Publications by authors named "Hans-Peter Mock"

102 Publications

Untargeted metabotyping to study phenylpropanoid diversity in crop plants.

Physiol Plant 2021 May 7. Epub 2021 May 7.

Leibniz Institute for Plant Genetics and Crop Plant Research, Gatersleben, Germany.

Plant genebanks constitute a key resource for breeding to ensure crop yield under changing environmental conditions. Because of their roles in a range of stress responses, phenylpropanoids are promising targets. Phenylpropanoids comprise a wide array of metabolites; however, studies regarding their diversity and the underlying genes are still limited for cereals. The assessment of barley diversity via genotyping-by-sequencing is in rapid progress. Exploring these resources by integrating genetic association studies to in-depth metabolomic profiling provides a valuable opportunity to study barley phenylpropanoid metabolism; but poses a challenge by demanding large-scale approaches. Here, we report an LC-PDA-MS workflow for barley high-throughput metabotyping. Without prior construction of a species-specific library, this method produced phenylpropanoid-enriched metabotypes with which the abundance of putative metabolic features was assessed across hundreds of samples in a single-processed data matrix. The robustness of the analytical performance was tested using a standard mix and extracts from two selected cultivars: Scarlett and Barke. The large-scale analysis of barley extracts showed (1) that barley flag leaf profiles were dominated by glycosylation derivatives of isovitexin, isoorientin, and isoscoparin; (2) proved the workflow's capability to discriminate within genotypes; (3) highlighted the role of glycosylation in barley phenylpropanoid diversity. Using the barley S42IL mapping population, the workflow proved useful for metabolic quantitative trait loci purposes. The protocol can be readily applied not only to explore the barley phenylpropanoid diversity represented in genebanks but also to study species whose profiles differ from those of cereals: the crop Helianthus annuus (sunflower) and the model plant Arabidopsis thaliana.
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http://dx.doi.org/10.1111/ppl.13458DOI Listing
May 2021

Function and Regulation of Chloroplast Peroxiredoxin IIE.

Antioxidants (Basel) 2021 Jan 21;10(2). Epub 2021 Jan 21.

Department of Biochemistry and Physiology of Plants, Faculty of Biology, University of Bielefeld, 33615 Bielefeld, Germany.

Peroxiredoxins (PRX) are thiol peroxidases that are highly conserved throughout all biological kingdoms. Increasing evidence suggests that their high reactivity toward peroxides has a function not only in antioxidant defense but in particular in redox regulation of the cell. Peroxiredoxin IIE (PRX-IIE) is one of three PRX types found in plastids and has previously been linked to pathogen defense and protection from protein nitration. However, its posttranslational regulation and its function in the chloroplast protein network remained to be explored. Using recombinant protein, it was shown that the peroxidatic Cys121 is subjected to multiple posttranslational modifications, namely disulfide formation, S-nitrosation, S-glutathionylation, and hyperoxidation. Slightly oxidized glutathione fostered S-glutathionylation and inhibited activity in vitro. Immobilized recombinant PRX-IIE allowed trapping and subsequent identification of interaction partners by mass spectrometry. Interaction with the 14-3-3 υ protein was confirmed in vitro and was shown to be stimulated under oxidizing conditions. Interactions did not depend on phosphorylation as revealed by testing phospho-mimicry variants of PRX-IIE. Based on these data it is proposed that 14-3-3υ guides PRX‑IIE to certain target proteins, possibly for redox regulation. These findings together with the other identified potential interaction partners of type II PRXs localized to plastids, mitochondria, and cytosol provide a new perspective on the redox regulatory network of the cell.
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http://dx.doi.org/10.3390/antiox10020152DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7909837PMC
January 2021

Effects of Arbuscular Mycorrhization on Fruit Quality in Industrialized Tomato Production.

Int J Mol Sci 2020 Sep 24;21(19). Epub 2020 Sep 24.

Leibniz Institute of Plant Biochemistry, Department of Cell and Metabolic Biology, 06120 Halle, Germany.

Industrialized tomato production faces a decrease in flavors and nutritional value due to conventional breeding. Moreover, tomato production heavily relies on nitrogen and phosphate fertilization. Phosphate uptake and improvement of fruit quality by arbuscular mycorrhizal (AM) fungi are well-studied. We addressed the question of whether commercially used tomato cultivars grown in a hydroponic system can be mycorrhizal, leading to improved fruit quality. Tomato plants inoculated with were grown under different phosphate concentrations and in substrates used in industrial tomato production. Changes in fruit gene expression and metabolite levels were checked by RNAseq and metabolite determination, respectively. The tests revealed that reduction of phosphate to 80% and use of mixed substrate allow AM establishment without affecting yield. By comparing green fruits from non-mycorrhizal and mycorrhizal plants, differentially expressed genes (DEGs) were found to possibly be involved in processes regulating fruit maturation and nutrition. Red fruits from mycorrhizal plants showed a trend of higher BRIX values and increased levels of carotenoids in comparison to those from non-mycorrhizal plants. Free amino acids exhibited up to four times higher levels in red fruits due to AM, showing the potential of mycorrhization to increase the nutritional value of tomatoes in industrialized production.
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http://dx.doi.org/10.3390/ijms21197029DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7582891PMC
September 2020

The transcription factor WRKY22 is required during cryo-stress acclimation in Arabidopsis shoot tips.

J Exp Bot 2020 08;71(16):4993-5009

Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Seeland, Germany.

Storage of meristematic tissue at ultra-low temperatures offers a mean to maintain valuable genetic resources from vegetatively reproduced plants. To reveal the biology underlying cryo-stress, shoot tips of the model plant Arabidopsis thaliana were subjected to a standard preservation procedure. A transcriptomic approach was taken to describe the subsequent cellular events which occurred. The cryoprotectant treatment induced the changes in the transcript levels of genes associated with RNA processing and primary metabolism. Explants of a mutant lacking a functional copy of the transcription factor WRKY22 were compromised for recovery. A number of putative downstream targets of WRKY22 were identified, some related to phytohormone-mediated defense, to the osmotic stress response, and to development. There were also alterations in the abundance of transcript produced by genes encoding photosynthesis-related proteins. The wrky22 mutant plants developed an open stomata phenotype in response to their exposure to the cryoprotectant solution. WRKY22 probably regulates a transcriptional network during cryo-stress, linking the explant's defense and osmotic stress responses to changes in its primary metabolism. A model is proposed linking WRKY53 and WRKY70 downstream of the action of WRKY22.
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http://dx.doi.org/10.1093/jxb/eraa224DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7475261PMC
August 2020

Proteomic Approaches to Identify Proteins Responsive to Cold Stress.

