Changes in root morphology of wheat caused by Azospirillum inoculation

1985 ◽  
Vol 31 (10) ◽  
pp. 881-887 ◽  
Author(s):  
Yoram Kapulnik ◽  
Yaacov Okon ◽  
Yigel Henis
Keyword(s):  
Cross Sections ◽  
Azospirillum Brasilense ◽  
Root Elongation ◽  
Root Hairs ◽  
Triticum Aestivum L ◽  
Wheat Root ◽  
Root Surface ◽  
Scanning Electron Micrographs ◽  
Bacterial Cells ◽  
Colony Forming Units

Wheat seeds (Triticum aestivum L.) were inoculated with Azospirillum brasilense Cd, Sp7, the local isolate Cd-1, and with other types of bacteria. Inoculation with 105 to 106 colony-forming units of Azospirillum caused the largest root elongation and total root surface of seedlings whereas 108 to 109 colony-forming units of Azospirillum caused inhibition of root development. Similar effects were obtained in 10 different cultivars of wheat inoculated with Azospirillum. Scanning electron micrographs of inoculated wheat root segments showed denser and longer root hairs as compared with the control inoculated with dead cells. This effect was less apparent in more mature roots. In inoculated roots bacteria were located mainly on the cell elongation area and on the bases of root hairs, but fewer bacterial cells were present on the root cap or adsorbed to root hairs. Cross sections of Azospirillum-inoculated roots showed prominent alterations of the cell arrangement in the layers of the cortex. The results suggest the existence of critical numbers of sites for Azospirillum colonization on the roots, to such an extent that root growth is affected.

Factors affecting adsorption of Azospirillum brasilense Cd to root hairs as compared with root surface of wheat

1989 ◽  
Vol 35 (10) ◽  
pp. 936-944 ◽  
Author(s):  
Yoav Bashan ◽  
Hanna Levanony
Keyword(s):  
Azospirillum Brasilense ◽  
Root Hairs ◽  
Growth Conditions ◽  
Root Surface ◽  
Logarithmic Phase ◽  
Bacterial Cells ◽  
Beneficial Bacteria ◽  
Factors Affecting ◽  
Associative Bacteria ◽  
Bacterial Adsorption

Electron microscopy of wheat (Triticum aestivum) roots inoculated with Azospirillum brasilense Cd revealed massive adsorption of bacterial cells to the root surface and less adsorption to root hairs. Quantitative analysis of A. brasilense Cd adsorption to root surface and to root hairs, confirmed qualitatively by light microscopy observations, revealed a bacterial adsorption ratio of 5 (+2): 1 (root surface: root hairs). Extreme bacterial adsorption ratios were recorded when bacteria were previously grown in the presence of KNO3 (27:1) or when bacterial cells were inoculated under hydroponic plant growth conditions (80:1). Adsorption of A. brasilense Cd to roots was directly related to the bacterial growth phase, with logarithmic phase cultures demonstrating a greater adsorption than stationary phase cultures. Adsorption to root hairs was dependent mainly on the number of root hairs developed under certain growth conditions. When very few root hairs had developed, most of the bacterial cells were adsorbed to the root surface. Factors such as starvation, bacteria grown in culture in the presence of KNO3, addition of several nutrients, and protease or NaEDTA treatments of bacterial cells before the adsorption assay decreased bacterial adsorption to root hairs. Other factors such as microaerophilic growth conditions, addition of several bacterial chemoattractants, and cellulase-treated root hairs enhanced bacterial adsorption. It is proposed that although A. brasilense Cd adsorbed to every part of the root system, more cells adsorbed to the root surface of wheat than to the root hairs.Key words: associative bacteria, Azospirillum, bacterial adsorption, beneficial bacteria, rhizosphere bacteria, root-hair colonization.

Enhancement of cell division in wheat root tips and growth of root elongation zone induced by Azospirillum brasilense Cd

1989 ◽  
Vol 67 (7) ◽  
pp. 2213-2216 ◽  
Author(s):  
Hanna Levanony ◽  
Y. Bashan
Keyword(s):  
Cell Division ◽  
Azospirillum Brasilense ◽  
Wheat Root ◽  
Rhizosphere Bacteria ◽  
Elongation Zone ◽  
Root Tips ◽  
Colony Forming Units ◽  
Seminal Roots ◽  
Second Wave ◽  
Intensive Growth

Inoculation by bacterial infiltration of germinating wheat seeds with 106–108 colony-forming units of the beneficial rhizosphere bacteria, Azospirillum brasilense Cd, significantly increased cell division in root tips during germination. The phenomenon occurred mainly in the second wave, i.e., 24 h after inoculation, of cell division in the meristem. Seed inoculation significantly enlarged the elongation zone of their roots. These inoculation effects suggest that the larger root system, which is usually observed in inoculated plants, may originate in part from the enhancement of cell division and the intensive growth of the elongation zone of seminal roots. Key words: Azospirillium, beneficial bacteria, bacteria–root interaction, cell division, rhizosphere bacteria, root growth.

