Changes in actin microfilament arrays in developing pea root nodule cells

Davidson, A L; Newcomb, William W.

doi:10.1139/b01-046

Cited by 5 publications

(3 citation statements)

References 51 publications

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“…Moreover, we hypothesize that disturbances in rosR mutant endocytosis are a consequence of inappropriate plant cell cytoskeleton arrangement, caused by alterations in bacterial surface properties. Actin microfilaments associated with unwalled membrane-surrounded droplets are involved in the release of bacteria and the separation of symbiosomes from the IT (Dawidson and Newcomb, 2001 ). Endocytosis also requires a close interaction between rhizobial cells and the surface of plant cell plasma membrane (Robertson et al, 1985 ; Rathbun et al, 2002 ; Bolaños et al, 2004 ).…”

Section: Discussionmentioning

confidence: 99%

The Regulatory Protein RosR Affects Rhizobium leguminosarum bv. trifolii Protein Profiles, Cell Surface Properties, and Symbiosis with Clover

et al. 2016

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Rhizobium leguminosarum bv. trifolii is capable of establishing a symbiotic relationship with plants from the genus Trifolium. Previously, a regulatory protein encoded by rosR was identified and characterized in this bacterium. RosR possesses a Cys 2 -His 2 -type zinc finger motif and belongs to Ros/MucR family of rhizobial transcriptional regulators. Transcriptome profiling of the rosR mutant revealed a role of this protein in several cellular processes, including the synthesis of cell-surface components and polysaccharides, motility, and bacterial metabolism. Here, we show that a mutation in rosR resulted in considerable changes in R. leguminosarum bv. trifolii protein profiles. Extracellular, membrane, and periplasmic protein profiles of R. leguminosarum bv. trifolii wild type and the rosR mutant were examined, and proteins with substantially different abundances between these strains were identified. Compared with the wild type, extracellular fraction of the rosR mutant contained greater amounts of several proteins, including Ca 2+ -binding cadherin-like proteins, a RTX-like protein, autoaggregation protein RapA1, and flagellins FlaA and FlaB. In contrast, several proteins involved in the uptake of various substrates were less abundant in the mutant strain (DppA, BraC, and SfuA). In addition, differences were observed in membrane proteins of the mutant and wild-type strains, which mainly concerned various transport system components. Using atomic force microscopy (AFM) imaging, we characterized the topography and surface properties of the rosR mutant and wild-type cells. We found that the mutation in rosR gene also affected surface properties of R. leguminosarum bv. trifolii. The mutant cells were significantly more hydrophobic than the wild-type cells, and their outer membrane was three times more permeable to the hydrophobic dye N-phenyl-1-naphthylamine. The mutation of rosR also caused defects in bacterial symbiotic interaction with clover plants. Compared with the wild type, the rosR mutant infected host plant roots much less effectively and its nodule occupation was disturbed. At the ultrastructural level, the Rachwał et al.RosR Affects Rhizobial Cell-Surface Properties most striking differences between the mutant and the wild-type nodules concerned the structure of infection threads, release of bacteria, and bacteroid differentiation. This confirms an essential role of RosR in establishment of successful symbiotic interaction of R. leguminosarum bv. trifolii with clover plants.

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Section: Discussionmentioning

confidence: 99%

The Regulatory Protein RosR Affects Rhizobium leguminosarum bv. trifolii Protein Profiles, Cell Surface Properties, and Symbiosis with Clover

et al. 2016

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“…Interestingly, an ortholog of this subunit was recently shown in Lotus to control rhizobial infection [61]. Therefore, control of the actin cytoskeleton likely also plays a key role in the nodule to control infection thread formation and possibly symbiosome formation [62].…”

Section: Cell/tissue-specific Characteristics Of Gene Expression In M...mentioning

confidence: 99%

Correction: Cell- and Tissue-Specific Transcriptome Analyses of Medicago truncatula Root Nodules

Limpens¹,

Moling²,

Hooiveld³

et al. 2014

PLoS ONE

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Legumes have the unique ability to host nitrogen-fixing Rhizobium bacteria as symbiosomes inside root nodule cells. To get insight into this key process, which forms the heart of the endosymbiosis, we isolated specific cells/tissues at different stages of symbiosome formation from nodules of the model legume Medicago truncatula using laser-capture microdissection. Next, we determined their associated expression profiles using Affymetrix Medicago GeneChips. Cells were collected from the nodule infection zone divided into a distal (where symbiosome formation and division occur) and proximal region (where symbiosomes are mainly differentiating), as well as infected cells from the fixation zone containing mature nitrogen fixing symbiosomes. As non-infected cells/tissue we included nodule meristem cells and uninfected cells from the fixation zone. Here, we present a comprehensive gene expression map of an indeterminate Medicago nodule and selected genes that show specific enriched expression in the different cells or tissues. Validation of the obtained expression profiles, by comparison to published gene expression profiles and experimental verification, indicates that the data can be used as digital ''in situ''. This digital ''in situ'' offers a genome-wide insight into genes specifically associated with subsequent stages of symbiosome and nodule cell development, and can serve to guide future functional studies.

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“…Nevertheless, after comparing fresh and fixed samples, Zhang et al conclude that such actin fragments are, indeed, a feature of cytoskeleton rearrangement during nodule cell maturation. Earlier studies on the actin cytoskeleton in pea (Davidson & Newcomb, 2001), soybean (Whitehead et al, 1998) and Medicago truncatula (Gavrin et al, 2015) were limited to chemically fixed nodules and in these studies the presence of actin filament fragments was either not noticed or attributed to an artifact of fixation. The question arises then as to whether these structures are limited to nodules or do they constitute a general feature of the plant actin cytoskeleton that has so far escaped attention?…”

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confidence: 99%