Effective and ineffective root nodules in Myrica faya

1976 ◽  
Vol 194 (1116) ◽  
pp. 285-293 ◽  
Keyword(s):  
Root Nodules ◽  
Light And Electron Microscopy ◽  
Nodule Formation ◽  
Culture Solution ◽  
Myrica Gale ◽  
Main Site ◽  
Myrica Faya ◽  
Modern Methods ◽  
Infected Cells ◽  
Nodule Endophytes

In cross-inoculation trials, inocula containing the nodule endophytes of Myrica gale, M. cerifera, M. cordifolia and M. pilulifera respectively were applied to the roots of young plants of M. faya Ait. growing in nitrogen-free culture solution. All four inocula induced nodule formation, and except where the M. gale inoculum had been used the nodules were of effective type and enabled the plants bearing them to grow nearly as well as other M. faya plants associated with the normal endophyte. The nodules induced by the M. gale endophyte were very numerous, but remained small and fixed no significant amount of nitrogen, and were thus ineffective. Light and electron microscopy showed that in the effective nodules induced by the normal endophyte or by that of M. cordifolia , the endophyte was confined to a layer 1-2 cells deep near the middle of the nodule cortex, and that in respect of the width of the hyphae and their production of club-shaped internally subdivided vesicles, the endophytes resembled closely those in the nodules of the few other species of Myrica that have been studied by modern methods of microscopy. In ineffective nodules the disposition of the infected cells was unchanged, but within the cells only a sparse development of the endophyte was observed, and no vesicles were found. The finding that nodules lacking vesicles showed little or no fixation is consistent with other evidence that the vesicles normally produced by non-legume nodule endophytes are the main site of nitrogen fixation.

Host–endophyte interactions in effective and ineffective nodules induced by the endophyte of Myrica gale

1983 ◽  
Vol 61 (11) ◽  
pp. 2898-2909 ◽  
Author(s):  
Kathryn A. VandenBosch ◽  
John G. Torrey
Keyword(s):  
Nitrogenase Activity ◽  
Root Nodules ◽  
Seedling Development ◽  
Nodule Development ◽  
Nodule Formation ◽  
Cortical Tissue ◽  
Intercellular Spaces ◽  
Cortical Cells ◽  
Myrica Gale ◽  
Infected Cells

Suspensions of crushed root nodules of Myrica gale containing the actinomycete Frankia induced nodule formation on roots of seedlings of M. gale and Comptonia peregrina grown in nutrient water culture. Nodules formed on M. gale were normal in structure and exhibited nitrogenase activity (measured as acetylene reduction) and provided the necessary nitrogen for seedling development. These effective nodules showed typical external and internal structure with the endophyte developing both vesicles and sporangia within cortical cells of the host tissue. Small nodules formed on C. peregrina representing the primary nodule stage. They lacked nitrogenase activity and were termed ineffective. Vesicles failed to develop within these ineffective nodules. However, sporangia were formed in infected cells and within intercellular spaces of the nodule cortical tissue. In addition, prominent amyloplasts occurred in infected cells of the ineffective nodules, a feature lacking in effective nodules. Exogenously supplied combined nitrogen increased seedling growth but did not improve nodule development or endophyte morphogenesis in the ineffective nodules.

Determinate development of nodule roots in actinomycete-induced root nodules of Myrica gale

1978 ◽  
Vol 56 (11) ◽  
pp. 1357-1364 ◽  
Author(s):  
John G. Torrey ◽  
Dale Callaham
Keyword(s):  
Root Development ◽  
Root Nodules ◽  
Cortical Cell ◽  
Gas Diffusion ◽  
Nodule Development ◽  
Nodule Formation ◽  
Low Oxygen ◽  
Cortical Cells ◽  
Continuous Growth ◽  
Myrica Gale