Methods Mol Biol 2020 ;2156:161-170

Department of Physiology and Cell Biology, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Stadt Seeland, Germany.

Changing environmental conditions greatly affect the accumulation of many proteins; therefore, the analysis of alterations in the proteome is essential to understand the plant response to abiotic stress. Proteomics provides a platform for the identification and quantification of plant proteins responsive to cold stress and taking part in cold acclimation. Here, we describe the preparation of proteins for LC-MS measurement to monitor the changes of protein patterns during cold treatment in Arabidopsis thaliana. In our protocol, proteins are precipitated using TCA/acetone, quantified with 2D Quant Kit and digested with trypsin using a filter-based method and analyzed using an LC-MS approach. The acquired results can be further applied for label-free protein quantification.
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http://dx.doi.org/10.1007/978-1-0716-0660-5_12DOI Listing
March 2021

Redox Conformation-Specific Protein-Protein Interactions of the 2-Cysteine Peroxiredoxin in Arabidopsis.

Antioxidants (Basel) 2020 Jun 11;9(6). Epub 2020 Jun 11.

Department of Biochemistry and Physiology of Plants, Faculty of Biology, University of Bielefeld, 33615 Bielefeld, Germany.

2-Cysteine peroxiredoxins (2-CysPRX) are highly abundant thiol peroxidases in chloroplasts and play key roles in reactive oxygen species (ROS) defense and redox signaling. Peroxide-dependent oxidation of cysteines induces conformational changes that alter the ability for protein-protein interactions. For regeneration, 2-CysPRXs withdraw electrons from thioredoxins (TRXs) and participate in redox-dependent regulation by affecting the redox state of TRX-dependent targets, for example, in chloroplast metabolism. This work explores the redox conformation-specific 2-CysPRX interactome using an affinity-based pull down with recombinant variants arrested in specific quaternary conformations. This allowed us to address a critical and poorly explored aspect of the redox-regulatory network and showed that the interaction of TRXs, their interaction partners, and 2-CysPRX occur under contrasting redox conditions. A set of 178 chloroplast proteins were identified from leaf proteins and included proteins with functions in photosynthesis, carbohydrate, fatty acid and amino acid metabolism, and defense. These processes are known to be deregulated in plants devoid of 2-CysPRX. Selected enzymes like LIPOXYGENASE 2, CHLOROPLAST PROTEIN 12-1, CHORISMATE SYNTHASE, ß-CARBONIC ANHYDRASE, and FERREDOXIN-dependent GLUTAMATE SYNTHASE 1 were subjected to far Western, isothermal titration calorimetry, and enzyme assays for validation. The pull down fractions frequently contained TRXs as well as their target proteins, for example, FRUCTOSE-1,6-BISPHOSPHATASE and MALATE DEHYDROGENASE. The difference between TRX-dependent indirect interactions of TRX targets and 2-CysPRX and direct 2-CysPRX binding is hypothesized to be related to quaternary structure formation, where 2-CysPRX oligomers function as scaffold for complex formation, whereas TRX oxidase activity of 2-CysPRX controls the redox state of TRX-related enzyme activity.
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http://dx.doi.org/10.3390/antiox9060515DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7346168PMC
June 2020

Cellulose defects in the Arabidopsis secondary cell wall promote early chloroplast development.

Plant J 2020 01 16;101(1):156-170. Epub 2019 Oct 16.

Plant Molecular Biology, Faculty of Biology, Ludwig-Maximilians University of Munich, Großhaderner Str. 2, 82152, Planegg-Martinsried, Germany.

Lincomycin (LIN)-mediated inhibition of protein synthesis in chloroplasts prevents the greening of seedlings, represses the activity of photosynthesis-related genes in the nucleus, including LHCB1.2, and induces the phenylpropanoid pathway, resulting in the production of anthocyanins. In genomes uncoupled (gun) mutants, LHCB1.2 expression is maintained in the presence of LIN or other inhibitors of early chloroplast development. In a screen using concentrations of LIN lower than those employed to isolate gun mutants, we have identified happy on lincomycin (holi) mutants. Several holi mutants show an increased tolerance to LIN, exhibiting de-repressed LHCB1.2 expression and chlorophyll synthesis in seedlings. The mutations responsible were identified by whole-genome single-nucleotide polymorphism (SNP) mapping, and most were found to affect the phenylpropanoid pathway; however, LHCB1.2 expression does not appear to be directly regulated by phenylpropanoids, as indicated by the metabolic profiling of mutants. The most potent holi mutant is defective in a subunit of cellulose synthase encoded by IRREGULAR XYLEM 3, and comparative analysis of this and other cell-wall mutants establishes a link between secondary cell-wall integrity and early chloroplast development, possibly involving altered ABA metabolism or sensing.
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http://dx.doi.org/10.1111/tpj.14527DOI Listing
January 2020

Barley cysteine protease PAP14 plays a role in degradation of chloroplast proteins.

J Exp Bot 2019 11;70(21):6057-6069

Institute of Botany, Christian-Albrechts-University of Kiel, Olshausenstraße 40, 24098 Kiel, Germany.

Chloroplast protein degradation is known to occur both inside chloroplasts and in the vacuole. Genes encoding cysteine proteases have been found to be highly expressed during leaf senescence. However, it remains unclear where they participate in chloroplast protein degradation. In this study HvPAP14, which belongs to the C1A family of cysteine proteases, was identified in senescing barley (Hordeum vulgare L.) leaves by affinity enrichment using the mechanism-based probe DCG-04 targeting cysteine proteases and subsequent mass spectrometry. Biochemical analyses and expression of a HvPAP14:RFP fusion construct in barley protoplasts was used to identify the subcellular localization and putative substrates of HvPAP14. The HvPAP14:RFP fusion protein was detected in the endoplasmic reticulum and in vesicular bodies. Immunological studies showed that HvPAP14 was mainly located in chloroplasts, where it was found in tight association with thylakoid membranes. The recombinant enzyme was activated by low pH, in accordance with the detection of HvPAP14 in the thylakoid lumen. Overexpression of HvPAP14 in barley revealed that the protease can cleave LHCB proteins and PSBO as well as the large subunit of Rubisco. HvPAP14 is involved in the normal turnover of chloroplast proteins and may have a function in bulk protein degradation during leaf senescence.
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http://dx.doi.org/10.1093/jxb/erz356DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6859807PMC
November 2019

Purple corn extract induces long-lasting reprogramming and M2 phenotypic switch of adipose tissue macrophages in obese mice.

