scholarly journals Evidence for Phosphate Starvation of Rhizobia without Terminal Differentiation in Legume Nodules

2018 ◽  
Vol 31 (10) ◽  
pp. 1060-1068 ◽  
Author(s):  
Yue Hu ◽  
Jian Jiao ◽  
Li Xue Liu ◽  
Yan Wei Sun ◽  
Wen Feng Chen ◽  
...  
Keyword(s):  
Rhizobium Leguminosarum ◽  
Root Nodule ◽  
Wild Type Strain ◽  
Root Nodules ◽  
Terminal Differentiation ◽  
Phosphate Transporter ◽  
Phosphate Homeostasis ◽  
Growth Defects ◽  
Basal Expression ◽  
Basal Expression Level

Phosphate homeostasis is tightly modulated in all organisms, including bacteria, which harbor both high- and low-affinity transporters acting under conditions of fluctuating phosphate levels. It was thought that nitrogen-fixing rhizobia, named bacteroids, inhabiting root nodules of legumes are not phosphate limited. Here, we show that the high-affinity phosphate transporter PstSCAB, rather than the low-affinity phosphate transporter Pit, is essential for effective nitrogen fixation of Sinorhizobium fredii in soybean nodules. Symbiotic and growth defects of the pst mutant can be effectively restored by knocking out PhoB, the transcriptional repressor of pit. The pst homologs of representative rhizobia were actively transcribed in bacteroids without terminal differentiation in nodules of diverse legumes (soybean, pigeonpea, cowpea, common bean, and Sophora flavescens) but exhibited a basal expression level in terminally differentiated bacteroids (alfalfa, pea, and peanut). Rhizobium leguminosarum bv. viciae Rlv3841 undergoes characteristic nonterminal and terminal differentiations in nodules of S. flavescens and pea, respectively. The pst mutant of Rlv3841 showed impaired adaptation to the nodule environment of S. flavescens but was indistinguishable from the wild-type strain in pea nodules. Taken together, root nodule rhizobia can be either phosphate limited or nonlimited regarding the rhizobial differentiation fate, which is a host-dependent feature.

Organization of microtubules in developing pea root nodule cells

2001 ◽  
Vol 79 (7) ◽  
pp. 777-786
Author(s):  
A L Davidson ◽  
W Newcomb
Keyword(s):  
Rhizobium Leguminosarum ◽  
Root Nodule ◽  
Root Nodules ◽  
Cell Cortex ◽  
Cortical Microtubules ◽  
Microtubule Organization ◽  
Pea Root ◽  
Fluorescence And Electron Microscopy ◽  
Infected Cells ◽  
Cytoplasmic Microtubules

Pisum sativum L. (pea) root nodule cells undergo many cellular changes in response to infection by Rhizobium leguminosarum bv. viciae. These include cell growth, organelle reorganization, and changes relating to the increase in the number of bacteria within the cell. The objective of this study was to characterize microtubule organization during nodule cell development. The organization of microtubules was examined in developing pea root nodules using fluorescence and electron microscopy techniques. Immunolabelling of microtubules in meristematic cells showed diffuse fluorescence in the cell cortex and adjacent to the nuclear envelope. Recently infected cells contained randomly oriented cortical microtubules and cytoplasmic microtubules that were fragmented with diffuse fluorescence. Infected cells contained an extensive network of long, randomly arranged cortical microtubules with some parallel bundles. Cytoplasmic microtubules in single optical sections of infected cells appeared as short undulating filaments; however, overlapping images from a Z-series of an infected cell showed that the microtubules are long and wavy, and generally radiate inward from the cell cortex.Key words: nodule, microtubules, Rhizobium, pea, symbiosis.

scholarly journals Role of Methylotrophy During Symbiosis Between Methylobacterium nodulans and Crotalaria podocarpa

2005 ◽  
Vol 18 (10) ◽  
pp. 1061-1068 ◽  
Author(s):  
Philippe Jourand ◽  
Adeline Renier ◽  
Sylvie Rapior ◽  
Sergio Miana de Faria ◽  
Yves Prin ◽  
...  
Keyword(s):  
Root Nodule ◽  
Wild Type Strain ◽  
Plant Biomass ◽  
Root Nodules ◽  
Methylotrophic Bacterium ◽  
Plant Nitrogen ◽  
Affected Plant ◽  
Whole Plant ◽  
Fixation Capacity