Young seedlings of Myrica gale L. grown in water culture were inoculated with a nodule suspension containing the effective actinomycete which induced root nodule formation. Nodule development was followed from initiation to nodule lobe formation and nodule root development using living materials and fixed nodules sectioned for light microscopy. After root hair infection and prenodule formation, three stages were observed: nodule lobe formation, a transition or arrested state, and nodule root development. The primary nodule lobe meristem originates endogenously and its formation involves pericycle, endodermis, and cortical cell derivatives. The lobe develops slowly to about 2 mm in length while the cortical cells are invaded by the actinomycete endophyte. After a period of arrest of variable duration, from a few days to several weeks, the nodule lobe meristem begins altered development, forming the elongate nodule root which undergoes slow but continuous growth to about 3- to 4-cm final length. New nodule lobe primordia are initiated endogenously at the base of existing nodules lobes, ultimately forming a cluster of nodule roots. Each nodule root, which elongates at about 0.1–1.0 mm per day, has a terminal apical meristem with reduced root cap formation and produces a modified root structure possessing an elaborate cortical intercellular space system and a reduced central cylinder. Nodule root growth is distinctive in that it shows strong negative geotropism. The endophyte is restricted to cortical cells of the nodule lobe and is totally absent from tissues of the nodule root. A probable role for nodule roots is to facilitate gas diffusion to the nitrogen-fixing endophyte site in the nodule lobe when nodules occur under conditions of low oxygen tension.

A morphometric study of effective nodules induced by Rhizobium loti and Bradyrhizobium sp. (Lotus) on Lotus pedunculatus

1985 ◽  
Vol 63 (1) ◽  
pp. 43-53 ◽  
Author(s):  
Susan M. Wood ◽  
David B. Layzell ◽  
William Newcomb ◽  
Clive E. Pankhurst
Keyword(s):  
Nitrogen Fixation ◽  
Root Nodules ◽  
Light And Electron Microscopy ◽  
Morphometric Study ◽  
Polar Bodies ◽  
Rhizobium Loti ◽  
Bradyrhizobium Sp ◽  
Infected Cells ◽  
Peribacteroid Space ◽  
Lotus Pedunculatus

Effective root nodules formed on Lotus pedunculatus by Rhizobium loti NZP2037 and Bradyrhizobium sp. (Lotus) CC814s were examined by light and electron microscopy. NZP2037 nodules were larger than CC814s nodules as a result of a much thicker nodule cortex. The smaller CC814s nodules had a much larger infected zone and, consequently, larger volumes of infected cells, peribacteroid space, and host cytosol per nodule. As well, CC814s nodules demonstrated a significantly higher number of bacteria which typically contained prominent polar bodies and beta-polyhydroxybutyrate (PHB) granules. The bacteria of NZP2037 nodules lacked the polar bodies, but PHB deposits were occasionally observed. A correlated physiological study in which acetylene reduction was used to estimate nitrogen fixation showed CC814s nodules to be more active than NZP2037 nodules (Pankhurst, C. E., and D. B. Layzell. 1984. Physiol. Plant. 62(3) : 404–409.). This measured difference in nitrogen-fixing activity was considered due to the degree of infection and bacterial proliferation as well as differences in the carbon and nitrogen metabolism of the two nodule types. The significance of the structural observations and morphometric analyses and their relationship to differences in nitrogen fixation are discussed.

scholarly journals Nodulation of Mimosa spp. by the β-Proteobacterium Ralstonia taiwanensis

2003 ◽  
Vol 16 (12) ◽  
pp. 1051-1061 ◽  
Author(s):  
Wen-Ming Chen ◽  
Euan K. James ◽  
Alan R. Prescott ◽  
Martin Kierans ◽  
Janet I. Sprent
Keyword(s):  
Laser Scanning ◽  
Fluorescent Protein ◽  
Nitrogenase Activity ◽  
Light And Electron Microscopy ◽  
Laser Scanning Microscopy ◽  
Host Cells ◽  
Confocal Laser ◽  
Nodule Formation ◽  
Infection Threads ◽  
Infected Cells