J Transl Med 2019 07 23;17(1):237. Epub 2019 Jul 23.

Dipartimento di Bioscienze, Università degli Studi di Milano, Milan, Italy.

Background: Obesity is a chronic and systemic inflammatory disorder and an important risk factor for the onset of several chronic syndromes. Adipose tissue (AT) plays a crucial role in the development of obesity, promoting the infiltration and accumulation of leukocytes in the tissue and sustaining adipocyte expansion. Anthocyanins exert a broad range of health benefits, but their effect in improving obesity-related inflammation in vivo has been poorly characterized. We examined the effects of a purple corn cob extract in the context of AT inflammation in a murine diet-induced obesity (DIO) model.

Methods: Male C57BL/6J mice were subjected to control diet (CTR + HO), high fat diet (HF + HO) or high fat diet plus purple corn extract (HF + RED) for 12 weeks. Blood glucose, AT, and liver gene expression, metabolism, biochemistry, and histology were analysed and flow cytometry was performed on AT leukocytes and Kupffer cells.

Results: RED extract intake resulted in lower MCP-1 mediated recruitment and proliferation of macrophages into crown-like structures in the AT. AT macrophages (ATM) of HF + RED group upregulated M2 markers (ArgI, Fizz1, TGFβ), downregulating inflammatory mediators (TNF-α, IL-6, IL-1β, COX-2) thanks to the suppression of NF-kB signalling. ATM also increased the expression of iron metabolism-related genes (FABP4, Hmox1, Ferroportin, CD163, TfR1, Ceruloplasmin, FtL1, FtH1) associated with a reduction in iron storage and increased turnover. ATM from HF + RED mice did not respond to LPS treatment ex vivo, confirming the long-lasting effects of the treatment on M2 polarization. Adipocytes of HF + RED group improved lipid metabolism and displayed a lower inflammation grade. Liver histology revealed a remarkable reduction of steatosis in the HF + RED group, and Kupffer cell profiling displayed a marked switch towards the M2 phenotype.

Conclusions: RED extract attenuated AT inflammation in vivo, with a long-lasting reprogramming of ATM and adipocyte profiles towards the anti-inflammatory phenotype, therefore representing a valuable supplement in the context of obesity-associated disorders.
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http://dx.doi.org/10.1186/s12967-019-1972-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6651915PMC
July 2019

Protein Composition and Baking Quality of Wheat Flour as Affected by Split Nitrogen Application.

Front Plant Sci 2019 15;10:642. Epub 2019 May 15.

Faculty of Agricultural and Nutritional Sciences, Institute of Plant Nutrition and Soil Science, Kiel University, Kiel, Germany.

Baking quality of wheat flour is determined by grain protein concentration (GPC) and its composition and is highly influenced by environmental factors such as nitrogen (N) fertilization management. This study investigated the effect of split N application on grain protein composition and baking quality of two winter wheat cultivars, Tobak and JB Asano, belonging to different baking quality classes. Bread loaf volumes in both cultivars were enhanced by split N application. In contrast, GPC was only significantly increased in JB Asano. Comparative 2-DE revealed that the relative volumes of 21 and 28 unique protein spots were significantly changed by split N application in Tobak and JB Asano, respectively. Specifically, the alterations in relative abundance of certain proteins, i.e., globulins, LMW-GS, α-, and γ-gliadins as well as α-amylase/trypsin inhibitors were more sensitive to split N application. Furthermore, certain proteins identified as globulins and alpha-amylase inhibitors were changed in both wheat cultivars under split N application. These results implied that the functions of these unique proteins might have played important roles in affecting baking quality of wheat flour, especially for cultivars (i.e., Tobak in the present study) the baking quality of which is less dependent on GPC.
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http://dx.doi.org/10.3389/fpls.2019.00642DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6530357PMC
May 2019

Hydroxycinnamic acids in sunflower leaves serve as UV-A screening pigments.

Photochem Photobiol Sci 2019 Jul;18(7):1649-1659

Department of Ecophysiology of Plants, Botanical Institute, Christian-Albrechts University Kiel, 24118 Kiel, Germany.

Flavonoids and hydroxycinnamic acid derivatives, which are located in the upper epidermis of plants, are well known to screen ultraviolet radiation, thus protecting the underlying tissue from these harmful wavelengths. Both classes of secondary products complement each other over the UV spectral region according to their absorption spectra: flavonoids are most efficient as UV-A attenuators while hydroxycinnamates (HCAs) screen well within the UV-B region. Analysis of epidermal transmittance revealed a substantial UV-A screen in Helianthus annuus L. cv. Peredovick. Identifying responsible pigments by HPLC-MS, we found surprisingly low amounts of flavonoids but dominant abundance of the HCA derivatives chlorogenic and di-caffeoyl quinic acid. Both display low UV-A absorbance and thus, should contribute only a little to UV-A protection. However, growth at high light led to a decrease of epidermal transmittance at 366 nm of up to 90%. Underpinning the screening role, HCA autofluorescence microscopy revealed storage to occur predominantly in vacuoles of the upper epidermis. UV-A treatment in the absence of D1-repair resulted in photosystem II inactivation proportional to epidermal UV-A transmittance. Our findings suggest that UV-A protection can be achieved solely with HCAs, apparently through accumulation of high amounts of these compounds.
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http://dx.doi.org/10.1039/c8pp00440dDOI Listing
July 2019

Cell Wall Invertase and Sugar Transporters Are Differentially Activated in Tomato Styles and Ovaries During Pollination and Fertilization.

Front Plant Sci 2019 18;10:506. Epub 2019 Apr 18.

School of Environmental and Life Sciences, The University of Newcastle, Callaghan, NSW, Australia.

