt nexus between plants and the atmosphere, their functioning affects atmospheric carbon dioxide and water contents. In the light of this vast importance for plant viability and global climate, it is mesmerizing how much there is yet to learn.
Arabidopsis CSLD5 Functions in Cell Plate Formation in a Cell Cycle-Dependent Manner.
2016; 28 (7): 1722-1737
In plants, the presence of a load-bearing cell wall presents unique challenges during cell division. Unlike other eukaryotes, which undergo contractile cytokinesis upon completion of mitosis, plants instead synthesize and assemble a new dividing cell wall to separate newly formed daughter cells. Here, we mine transcriptome data from individual cell types in the Arabidopsis thaliana stomatal lineage and identify CSLD5, a member of the Cellulose Synthase Like-D family, as a cell wall biosynthesis enzyme uniquely enriched in rapidly dividing cell populations. We further show that CSLD5 is a direct target of SPEECHLESS, the master transcriptional regulator of these divisions during stomatal development. Using a combination of genetic analysis and in vivo localization of fluorescently tagged fusion proteins, we show that CSLD5 preferentially accumulates in dividing plant cells where it participates in the construction of newly forming cell plates. We show that CSLD5 is an unstable protein that is rapidly degraded upon completion of cell division and that the protein turnover characteristics of CSLD5 are altered in ccs52a2 mutants, indicating that CSLD5 turnover may be regulated by a cell cycle-associated E3-ubiquitin ligase, the anaphase-promoting complex.
View details for DOI 10.1105/tpc.16.00203
View details for PubMedID 27354558
Patterning and Lifetime of Plasma Membrane-Localized Cellulose Synthase Is Dependent on Actin Organization in Arabidopsis Interphase Cells
2013; 162 (2): 675-688
The actin and microtubule cytoskeletons regulate cell shape across phyla, from bacteria to metazoans. In organisms with cell walls, the wall acts as a primary constraint of shape, and generation of specific cell shape depends on cytoskeletal organization for wall deposition and/or cell expansion. In higher plants, cortical microtubules help to organize cell wall construction by positioning the delivery of cellulose synthase (CesA) complexes and guiding their trajectories to orient newly synthesized cellulose microfibrils. The actin cytoskeleton is required for normal distribution of CesAs to the plasma membrane, but more specific roles for actin in cell wall assembly and organization remain largely elusive. We show that the actin cytoskeleton functions to regulate the CesA delivery rate to, and lifetime of CesAs at, the plasma membrane, which affects cellulose production. Furthermore, quantitative image analyses revealed that actin organization affects CesA tracking behavior at the plasma membrane and that small CesA compartments were associated with the actin cytoskeleton. By contrast, localized insertion of CesAs adjacent to cortical microtubules was not affected by the actin organization. Hence, both actin and microtubule cytoskeletons play important roles in regulating CesA trafficking, cellulose deposition, and organization of cell wall biogenesis.
View details for DOI 10.1104/pp.113.215277
View details for Web of Science ID 000319819900012
View details for PubMedID 23606596
Impaired Cellulose Synthase Guidance Leads to Stem Torsion and Twists Phyllotactic Patterns in Arabidopsis
2013; 23 (10): 895-900
The parallel alignment of stiff cellulose microfibrils in plant-cell walls mediates anisotropic growth. This is largely controlled by cortical microtubules, which drive the insertion and trajectory of the cellulose synthase (CESA) complex at the plasma membrane. The CESA interactive protein 1 (CSI1) acts as a physical linker between CESA and cortical microtubules. Here we show that the inflorescence stems of csi1 mutants exhibit subtle right-handed torsion. Because cellulose deposition is largely uncoupled from cortical microtubules in csi1, we hypothesize that strictly transverse deposition of microfibrils in the wild-type is replaced by a helical orientation of uniform handedness in the mutant and that the helical microfibril alignment generates torsion. Interestingly, both elastic and viscous models for an expanding cell predict that a net helical orientation of microfibrils gives rise to a torque. We indeed observed tilted microfibrils in csi1 cells, and the torsion was almost absent in a csi1 prc1 background with impaired cellulose synthesis. In addition, the stem torsion led to a novel bimodal and robust phyllotactic pattern in the csi1 mutant, illustrating how growth perturbations can replace one robust mathematical pattern with a different, equally robust pattern.
