Studies on the Mycorrhizae of Eucalyptus regnans F.muell

1976 ◽  
Vol 24 (6) ◽  
pp. 723 ◽  
Author(s):  
DH Ashton
Keyword(s):  
Lateral Roots ◽  
Mycorrhizal Fungus ◽  
Root Hairs ◽  
High Light Intensity ◽  
Eucalyptus Regnans ◽  
Carbon 14 ◽  
Nitrogenous Fertilizer ◽  
External Mycelium ◽  
Mycorrhizal Development ◽  
Growth Of Seedlings

Eucalyptus regnans mycorrhizae vary from simple to coralloid forms, and their surfaces are commonly smooth or conspicuously enmeshed with external mycelium. At least 18 different basidiomycetes may be intimately associated with dense weft-type mycorrhizae; six agarics have been induced to form simple or diffuse mycorrhizae under sterile conditions. Individual mycorrhizae vary in form and colour with both age and the nature of the symbiont. In the field, mycorrhizae are longer-lived than uninfected lateral roots. The earliest stages of infection of new roots appear to occur via root hairs, and intracellular hyphae are produced. This is rapidly followed by the development of either ectendotrophic, ectotrophic or superficial mycorrhizae. Mycorrhizal development is enhanced by high light intensity, diminished by high levels of nitrogenous fertilizer, but apparently unaffected by high levels of phosphate. Experiments suggest that a transfer of carbon-14 takes place from the leaves to the mycorrhizal mantle. Inoculation of E. regnans by Mesophellia arenaria in relatively rich loams of south Gippsland improved the growth of E. regnans seedlings in both field and the glasshouse. The sterilization by gamma-rays of krasnozem topsoil from the forest improved the growth of E. regnans seedlings. Growth of seedlings was further enhanced by the inoculation of such soil with a mycorrhizal fungus (probably inocybe olivaceofulvus).

scholarly journals Overexpression of OsPIN2 Regulates Root Growth and Formation in Response to Phosphate Deficiency in Rice

2019 ◽  
Vol 20 (20) ◽  
pp. 5144
Author(s):  
Huwei Sun ◽  
Xiaoli Guo ◽  
Fugui Xu ◽  
Daxia Wu ◽  
Xuhong Zhang ◽  
...  
Keyword(s):  
Root Growth ◽  
Growth And Development ◽  
Plant Root ◽  
Lateral Roots ◽  
Root Hairs ◽  
Phosphate Deficiency ◽  
P Deficiency ◽  
Auxin Distribution ◽  
Seminal Roots ◽  
Underlying Mechanisms

The response of root architecture to phosphate (P) deficiency is critical in plant growth and development. Auxin is a key regulator of plant root growth in response to P deficiency, but the underlying mechanisms are unclear. In this study, phenotypic and genetic analyses were undertaken to explore the role of OsPIN2, an auxin efflux transporter, in regulating the growth and development of rice roots under normal nutrition condition (control) and low-phosphate condition (LP). Higher expression of OsPIN2 was observed in rice plants under LP compared to the control. Meanwhile, the auxin levels of roots were increased under LP relative to control condition in wild-type (WT) plants. Compared to WT plants, two overexpression (OE) lines had higher auxin levels in the roots under control and LP. LP led to increased seminal roots (SRs) length and the root hairs (RHs) density, but decreased lateral roots (LRs) density in WT plants. However, overexpression of OsPIN2 caused a loss of sensitivity in the root response to P deficiency. The OE lines had a shorter SR length, lower LR density, and greater RH density than WT plants under control. However, the LR and RH densities in the OE lines were similar to those in WT plants under LP. Compared to WT plants, overexpression of OsPIN2 had a shorter root length through decreased root cell elongation under control and LP. Surprisingly, overexpression of OsPIN2 might increase auxin distribution in epidermis of root, resulting in greater RH formation but less LR development in OE plants than in WT plants in the control condition but levels similar of these under LP. These results suggest that higher OsPIN2 expression regulates rice root growth and development maybe by changing auxin distribution in roots under LP condition.

scholarly journals Nodulation of Aeschynomene afraspera and A. indica by Photosynthetic Bradyrhizobium Sp. Strain ORS285: The Nod-Dependent Versus the Nod-Independent Symbiotic Interaction

2011 ◽  
Vol 24 (11) ◽  
pp. 1359-1371 ◽  
Author(s):  
Katia Bonaldi ◽  
Daniel Gargani ◽  
Yves Prin ◽  
Joel Fardoux ◽  
Djamel Gully ◽  
...  
Keyword(s):  
Fluorescent Protein ◽  
Lateral Roots ◽  
Root Hairs ◽  
Infection Process ◽  
Cortical Cells ◽  
Symbiotic Interaction ◽  
Root Cortex ◽  
Bradyrhizobium Sp ◽  
Infected Cells ◽  
Green Fluorescent

