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Mueller S.J.,Albert Ludwigs University of Freiburg | Reski R.,Albert Ludwigs University of Freiburg | Reski R.,Center for Biological Signalling Studies | Reski R.,FRIAS Freiburg Institute for Advanced Studies | Reski R.,TIP Trinational Institute for Plant Research
Plant Signaling and Behavior

Compartmentation is a fundamental feature of eukaryotic cells and the basis for metabolic complexity. We recently reported on the protein compartmentation in the moss Physcomitrella patens. This study utilized a combination of quantitative proteomics, comparative genomics, and single protein tagging and provided data on the postendosymbiotic evolution of plastids and mitochondria, on organellar communication, as well as on inter- and intracellular heterogeneity of organelles. We highlight potential organelle interaction hubs with specific protein content such as plastid stromules, and report on the plasticity of protein targeting to organelles. © 2014 Landes Bioscience. Source

Beike A.K.,Albert Ludwigs University of Freiburg | Lang D.,Albert Ludwigs University of Freiburg | Zimmer A.D.,Albert Ludwigs University of Freiburg | Zimmer A.D.,University Hospital Freiburg | And 10 more authors.
New Phytologist

Summary: The whole-genome transcriptomic cold stress response of the moss Physcomitrella patens was analyzed and correlated with phenotypic and metabolic changes. Based on time-series microarray experiments and quantitative real-time polymerase chain reaction, we characterized the transcriptomic changes related to early stress signaling and the initiation of cold acclimation. Transcription-associated protein (TAP)-encoding genes of P. patens and Arabidopsis thaliana were classified using generalized linear models. Physiological responses were monitored with pulse-amplitude-modulated fluorometry, high-performance liquid chromatography and targeted high-performance mass spectrometry. The transcript levels of 3220 genes were significantly affected by cold. Comparative classification revealed a global specialization of TAP families, a transcript accumulation of transcriptional regulators of the stimulus/stress response and a transcript decline of developmental regulators. Although transcripts of the intermediate to later response are from evolutionarily conserved genes, the early response is dominated by species-specific genes. These orphan genes may encode as yet unknown acclimation processes. © 2014 New Phytologist Trust. Source

Schuessele C.,Albert Ludwigs University of Freiburg | Hoernstein S.N.W.,Albert Ludwigs University of Freiburg | Mueller S.J.,Albert Ludwigs University of Freiburg | Rodriguez-Franco M.,Albert Ludwigs University of Freiburg | And 5 more authors.
New Phytologist

The importance of the arginyl-tRNA protein transferase (ATE), the enzyme mediating post-translation arginylation of proteins in the N-end rule degradation (NERD) pathway of protein stability, was analysed in Physcomitrella patens and compared to its known functions in other eukaryotes. We characterize ATE:GUS reporter lines as well as ATE mutants in P. patens to study the impact and function of arginylation on moss development and physiology. ATE protein abundance is spatially and temporally regulated in P. patens by hormones and light and is highly abundant in meristematic cells. Further, the amount of ATE transcript is regulated during abscisic acid signalling and downstream of auxin signalling. Loss-of-function mutants exhibit defects at various levels, most severely in developing gametophores, in chloroplast starch accumulation and senescence. Thus, arginylation is necessary for moss gametophyte development, in contrast to the situation in flowering plants. Our analysis further substantiates the conservation of the N-end rule pathway components in land plants and highlights lineage-specific features. We introduce moss as a model system to characterize the role of the NERD pathway as an additional layer of complexity in eukaryotic development. © 2016 New Phytologist Trust. Source

Harb J.,Birzeit University | Saleh O.,Albert Ludwigs University of Freiburg | Saleh O.,TIP Trinational Institute for Plant Research | Kittemann D.,University of Hohenheim | And 7 more authors.
Journal of Agricultural and Food Chemistry

Blueberries are highly perishable fruits, and consequently, storage under high CO2 and low O2 levels is recommended to preserve the highly appreciated polyphenols. However, high CO2 levels might be detrimental for certain cultivars. The aim of this study was to investigate the impact of storage conditions on various quality parameters, including polyphenol composition in 'Duke' berries. Results show that storage under 18 kPa CO2, coupled with 3 kPa O2, resulted in accelerated softening of berries, which was accompanied by lower levels compared to other conditions of hexosides and arabinosides of malvidin, petunidin, cyanidine, and delphinidin. However, this storage condition had no negative impact on chlorogenic acid levels. Expression data of key polyphenol-biosynthesis genes showed higher expression levels of all investigated genes at harvest time compared to all storage conditions. Of particular importance is the expression level of chalcone synthase (VcCHS), which is severely affected by storage at 18 kPa CO2. © 2014 American Chemical Society. Source

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