Several β-proteobacteria have been isolated from legume root nodules and some of these are thought to be capable of nodulating and fixing N2. However, in no case has there been detailed studies confirming that they are the active symbionts. Here, Ralstonia taiwanensis LMG19424, which was originally isolated from Mimosa pudica nodules, was transformed to carry the green fluorescent protein (gfp) reporter gene before being used to inoculate axenically-grown seedlings of M. pudica and M. diplotricha. Plants were harvested at various intervals for 56 days after inoculation, then examined for evidence of infection and nodule formation. Nodulation of both Mimosa spp. was abundant, and acetylene reduction assays confirmed that nodules had nitrogenase activity. Confocal laser scanning microscopy (CLSM) showed that fresh M. pudica nodules with nitrogenase activity had infected cells containing bacteroids expressing gfp. In parallel, fixed and embedded nodules from both Mimosa spp. were sectioned for light and electron microscopy, followed by immunogold labeling with antibodies raised against gfp and nitrogenase Fe (nifH) protein. Significant immunolabeling with these antibodies confirmed that R. taiwanensis LMG19424 is an effective N2-fixing symbiont of Mimosa spp. Both species were infected via root hairs and, in all respects, the nodule ontogeny and development was similar to that described for other mimosoid legumes. The nodules were indeterminate with a persistent meristem, an invasion zone containing host cells being invaded via prominent infection threads, and an N2-fixing zone with infected cells containing membrane-bound symbiosomes.

scholarly journals Rock-Solubilizing Microbial Inoculums Have Enormous Potential as Ecological Remediation Agents to Promote Plant Growth

Forests ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 357
Author(s):  
Zhaohui Jia ◽  
Miaojing Meng ◽  
Chong Li ◽  
Bo Zhang ◽  
Lu Zhai ◽  
...  
Keyword(s):  
Plant Growth ◽  
Leaf Area ◽  
Ecological Restoration ◽  
Root Nodules ◽  
Robinia Pseudoacacia ◽  
Growth Index ◽  
Nodule Formation ◽  
Bare Rock ◽  
Mining Sites ◽  
Robinia Pseudoacacia L

Anthropogenic overexploitation poses significant threats to the ecosystems that surround mining sites, which also have tremendous negative impacts on human health and society safety. The technological capacity of the ecological restoration of mine sites is imminent, however, it remains a challenge to sustain the green restorative effects of ecological reconstruction. As a promising and environmentally friendly method, the use of microbial technologies to improve existing ecological restoration strategies have shown to be effective. Nonetheless, research into the mechanisms and influences of rock-solubilizing microbial inoculums on plant growth is negligible and the lack of this knowledge inhibits the broader application of this technology. We compared the effects of rock-solubilizing microbial inoculums on two plant species. The results revealed that rock-solubilizing microbial inoculums significantly increased the number of nodules and the total nodule volume of Robinia pseudoacacia L. but not of Lespedeza bicolor Turcz. The reason of the opposite reactions is possibly because the growth of R. pseudoacacia was significantly correlated with nodule formation, whereas L. bicolor’s growth index was more closely related to soil characteristics and if soil nitrogen content was sufficient to support its growth. Further, we found that soil sucrase activity contributed the most to the height of R. pseudoacacia, and the total volume of root nodules contributed most to its ground diameter and leaf area. Differently, we found a high contribution of total soil carbon to seedling height and ground diameter of L. bicolor, and the soil phosphatase activity contributed the most to the L. bicolor’ s leaf area. Our work suggests that the addition of rock-solubilizing microbial inoculums can enhance the supply capacity of soil nutrients and the ability of plants to take up nutrients for the promotion of plant growth. Altogether, our study provides technical support for the practical application of rock-solubilizing microbes on bare rock in the future.