Flowering plants depend on pollination and fertilization to activate the transition from ovule to seed and ovary to fruit, namely seed and fruit set, which are key for completing the plant life cycle and realizing crop yield potential. These processes are highly energy consuming and rely on the efficient use of sucrose as the major nutrient and energy source. However, it remains elusive as how sucrose imported into and utilizated within the female reproductive organ is regulated in response to pollination and fertilization. Here, we explored this issue in tomato by focusing on genes encoding cell wall invertase (CWIN) and sugar transporters, which are major players in sucrose phloem unloading, and sink development. The transcript level of a major CWIN gene, , and CWIN activity were significantly increased in style at 4 h after pollination (HAP) in comparison with that in the non-pollination control, and this was sustained at 2 days after pollination (DAP). In the ovaries, however, CWIN activity and expression did not increase until 2 DAP when fertilization occurred. Interestingly, a CWIN inhibitor gene was repressed in the pollinated style at 2 DAP. In response to pollination, the style exhibited increased expressions of genes encoding hexose transporters, , , , and sucrose transporters , , and from 4 HAP to 2 DAP. Upon fertilization, and and , but not , were also stimulated in fruitlets at 2 DAP. Together, the findings reveal that styles respond promptly and more broadly to pollination for activation of CWIN and sugar transporters to fuel pollen tube elongation, whereas the ovaries do not exhibit activation for some of these genes until fertilization occurs.

Highlights: Expression of genes encoding cell wall invertases and sugar transporters was stimulated in pollinated style and fertilized ovaries in tomato.
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http://dx.doi.org/10.3389/fpls.2019.00506DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6482350PMC
April 2019

Accessing to the Nicotiana tabacum leaf antimicrobial activity: In-silico and in-vitro investigations.

Plant Physiol Biochem 2019 Jun 22;139:591-599. Epub 2019 Apr 22.

Instituto Tecnológico de Ciudad Cuauhtémoc, Mexico. Electronic address:

In this research, in-silico and in-vitro approaches were adopted with the aim to investigate the relationship between the tobacco leaf structures (trichomes) and the production of secondary metabolites with antimicrobial activity. Machine learning techniques were used to know the correlation between phenotypic traits and the production of secondary metabolites in Nicotiana tabacum plants. Then, an in-vitro experimental study was carried out to corroborate the proposed model. The relationship between the morphology and distribution of the different types of trichomes in the upper and lower leaves with the contrasting profiles of the chemical composition (diterpenes and sugar esters) of the leaf exudates between different lines of tobacco were found. We determined the influence of each trichome type with secondary metabolites production and the necessary concentration to achieve antimicrobial and antioxidant activity.
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http://dx.doi.org/10.1016/j.plaphy.2019.04.015DOI Listing
June 2019

Proteomic and physiological assessment of stress sensitive and tolerant variety of tomato treated with brassinosteroids and hydrogen peroxide under low-temperature stress.

Food Chem 2019 Aug 13;289:500-511. Epub 2019 Mar 13.

Vegetable Research Institute, Guangdong Academy of Agricultural Sciences/Guangdong Key Laboratory for New Technology Research of Vegetables, Guangzhou 510640, PR China.

The aim of current investigation was to perform proteomics and physio-chemical studies to dissect the changes in contrasting varieties (S-22 and PKM-1) of Lycopersicon esculentum under low-temperature stress. Plant grown under variable low-temperature stress were analysed for their growth biomarkers, antioxidant enzyme activities, and other physiological parameters, which headed toward the determination of protein species responding to low-temperature and 24-epibrassinolide (EBL) concentrations. The plants grown under temperatures, 20/14, 12/7, and 10/3 °C recorded significantly lower growth biomarkers, SPAD chlorophyll, net photosynthetic rate and carbonic anhydrase activity in S-22 and PKM-1. Moreover, the combined effect of EBL and hydrogen peroxide (HO) significantly improved the parameters mentioned above and consecutively upgraded the different antioxidant enzymes (CAT and SOD) with higher accumulation of proline under stress and stress-free environments. Furthermore, proteomics study revealed that the maximum number of differentially expressed proteins were detected in S-22 (EBL + HO); while treatment with EBL + HO + low temperature lost expression of 20 proteins. Overall, three proteins (O80577, Q9FJQ8, and Q9SKL2) took a substantial part in the biosynthesis of citrate cycle pathway and enhanced the growth and photosynthetic efficiency of tomato plants under low-temperature stress.
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http://dx.doi.org/10.1016/j.foodchem.2019.03.029DOI Listing
August 2019

Silicon decreases cadmium concentrations by modulating root endodermal suberin development in wheat plants.

J Hazard Mater 2019 02 24;364:581-590. Epub 2018 Oct 24.

Institute of Plant Nutrition and Soil Science, Kiel University, Hermann-Rodewald-Str. 2, 24118, Kiel, Germany. Electronic address:

Silicon (Si) can alleviate cadmium (Cd) toxicity in many plants, but mechanisms underlying this beneficial effect are still lacking. In this study, the roles of Si in time-dependent apoplastic and symplastic Cd absorption by roots of wheat plants were investigated. Results showed that, during short-term Cd exposure, the symplastic pathway of Cd in roots was not significantly affected by Si. Cell wall properties and cell wall-bound Cd regarding the apoplastic pathway were unaffected by Si either. Nevertheless, Cd concentrations in the apoplastic fluid of roots were decreased by Si. The reason could be that Si delayed endodermal suberization of roots resulting in promoted apoplastic Cd translocation to shoots, thus decreasing Cd in the apoplastic fluid of roots after short-term Cd stress. By contrast, after long-term Cd stress, cell wall properties and the expression of genes related to Cd influx and transport were unaffected. Intriguingly, Si up-regulated the expression of the Cd efflux-related gene TaTM20 and repressed apoplastic Cd translocation to shoots, which might contribute to decrease of Cd after long-term Cd exposure. Taken together, these results indicate that Si-dependent decrease in root Cd concentrations during short-term Cd exposure helps plants to mitigate Cd toxicity in the long-term.
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http://dx.doi.org/10.1016/j.jhazmat.2018.10.052DOI Listing
February 2019

Sulfate supply enhances cadmium tolerance in Vicia faba L. plants.