Some rare leguminous plants of the genus Crotalaria are specifically nodulated by the methylotrophic bacterium Methylobacterium nodulans. In this study, the expression and role of bacterial methylotrophy were investigated during symbiosis between M. nodulans, strain ORS 2060T, and its host legume, Crotalaria podocarpa. Using lacZ fusion to the mxaF gene, we showed that the methylotroph genes are expressed in the root nodules, suggesting methylotrophic activity during symbiosis. In addition, loss of the bacterial methylotrophic function significantly affected plant development. Indeed, inoculation of M. nodulans nonmethylotroph mutants in C. podocarpa decreased the total root nodule number per plant up to 60%, decreased the whole-plant nitrogen fixation capacity up to 42%, and reduced the total dry plant biomass up to 46% compared with the wild-type strain. In contrast, inoculation of the legume C. podocarpa with nonmethylotrophic mutants complemented with functional mxa genes restored the symbiotic wild phenotype. These results demonstrate the key role of methylotrophy during symbiosis between M. nodulans and C. podocarpa.

scholarly journals Autoregulation of Root Nodule Formation: Signals of Both Symbiotic Partners Studied in a Split-Root System of Vicia sativa subsp. nigra

2002 ◽  
Vol 15 (4) ◽  
pp. 341-349 ◽  
Author(s):  
Anton A. N. van Brussel ◽  
Teun Tak ◽  
Kees J. M. Boot ◽  
Jan W. Kijne
Keyword(s):  
Rhizobium Leguminosarum ◽  
Root Nodule ◽  
Root Nodules ◽  
Nodule Formation ◽  
Vicia Sativa ◽  
Nod Factors ◽  
Split Root ◽  
Split Root System ◽  
Root Nodule Formation ◽  
Plant Signals

Inhibition of root nodule formation on leguminous plants by already induced or existing root nodules is called autoregulation of root nodule formation (AUT). Optimal conditions for AUT were determined using a split-root technique newly developed for Vicia sativa subsp. nigra. Infection of a root A with nodulating Rhizobium leguminosarum bv. viciae bacteria systemically inhibited nodulation of a spatially separated root B inoculated 2 days later with the same bacteria. This treatment gives complete AUT (total absence of nodules on root B). Only partial AUT of root B was obtained by incubation of root A with mitogenic nodulation (Nod) factors or with a noninfective strain producing normal mitogenic Nod factors. Nonmitogenic Nod factors did not evoke AUT. We identified two systemic plant signals induced by Rhizobium bacteria. Signal 1 (at weak buffering) was correlated with sink formation in root A and induced acidification of B-root medium. This signal is induced by treatment of root A with (i) nodulating rhizobia, (ii) mitogenic Nod factors, (iii) nonmitogenic Nod factors, or (iv) the cytokinin zeatin. Signal 2 (at strong buffering) could only be evoked by treatment with nodulating rhizobia or with mitogenic Nod factors. Most probably, this signal represents the specific AUT signal. Induction of complete AUT appears to require actively dividing nodule cells in nodule primordia, nodule meristems, or both of root A.

scholarly journals Morphogenesis of root nodules in white clover. III. The effect of mutation in nod IJ genes of the microsymbiont upon the DNA level in the host tissue

2014 ◽  
Vol 67 (1) ◽  
pp. 23-29
Author(s):  
Barbara Łotocka ◽  
Władysław Golinowski
Keyword(s):  
White Clover ◽  
Rhizobium Leguminosarum ◽  
Root Nodule ◽  
Nuclear Dna ◽  
Root Nodules ◽  
Root Hairs ◽  
Infection Threads ◽  
Dna Contents ◽  
Mutant Strains ◽  
Nuclear Dna Contents

On the basis of cytophotometric measurements a slightly increased DNA level in the nuclei of curled root hairs containing infection threads was observed in white clover inoculated with wild and mutant strains of <em>Rhizobium leguminosarum</em> biovar. <em>trifolii</em>, as compared to normal root hairs of te same plants. Cells of the root nodule primordia in 72 h after the inoculation, as compared to the root primary cortex, demonstrated an increased level of the nuclear DNA. No differences were observed in the nuclear DNA contents in individual layers of the cortex of the 28 day-old nodules. Generally it was low, varying from 2c to 4c. The meristematic and bacteroidal tissues in the effective nodules were characterized by a higher DNA level, as compared to the respective zones in ineffective nodules induced with the strains ANU261 (<em>nod I<sup>*</sup></em>) and ANU262 (<em>nod J<sup>*</sup></em>). The DNA level in the effective bacteroidal tissue varied from 4c to 32c, while in the tissue containing the strain ANU26l only the 2c-8c nuclei could be found and in the tissue with the strain ANU262 - the 4c-16c nuclei.

scholarly journals Genetic description of root nodule bacteria of Lathyrus species growing in the territory of Republic Bashkortostan

2011 ◽  
Vol 9 (2) ◽  
pp. 3-8
Author(s):  
◽  
Konstantin G Ptitsyn ◽  
Albert A Muldashev ◽  
Aleksei K Baymiev
Keyword(s):  
Genetic Diversity ◽  
Plant Species ◽  
Rhizobium Leguminosarum ◽  
Root Nodule ◽  
Root Nodules ◽  
Nodule Bacteria ◽  
Root Nodule Bacteria ◽  
The Given