View details for DOI 10.1016/j.cub.2013.04.013
View details for Web of Science ID 000319482900025
View details for PubMedID 23623553
Cracking the elusive alignment hypothesis: the microtubule-cellulose synthase nexus unraveled
TRENDS IN PLANT SCIENCE
2012; 17 (11): 666-674
Directed plant cell growth is governed by deposition and alterations of cell wall components under turgor pressure. A key regulatory element of anisotropic growth, and hence cell shape, is the directional deposition of cellulose microfibrils. The microfibrils are synthesized by plasma membrane-located cellulose synthase complexes that co-align with and move along cortical microtubules. That the parallel relation between cortical microtubules and extracellular microfibrils is causal has been named the alignment hypothesis. Three recent studies revealed that the previously identified pom2 mutant codes for a large cellulose synthases interacting (CSI1) protein which also binds cortical microtubules. This review summarizes these findings, provides structure-function models and discusses the inferred mechanisms in the context of plant growth.
View details for DOI 10.1016/j.tplants.2012.06.003
View details for Web of Science ID 000311924800006
View details for PubMedID 22784824
POM-POM2/CELLULOSE SYNTHASE INTERACTING1 Is Essential for the Functional Association of Cellulose Synthase and Microtubules in Arabidopsis
2012; 24 (1): 163-177
In plants, regulation of cellulose synthesis is fundamental for morphogenesis and plant growth. Cellulose is synthesized at the plasma membrane, and the orientation of synthesis is guided by cortical microtubules; however, the guiding mechanism is currently unknown. We show that the conditional root elongation pom2 mutants are impaired in cell elongation, fertility, and microtubule-related functions. Map-based cloning of the POM-POM2 locus revealed that it is allelic to CELLULOSE SYNTHASE INTERACTING1 (CSI1). Fluorescently tagged POM2/CSI1s associated with both plasma membrane-located cellulose synthases (CESAs) and post-Golgi CESA-containing compartments. Interestingly, while CESA insertions coincided with cortical microtubules in the pom2/csi1 mutants, the microtubule-defined movement of the CESAs was significantly reduced in the mutant. We propose that POM2/CSI1 provides a scaffold between the CESAs and cortical microtubules that guide cellulose synthesis.
View details for DOI 10.1105/tpc.111.093575
View details for Web of Science ID 000300881800016
View details for PubMedID 22294619
Identification of a cellulose synthase-associated protein required for cellulose biosynthesis
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2010; 107 (29): 12866-12871
Cellulose synthase-interactive protein 1 (CSI1) was identified in a two-hybrid screen for proteins that interact with cellulose synthase (CESA) isoforms involved in primary plant cell wall synthesis. CSI1 encodes a 2,150-amino acid protein that contains 10 predicted Armadillo repeats and a C2 domain. Mutations in CSI1 cause defective cell elongation in hypocotyls and roots and reduce cellulose content. CSI1 is associated with CESA complexes, and csi1 mutants affect the distribution and movement of CESA complexes in the plasma membrane.
View details for DOI 10.1073/pnas.1007092107
View details for Web of Science ID 000280144500031
View details for PubMedID 20616083
Transcriptional Wiring of Cell Wall-Related Genes in Arabidopsis
2009; 2 (5): 1015-1024
Transcriptional coordination, or co-expression, of genes may signify functional relatedness of the corresponding proteins. For example, several genes involved in secondary cell wall cellulose biosynthesis are co-expressed with genes engaged in the synthesis of xylan, which is a major component of the secondary cell wall. To extend these types of analyses, we investigated the co-expression relationships of all Carbohydrate-Active enZYmes (CAZy)-related genes for Arabidopsis thaliana. Thus, the intention was to transcriptionally link different cell wall-related processes to each other, and also to other biological functions. To facilitate easy manual inspection, we have displayed these interactions as networks and matrices, and created a web-based interface (http://aranet.mpimp-golm.mpg.de/corecarb) containing downloadable files for all the transcriptional associations.
View details for DOI 10.1093/mp/ssp055
View details for Web of Science ID 000270218900017
View details for PubMedID 19825676