Seasonal pattern of energy use, respiration, and nitrogenase activity in root nodules of Myrica gale

1983 ◽  
Vol 61 (11) ◽  
pp. 2937-2942 ◽  
Author(s):  
Christa R. Schwintzer ◽  
John D. Tjepkema
Keyword(s):  
Energy Cost ◽  
Energy Use ◽  
Nitrogenase Activity ◽  
Root Nodules ◽  
Seasonal Pattern ◽  
Uptake Ratio ◽  
Experimental Conditions ◽  
Myrica Gale ◽  
Net Production ◽  
N Requirement

Annual CO2 evolution, H2 evolution, and C2H2 reduction were measured in root nodules from a vigorous Myrica gale stand in a Massachusetts peatland at 3-week intervals in 1980. Nodule activity was approximately the same under the experimental conditions (excised nodules reducing C2H2) as in nature (attached nodules reducing N2) and the CO2 evolution to O2 uptake ratio averaged 1.07. Nitrogenase activity was first detectable in late May, reached its maximum [Formula: see text] in mid-July, and disappeared in late October. The seasonal pattern of CO2 evolution was similar except that it continued at low rates when nitrogenase activity was absent. Hydrogen evolution was barely detectable. The energy cost of nitrogen fixation, expressed as the molar CO2:C2H4 ratio, was relatively low [Formula: see text] throughout the period of substantial nitrogenase activity and had a mean annual value of 4.9. Annual N2 fixation was estimated to be 2.8 g N m−2year−1, contributing about 33% of the annual N requirement measured in 1979. Annual C use by nodules was about 21.0 g C m−2 year−1. If this C were available for additional net production, it would increase it by about 5.5%.

Morphological and biochemical changes in peanut nodules during photosynthate stress

1992 ◽  
Vol 38 (6) ◽  
pp. 526-533 ◽  
Author(s):  
A. B. M. Siddique ◽  
A. K. Bal
Keyword(s):  
Nitrogen Fixation ◽  
Root Nodules ◽  
Ultrastructural Level ◽  
Malate Synthase ◽  
Morphological Evidence ◽  
Lipid Bodies ◽  
Biochemical Status ◽  
Short Period ◽  
Infected Cells ◽  
Ultrastructural Damage

Nitrogen fixation in legume root nodules is believed to be supported by the supply of photosynthate of the current photoperiod. However, in peanut nodules, prolonged periods of darkness or detopping do not disrupt nitrogen fixation for at least 48 h. During this period, nodule oleosomes (lipid bodies) have been shown to decrease in number within the infected cells, and it has been suggested that lipids from oleosomes are mobilized to maintain the energy and carbon requirements of the nitrogen-fixing nodules. We present morphological evidence, at the ultrastructural level, for the utilization of oleosomes during photosynthate stress. The biochemical status of the nodule has also been assessed and correlated with ultrastructure. For comparison cowpea nodules were used that totally lacked oleosomes. In peanut nodules leghemoglobin and total protein remained unchanged along with integrated ultrastructure on nodule cells for 48 h, whereas in cowpea a decline in proteins with ultrastructural damage became apparent within a very short period of photosynthate stress. In peanut nodules empty or partially empty oleosomes were taken as evidence for their utilization during the stress period. Key words: N2 fixation, photosynthate stress, lipid bodies, catalase, malate synthase, peanut nodule, β-oxidation.

Factors involved in the amelioration of retarded symbiosis in Tinaroo glycine

1974 ◽  
Vol 25 (4) ◽  
pp. 577 ◽  
Author(s):  
A Diatloff
Keyword(s):  
Nitrogen Fixation ◽  
Ammonium Nitrate ◽  
Root Nodules ◽  
Host Cells ◽  
Starch Accumulation ◽  
Nodule Formation ◽  
Carbon And Nitrogen ◽  
Slow Development ◽  
Structural Differences ◽  
Envelope Membranes

