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 FrankiaDiversity in Host Plant Root Nodules Is Independent of Abundance or Relative Diversity ofFrankiaPopulations in Corresponding Rhizosphere Soils

2017 ◽  
Vol 84 (5) ◽  
Author(s):  
Seifeddine Ben Tekaya ◽  
Trina Guerra ◽  
David Rodriguez ◽  
Jeffrey O. Dawson ◽  
Dittmar Hahn
Keyword(s):  
Host Plant ◽  
Root Nodule ◽  
Root Nodules ◽  
Actinorhizal Plants ◽  
Nodule Formation ◽  
Nitrogen Fixing ◽  
Content Type ◽  
Rhizosphere Soils ◽  
Root Nodule Formation ◽  
Host Infection

ABSTRACTActinorhizal plants form nitrogen-fixing root nodules in symbiosis with soil-dwelling actinobacteria within the genusFrankia, and specificFrankiataxonomic clusters nodulate plants in corresponding host infection groups. In same-soil microcosms, we observed that some host species were nodulated (Alnus glutinosa,Alnus cordata,Shepherdia argentea,Casuarina equisetifolia) while others were not (Alnus viridis,Hippophaë rhamnoides). Nodule populations were represented by eight different sequences ofnifHgene fragments. Two of these sequences characterized frankiae inS. argenteanodules, and three others characterized frankiae inA. glutinosanodules. Frankiae inA. cordatanodules were represented by five sequences, one of which was also found in nodules fromA. glutinosaandC. equisetifolia, while another was detected in nodules fromA. glutinosa. Quantitative PCR assays showed that vegetation generally increased the abundance of frankiae in soil, independently of the target gene (i.e.,nifHor the 23S rRNA gene). Targeted Illumina sequencing ofFrankia-specificnifHgene fragments detected 24 unique sequences from rhizosphere soils, 4 of which were also found in nodules, while the remaining 4 sequences in nodules were not found in soils. Seven of the 24 sequences from soils represented >90% of the reads obtained in most samples; the 2 most abundant sequences from soils were not found in root nodules, and only 2 of the sequences from soils were detected in nodules. These results demonstrate large differences between detectableFrankiapopulations in soil and those in root nodules, suggesting that root nodule formation is not a function of the abundance or relative diversity of specificFrankiapopulations in soils.IMPORTANCEThe nitrogen-fixing actinobacteriumFrankiaforms root nodules on actinorhizal plants, with members of specificFrankiataxonomic clusters nodulating plants in corresponding host infection groups. We assessedFrankiadiversity in root nodules of different host plant species, and we related specific populations to the abundance and relative distribution of indigenous frankiae in rhizosphere soils. Large differences were observed between detectableFrankiapopulations in soil and those in root nodules, suggesting that root nodule formation is not a function of the abundance or relative diversity of specificFrankiapopulations in soils but rather results from plants potentially selecting frankiae from the soil for root nodule formation. These data also highlight the necessity of using a combination of different assessment tools so as to adequately address methodological constraints that could produce contradictory data sets.

scholarly journals Lipochitin Oligosaccharides from Rhizobium leguminosarum bv. viciae Reduce Auxin Transport Capacity in Vicia sativa subsp. nigra Roots

1999 ◽  
Vol 12 (10) ◽  
pp. 839-844 ◽  
Author(s):  
Kees J. M. Boot ◽  
Anton A. N. van Brussel ◽  
Teun Tak ◽  
Herman P. Spaink ◽  
Jan W. Kijne
Keyword(s):  
Rhizobium Leguminosarum ◽  
Root Nodule ◽  
Auxin Transport ◽  
Cortical Cell ◽  
Specific Effect ◽  
Polar Auxin Transport ◽  
Vicia Sativa ◽  
Transport Capacity ◽  
Transport Inhibition ◽  
Split Root System

