THE INDOLEACETIC ACID CONTENT OF ROOT NODULES AND ROOTS OF CYCAS CIRCINALIS L. WITH REGARD TO OTHER ROOT-NODULE SYSTEMS

1968 ◽  
Vol 17 (6) ◽  
pp. 496-498 ◽  
Author(s):  
J. Dullaart
Keyword(s):  
Acid Content ◽  
Root Nodule ◽  
Indoleacetic Acid ◽  
Root Nodules ◽  
Cycas Circinalis

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.

scholarly journals A New Species of Devosia That Forms a Unique Nitrogen-Fixing Root-Nodule Symbiosis with the Aquatic Legume Neptunia natans (L.f.) Druce

2002 ◽  
Vol 68 (11) ◽  
pp. 5217-5222 ◽  
Author(s):  
Raul Rivas ◽  
Encarna Velázquez ◽  
Anne Willems ◽  
Nieves Vizcaíno ◽  
Nanjappa S. Subba-Rao ◽  
...  
Keyword(s):  
Root Nodule ◽  
Root Nodules ◽  
Infection Process ◽  
Nitrogen Fixing ◽  
Rhizobium Tropici ◽  
Rdna Sequences ◽  
Root Nodule Symbiosis ◽  
16S Rdna Sequences ◽  
The Common ◽  
Nodule Symbiosis

ABSTRACT Rhizobia are the common bacterial symbionts that form nitrogen-fixing root nodules in legumes. However, recently other bacteria have been shown to nodulate and fix nitrogen symbiotically with these plants. Neptunia natans is an aquatic legume indigenous to tropical and subtropical regions and in African soils is nodulated by Allorhizobium undicola. This legume develops an unusual root-nodule symbiosis on floating stems in aquatic environments through a unique infection process. Here, we analyzed the low-molecular-weight RNA and 16S ribosomal DNA (rDNA) sequence of the same fast-growing isolates from India that were previously used to define the developmental morphology of the unique infection process in this symbiosis with N. natans and found that they are phylogenetically located in the genus Devosia, not Allorhizobium or Rhizobium. The 16S rDNA sequences of these two Neptunia-nodulating Devosia strains differ from the only species currently described in that genus, Devosia riboflavina. From the same isolated colonies, we also located their nodD and nifH genes involved in nodulation and nitrogen fixation on a plasmid of approximately 170 kb. Sequence analysis showed that their nodD and nifH genes are most closely related to nodD and nifH of Rhizobium tropici, suggesting that this newly described Neptunia-nodulating Devosia species may have acquired these symbiotic genes by horizontal transfer.

Natural Diversity of Frankia Strains in Actinorhizal Root Nodules from Promiscuous Hosts in the Family Myricaceae

1999 ◽  
Vol 65 (10) ◽  
pp. 4521-4527 ◽  
Author(s):  
Michael L. Clawson ◽  
David R. Benson
Keyword(s):  
Molecular Diversity ◽  
Root Nodule ◽  
Root Nodules ◽  
Reservoir Host ◽  
Rrna Gene ◽  
16S Rrna Gene Sequences ◽  
Myrica Gale ◽  
The Family ◽  
The Common ◽  
Selection Of

ABSTRACT Actinorhizal plants invade nitrogen-poor soils because of their ability to form root nodule symbioses with N2-fixing actinomycetes known as Frankia. Frankia strains are difficult to isolate, so the diversity of strains inhabiting nodules in nature is not known. To address this problem, we have used the variability in bacterial 16S rRNA gene sequences amplified from root nodules as a means to estimate molecular diversity. Nodules were collected from 96 sites primarily in northeastern North America; each site contained one of three species of the family Myricaceae. Plants in this family are considered to be promiscuous hosts because several species are effectively nodulated by most isolated strains ofFrankia in the greenhouse. We found that strain evenness varies greatly between the plant species so that estimating total strain richness of Frankia within myricaceous nodules with the sample size used was problematical. Nevertheless, Myrica pensylvanica, the common bayberry, was found to have sufficient diversity to serve as a reservoir host for Frankia strains that infect plants from other actinorhizal families. Myrica gale, sweet gale, yielded a few dominant sequences, indicating either symbiont specialization or niche selection of particular ecotypes. Strains in Comptonia peregrina nodules had an intermediate level of diversity and were all from a single major group of Frankia.