scholarly journals A Transcriptional Regulator of the LuxR-UhpA Family, FlcA, Controls Flocculation and Wheat Root Surface Colonization by Azospirillum brasilense Sp7

1998 ◽  
Vol 11 (3) ◽  
pp. 177-187 ◽  
Author(s):  
Lily Pereg-Gerk ◽  
Annick Paquelin ◽  
Pierre Gounon ◽  
Ivan R. Kennedy ◽  
Claudine Elmerich
Keyword(s):  
Azospirillum Brasilense ◽  
Plant Root ◽  
Regulatory Gene ◽  
Wheat Root ◽  
Root Surface ◽  
Glycerol Metabolism ◽  
Spontaneous Mutant ◽  
New Information ◽  
Azospirillum Brasilense Sp7

Genetic complementation of a spontaneous mutant, impaired in flocculation, Congo red binding, and colonization of root surface, led to the identification of a new regulatory gene in Azospirillum brasilense Sp7, designated flcA. The deduced amino acid sequence of flcA shared high similarity with a family of transcriptional activators of the LuxR-UhpA family. The most significant match was with the AgmR protein, an activator for glycerol metabolism in Pseudomonas aeruginosa. Derivatives of Sp7 resulting from site-directed Tn5 mutagenesis in the flcA coding sequence were constructed by marker exchange. Characterization of the resulting mutant strains showed that flcA controls the production of capsular polysaccharides, the flocculation process in culture, and the colonization of the root surface of wheat. This study provides new information on the genetic control of the mechanism of plant root colonization by Azospirillum.

Effectiveness of complex inoculation of spring wheat with N[2] -fi xing bacteria Azospirillum brasilense and mold-antagonist Chaetomium cochliodes

2014 ◽  
Vol 1 (3) ◽  
pp. 57-61
Author(s):  
E. Kopylov
Keyword(s):  
Spring Wheat ◽  
Root Zone ◽  
Wheat Root ◽  
Root Surface ◽  
Atmospheric Nitrogen ◽  
Rhizospheric Soil ◽  
Chain Reaction ◽  
Wheat Roots ◽  
Chlorophyll A And B ◽  
Polymerase Chain

Aim. To study the specifi cities of complex inoculation of spring wheat roots with the bacteria of Azospirillum genus and Chaetomium cochliodes Palliser 3250, and the isolation of bacteria of Azospirillum genus, capable of fi xing atmospheric nitrogen, from the rhizospheric soil, washed-off roots and histoshere. Materials and meth- ods. The phenotypic features of the selected bacteria were identifi ed according to Bergi key. The molecular the polymerase chain reaction and genetic analysis was used for the identifi cation the bacteria. Results. It has been demonstrated that during the introduction into the root system of spring wheat the strain of A. brasilensе 102 actively colonizes rhizospheric soil, root surface and is capable of penetrating into the inner plant tissues. Conclusions. The soil ascomucete of C. cochliodes 3250 promotes better settling down of Azospirillum cells in spring wheat root zone, especially in plant histosphere which induces the increase in the content of chlorophyll a and b in the leaves and yield of the crop.

scholarly journals Remodeling of root morphology by CuO and ZnO nanoparticles: effects on drought tolerance for plants colonized by a beneficial pseudomonad

Botany ◽  
2018 ◽  
Vol 96 (3) ◽  
pp. 175-186 ◽  
Author(s):  
Kwang-Yeol Yang ◽  
Stephanie Doxey ◽  
Joan E. McLean ◽  
David Britt ◽  
Andre Watson ◽  
...  
Keyword(s):  
Calcareous Soils ◽  
Root Hairs ◽  
Triticum Aestivum L ◽  
Metal Stress ◽  
Root Tip ◽  
Zno Nps ◽  
Wheat Seedlings ◽  
Cuo Nps ◽  
Expression Of Genes ◽  
Induced Tolerance

Formulations that include nanoparticles of CuO and ZnO are being considered for agricultural applications as fertilizers because they act as sources of Cu or Zn. Currently, few studies of the effects of these nanoparticles (NPs) consider the three-way interactions of NPs with the plant plus its microbiome. At doses that produced root shortening by both nanoparticles (NPs), CuO NPs induced the proliferation of elongated root hairs close to the root tip, and ZnO NPs increased lateral root formation in wheat seedlings (Triticum aestivum L.). These responses occurred with roots colonized by a beneficial bacterium, Pseudomonas chlororaphis O6 (PcO6), originally isolated from roots of wheat grown under dryland farming in calcareous soils. The PcO6-induced tolerance to drought stress in wheat seedlings was not impaired by the NPs. Rather, growth of the PcO6-colonized plants with NPs resulted in systemic increases in the expression of genes associated with tolerance to water stress. Increased expression in the shoots of other genes related to metal stress was consistent with higher levels of Cu and Zn in PcO6-colonized shoots grown with the NPs. This work demonstrates that plants grown with CuO or ZnO NPs showed cross-protection from different challenges such as metal stress and drought.