Root nodules formed on Tinaroo glycine (Glycine wightii) were slow to pigment and begin fixing nitrogen. Various carbon and nitrogen compounds enhanced nodule pigmentation, the greening of the plants, and the rate of nitrogen fixation at 42 days. Of these inositol, glucose, ammonium nitrate (as both foliar and root applications) and coconut milk were most effective. Riboflavin, sodium glutamate and nodule infusion had little effect. There were no structural differences between nodules enhanced respectively by glucose and ammonium nitrate. Nodules on control plants showed slow development of the bacteroids and envelope membranes, with copious starch accumulation in uninvaded host cells. It was concluded that the retarded symbiosis in formed nodules was due initially to tardy nodule formation depleting the nitrogen reserves in the seeds before nitrogen fixation began. Because of the interaction of photosynthesis and nitrogen fixation, self-regeneration of nitrogen fixation in chlorotic plants was slow without an external stimulus. It is suggested that by selecting lines of the legume with larger seeds or by incorporating nitrogen in seed pellets the problem might be overcome.

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 Accumulation and Distribution of Fertilizer Nitrogen and Nodule-Fixed Nitrogen in Soybeans with Dual Root Systems

Agronomy ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 397 ◽  
Author(s):  
Rui Zhang ◽  
Cong Wang ◽  
Wenzhi Teng ◽  
Jing Wang ◽  
Xiaochen Lyu ◽  
...  
Keyword(s):  
Root System ◽  
Root Nodules ◽  
Culture Conditions ◽  
Sand Culture ◽  
Nodule Formation ◽  
N Fixation ◽  
Fertilizer N ◽  
N Accumulation ◽  
Biological N Fixation ◽  
Nodule Growth

The soybean (Glycine max L. Merr.) is a crop with a high demand for nitrogen (N). The root nodules that form in soybeans can fix atmospheric N effectively, yet the goal of achieving high yields cannot be met by relying solely on nodule-fixed N. Nonetheless, the application of N fertilizer may inhibit nodule formation and biological N fixation (BNF), but the underpinning mechanisms are still unclear. In this study, we grafted the roots of non-nodulated soybeans onto nodulated soybeans to generate plants with dual root system. The experiment included three treatments conducted under sand culture conditions with NO 3 − and NH 4 + as N sources. Treatment I: The non-nodulated roots on one side received 50 mg·L−1 15 NO 3 − or 15NH4+, and the nodulated roots on the other side were not treated. Treatment II: The non-nodulated roots received 50 mg·L−1 15 NO 3 − or 15 NH 4 + , and the nodulated roots received 50 mg·L−1 14 NO 3 − or 14 NH 4 + . Treatment III: Both non-nodulated and nodulated roots received 50 mg·L−1 15 NO 3 − or 15 NH 4 + . The results showed the following: (1) Up to 81.5%–87.1% of the N absorbed by the soybean roots and fixed by the root nodules was allocated to shoot growth, leaving 12.9%–18.5% for root and nodule growth. Soybeans preferentially used fertilizer N in the presence of a NO 3 − or NH 4 + supply. After the absorbed fertilizer N and nodule-fixed N was transported to the shoots, a portion of it was redistributed to the roots and nodules. The N required for root growth was primarily derived from the NO 3 − or NH 4 + assimilated by the roots and the N fixed by the nodules, with a small portion translocated from the shoots. The N required for nodule growth was primarily contributed by nodule-fixed N with a small portion translocated from the shoots, whereas the NO 3 − or NH 4 + that was assimilated by the roots was not directly supplied to the nodules. (2) Based on observations of the shoots and one side of the roots and nodules in the dual root system as an N translocation system, we proposed a method for calculating the N translocation from soybean shoots to roots and nodules during the R1–R5 stages based on the difference in the 15N abundance. Our calculations showed that when adding N at a concentration of 50 mg·L−1, the N translocated from the shoots during the R1–R5 stages accounts for 29.6%–52.3% of the N accumulation in nodulated roots (Rootn) and 9.4%–16.6% of the N accumulation in Nodulen of soybeans. Through the study of this experiment, the absorption, distribution and redistribution characteristics of fertilizer N and root nodule N fixation in soybean can be clarified, providing a theoretical reference for analyzing the mechanisms of the interaction between fertilizer N and nodule-fixed N.

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