scholarly journals Expression Analysis of PIN Genes in Root Tips and Nodules of Lotus japonicus

2019 ◽  
Vol 20 (2) ◽  
pp. 235 ◽  
Author(s):  
Izabela Sańko-Sawczenko ◽  
Dominika Dmitruk ◽  
Barbara Łotocka ◽  
Elżbieta Różańska ◽  
Weronika Czarnocka
Keyword(s):  
Root Nodule ◽  
Root Nodules ◽  
Quantitative Polymerase Chain Reaction ◽  
Lotus Japonicus ◽  
Nodule Development ◽  
Vascular Bundles ◽  
Root Tips ◽  
Gus Reporter ◽  
Gene Assay ◽  
Development And Differentiation

Auxins are postulated to be one of the pivotal factors in nodulation. However, their transporters in Lotus japonicus, the model species for the study of the development of determinate-type root nodules, have been scarcely described so far, and thus their role in nodulation has remained unknown. Our research is the first focusing on polar auxin transporters in L. japonicus. We analyzed and compared expression of PINs in 20 days post rhizobial inoculation (dpi) and 54 dpi root nodules of L. japonicus by real-time quantitative polymerase chain reaction (qPCR) along with the histochemical β-glucuronidase (GUS) reporter gene assay in transgenic hairy roots. The results indicate that LjPINs are essential during root nodule development since they are predominantly expressed in the primordia and young, developing nodules. However, along with differentiation, expression levels of several PINs decreased and occurred particularly in the nodule vascular bundles, especially in connection with the root’s stele. Moreover, our study demonstrated the importance of both polar auxin transport and auxin intracellular homeostasis during L. japonicus root nodule development and differentiation.

A shared gene drives lateral root development and root nodule symbiosis pathways in Lotus

Science ◽  
2019 ◽  
Vol 366 (6468) ◽  
pp. 1021-1023 ◽  
Author(s):  
Takashi Soyano ◽  
Yoshikazu Shimoda ◽  
Masayoshi Kawaguchi ◽  
Makoto Hayashi
Keyword(s):  
Root Development ◽  
Lateral Root ◽  
Root Nodule ◽  
Root Nodules ◽  
Lotus Japonicus ◽  
Cortical Cell ◽  
Cortical Cells ◽  
Lateral Root Development ◽  
Lateral Organ ◽  
Nodule Symbiosis

Legumes develop root nodules in symbiosis with nitrogen-fixing rhizobial bacteria. Rhizobia evoke cell division of differentiated cortical cells into root nodule primordia for accommodating bacterial symbionts. In this study, we show that NODULE INCEPTION (NIN), a transcription factor in Lotus japonicus that is essential for initiating cortical cell divisions during nodulation, regulates the gene ASYMMETRIC LEAVES 2-LIKE18/LATERAL ORGAN BOUNDARIES DOMAIN16a (ASL18/LBD16a). Orthologs of ASL18/LBD16a in nonlegume plants are required for lateral root development. Coexpression of ASL18a and the CCAAT box–binding protein Nuclear Factor-Y (NF-Y) subunits, which are also directly targeted by NIN, partially suppressed the nodulation-defective phenotype of L. japonicusdaphne mutants, in which cortical expression of NIN was attenuated. Our results demonstrate that ASL18a and NF-Y together regulate nodule organogenesis. Thus, a lateral root developmental pathway is incorporated downstream of NIN to drive nodule symbiosis.