The genetic diversity and phylogeny of rhizobia isolated from nodules of 9 wild-growing Lathyrus L. species (Fabaceae) growing in Republic Bashkortostan were studied. It is shown that for the given plants is characteristic that the big variety of heterogeneous strains of root nodule bacteria. Nevertheless, it is revealed that the majority of them in phylogenetics are closely related to Rhizobium leguminosarum. However, some plant species are found out also nodule bacteria which were considered earlier unusual for Lathyrus. So, L. vernus L. Bernh. and L. sylvestris L. are found out a root nodule bacteria close to R. tropici, L. palustris L. — Agrobacterium sp., and L. gmelinii Fritsch all isolated with us bacteria from root nodules by the sequence of genes of 16S рРНК have appeared are closely related to Phyllobacterium myrsinacearum. 

scholarly journals Aboveground plant-to-plant communication reduces root nodule symbiosis and soil nutrient concentrations

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yuta Takahashi ◽  
Kaori Shiojiri ◽  
Akira Yamawo
Keyword(s):  
Root Nodule ◽  
Total Phenolics ◽  
Root Nodules ◽  
Soil Nutrient ◽  
Chemical Defenses ◽  
Nutrient Concentrations ◽  
Soil C ◽  
Plant Communication ◽  
Root Nodule Symbiosis ◽  
Nodule Symbiosis

AbstractAboveground communication between plants is well known to change defense traits in leaves, but its effects on belowground plant traits and soil characteristics have not been elucidated. We hypothesized that aboveground plant-to-plant communication reduces root nodule symbiosis via induction of bactericidal chemical defense substances and changes the soil nutrient environment. Soybean plants were exposed to the volatile organic compounds (VOCs) from damaged shoots of Solidago canadensis var. scabra, and leaf defense traits (total phenolics, saponins), root saponins, and root nodule symbiosis traits (number and biomass of root nodules) were measured. Soil C/N ratios and mineral concentrations were also measured to estimate the effects of resource uptake by the plants. We found that total phenolics were not affected. However, plants that received VOCs had higher saponin concentrations in both leaves and roots, and fewer root nodules than untreated plants. Although the concentrations of soil minerals did not differ between treatments, soil C/N ratio was significantly higher in the soil of communicated plants. Thus, the aboveground plant-to-plant communication led to reductions in root nodule symbiosis and soil nutrient concentrations. Our results suggest that there are broader effects of induced chemical defenses in aboveground plant organs upon belowground microbial interactions and soil nutrients, and emphasize that plant response based on plant-to-plant communications are a bridge between above- and below-ground ecosystems.

scholarly journals Coalescence of rhizobial communities in soil interacts with fertilization and determines the assembly of rhizobia in root nodules

2020 ◽  
Author(s):  
Josep Ramoneda ◽  
Johannes Le Roux ◽  
Stefanie Stadelmann ◽  
Emmanuel Frossard ◽  
Beat Frey ◽  
...  
Keyword(s):  
Microbial Community ◽  
Soil Microbial Community ◽  
Root Nodule ◽  
Root Nodules ◽  
Arable Land ◽  
Soil Microbial ◽  
Soil Mixing ◽  
Environmental Setting ◽  
Widespread Phenomenon ◽  
The Individual

AbstractSoil microbial community coalescence, whereby entire microbial communities mix and compete in a new environmental setting, is a widespread phenomenon whose applicability for targeted root microbiome assembly has not been studied. Using a legume shrub adapted to nutrient poor soil, we tested for the first time how the assembly of communities of rhizobial root nodule symbionts is affected by the interaction of coalescence and fertilization. Seedlings of the rooibos [Aspalathus linearis (Burm.f.) Dahlg.], were raised in pairwise mixtures of soil from cultivated and uncultivated land of five farms, as well as the individual mixture components. A fragment of the symbiosis maker gene, nodA, was sequenced to characterize the taxonomic turnover of the rhizobia associated with all root nodules at the age of eight month. Soil mixing promoted taxonomic turnover in the rhizobial communities, while fertilization amplified such turnover by increasing the number of rhizobia that became more abundant after soil mixing. Soil mixing and fertilization had a synergistic effect on the abundance of a particular taxon, which was rare in the component soils but became highly abundant in fertilized plants raised in soil mixtures. These findings provide the first evidence that fertilizer addition can interact with soil microbial community coalescence, probably through increasing the chances for rare strains to prioritize root nodule colonization. The combination of soil mixing and fertilizer addition may be a still unexplored measure to (re)introduce root microbial mutualists in arable land.

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