Papers by Katharina Pawlowski
Frontiers in plant science, Apr 9, 2024
Molecular Plant-microbe Interactions, 2000
Recent phylogenetic studies have implied that all plants able to enter root nodule symbioses with... more Recent phylogenetic studies have implied that all plants able to enter root nodule symbioses with nitrogen-fixing bacteria go back to a common ancestor (D. E. Soltis, P.
Molecular Microbiology, Jun 1, 1989
The nucteotrde sequence of the Azorhizobium caulinodans ORS571 nlfA locus was determined and the ... more The nucteotrde sequence of the Azorhizobium caulinodans ORS571 nlfA locus was determined and the deduced NtfA amino acid sequence compared with that of NifA from other nitrogen-fixing species. Highly conserved domains, including helix-turn-helix and ATP-binding motifs, and specific conserved residues, such as a cluster of cysteines, were identified. The nif A 5' upstream region was found to contain DNA sequence motifs highly homologous to promoter elements involved in n/M/nfr-mediated control and a consensus element found in the 5' upstream region of the Bradyrhizobium japonicum 5-aminolevulinic acid synthase [hemA) gene and of Escherichia co/f genes activated during anaerobiosis via the fnr (fumarate nitrate reduction) control system. A nifA-lac fusion was constructed using miniMu-/ac and its activity measured in different genetic backgrounds and under various physiological conditions (in culture and in planta). NifA expression was found to be negatively autoregulated, repressed by rich nitrogen sources and high oxygen concentrations, and controlled (partially) by the ntrC gene, both in culture and in pianta. DNA supercoiling was also implicated in nifA regulation, since DNA gyrase inhibitors severely repressed nifAiac expression.
Cloning and characterization of nifA and ntrC genes of the stem nodulating bacterium ORS571, the nitrogen fixing symbiont of Sesbania rostrata: Regulation of nitrogen fixation (nif) genes in the free living versus symbiotic state
Molecular Genetics And Genomics, Feb 1, 1987
Frontiers for Young Minds, Jan 18, 2022
Symbiotic Nitrogen Fixation
The Plant Cell, Jul 1, 1995
3-Pentanol glycosides from root nodules of the actinorhizal plant Alnus cremastogyne
Phytochemistry, Mar 1, 2023
Shared and divergent genomic changes associated with the evolutionary transitions of Nostoc to a plant symbiont
Frontiers in Ecology and Evolution
Recent advances in plant developmental genetics together with rapid accumulation of transcriptomi... more Recent advances in plant developmental genetics together with rapid accumulation of transcriptomic data on plants from divergent lineages provide an exciting opportunity to explore the evolution of plant morphology. To understand leaf origin in sporophytes of land plants, we have combined the available molecular and structural data on development of leaves with different morphologies in different plant lineages: clubmosses, spikemosses, leptosporangiate ferns, ophioglossioid ferns, marattioid ferns, whisk ferns, horsetails, and conifers. Specifically, we address the peculiarities of proximo-distal, ad/abaxial, and lateral development; presence/absence of mesophyll differentiation into palisade and spongy parenchyma; and type of leaf vascular bundles (collateral and bicollateral). Furthermore, taxon-specific and morphology-specific features of leaf development are considered in the context of the organization of shoot apical meristems (SAMs)—monoplex, simplex, or duplex—that produce ...
International Journal of Systematic and Evolutionary Microbiology
An actinobacterial strain, CMB-FB, was isolated from surface-sterilized root nodules of a Coriari... more An actinobacterial strain, CMB-FB, was isolated from surface-sterilized root nodules of a Coriaria intermedia plant growing along Halsema Highway in the province of Benguet (Luzon, Philippines). The 16S rRNA gene sequence of CMB-FB showed high sequence similarity to those of the type strains of Streptomyces rishiriensis (99.4 %), Streptomyces humidus (99.1 %), Streptomyces cacaoi subsp. asoensis (99.0 %), and Streptomyces phaeofaciens (98.6 %). The major menaquinones of CMB-FB were composed of MK-9(H4), MK-9(H6) and MK-9(H8), and there was a minor contribution of MK-9(H10). The polar lipid profile consisted of phosphatidylethanolamine, unidentified aminolipids and phospholipids, a glycophospholipid and four unidentified lipids. The diagnostic diamino acid of the peptidoglycan was meso-diaminopimelic acid. The major fatty acids were iso-C16 : 0, anteiso-C15 : 0 and anteiso-C17 : 0. The results of physiological analysis indicated that CMB-FB was mesophilic. The results of phylogenetic...