Here, we present a comparative analysis of the nodulation processes of Aeschynomene afraspera and A. indica that differ in their requirement for Nod factors (NF) to initiate symbiosis with photosynthetic bradyrhizobia. The infection process and nodule organogenesis was examined using the green fluorescent protein–labeled Bradyrhizobium sp. strain ORS285 able to nodulate both species. In A. indica, when the NF-independent strategy is used, bacteria penetrated the root intercellularly between axillary root hairs and invaded the subepidermal cortical cells by invagination of the host cell wall. Whereas the first infected cortical cells collapsed, the infected ones immediately beneath kept their integrity and divided repeatedly to form the nodule. In A. afraspera, when the NF-dependent strategy is used, bacteria entered the plant through epidermal fissures generated by the emergence of lateral roots and spread deeper intercellularly in the root cortex, infecting some cortical cells during their progression. Whereas the infected cells of the lower cortical layers divided rapidly to form the nodule, the infected cells of the upper layers gave rise to an outgrowth in which the bacteria remained enclosed in large tubular structures. Together, two distinct modes of infection and nodule organogenesis coexist in Aeschynomene legumes, each displaying original features.

The effect of Cylindrocarpon destructans on the growth of Eucalyptus regnans seedlings in air-dried and undried forest soil

2010 ◽  
Vol 58 (2) ◽  
pp. 133 ◽  
Author(s):  
T. M. Iles ◽  
D. H. Ashton ◽  
K. J. Kelliher ◽  
P. J. Keane
Keyword(s):  
Root Growth ◽  
Forest Soil ◽  
Seedling Growth ◽  
Frequency Of Occurrence ◽  
Root Tips ◽  
Eucalyptus Regnans ◽  
Cylindrocarpon Destructans ◽  
Pot Experiments ◽  
Growth Of Seedlings

The growth of Eucalyptus regnans F.Muell. (mountain ash) seedlings is poor in natural forest soil, where purple coloration of the foliage indicates P deficiency and where the fungus Cylindrocarpon destructans (Zinsm.) Scholten is commonly isolated from the roots of the seedlings. When forest soil is air-dried, P acquisiton and growth of seedlings are markedly improved, although the degree of growth stimulation varies considerably at different times, as does the frequency of occurrence of C. destructans on the roots. C. destructans has been implicated as a possible reason for suppressed growth of seedlings in undried natural soil. To find out whether C. destructans contributes to growth inhibition of E. regnans seedlings in undried forest soil, the effect of three isolates of C. destructans on the root growth of E. regnans seedlings was tested in Petri dish experiments in vitro and the effect of C. destructans inoculation on seedling growth both in air-dried and undried forest soil was tested in pot experiments. The frequency of occurrence of C. destructans on the roots varied at different times, and was not consistently higher in undried than in air-dried soil, even though the growth of the seedlings was always poor in undried soil compared with that in air-dried soil. In vitro, C. destructans decreased the root growth significantly and caused blackening of root tips. This effect was removed by adding natural air-dried or undried soil. In pot experiments using undried forest soil, there was no evidence of either direct toxic effect or any other adverse effect on the roots when soil was inoculated with this fungus, even when the growth of the seedlings was reduced to ~1/2 of that in uninoculated undried soil. In air-dried soil, inoculation with the fungus did not significantly reduce seedling growth. Although potentially pathogenic and able to cause blackening of root tips, C. destructans is unlikely to be the main reason for poor seedling growth in undried forest soil. It appears to be antagonistic rather than pathogenic, suppressing seedling growth only under unfavourable conditions, such as in undried soil, possibly by competing for limited nutrients, or by suppressing other beneficial micro-organisms. The results are discussed in the context of field conditions.

Interactions between the external mycelium of the mycorrhizal fungus Glomus intraradices and other soil microorganisms as affected by organic matter

2006 ◽  
Vol 38 (5) ◽  
pp. 1008-1014 ◽  
Author(s):  
A ALBERTSEN ◽  
S RAVNSKOV ◽  
H GREEN ◽  
D JENSEN ◽  
J LARSEN
Keyword(s):  
Organic Matter ◽  
Soil Microorganisms ◽  
Glomus Intraradices ◽  
Mycorrhizal Fungus ◽  
External Mycelium

scholarly journals Hormonal response and root architecture in Arabidopsis thaliana subjected to heavy metals

2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Antonella Vitti ◽  
Maria Nuzzaci ◽  
Antonio Scopa ◽  
Giuseppe Tataranni ◽  
Imma Tamburrino ◽  
...  
Keyword(s):  
Root Architecture ◽  
Lateral Roots ◽  
Root Hairs ◽  
Polymerase Chain Reaction Analysis ◽  
Zeatin Riboside ◽  
Morphological Alterations ◽  
Cytokinin Synthesis ◽  
Polymerase Chain ◽  
Abscisic Acid Level ◽  
Indole 3 Acetic Acid