Environ Sci Pollut Res Int 2018 Nov 2;25(33):33794-33805. Epub 2018 Oct 2.

Institute of Plant Nutrition and Soil Science, Kiel University, Hermann-Rodewald-Str. 2, 24118, Kiel, Germany.

Sulfur deficiency and cadmium (Cd) pollution are two ubiquitous constraints affecting plant growth in agricultural soils. However, facing the situation of sulfur deficiency, whether surplus sulfate supply can affect Cd toxicity in plants is still unclear. Therefore, in the present study, experiments with deficient, sufficient, and excess sulfate levels under Cd stress were conducted in faba bean plants hydroponically. We found that sulfate supply significantly increased biomass of Cd-stressed plants when compared with deficient sulfate treatment. Intriguingly, sulfate application also increased Cd concentrations in leaves. Based on increased Cd concentrations without retarding plant growth, we conclude that sulfate supply enhances Cd tolerance in faba bean plants. Sulfate application increased CdSO proportion in the growth medium which is partially related to the increase of Cd in plants because the diffusion of CdSO is faster than Cd in plants. Further study on Cd localization showed that this heavy metal was prone to accumulate in the epidermis of leaves as affected by sulfate which might contribute to enhancement of Cd tolerance. Oxidative stress induced by Cd toxicity was alleviated by surplus sulfate supply compared with deficient sulfate. Although capacities of total antioxidants were increased by sulfate in Cd-stressed plants, phenolic compounds as one kind of important antioxidants were unchanged, suggesting that sulfate has no effect on phenolic compounds for scavenging ROS under Cd stress. Taken together, sulfate accelerates Cd accumulation in the epidermis of leaves in faba bean giving rise to higher Cd tolerance.
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http://dx.doi.org/10.1007/s11356-018-3266-6DOI Listing
November 2018

Changes of soluble sugars and ATP content during DMSO droplet freezing and PVS3 droplet vitrification of potato shoot tips.

Cryobiology 2018 12 23;85:79-86. Epub 2018 Sep 23.

Leibniz Institute of Plant Genetics and Crop Plant Research (IPK Gatersleben), Corrensstraße 3, 06466, Seeland, Germany. Electronic address:

The potato's great genetic diversity needs to be maintained for future agricultural applications and can be preserved at ultra-low temperatures. To decipher detailed physiological processes, the aim of the study was to analyze the regrowth in 28 gene bank accessions and to reveal metabolite changes in a subset of four accessions that showed pronounced differences after shoot tip cryopreservation using DMSO droplet freezing and PVS3 droplet vitrification. Regrowth varied in all 28 genotypes ranging from 5% ('Kagiri') to 100% ('Karakter') and was higher after PVS3 droplet vitrification (71 ± 19%) than after cryopreservation using DMSO (54 ± 17%). Sucrose, glucose, and fructose were analyzed and showed significant increases after pre-culture in combination with PVS3 or DMSO and liquid nitrogen treatment and were reduced during regeneration. In contrast, adenosine triphosphate (ATP) reached its minimum concentration after cryoprotection and liquid nitrogen treatment and recovered most quickly after PVS3 droplet vitrification. A shortening of the explant pre-culture period reduced dramatically the regrowth after PVS3 vitrification. However, correlations between the shoot tip regrowth and sugar concentration were absent and significant at a low extent with ATP (r = 0.4, P < 0.01). Interestingly, several sub-cultivations of the donor plants from the previous stock affected negatively the regrowth. In conclusion, the cryopreservation protocol, genotypes, pre-culture period and number of sub-cultures affect the regrowth ability of explants, which was best estimated by the ATP concentration after low-temperature treatment. Due to the superior performance of PVS3, the routine potato cryopreservation at the Gatersleben gene bank was changed to PVS3 droplet vitrification.
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http://dx.doi.org/10.1016/j.cryobiol.2018.09.005DOI Listing
December 2018

ATP Content and Cell Viability as Indicators for Cryostress Across the Diversity of Life.

Front Physiol 2018 17;9:921. Epub 2018 Jul 17.

Leibniz Institute DSMZ - German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany.

In many natural environments, organisms get exposed to low temperature and/or to strong temperature shifts. Also, standard preservation protocols for live cells or tissues involve ultradeep freezing in or above liquid nitrogen (-196°C or -150°C, respectively). To which extent these conditions cause cold- or cryostress has rarely been investigated systematically. Using ATP content as an indicator of the physiological state of cells, we found that representatives of bacteria, fungi, algae, plant tissue, as well as plant and human cell lines exhibited similar responses during freezing and thawing. Compared to optimum growth conditions, the cellular ATP content of most model organisms decreased significantly upon treatment with cryoprotectant and cooling to up to -196°C. After thawing and a longer period of regeneration, the initial ATP content was restored or even exceeded the initial ATP levels. To assess the implications of cellular ATP concentration for the physiology of cryostress, cell viability was determined in parallel using independent approaches. A significantly positive correlation of ATP content and viability was detected only in the cryosensitive algae SAG 11-32b and NC64A, and in plant cell lines of . When comparing mesophilic with psychrophilic bacteria of the same genera, and cryosensitive with cryotolerant algae, ATP levels of actively growing cells were generally higher in the psychrophilic and cryotolerant representatives. During exposure to ultralow temperatures, however, psychrophilic and cryotolerant species showed a decline in ATP content similar to their mesophilic or cryosensitive counterparts. Nevertheless, psychrophilic and cryotolerant species attained better culturability after freezing. Cellular ATP concentrations and viability measurements thus monitor different features of live cells during their exposure to ultralow temperatures and cryostress.
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http://dx.doi.org/10.3389/fphys.2018.00921DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6056685PMC
July 2018

Colour bio-factories: Towards scale-up production of anthocyanins in plant cell cultures.

Metab Eng 2018 07 8;48:218-232. Epub 2018 Jun 8.