scholarly journals The Biology of Frankia sp. Strains in the Post-Genome Era

2011 ◽  
Vol 24 (11) ◽  
pp. 1310-1316 ◽  
Author(s):  
David R. Benson ◽  
James M. Brooks ◽  
Ying Huang ◽  
Derek M. Bickhart ◽  
Juliana E. Mastronunzio
Keyword(s):  
Root Nodule ◽  
Root Nodules ◽  
Ammonium Assimilation ◽  
Defense Responses ◽  
Nodule Formation ◽  
Plant Defense Responses ◽  
Plant Host ◽  
Future Studies ◽  
Microbiological Techniques ◽  
Bacterial Genes

Progress in understanding symbiotic determinants involved in the N2-fixing actinorhizal plant symbioses has been slow but steady. Problems persist with studying the bacterial contributions to the symbiosis using traditional microbiological techniques. However, recent years have seen the emergence of several genomes from Frankia sp. strains and the development of techniques for manipulating plant gene expression. Approaches to understanding the bacterial side of the symbiosis have employed a range of techniques that reveal the proteomes and transcriptomes from both cultured and symbiotic frankiae. The picture beginning to emerge provides some perspective on the heterogeneity of frankial populations in both conditions. In general, frankial populations in root nodules seem to maintain a rather robust metabolism that includes nitrogen fixation and substantial biosynthesis and energy-generating pathways, along with a modified ammonium assimilation program. To date, particular bacterial genes have not been implicated in root nodule formation but some hypotheses are emerging with regard to how the plant and microorganism manage to coexist. In particular, frankiae seem to present a nonpathogenic presence to the plant that may have the effect of minimizing some plant defense responses. Future studies using high-throughput approaches will likely clarify the range of bacterial responses to symbiosis that will need to be understood in light of the more rapidly advancing work on the plant host.

Studies on possible routes of ammonium assimilation in soybean root nodule bacteroids

1973 ◽  
Vol 19 (12) ◽  
pp. 1493-1499 ◽  
Author(s):  
Stanley D. Dunn ◽  
Robert V. Klucas
Keyword(s):  
Glutamine Synthetase ◽  
Nitrogen Assimilation ◽  
Reductive Amination ◽  
Root Nodule ◽  
Root Nodules ◽  
Ammonium Assimilation ◽  
Kinetic Properties ◽  
Transferase Activity ◽  
Soybean Root

Glutamine amide–2-oxoglutarate aminotransferase NAD+ oxidoreductase (GOGAT), glutamine synthetase (GS), glutamate dehydrogenase (GD), and alanine dehydrogenase (AD) were studied in soybean root nodules. GS, GOGAT, and AD were present in bacteroids at levels that could account for ammonium assimilation, but GD activity was quite low. The total activities of GS and GD were higher in the cytosol than in the bacteroids by factors of 20 and 7, respectively, whereas GOGAT was not detected in the cytosol. GS (transferase activity) was inhibited by alanine, CTP, glycine, and tryptophan at 5 mM but was relatively unaffected by asparagine, aspartic acid, CMP, glucosamine, and histidine at 5 mM. GOGAT activity was unaffected by ATP, ADP, 8-hydroxyquinoline, and 1,10-phenanthroline but was inhibited by EDTA, citrate, and parachloromercuribenzoate. GOGAT activity (reductive amination) was also inhibited 97% by preincubation with 10−4 M azaserine for 30 min but GD activity was inhibited only 13%. The apparent Km values for NH4+ by AD was 7.4 × 10−3 M and by GD was 7.3 × 10−2 M while for glutamine by GOGAT it was 9.3 × 10−5 M. Activities and kinetic properties for these enzymes may suggest potential routes of nitrogen assimilation in vivo.

