Julia Kehr's Publications List

The distinct functional roles of the inner and outer chloroplast envelope of pea (Pisum sativum) as revealed by proteomic approaches

2014-05-05T15:10:07Z

E Gutierrez-Carbonell, D Takahashi, G Lattanzio, J Rodríguez-Celma, J Kehr, J Soll, K Philippar, M Uemura, J Abadía, AF López-Millán (2014) Journal of Proteome Research : in press

Laser microdissection coupled to transcriptional profiling of arabidopsis roots inoculated by Plasmodiophora brassicae indicates a role for brassinosteroids in clubroot formation.

2014-05-05T15:15:02Z

The clubroot disease caused by the obligate biotrophic protist Plasmodiophora brassicae on host plants of the Brassicaceae family is characterized by enhanced cell division and cell expansion. Since a typical root section of an infected plant always includes different stages of the pathogen as well as uninfected cells, we were interested in investigating specific developmental stages of the pathog...

Astrid Schuller, Julia Kehr, Jutta Ludwig-Müller (2014) Plant & Cell Physiology 55: 2 392-411

Endogenous RNA constituents of the phloem and their possible roles in long-distance signaling

2013-08-07T12:10:29Z

J Kehr, A Buhtz (2013) Phloem: Molecular Cell Biology, Systemic Communication, Biotic Interactions

Sampling and analysis of phloem sap

2013-08-07T12:20:58Z

S Dinant, J Kehr (2013) Plant Mineral Nutrients: Methods and Protocols

Protein profile of Lupinus texensis phloem sap exudates: searching for Fe and Zn containing proteins

2013-08-07T12:14:23Z

The aim of this study was to obtain a comprehensive overview of the phloem sap protein profile of Lupinus texensis, with a special focus on proteins binding Fe and Zn. L. texensis was chosen as model plant given the simplicity to obtain exudates from sieve elements. Protein profiling by 2DE revealed 249 spots, and 54 of them were unambiguously identified by MALDI-MS and ESI-MS/MS. The largest numb...

Lattanzio G, Andaluz S, Matros A, Calvete JJ, Kehr J, Abadia A, Abadia J, Lopez-Millan AF (2013) Proteomics 13: 2283-2296

Systemic regulation of mineral homeostasis by micro RNAs.

2014-05-05T15:14:46Z

Plants frequently have to cope with environments with sub-optimal mineral nutrient availability. Therefore they need to constantly sense changes of ion concentrations in their environment. Nutrient availabilities and needs have to be tightly coordinated between organs to ensure a balance between uptake and demand for metabolism, growth, reproduction, and defense reactions. To this end information ...

Julia Kehr (2013) Frontiers in Plant Science 4:

Long-distance signaling by small RNAs through the phloem

2013-08-07T12:07:21Z

J Kehr (2012) Short and Long Distance Signaling

Roles of miRNAs in nutrient signaling and homeostasis

2013-08-07T12:08:08Z

J Kehr (2012) MicroRNAs in plant development and stress responses

Phloem small RNAs, nutrient stress responses, and systemic mobility

2013-08-07T11:59:00Z

A Buhtz, J Pieritz, F Springer, J Kehr (2010) BMC Plant Biology 10: 64

Y3IP1, a nucleus- encoded thylakoid protein, cooperates with the plastid-encoded Ycf3 protein in photosystem I assembly

2013-08-07T11:56:50Z

The intricate assembly of photosystem I (PSI), a large multiprotein complex in the thylakoid membrane, depends on auxiliary protein factors. One of the essential assembly factors for PSI is encoded by ycf3 (hypothetical chloroplast reading frame number 3) in the chloroplast genome of algae and higher plants. To identify novel factors involved in PSI assembly, we constructed an epitope-tagged versi...