scholarly journals Enhancement of drought tolerance in Triticum aestivum L. seedlings using Azospirillum brasilense NO40 and Stenotrophomonas maltophilia B11

2021 ◽  
Vol 45 (1) ◽  
Author(s):  
Wedad A. Kasim ◽  
Mohamed E. H. Osman ◽  
Mohamed N. Omar ◽  
Samar Salama
Keyword(s):  
Triticum Aestivum ◽  
Drought Stress ◽  
Drought Tolerance ◽  
Azospirillum Brasilense ◽  
Stenotrophomonas Maltophilia ◽  
Protein Pattern ◽  
Triticum Aestivum L ◽  
Protein Patterns ◽  
Wheat Seedlings ◽  
Enhanced Production

Abstract Background The effectiveness of two PGPB; Azospirillum brasilense NO40 and Stenotrophomonas maltophilia B11 was investigated in enhancing the drought tolerance of wheat (Triticum aestivum L.) seedlings cultivar Gemiza9. The inoculated or uninoculated grains were sown in unsterilized sandy soil and watered normally untill the 8th day. Drought stress was initiated by completely withholding water for 7 days (until wilting). Samples were collected after 15 days from sowing to evaluate some growth criteria, damage and defense indicators and to analyze the roots’ protein pattern. Results The results showed that inoculating wheat seedlings with these strains significantly diminished the inhibitory effects of drought stress on the relative water content of roots, shoots and leaves; area of leaves; contents of pigments (chlorophyll a and b) and ascorbic acid; and on the protein patterns of roots. Moreover, the bacterial inoculation notably reduced the drought-induced damage indicated by lower leakage of electrolytes and less accumulation of Malondialdehyde and hydrogen peroxide, surprisingly with less enhanced production of proline and activities of catalase and peroxidase than their uninoculated counterparts. Under normal conditions, inoculating wheat plants with these PGPB resulted in significantly promoted growth and elevated contents of pigments and altered protein patterns of roots. Conclusion Overall, we can say that both Azospirillum brasilense NO40 and Stenotrophomonas maltophilia B11 were able to deactivate the growth inhibition in wheat seedlings to some extent, while maintaining a certain level of efficient protection against damage under drought stress.

Cytological and histochemical characteristics of the axenic root surface of Alnus glutinosa

1986 ◽  
Vol 64 (10) ◽  
pp. 2216-2226 ◽  
Author(s):  
Yves Prin ◽  
Mireille Rougier
Keyword(s):  
Cell Wall ◽  
Root Hair ◽  
Root Hairs ◽  
Root Apex ◽  
Alnus Glutinosa ◽  
Root Surface ◽  
Infection Process ◽  
Root Cap ◽  
A Cell ◽  
Histochemical Tests

The aim of the present study was to investigate the Alnus root surface using seedlings grown axenically. This study has focused on root zones where infection by the symbiotic actinomycete Frankia takes place. The zones examined extend from the root cap to the emerging root hair zone. The root cap ensheaths the Alnus root apex and extends over the root surface as a layer of highly flattened cells closely appressed to the root epidermal cell wall. These cells contain phenolic compounds as demonstrated by various histochemical tests. They are externally bordered by a thin cell wall coated by a thin mucilage layer. The root cap is ruptured when underlying epidermal cells elongate, and cell remnants are still found in the emerging root hair zone. Young emerging root hairs are bordered externally by a cell wall covered by a thin mucilage layer which reacts positively to the tests used for the detection of polysaccharides, glycoproteins, and anionic sites. The characteristics of the Alnus root surface and the biological function of mucilage and phenols present at the root surface are discussed in relation to the infection process.

scholarly journals Compatibility of Azospirillum brasilense with fungicide and insecticide and its effects on the physiological quality of wheat seeds

2018 ◽  
Vol 39 (2) ◽  
pp. 855 ◽  
Author(s):  
Janete Denardi Munareto ◽  
Thomas Newton Martin ◽  
Tania Maria Müller ◽  
Ubirajara Russi Nunes ◽  
Guilherme Bergeijer da Rosa ◽  
...  
Keyword(s):  
Azospirillum Brasilense ◽  
Seed Treatment ◽  
Accelerated Aging ◽  
Triticum Aestivum L ◽  
Wheat Cultivars ◽  
Pests And Diseases ◽  
Physiological Quality ◽  
Growth Promoting ◽  
Germination Vigor