Leibniz Institute of Plant Genetics and Crop Plant Research (IPK-Gatersleben), Department of Physiology and Cell Biology, Corrensstraße 3, 06466 Stadt Seeland, OT Gatersleben, Germany. Electronic address:

Anthocyanins are widely distributed, glycosylated, water-soluble plant pigments, which give many fruits and flowers their red, purple or blue colouration. Their beneficial effects in a dietary context have encouraged increasing use of anthocyanins as natural colourants in the food and cosmetic industries. However, the limited availability and diversity of anthocyanins commercially have initiated searches for alternative sources of these natural colourants. In plants, high-level production of secondary metabolites, such as anthocyanins, can be achieved by engineering of regulatory genes as well as genes encoding biosynthetic enzymes. We have used tobacco lines which constitutively produce high levels of cyanidin 3-O-rutinoside, delphinidin 3-O-rutinoside or a novel anthocyanin, acylated cyanidin 3-O-(coumaroyl) rutinoside to generate cell suspension cultures. The cell lines are stable in their production rates and superior to conventional plant cell cultures. Scale-up of anthocyanin production in small scale fermenters has been demonstrated. The cell cultures have also proven to be a suitable system for production of C-labelled anthocyanins. Our method for anthocyanin production is transferable to other plant species, such as Arabidopsis thaliana, demonstrating the potential of this approach for making a wide range of highly-decorated anthocyanins. The tobacco cell cultures represent a customisable and sustainable alternative to conventional anthocyanin production platforms and have considerable potential for use in industrial and medical applications of anthocyanins.
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http://dx.doi.org/10.1016/j.ymben.2018.06.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6075943PMC
July 2018

Changes in isovitexin-O-glycosylation during the development of young barley plants.

Phytochemistry 2018 Apr 6;148:11-20. Epub 2018 Feb 6.

Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Department of Physiology and Cell Biology, Corrensstraße 3, 06466 Seeland, Germany. Electronic address:

Phenylpropanoids are a class of plant natural products that have many biological functions, including stress defence. In barley, phenylpropanoids have been described as having protective properties against excess UV-B radiation and have been linked to resistance to pathogens. Although the phenylpropanoid composition of barley has recently been addressed in more detail, the biosynthesis and regulation of this pathway have not been fully established. Barley introgression lines, such as the S42IL-population offer a set of genetically diverse plants that enable the correlation of metabolic data to distinct genetic regions on the barley genome and, subsequently, identification of relevant genes. The phenylpropanoid profiles of the first and third leaf of barley seedlings in Scarlett and four members of the S42IL-population were obtained by LC-MS. Comparison of the leaf profiles revealed a change in the glycosylation pattern of the flavone-6-C-glucoside isovitexin in the elite cultivar Scarlett. The change was characterized by the stepwise decrease in isovitexin-7-O-glucoside (saponarin) and an increase in isovitexin-2″-O-β-D-glucoside content. The lines S42IL-101-, -177 and -178 were completely devoid of isovitexin-2″-O-β-D-glucoside. Parallel glucosyltransferase assays were consistent with the observed metabolic patterns. The genetic region responsible for this metabolic effect was located on chromosome 1H between 0.21 and 15.08 cM, encompassing 505 gene candidates in the genome of the sequenced cultivar Morex. Only one of these genes displayed sequence similarity with glucosyltransferases of plant secondary metabolism that possessed the characteristic PSPG motif.
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http://dx.doi.org/10.1016/j.phytochem.2018.01.001DOI Listing
April 2018

Plasma membrane proteome analysis identifies a role of barley membrane steroid binding protein in root architecture response to salinity.

Plant Cell Environ 2018 06 15;41(6):1311-1330. Epub 2018 Mar 15.

Leibniz Institute of Plant Genetics and Crop Plant Research, Corrensstraße 3, 06466, Stadt Seeland, Gatersleben, Germany.

Although the physiological consequences of plant growth under saline conditions have been well described, understanding the core mechanisms conferring plant salt adaptation has only started. We target the root plasma membrane proteomes of two barley varieties, cvs. Steptoe and Morex, with contrasting salinity tolerance. In total, 588 plasma membrane proteins were identified by mass spectrometry, of which 182 were either cultivar or salinity stress responsive. Three candidate proteins with increased abundance in the tolerant cv. Morex were involved either in sterol binding (a GTPase-activating protein for the adenosine diphosphate ribosylation factor [ZIGA2], and a membrane steroid binding protein [MSBP]) or in phospholipid synthesis (phosphoethanolamine methyltransferase [PEAMT]). Overexpression of barley MSBP conferred salinity tolerance to yeast cells, whereas the knock-out of the heterologous AtMSBP1 increased salt sensitivity in Arabidopsis. Atmsbp1 plants showed a reduced number of lateral roots under salinity, and root-tip-specific expression of barley MSBP in Atmsbp1 complemented this phenotype. In barley, an increased abundance of MSBP correlates with reduced root length and lateral root formation as well as increased levels of auxin under salinity being stronger in the tolerant cv. Morex. Hence, we concluded the involvement of MSBP in phytohormone-directed adaptation of root architecture in response to salinity.
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http://dx.doi.org/10.1111/pce.13154DOI Listing
June 2018

Accumulation of the coumarin scopolin under abiotic stress conditions is mediated by the Arabidopsis thaliana THO/TREX complex.

Plant J 2018 02 10;93(3):431-444. Epub 2018 Jan 10.

Department of Physiology and Cell Biology, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstraße 3, 06466, Seeland, OT Gatersleben, Germany.

Secondary metabolites are involved in the plant stress response. Among these are scopolin and its active form scopoletin, which are coumarin derivatives associated with reactive oxygen species scavenging and pathogen defence. Here we show that scopolin accumulation can be induced in the root by osmotic stress and in the leaf by low-temperature stress in Arabidopsis thaliana. A genetic screen for altered scopolin levels in A. thaliana revealed a mutant compromised in scopolin accumulation in response to stress; the lesion was present in a homologue of THO1 coding for a subunit of the THO/TREX complex. The THO/TREX complex contributes to RNA silencing, supposedly by trafficking precursors of small RNAs. Mutants defective in THO, AGO1, SDS3 and RDR6 were impaired with respect to scopolin accumulation in response to stress, suggesting a mechanism based on RNA silencing such as the trans-acting small interfering RNA pathway, which requires THO/TREX function.
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http://dx.doi.org/10.1111/tpj.13797DOI Listing
February 2018

Nitrogen Deficiency Induced Alterations in the Root Proteome of a Pair of Potato (Solanum tuberosum L.) Varieties Contrasting for their Response to Low N.

Proteomics 2017 Dec;17(23-24)

Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany.