CA Albus, S Ruf, MA Schöttler, W Lein, J Kehr, R Bock (2010) Plant Cell 22: 2838-2855

Phloem sap intricacy and interplay with aphid feeding

2013-08-07T12:01:10Z

Aphididae feed upon the plant sieve elements (SE), where they ingest sugars, nitrogen compounds and other nutrients. For ingestion, aphid stylets penetrate SE, and because of the high hydrostatic pressure in SE, phloem sap exudes out into the stylets. Severing stylets to sample phloem exudates (i.e. stylectomy) has been used extensively for the study of phloem contents. Alternative sampling techni...

S Dinant, JL Bonnemain, C Girousse, J Kehr (2010) C R Biol 333: 504-515

Brassica proteomics and metabolomics

2013-08-07T12:03:49Z

J Kehr, A Buhtz (2010) Brassica oilseeds

Long-distance transport of macromolecules through the phloem

2013-08-07T11:53:07Z

Long-distance phloem transport of small metabolites has long been the subject of many different studies concentrating on resource allocation and signalling between plant organs. Also, phloem movement of viruses has long been examined as the route for systemic infection of the plant. Only recently, the transport of macromolecules, such as proteins and nucleic acids, has received increasing attentio...

J Kehr (2009) F1000 Biol Rep

Identification of nutrient-responsive Arabidopsis and rapeseed microRNAs by comprehensive real-time polymerase chain reaction profiling and small RNA sequencing

2013-08-07T11:54:40Z

Comprehensive expression profiles of Arabidopsis (Arabidopsis thaliana) MIRNA genes and mature microRNAs (miRs) are currently not available. We established a quantitative real-time polymerase chain reaction platform that allows rapid and sensitive quantification of 177 Arabidopsis primary miR transcripts (pri-miRs). The platform was used to detect phosphorus (P) or nitrogen (N) status-responsive p...

DB Pant, M Musialak-Lange, P Nuc , P May, A Buhtz, J Kehr, D Walther, WR Scheible (2009) Plant Physiology 150: 1541-1555

Long distance transport and movement of RNA through the phloem.

2008-08-08T10:40:03Z

Cell-to-cell communication is essential for plant development and adaptation to environmental changes. As a strategy for efficient intercellular communication, plants have evolved a plant-specific symplasmic network connected via plasmodesmata that allows a locally restricted information exchange from cell to cell. A rapid information transfer over long distances is enabled via the phloem transpor...

Julia Kehr, Anja Buhtz (2008) J Exp Bot 59: 1 85-92

MicroRNA399 is a long-distance signal for the regulation of plant phosphate homeostasis.

2008-08-08T10:40:03Z

The presence of microRNA species in plant phloem sap suggests potential signaling roles by long-distance regulation of gene expression. Proof for such a role for a phloem-mobile microRNA is lacking. Here we show that phosphate (Pi) starvation-induced microRNA399 (miR399) is present in the phloem sap of two diverse plant species, rapeseed and pumpkin, and levels are strongly and specifically increa...

Bikram Datt Pant, Anja Buhtz, Julia Kehr, Wolf-Rüdiger Scheible (2008) Plant J 53: 5 731-738

Identification and characterization of small RNAs from the phloem of Brassica napus.

2008-08-08T10:40:03Z

Systemic signalling is indispensable for the coordination of diverse physiological processes during development, defence and nutrient allocation. Indirect evidence suggests that plant small RNAs (smRNAs) could be involved in long-distance information transfer via the vasculature of the plant. Analyses of the smRNA complements of vascular exudates from oilseed rape (Brassica napus) showed that xyle...

Anja Buhtz, Franziska Springer, Louise Chappell, David C Baulcombe, Julia Kehr (2008) Plant J 53: 5 739-749

Adaptation of aphid stylectomy for analyses of proteins and mRNAs in barley phloem sap.