Influence of Crop Establishment Practices and Microbial Inoculants on Nodulation of Summer Green Gram (Vigna radiata) and Soil Quality Parameters

2020 ◽  
Author(s):  
Y. V. Singh ◽  
Ruxanabi Naragund ◽  
Pranita Jaiswal ◽  
R. S. Bana ◽  
A. K. Choudhary
Keyword(s):  
Soil Quality ◽  
Vigna Radiata ◽  
Root Nodule ◽  
Root Nodules ◽  
Am Fungi ◽  
Quality Parameters ◽  
Green Gram ◽  
Zero Tillage ◽  
Microbial Inoculation ◽  
Crop Establishment

A field experiment was carried out during summer season in 2018 at New Delhi to study the effect of crop establishment practices and microbial inoculation on nodulation of summer green gram [Vigna radiata (L.) Wilczek] and soil quality parameters. The experiment was laid out in split plot design and treatments were replicated thrice. The experiment included nine treatment combinations including three crop establishment practices viz., conventional tillage, zero tillage and zero tillage with chick pea residue @ 2.5 t/ha in main plots and three microbial inoculation treatment viz., control (no inoculation), dual inoculation of Rhizobium + PSB and combined inoculation of Rhizobium+ Phosphate Solubilizing Bacteria (PSB) + Arbuscular Mycorrhizal (AM) Fungi in sub-plots. Results showed that zero tillage with residue produced significantly higher no. of root nodules/plant and root nodule weight/ plant at 25, 35 and 45 DAS. The same treatment showed significantly superior soil chemical parameters viz., available N, P and K and soil microbial parameters like dehydrogenase activity, alkaline phosphatase activity and microbial biomass carbon (MBC) over other two treatments. Seed inoculation with Rhizobium+ PSB + AM Fungi was significantly superior to other two treatments with regard to no. of root nodules/ plant and root nodule weight/ plant at 25, 35 and 45 DAS, soil chemical and microbial parameters.

scholarly journals Inhibition of Glutamine Synthetase by Phosphinothricin Leads to Transcriptome Reprograming in Root Nodules of Medicago truncatula

2012 ◽  
Vol 25 (7) ◽  
pp. 976-992 ◽  
Author(s):  
Ana R. Seabra ◽  
Patrícia A. Pereira ◽  
Jörg D. Becker ◽  
Helena G. Carvalho
Keyword(s):  
Glutamine Synthetase ◽  
Medicago Truncatula ◽  
Root Nodule ◽  
Higher Plants ◽  
Cell Metabolism ◽  
Root Nodules ◽  
Organic N ◽  
N Availability ◽  
Time Points ◽  
N Assimilation

Glutamine synthetase (GS) is a vital enzyme for the assimilation of ammonia into amino acids in higher plants. In legumes, GS plays a crucial role in the assimilation of the ammonium released by nitrogen-fixing bacteria in root nodules, constituting an important metabolic knob controlling the nitrogen (N) assimilatory pathways. To identify new regulators of nodule metabolism, we profiled the transcriptome of Medicago truncatula nodules impaired in N assimilation by specifically inhibiting GS activity using phosphinothricin (PPT). Global transcript expression of nodules collected before and after PPT addition (4, 8, and 24 h) was assessed using Affymetrix M. truncatula GeneChip arrays. Hundreds of genes were regulated at the three time points, illustrating the dramatic alterations in cell metabolism that are imposed on the nodules upon GS inhibition. The data indicate that GS inhibition triggers a fast plant defense response, induces premature nodule senescence, and promotes loss of root nodule identity. Consecutive metabolic changes were identified at the three time points analyzed. The results point to a fast repression of asparagine synthesis and of the glycolytic pathway and to the synthesis of glutamate via reactions alternative to the GS/GOGAT cycle. Several genes potentially involved in the molecular surveillance for internal organic N availability are identified and a number of transporters potentially important for nodule functioning are pinpointed. The data provided by this study contributes to the mapping of regulatory and metabolic networks involved in root nodule functioning and highlight candidate modulators for functional analysis.

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