Improving crop nitrogen use efficiency is important both from the economic and the environmental viewpoint. Here, the aim is to highlight differences between the proteomic response of the roots of two potato cultivars contrasting in their response to nitrogen (N) deficiency, in an effort to understand which proteins and metabolic pathways contribute to the tolerance of N deprivation. The two cultivars ''Topas'' (tolerant) and ''Lambada'' (sensitive) are grown under both an N sufficient and an N deficient regime, using an in vitro-based cultivation system. Responsive proteins are identified and quantified using label-free quantitative shotgun proteomics. The contrasting cultivars differed with respect to components of the glutamine synthetase/glutamine oxoglutarate aminotransferase pathway, tricarboxylic acid cycle, the glycolysis/gluconeogenesis pathway as well as protein and amino acid synthesis machinery. Additional differences are associated with protein catabolism and defense mechanisms.
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http://dx.doi.org/10.1002/pmic.201700231DOI Listing
December 2017

Mini-Scale Isolation and Preparation of Plasma Membrane Proteins from Potato Roots for LC/MS Analysis.

Methods Mol Biol 2018 ;1696:195-204

Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), OT Gatersleben, Corrensstrasse 3, 06466, Stadt Seeland, Germany.

Plasma membrane (PM) proteins are of special interest due to their function in exchanging material and information with the external environment as well as their role in cellular regulation. In quantitative proteomic studies PM proteins are underrepresented mostly because they constitute only small percent of all membrane proteins. Strong demand is placed on plasma membrane enrichment methods. For decades two-phase partitioning Dextran T500/PEG 3350 isolation protocols were applied for many different animal and plant species and also a variety of tissue types. The typical quantity of material used in the enrichment protocols is 10-30 g of fresh weight. The main difficulty of working with in vitro cultivated plants is the low amount of material, especially when roots are examined. In addition, roots are frequently characterized by low protein concentrations. Our protocol established for roots of in vitro cultivated potato plants is adjusted to amounts of fresh weight not exceeding 7.5 g and allows studying the plasma membrane proteome by LC-MS.
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http://dx.doi.org/10.1007/978-1-4939-7411-5_13DOI Listing
June 2018

Hop/Sti1 - A Two-Faced Cochaperone Involved in Pattern Recognition Receptor Maturation and Viral Infection.

Front Plant Sci 2017 11;8:1754. Epub 2017 Oct 11.

Department of Biology, Division of Biochemistry, Friedrich-Alexander University Erlangen-Nuremberg, Erlangen, Germany.

Perception of pathogens by host pattern recognition receptors (PRRs) or R proteins is a prerequisite to promote successful immune responses. The Hsp70/Hsp90 organizing protein Hop/Sti1, a multifunctional cochaperone, has been implicated in the maturation of a receptor-like kinase (RLK) necessary for chitin sensing. However, it remains unknown whether Hop/Sti1 is generally participating in PRR genesis. Using RNA-interference (RNAi), we silenced Hop/Sti1 expression in to gain further insight into the role of the cochaperone in plant defense responses. As expected, transgenic plants do not respond to chitin treatment anymore. In contrast to this, trafficking and functionality of the flagellin PRR FLS2 were unaltered, suggesting a selective involvement of Hop/Sti1 during PRR maturation. Furthermore, Hop/Sti1 was identified as a cellular determinant of Potato virus Y (PVY) symptom development in tobacco, since PVY was able to accumulate to near wild-type level without provoking the usual veinal necrosis phenotype. In addition, typical antiviral host defense responses were suppressed in the transgenic plants. These data suggest that perception of PVY is dependent on Hop/Sti1-mediated receptor maturation, while viral symptoms represent a failing attempt to restrict PVY spread. In addition, Hop/Sti1 colocalized with virus-induced membrane aggregates in wild-type plants. The retention of Hop/Sti1 in potential viral replication complexes suggests a role during viral translation/replication, explaining why RNAi-lines do not exhibit increased susceptibility to PVY. This study provides evidence for a dual role of Hop/Sti1 in PRR maturation and pathogen perception as well as in promoting viral proliferation.
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http://dx.doi.org/10.3389/fpls.2017.01754DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5641557PMC
October 2017

Comparative shoot proteome analysis of two potato (Solanum tuberosum L.) genotypes contrasting in nitrogen deficiency responses in vitro.

J Proteomics 2017 08 18;166:68-82. Epub 2017 Jul 18.

Julius Kühn-Institute (JKI), Federal Research Centre for Cultivated Plants, Institute for Resistance Research and Stress Tolerance, OT Groß Lüsewitz, Rudolf-Schick-Platz 3, 18190 Sanitz, Germany. Electronic address:

Aiming at a better understanding of the physiological and biochemical background of nitrogen use efficiency, alterations in the shoot proteome under N-deficiency were investigated in two contrasting potato genotypes grown in vitro with 60 and 7.5mM N, respectively. A gel based proteomic approach was applied to identify candidate proteins associated with genotype specific responses to N-deficiency. 21% of the detected proteins differed in abundance between the two genotypes. Between control and N-deficiency conditions 19.5% were differentially accumulated in the sensitive and 15% in the tolerant genotype. 93% of the highly N-deficiency responsive proteins were identified by MALDI TOF/TOF mass spectrometry. The major part was associated with photosynthesis, carbohydrate metabolism, stress response and regulation. Differential accumulation of enzymes involved in the Calvin cycle and glycolysis suggest activation of alternative carbohydrate pathways. In the tolerant genotype, increased abundance under N-deficiency was also found for enzymes involved in chlorophyll synthesis and stability of enzymes, which increase photosynthetic carbon fixation efficiency. Out of a total of 106 differentially abundant proteins, only eight were detected in both genotypes. Our findings suggest that mutually responsive proteins reflect universal stress responses while adaptation to N-deficiency in metabolic pathways is more genotype specific.

Significance: Nitrogen losses from arable farm land considerably contribute to environmental pollution. In potato, this is a special problem due cultivation on light soils, irrigation and the shallow root system. Therefore, breeding of cultivars with improved nitrogen use efficiency and stable yields under reduced N fertilization is an important issue. Knowledge of genotype dependent adaptation to N-deficiency at the proteome level can help to understand regulation of N efficiency and development of N-efficient cultivars.
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http://dx.doi.org/10.1016/j.jprot.2017.07.010DOI Listing
August 2017

Metabolite profiling of red and blue potatoes revealed cultivar and tissue specific patterns for anthocyanins and other polyphenols.