2008-08-08T10:40:03Z

Sieve tubes are transport conduits not only for photoassimilates but also for macromolecules and other compounds that are involved in sieve tube maintenance and systemic signalling. In order to gain sufficient amounts of pure phloem exudates from barley plants for analyses of the protein and mRNA composition, a previously described stylectomy set-up was optimized. Aphids were placed in sealed cage...

Gaupels, Buhtz, Knauer, Deshmukh, Waller, van Bel, Kogel, Kehr (2008) J Exp Bot :

Identification of high levels of phytochelatins, glutathione and cadmium in the phloem sap of Brassica napus. A role for thiol-peptides in the long-distance transport of cadmium and the effect of cadmium on iron translocation.

2008-08-08T10:40:03Z

Phytochelatins (PCs) are glutathione-derived peptides that function in heavy metal detoxification in plants and certain fungi. Recent research in Arabidopsis has shown that PCs undergo long-distance transport between roots and shoots. However, it remains unknown which tissues or vascular systems, xylem or phloem, mediate PC translocation and whether PC transport contributes to physiologically rele...

David G Mendoza-Cózatl, Emerald Butko, Franziska Springer, Justin W Torpey, Elizabeth A Komives, Julia Kehr, Julian I Schroeder (2008) Plant J 54: 2 249-259

Phloem sap proteins: their identities and potential roles in the interaction between plants and phloem-feeding insects.

2008-08-08T10:47:02Z

The phloem is a well-known target of sucking and piercing insects that utilize the transported fluid as their major nutrient source. In addition to small molecules like sugars and amino acids, phloem sap of higher land plants contains proteins that can accumulate up to high concentrations. Although the knowledge about the identities of these phloem sap proteins is increasing, the functions of most...

Julia Kehr (2006) J Exp Bot 57: 4 767-774

Preparation and quality assessment of RNA from cell-specific samples obtained by laser microdissection.

2013-08-07T12:21:40Z

Laser microdissection is a powerful tool to obtain cell-specific isolates from complex tissue samples. This chapter outlines how to prepare plant material for microdissection and methods to extract and measure high-quality RNA suitable for a variety of different downstream applications.

Regine Kleber, Julia Kehr (2006) Methods Mol Biol Methods Mol Biol 323: 367-377

Analysis of photosynthetic complexes from a cyanobacterial ycf37 mutant.

2008-08-08T10:47:02Z

The Ycf37 protein has been suggested to be involved in the biogenesis and/or stability of the cyanobacterial photosystem I (PSI). With Ycf37 specific antibodies, we analyzed the localization of Ycf37 within the thylakoid membranes of the cyanobacterium Synechocystis sp. PCC 6803. Inspection of a sucrose gradient profile indicated that small amounts of Ycf37 co-fractionated with monomeric photosynt...

Ulf Dühring, Klaus-Dieter Irrgang, Katja Lünser, Julia Kehr, Annegret Wilde (2006) Biochim Biophys Acta 1757: 1 3-11

Towards the proteome of Brassica napus phloem sap.

2008-08-08T10:47:02Z

The soluble proteins in sieve tube exudate from Brassica napus plants were systematically analyzed by 1-DE and high-resolution 2-DE, partial amino acid sequence determination by MS/MS, followed by database searches. 140 proteins could be identified by their high similarity to database sequences (135 from 2-DE, 5 additional from 1-DE). Most analyzed spots led to successful protein identifications, ...

Patrick Giavalisco, Kristin Kapitza, Anna Kolasa, Anja Buhtz, Julia Kehr (2006) Proteomics 6: 3 896-909

Protein extraction from xylem and phloem sap

2013-08-07T12:20:32Z

It is well known that phloem and xylem vessels transport small nutrient molecules over long distances in higher plants. The finding that proteins also occur in both transport fluids was unexpected, and the function of most of these proteins is not yet well understood. This chapter outlines how proteins can be obtained and purified from xylem and phloem saps to perform subsequent proteomic analyses...