Induction of the formation of root nodule primordia in legume roots by symbiotic rhizobia is probably preceded by a change in plant hormone physiology. We used a Vicia sativa (vetch) split root system to study the effect of inoculation with rhizobia or purified Nod factors (lipochitin oligosaccharides, LCOs) on polar auxin transport in roots. Addition of R. leguminosarum bv. viciae, the infective symbiote of vetch, to roots of its host plant reduced polar auxin transport capacity of these roots within 24 h, in contrast to addition of non-nodulating, Sym plasmid-cured rhizobia. Addition of purified vetch-specific LCOs (NodRlv-IV/V[18:4,Ac]) caused a transient reduction in as little as 4 h after application, while after 16 h a second, stronger, and prolonged inhibition was observed that lasted at least 48 h. This reduction of auxin transport capacity was in the same order of magnitude as inhibition by N-(1-naphthyl)phthalamic acid (NPA). Purified LCOs (NodRm-IV[16:2,Ac,S]) from Sinorhizobium meliloti, the symbiote of alfalfa, and chitopentaose were inactive, which indicates a specific effect of LCOs produced by R. leguminosarum bv. viciae. Auxin transport inhibition was restricted to the apical nodulation-susceptible part of the roots, whereas the upper parts of the roots showed no difference in auxin transport after treatment. The effect could be observed with as low as 10-9 M NodRlv-IV/V[18:4,Ac] LCOs. Reduction of auxin transport by LCOs could not be inhibited by nitrate. Since inhibition of auxin transport capacity preceded the first root cortical cell divisions that result in root primordium formation, our results suggest a direct relationship between LCOs, polar auxin transport, and root nodule initiation, consistent with the hypothesis of U. Mathesius, H. R. M. Schlaman, H. P. Spaink, C. Sautter, B. G. Rolfe, and M. A. Djordjevic (Plant J. 14:23–34, 1998). However, nonmitogenic NodRlv-IV/V[18:1,Ac] showed a similar effect, which suggests that mitogenicity results from additional effects, in concert with auxin transport inhibition.

EFFECT OF MOLYBDENUM APPLICATIONS ON LEGUMINOUS HAY CROPS IN PRINCE EDWARD ISLAND

1957 ◽  
Vol 37 (3) ◽  
pp. 193-195 ◽  
Author(s):  
D. B. Robinson ◽  
K. E. LeLacheur ◽  
G. A. Brossard
Keyword(s):  
Soil Type ◽  
Prince Edward Island ◽  
Root Nodule ◽  
Root Nodules ◽  
Red Clover ◽  
Soil Types ◽  
Nodule Formation ◽  
Root Nodule Formation ◽  
Clover Root ◽  
Better Than

Seed treatments of molybdenum were found to increase yields of early red clover on three soil types in Prince Edward Island. Plots receiving 8 or more ounces of molybdenum per acre were significantly better than the control plots. Applications of 1000 lb. and 2000 lb. of ground limestone per acre had no effect on the yields of molybdenum-treated clover but the uptake of molybdenum by plants was highest where the 2000 lb.-per-acre rate was applied. The influence of added molybdenum on clover root nodule formation was determined on one soil type. Eight ounces of molybdenum per acre gave a significant increase in the weight of root nodules on the treated plants.

scholarly journals Heterologous Expression of Rhizobial CelC2 Cellulase Impairs Symbiotic Signaling and Nodulation in Medicago truncatula

2018 ◽  
Vol 31 (5) ◽  
pp. 568-575 ◽  
Author(s):  
Marta Robledo ◽  
Esther Menéndez ◽  
Jose Ignacio Jiménez-Zurdo ◽  
Raúl Rivas ◽  
Encarna Velázquez ◽  
...  
Keyword(s):  
Medicago Truncatula ◽  
Cell Walls ◽  
Rhizobium Leguminosarum ◽  
Root Nodules ◽  
Root Hairs ◽  
Nod Factors ◽  
Model Legume ◽  
Ensifer Meliloti ◽  
Early Nodulin ◽  
The Impact

The infection of legume plants by rhizobia is tightly regulated to ensure accurate bacterial penetration, infection, and development of functionally efficient nitrogen-fixing root nodules. Rhizobial Nod factors (NF) have key roles in the elicitation of nodulation signaling. Infection of white clover roots also involves the tightly regulated specific breakdown of the noncrystalline apex of cell walls in growing root hairs, which is mediated by Rhizobium leguminosarum bv. trifolii cellulase CelC2. Here, we have analyzed the impact of this endoglucanase on symbiotic signaling in the model legume Medicago truncatula. Ensifer meliloti constitutively expressing celC gene exhibited delayed nodulation and elicited aberrant ineffective nodules, hampering plant growth in the absence of nitrogen. Cotreatment of roots with NF and CelC2 altered Ca2+ spiking in root hairs and induction of the early nodulin gene ENOD11. Our data suggest that CelC2 alters early signaling between partners in the rhizobia-legume interaction.

Root Nodule Formation on the Garden Bean, Studied by a Technique of Tissue Culture

1933 ◽  
Vol 95 (2) ◽  
pp. 316-329 ◽  
Author(s):  
Keith H. Lewis ◽  
Elizabeth McCoy
Keyword(s):  
Tissue Culture ◽  
Root Nodule ◽  
Nodule Formation ◽  
Root Nodule Formation
Sign in / Sign up

Export Citation Format

Share Document