Seed treatment is a practice that helps the initial establishment of the crop without the effects caused by pests and diseases. The association of diazotrophic bacteria with grasses has been used in the supply of nitrogen to plants; however, these microorganisms produce growth-promoting substances, which promote benefits in the growth and development of the crops. Thus, the objective of this study was to evaluate the compatibility of Azospirillum brasilense associated with the fungicide difenoconazole and the insecticide thiamethoxam by observing the effects on the quality of seed emergence of three wheat cultivars (Triticum aestivum L.). Three wheat cultivars, arranged in a 4 x 2 factorial system with four replicates, were tested. The treatments were the control; difenoconazole (Spectro® at a dose of 150 mL per 100 kg of seed); thiamethoxam (Cruiser® FS 350 at a dose of 200 mL per 100 kg seed) and difenoconazole + thiamethoxam, applied on wheat cultivars TBIO Mestre, TBIO Itaipu and TBIO Sinuelo. Bacteria from the Azospirillum genus were used in the inoculation. The wheat seed retains its quality when it checks the germination, vigor and independent accelerated aging, whether or not fungicide, insecticide and A. brasilense were used. The insecticide thiamethoxam increased the length of shoots and roots and provided compatibility with A. brasilense, and fungicide inhibited the length of shoots and roots and was antagonistic to the bacterium A. brasilense.

Structure and ontogeny of Betula alleghaniensis – Pisolithus tinctorius ectomycorrhizae

1990 ◽  
Vol 68 (3) ◽  
pp. 579-593 ◽  
Author(s):  
H. B. Massicotte ◽  
R. L. Peterson ◽  
C. A. Ackerley ◽  
L. H. Melville
Keyword(s):  
Root Hairs ◽  
Root Surface ◽  
Pisolithus Tinctorius ◽  
Initial Contact ◽  
Broad Host Range ◽  
Betula Alleghaniensis ◽  
Cortical Cells ◽  
Structural Modifications ◽  
Hartig Net ◽  
Primary Roots

The ontogeny and ultrastructure of ectomycorrhizae synthesized between Betula alleghaniensis (yellow birch) and Pisolithus tinctorius, a broad host range fungus, were studied to determine the structural modifications in both symbionts during ectomycorrhiza establishment. A number of stages, including initial contact of hyphae with the root surface, early mantle formation, and mature mantle formation, were distinguished. Interactions between hyphae and root hairs were frequent. As a paraepidermal Hartig net developed, root epidermal cells elongated in a radial direction, but wall ingrowths were not formed. Repeated branching of Hartig net hyphae resulted in extensive fine branches and the compartmentalization of hyphal cytoplasm. Nuclei and elongated mitochondria were frequently located in the narrow cytoplasmic compartments, and [Formula: see text] thickenings developed along walls of cortical cells in primary roots.

scholarly journals Multiwalled carbon nanotubes in alfalfa and wheat: toxicology and uptake

2012 ◽  
Vol 9 (77) ◽  
pp. 3514-3527 ◽  
Author(s):  
Pola Miralles ◽  
Errin Johnson ◽  
Tamara L. Church ◽  
Andrew T. Harris
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Root Elongation ◽  
Wheat Root ◽  
Root Tip ◽  
Multiwalled Carbon ◽  
Wheat Seedlings ◽  
Industrial Grade ◽  
High Concentrations ◽  
Multiwalled Cnts

Data on the bioavailability and toxicity of carbon nanotubes (CNTs) in the environment, and, in particular, on their interactions with vascular plants, are limited. We investigated the effects of industrial-grade multiwalled CNTs (75 wt% CNTs) and their impurities on alfalfa and wheat. Phytotoxicity assays were performed during both seed germination and seedling growth. The germinations of both species were tolerant of up to 2560 mg l −1 CNTs, and root elongation was enhanced in alfalfa and wheat seedlings exposed to CNTs. Remarkably, catalyst impurities also enhanced root elongation in alfalfa seedlings as well as wheat germination. Thus the impurities, not solely the CNTs, impacted the plants. CNT internalization by plants was investigated using electron microscopy and two-dimensional Raman mapping. The latter showed that CNTs were adsorbed onto the root surfaces of alfalfa and wheat without significant uptake or translocation. Electron microscopy investigations of internalization were inconclusive owing to poor contrast, so Fe 3 O 4 -functionalized CNTs were prepared and studied using energy-filter mapping of Fe 3 O 4 . CNTs bearing Fe 3 O 4 nanoparticles were detected in the epidermis of one wheat root tip only, suggesting that internalization was possible but unusual. Thus, alfalfa and wheat tolerated high concentrations of industrial-grade multiwalled CNTs, which adsorbed onto their roots but were rarely taken up.

Sign in / Sign up

Export Citation Format

Share Document