Julia Kehr, Martijn Rep (2006) Methods Mol Biol Methods in Molecular Biology 355: 27-35

Effect of water stress on lupin stem protein analysed by two-dimensional gel electrophoresis.

2008-08-08T10:47:02Z

Lupinus albus plants can withstand severe drought stress and show signs of recovery 24 h after rewatering (RW). Two-dimensional gel electrophoresis was used to evaluate the effect of water deficit (WD) on the protein composition of the two components of the lupin stem (stele and cortex). This was performed at three distinct stress levels: an early stage, a severe WD, and early recovery. Protein ch...

C Pinheiro, J Kehr, C P Ricardo (2005) Planta 221: 5 716-728

Metabolic profiling of laser microdissected vascular bundles of Arabidopsis thaliana.

2008-08-08T10:47:02Z

BACKGROUND: Laser microdissection is a useful tool for collecting tissue-specific samples or even single cells from animal and plant tissue sections. This technique has been successfully employed to study cell type-specific expression at the RNA, and more recently also at the protein level. However, metabolites were not amenable to analysis after laser microdissection, due to the procedures routin...

Martina Schad, Rajsree Mungur, Oliver Fiehn, Julia Kehr (2005) Plant Methods 1: 1

Evaluation of two-dimensional electrophoresis and liquid chromatography--tandem mass spectrometry for tissue-specific protein profiling of laser-microdissected plant samples.

2008-08-08T10:47:02Z

Laser microdissection (LM) allows the collection of homogeneous tissue- and cell-specific plant samples. The employment of this technique with subsequent protein analysis has thus far not been reported for plant tissues, probably due to the difficulties associated with defining a reasonable cellular morphology and, in parallel, allowing efficient protein extraction from tissue samples. The relativ...

Martina Schad, Mary S Lipton, Patrick Giavalisco, Richard D Smith, Julia Kehr (2005) Electrophoresis 26: 14 2729-2738

Analysis of xylem sap proteins from Brassica napus.

2008-08-08T10:47:02Z

BACKGROUND: Substance transport in higher land plants is mediated by vascular bundles, consisting of phloem and xylem strands that interconnect all plant organs. While the phloem mainly allocates photoassimilates, the role of the xylem is the transport of water and inorganic nutrients from roots to all aerial plant parts. Only recently it was noticed that in addition to mineral salts, xylem sap co...

Julia Kehr, Anja Buhtz, Patrick Giavalisco (2005) BMC Plant Biol 5:

Proteomics of curcurbit phloem exudate reveals a network of defence proteins.

2008-08-08T10:47:02Z

Many different proteins can be separated from the sap of mature sieve tubes of different plant species. To date, only a limited number of those have been identified and functionally characterised. Due to sieve tubes inability of transcription and translation, the proteins are most probably synthesised in the intimately connected companion cells and transported into the sieve elements through plasm...

Christina Walz, Patrick Giavalisco, Martina Schad, Melanie Juenger, Joachim Klose, Julia Kehr (2004) Phytochemistry 65: 12 1795-1804

Xylem sap protein composition is conserved among different plant species.

2008-08-08T10:47:02Z

Xylem sap from broccoli (Brassica oleracea L. cv. Calabrais), rape (Brassica napus L. cv. Drakkar), pumpkin (Cucurbita maxima Duch. cv. gelber Zentner) and cucumber (Cucumis sativus L. cv. Hoffmanns Giganta) was collected by root pressure exudation from the surface of cut stems of healthy, adult plants. Total protein concentrations were in the range of 100 microg ml(-1). One-dimensional gel electr...

Anja Buhtz, Anna Kolasa, Kathleen Arlt, Christina Walz, Julia Kehr (2004) Planta 219: 4 610-618

Overexpression of the sucrose transporter SoSUT1 in potato results in alterations in leaf carbon partitioning and in tuber metabolism but has little impact on tuber morphology.