Frankia cluster-2 are diazotrophs that engage in root nodule symbiosis with host plants of the Cu... more Frankia cluster-2 are diazotrophs that engage in root nodule symbiosis with host plants of the Cucurbitales and the Rosales. They are rarely found in the soil in the absence of their hosts. Previous studies have shown that an assimilated nitrogen source, presumable arginine, is exported to the host in nodules of Datisca glomerata (Cucurbitales), but not in the nodules of Ceanothus thyrsiflorus (Rosales). To investigate if an assimilated nitrogen form is commonly exported by cluster-2 strains, and which nitrogen source would then be exported to C. thyrsiflorus, gene expression levels, metabolite profiles and enzyme activities were analysed. We found that the export of assimilated nitrogen in symbiosis is a common feature for Frankia cluster-2 strains, but which source is host-plant dependent. We also identified several gene losses. The ammonium assimilation via the GS/GOGAT cycle for export to the host, entails a high demand of 2-oxoglutarate from the TCA cycle. This specialised metabolism seems to have led to genome reduction: we show that Frankia cluster-2 strains have lost the glyoxylate shunt and succinate semialdehyde dehydrogenase, leading to a linearization of the TCA cycle. This could explain the low saprotrophic potential of Frankia cluster-2.
Cucurbitales vs. Rosales : Analysis of bacterial metabolism based on candidate gene expression profiling in root nodules of Datisca glomerata and Ceanothus thyrsiflorus
Cucurbitales vs. Rosales : Analysis of bacterial metabolism based on candidate gene expression pr... more Cucurbitales vs. Rosales : Analysis of bacterial metabolism based on candidate gene expression profiling in root nodules of Datisca glomerata and Ceanothus thyrsiflorus
Genome Biology and Evolution, Jul 19, 2019
Frankia strains induce the formation of nitrogen-fixing nodules on roots of actinorhizal plants. ... more Frankia strains induce the formation of nitrogen-fixing nodules on roots of actinorhizal plants. Phylogenetically, Frankia strains can be grouped in four clusters. The earliest divergent cluster, cluster-2, has a particularly wide host range. The analysis of cluster-2 strains has been hampered by the fact that with two exceptions, they could never be cultured. In this study, 12 Frankia-enriched metagenomes of Frankia cluster-2 strains or strain assemblages were sequenced based on seven inoculum sources. Sequences obtained via DNA isolated from whole nodules were compared with those of DNA isolated from fractionated preparations enhanced in the Frankia symbiotic structures. The results show that cluster-2 inocula represent groups of strains, and that strains not represented in symbiotic structures, that is, unable to perform symbiotic nitrogen fixation, may still be able to colonize nodules. Transposase gene abundance was compared in the different Frankia-enriched metagenomes with the result that North American strains contain more transposase genes than Eurasian strains. An analysis of the evolution and distribution of the host plants indicated that bursts of transposition may have coincided with niche competition with other cluster-2 Frankia strains. The first genome of an inoculum from the Southern Hemisphere, obtained from nodules of Coriaria papuana in Papua New Guinea, represents a novel species, postulated as Candidatus Frankia meridionalis. All Frankia-enriched metagenomes obtained in this study contained homologs of the canonical nod genes nodABC; the North American genomes also contained the sulfotransferase gene nodH, while the genome from the Southern Hemisphere only contained nodC and a truncated copy of nodB.