Planta 2017 Aug 29;246(2):281-297. Epub 2017 Jun 29.

Department of Physiology and Cell Biology, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK-Gatersleben), Corrensstraße 3, 06466, Stadt Seeland OT Gatersleben, Germany.

Main Conclusion: Metabolite profiling of tuber flesh and peel for selected colored potato varieties revealed cultivar and tissue specific profiles of anthocyanins and other polyphenols with variations in composition and concentration. Starchy tubers of Solanum tuberosum are a staple crop and food in many countries. Among cultivated potato varieties a huge biodiversity exists, including an increasing number of red and purple colored cultivars. This coloration relates to the accumulation of anthocyanins and is supposed to offer nutritional benefits possibly associated with the antioxidative capacity of anthocyanins. However, the anthocyanin composition and its relation to the overall polyphenol constitution in colored potato tubers have not been investigated closely. This study focuses on the phytochemical characterization of the phenolic composition of a variety of colored potato tubers, both for peel and flesh tissues. First, liquid chromatography (LC) separation coupled to UV and mass spectrometry (MS) detection of polyphenolic compounds of potato tubers from 57 cultivars was used to assign groups of potato cultivars differing in their anthocyanin and polyphenol profiles. Tissues from 19 selected cultivars were then analyzed by LC separation coupled to multiple reaction monitoring (MRM) to detect quantitative differences in anthocyanin and polyphenol composition. The measured intensities of 21 anthocyanins present in the analyzed potato cultivars and tissues could be correlated with the specific tuber coloration. Besides secondary metabolites well-known for potato tubers, the metabolic profiling led to the detection of two anthocyanins not described for potato tuber previously, which we tentatively annotated as pelargonidin feruloyl-xylosyl-glucosyl-galactoside and cyanidin 3-p-coumaroylrutinoside-5-glucoside. We detected significant correlations between some of the measured metabolites, as for example the negative correlation between the main anthocyanins of red and blue potato cultivars. Mainly hydroxylation and methylation patterns of the B-ring of dihydroflavonols, leading to the formation of specific anthocyanidin backbones, can be assigned to a distinct coloring of the potato cultivars and tuber tissues. However, basically the same glycosylation and acylation reactions occur regardless of the main anthocyanidin precursor present in the respective red and blue/purple tissue. Thus, the different anthocyanin profiles in red and blue potato cultivars likely relate to superior regulation of the expression and activities of hydroxylases and methyltransferases rather than to differences for downstream glycosyl- and acyltransferases. In this regard, the characterized potato cultivars represent a valuable resource for the molecular analysis of the genetic background and the regulation of anthocyanin side chain modification.
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http://dx.doi.org/10.1007/s00425-017-2718-4DOI Listing
August 2017

Proteomic comparison of Chelidonium majus L. latex in different phases of plant development.

Plant Physiol Biochem 2017 Mar 13;112:312-325. Epub 2017 Jan 13.

Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, D-06466 Gatersleben, Germany.

Chelidonium majus L. (Papaveraceae) latex is used in traditinonal folk medicine to treat papillae, warts, condylomas, which are visible effects of human papilloma virus (HPV) infections. The aim of this work was to provide new insights into the biology and medicinal use of C. majus milky sap in the flowering and fruit ripening period of the plant by comparing the protein content between samples collected on respective developmental stages using LC-MS-based label-free proteome approach. For quantification, the multiplexed LC-MS data were processed using comparative chemometric approach. Progenesis LC-MS results showed that in green fruit phase (stage IV), comparing to flowering phase (stage III) of plant development, a range of proteins with higher abundance were identified as stress- and defense-related. On the other hand at stage III very intense protein synthesis, processes of transcription, protein folding and active transport of molecules (ABC transporters) are well represented. 2-DE protein maps showed an abundant set of spots with similar MWs (about 30-35 kDa) and pIs (ca. 5.5-6.5), which were identified as major latex proteins (MLPs). Therefore we suggest that biological activity of C. majus latex could be related to its protein content, which shifts during plant development from intense biosynthetic processes (biosynthesis and transport of small molecules, like alkaloids) to plant defense mechanisms against pathogens. Further studies will help to elucidate if these defense-related and pathogenesis-related proteins, like MLP, together with small-molecule compounds, could inhibit viral infection, what could be a step to fully understand the medicinal activity of C. majus latex.
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http://dx.doi.org/10.1016/j.plaphy.2017.01.010DOI Listing
March 2017

Genome-metabolite associations revealed low heritability, high genetic complexity, and causal relations for leaf metabolites in winter wheat (Triticum aestivum).

J Exp Bot 2017 01;68(3):415-428

Department of Physiology and Cell Biology, Applied Biochemistry, Leibniz Institute of Plant Genetics and Crop Plant Research, Gatersleben, Germany.

We investigated associations between the metabolic phenotype, consisting of quantitative data of 76 metabolites from 135 contrasting winter wheat (Triticum aestivum) lines, and 17 372 single nucleotide polymorphism (SNP) markers. Metabolite profiles were generated from flag leaves of plants from three different environments, with average repeatabilities of 0.5-0.6. The average heritability of 0.25 was unaffected by the heading date. Correlations among metabolites reflected their functional grouping, highlighting the strict coordination of various routes of the citric acid cycle. Genome-wide association studies identified significant associations for six metabolic traits, namely oxalic acid, ornithine, L-arginine, pentose alcohol III, L-tyrosine, and a sugar oligomer (oligo II), with between one and 17 associated SNPs. Notable associations with genes regulating transcription or translation explained between 2.8% and 32.5% of the genotypic variance (pG). Further candidate genes comprised metabolite carriers (pG 32.5-38.1%), regulatory proteins (pG 0.3-11.1%), and metabolic enzymes (pG 2.5-32.5%). The combinatorial use of genomic and metabolic data to construct partially directed networks revealed causal inferences in the correlated metabolite traits and associated SNPs. The evaluated causal relationships will provide a basis for predicting the effects of genetic interferences on groups of correlated metabolic traits, and thus on specific metabolic phenotypes.
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http://dx.doi.org/10.1093/jxb/erw441DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5441906PMC
January 2017