2008-08-08T10:47:02Z

The aim of this work was to examine the consequences of the heterologous expression of a spinach ( Spinacia oleracea L.) sucrose transporter ( SoSUT1) in potato ( Solanum tuberosum L.). Many studies have indicated that reduction of the expression of this class of sucrose transporter has deleterious effects on plant growth and development; however, until now the possibility of improving plant perfo...

Georg Leggewie, Anna Kolbe, Rémi Lemoine, Ute Roessner, Anna Lytovchenko, Ellen Zuther, Julia Kehr, Wolf B Frommer, Jörg W Riesmeier, Lothar Willmitzer, Alisdair R Fernie (2003) Planta 217: 1 158-167

Single cell technology.

2008-08-08T10:47:02Z

Complexity is a fundamental feature of life. Like animals, higher plants consist of a multitude of different distinct tissues and cell types, each contributing to the overall performance of the whole organism. Our understanding and knowledge of physiology will greatly increase as our ability to spatially resolve molecular and biochemical processes improves. Differential analysis of individual tiss...

Julia Kehr (2003) Curr Opin Plant Biol 6: 6 617-621

A simple, chisel assisted mechanical microdissection system for harvesting homogenous plant tissue suitable for the analysis of nucleic acids and proteins.

2008-08-08T10:50:13Z

S Brandt, C Walz, M Schad, N Pavlovic, J Kehr (2003) Plant Molecular Biology Reporter 21: 417-427

Using array hybridization to monitor gene expression at the single cell level.

2008-08-08T10:47:02Z

Advances in high-throughput genome sequencing demand the development of more efficient ways of examining gene expression at a cellular level. During recent years, polymerase chain reaction (PCR)-based methods have been developed that allow the amplification of mRNA from small amounts of material, even from single animal cells. In parallel, several analytical tools permit a global monitoring of gen...

Stephan Brandt, Sebastian Kloska, Thomas Altmann, Julia Kehr (2002) J Exp Bot 53: 379 2315-2323

Evidence for the presence and activity of a complete antioxidant defence system in mature sieve tubes.

2008-08-08T10:47:02Z

The phloem is the major route for the transport of solutes and nutrients from source to sink organs in plants. The functional transport phloem consists of parenchymal tissue, enucleate sieve elements, and the intimately connected companion cells. The general absence of a nucleus and functional ribosomes in sieve tubes poses problems especially for damage avoidance and repair of sieve element compo...

Christina Walz, Melanie Juenger, Martina Schad, Julia Kehr (2002) Plant J 31: 2 189-197

Amino acid analysis in five pooled single plant cell samples using capillary electrophoresis coupled to laser-induced fluorescence detection.

2008-08-08T10:47:02Z

In this study 21 amino acid standards, samples of pure phloem sap and samples of pooled mesophyll cells were derivatized with fluorescein isothiocyanate, separated by capillary electrophoresis and detected with laser-induced fluorescence at 488 nm. Two different background electrolytes, a sodium borate buffer containing sodium dodecyl sulfate and a sodium borate buffer containing alpha-cyclodextri...

K Arlt, S Brandt, J Kehr (2001) J Chromatogr A 926: 2 319-325

Matrix-assisted laser desorption/ionization time of flight mass spectrometry peptide mass fingerprints and post source decay: a tool for the identification and analysis of phloem proteins from Cucurbita maxima Duch. separated by two-dimensional polyacrylamide gel electrophoresis.

2008-08-08T10:47:02Z

A combination of gel electrophoresis and mass spectrometry was used to analyze the soluble proteins from phloem sap of Cucurbita maxima Duch. Phloem proteins were separated using two-dimensional gel electrophoresis. Coomassie-stained spots were cut out and subjected to tryptic digestion. To identify proteins, peptide mass fingerprints were determined by matrix-assisted laser desorption/ionization ...

S Haebel, J Kehr (2001) Planta 213: 4 586-593

High resolution spatial analysis of plant systems.