Physiologia Plantarum, Oct 4, 2012
The oxygen protection system for the bacterial nitrogen-fixing enzyme complex nitrogenase in acti... more The oxygen protection system for the bacterial nitrogen-fixing enzyme complex nitrogenase in actinorhizal nodules of Casuarina glauca resembles that of legume nodules: infected cells contain large amounts of the oxygenbinding protein hemoglobin and are surrounded by an oxygen diffusion barrier. However, while in legume nodules infected cells are located in the central tissue, actinorhizal nodules are composed of modified lateral roots with infected cells in the expanded cortex. Since an oxygen diffusion barrier around the entire cortex would also block oxygen access to the central vascular system where it is required to provide energy for transport processes, here each individual infected cell is surrounded with an oxygen diffusion barrier. In order to assess the effect of these oxygen diffusion barriers on oxygen supply for energy production for transport processes, apoplastic and symplastic sugar transport pathways in C. glauca nodules were examined. The results support the idea that sugar transport to and within the nodule cortex relies to a large extent on the less energy-demanding symplastic mechanism. This is in line with the assumption that oxygen access to the nodule vascular system is substantially restricted. In spite of this dependence on symplastic transport processes to supply sugars to infected cells, plasmodesmal connections between infected cells, and to a lesser degree with uninfected cells, were reduced during the differentiation of infected cells.
Distinct roles of <i>Lotus japonicus SYMRK and SYM15</i> in root colonization and arbuscule formation
New Phytologist, Jul 1, 2004
ABSTRACT
bioRxiv (Cold Spring Harbor Laboratory), Apr 6, 2023
Plant root nodule symbiosis (RNS) with mutualistic nitrogen-fixing bacteria is restricted to a si... more Plant root nodule symbiosis (RNS) with mutualistic nitrogen-fixing bacteria is restricted to a single clade of angiosperms, the Nitrogen-Fixing Nodulation Clade (NFNC), and is best understood in the legume family. It is widely accepted that nodulation originated through the assembly of modules recruited from existing functions, such as mycorrhizal symbiosis, polar growth, and lateral root development. Because nodulating species are scattered within the NFNC, the number of times nodulation has evolved or has been lost has been a matter of considerable speculation. This interesting evolutionary question has practical implications concerning the ease with which nodulation might be engineered in nonnodulating crop plants. Nodulating species share many commonalities, due either to divergence from a common ancestor over 100 million years ago or to convergence or deep homology following independent origins over that same time period. In either case, comparative analyses of diverse nodulation syndromes can provide insights into constraints on nodulation-what must be acquired or cannot be lost for a functional symbiosis-and what the latitude is for variation in the symbiosis. However, much remains to be learned about nodulation, especially outside of legumes. Here we present new information across the spectrum of nodulating groups. We find no evidence for convergence at the level of amino acid residues or gene family expansion across the NFNC. Our phylogenomic analyses further emphasize the uniqueness of the transcription factor, NIN, as a master regulator of nodulation, and identify key mutations affecting its function across the NFNC. We find that nodulation genes are over-represented among orthologous gene groups (OGs) present in the NFNC common ancestor, but that lineage-specific OGs play major roles in nodulation. We identified over 900,000 conserved noncoding elements (CNEs), of which .
International Journal of Molecular Sciences, Apr 21, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Metagenomes from the earliest divergent Frankia cluster : They come in teams
Candidatus Frankia datiscae Dg1, the actinobacterial microsymbiont of Datisca glomerata, uses Nod factors for the infection of its host plant
Candidatus Frankia datiscae Dg1, the actinobacterial microsymbiont of Datisca glomerata, uses Nod... more Candidatus Frankia datiscae Dg1, the actinobacterial microsymbiont of Datisca glomerata, uses Nod factors for the infection of its host plant
Evolution of Signaling in Plant Symbioses
Frontiers research topics, 2020
This eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics... more This eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contac
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Papers by Katharina Pawlowski