2008-08-08T10:47:02Z

Analysis of organisms using techniques that provide high spatial and temporal resolution is of increasing interest in many disciplines of biomedical research. Although the examination of animal tissues has been the main focus to date, the recent development and improvement of methods for the sampling and handling of single cells and for their biochemical analysis now provide tools for investigatin...

J Kehr (2001) Curr Opin Plant Biol 4: 3 197-201

Immunological analysis of phloem sap of Bacillus thuringiensis corn and of the nontarget herbivore Rhopalosiphum padi (Homoptera: Aphididae) for the presence of Cry1Ab.

2008-08-08T10:47:02Z

Phloem sap of transgenic Bacillus thuringiensis (Bt) corn expressing a truncated form of the B. thuringiensis delta-endotoxin Cry1Ab, sap sucking aphids feeding on Bt corn and their honeydew were analysed for presence of Cry1Ab using ELISA. Phloem sap of Bt and non-Bt corn was collected using a newly developed technique with a microcapillary being directly inserted into the phloem tubes. Using thi...

A Raps, J Kehr, P Gugerli, W J Moar, F Bigler, A Hilbeck (2001) Mol Ecol 10: 2 525-533

An Arabidopsis inositol phospholipid kinase strongly expressed in procambial cells: synthesis of PtdIns(4,5)P2 and PtdIns(3,4,5)P3 in insect cells by 5-phosphorylation of precursors.

2008-08-08T10:47:02Z

We have cloned a phosphatidylinositol-4-phosphate 5-kinase (PIP5K) cDNA (AtP5K1) from Arabidopsis thaliana. By the application of cell permeabilization and short-term nonequilibrium labelling we show that expression of AtP5K1 in Baculovirus-infected insect (Spodoptera frugiperda) cells directs synthesis of PtdIns(4,5)P2 and PtdIns(3,4,5)P3. The same phosphoinositides were produced by isolated whol...

S Elge, C Brearley, H J Xia, J Kehr, H W Xue, B Mueller-Roeber (2001) Plant J 26: 6 561-571

Analysis of phloem protein patterns from different organs of Cucurbita maxima Duch. by matrix-assisted laser desorption/ionization time of flight mass spectroscopy combined with sodium dodecyl sulfate polyacrylamide gel electrophoresis.

2008-08-08T10:47:02Z

Sieve tubes mediate the long-distance transport of nutrients and signals between source and sink organs of plants. To detect mobile phloem proteins that are differentially distributed in source and sink organs of Cucurbita maxima, we used both one-dimensional gel electrophoresis (SDS-PAGE) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Both techniq...

J Kehr, S Haebel, S Blechschmidt-Schneider, L Willmitzer, M Steup, J Fisahn (1999) Planta 207: 4 612-619

Technical Advance: A rapid method for detection of plant gene transcripts from single epidermal, mesophyll and companion cells of intact leaves.

2008-08-08T10:47:02Z

A protocol for the detection of gene transcripts from single plant cells in living, undamaged plant tissue is described. Samples of leaf epidermal, mesophyll and companion cells were extracted by using glass microcapillaries and directly subjected to RT-PCR without any purification steps nor time consuming construction of cDNA libraries. The procedure is not restricted to surface cells or outer ce...

Brandt, Kehr, Walz, Imlau, Willmitzer, Fisahn (1999) Plant J 20: 2 245-250

Transgenic plants changed in carbon allocation pattern display a shift in diurnal growth pattern.

2008-08-08T10:47:02Z

Photosynthesis, partitioning of carbohydrates and growth have to be highly orchestrated to enable an efficient performance of plants. To study the diurnal relationships between carbon distribution and growth, we analysed transgenic potato plants with altered carbon allocation patterns. To modify carbohydrate supply of growing sinks, we used plants that accumulated starch as a consequence of inhibi...

J Kehr, F Hustiak, C Walz, L Willmitzer, J Fisahn (1998) Plant J 16: 4 497-503