In this work, specific concentrations of cadmium, copper and zinc in double combination, were supplied for 12 days to growing seedlings of the model species <em>Arabidopsis</em> <em>thaliana</em>. Metal accumulation was measured in roots and shoots. Microscopic analyses revealed that root morphology was affected by metals, and that the root and shoot levels of indole-3-acetic acid, <em>trans</em>-zeatin riboside and dihydrozeatin riboside varied accordingly. Minor modifications in gibberellic acid levels occurred in the Zinc treatments, whereas abscisic acid level did not change after the exposition to metals. Reverse transcription polymerase chain reaction analysis of some genes involved in auxin and cytokinin synthesis (<em>AtAAO</em>, <em>AtNIT</em> and <em>AtIPT</em>) revealed that their expression were not affected by metal treatments. The root morphological alterations that resulted in an increased surface area, due to the formation of root hairs and lateral roots, could be signs of the response to metal stress in terms of a functionally-addressed reorientation of root growth. The root system plasticity observed could be important for better understanding the manner in which the root architecture is shaped by environmental and hormonal stimuli.

Anatomical Aspects of Water Movement Through Stems of Mountain Ash (Eucalyptus regnans F. Muell.)

1985 ◽  
Vol 33 (3) ◽  
pp. 287 ◽  
Author(s):  
NJ Legge
Keyword(s):  
Surface Area ◽  
Microscopic Examination ◽  
Water Movement ◽  
Lateral Roots ◽  
Age Classes ◽  
Young Tree ◽  
Eucalyptus Regnans ◽  
Mountain Ash ◽  
Limited Degree ◽  
Old Trees

Introduction of a stain through the severed roots of Eucalyptus regnans of two age classes showed that a spiral interlocked sap ascent pattern in young trees tended towards a vertical sectorial pattern by age 40 years. Microscopic examination of the stained wood suggests that intercellular water movement occurs principally via the pits. Serial transverse sections of wood from a young tree showed a limited degree of intervessel contact, with a network coefficient of 13.7 contacts m-1 and approx. 0.9% of vessel surface area in contact with other vessels. Analysis of the frequency of vessel endings indicates an average vessel length of approx. 1.8 m. Trunk segments of 40-year-old trees had relative conductivities of approx. 3.3 x 10-11 m2, while small lateral roots had values up to 10 times greater.

Micropropagation of Juvenile Eucalyptus regnans (Mountain Ash)

1991 ◽  
Vol 39 (2) ◽  
pp. 179 ◽  
Author(s):  
C Blomstedt ◽  
J Cameron ◽  
P Whiteman ◽  
SF Chandler
Keyword(s):  
Woody Plant ◽  
Basal Medium ◽  
High Light Intensity ◽  
Shoot Cultures ◽  
Light Conditions ◽  
Indolebutyric Acid ◽  
Eucalyptus Regnans ◽  
Mountain Ash ◽  
Napthaleneacetic Acid

Node-derived shoot cultures of Eucalyptus regnans were established from in vitro grown seedlings on Murashige and Skoog basal medium supplemented with 0.5 mg L-1 (2 μm) zeatin and 0.05 mg L-1 (0.3 μm) napthaleneacetic acid. A double sterilisation method was essential to obtain clean material from seed. Microcuttings from established cultures were used to develop an efficient method for in vitro rooting. Rooting was best after a 7 day pulse on 20 mg L-1 (98 μm) indolebutyric acid. Hoagland's or Woody Plant Medium supported better rooting than MS basal medium and rooting was significantly enhanced by subculture to activated charcoal after the auxin pulse. Carbohydrate (sucrose or glucose) was essential for rooting while high light intensity was inhibitory. Optimal light conditions were a 12 h day (17 W m-2). In all, 90% of plantlets established in the nursery survived the winter.

Direct observation of fungal aggregates in sand dune soil

1978 ◽  
Vol 24 (3) ◽  
pp. 333-335 ◽  
Author(s):  
K. S. Clough ◽  
J. C. Sutton
Keyword(s):  
Sand Dune ◽  
Sand Dunes ◽  
Mycorrhizal Fungus ◽  
Lake Huron ◽  
Dominant Factor ◽  
Phaseolus Vulgaris L ◽  
External Mycelium ◽  
Grass Hosts ◽  
Dune Soil ◽  
Scanning Electron

The mycorrhizal fungus Glomus in association with bean hosts, Phaseolus vulgaris L., growing in pot cultures and grass hosts, Calamovilfa longiflora (Hook.) Scribn and Andropogon sp. growing on Lake Huron sand dunes produced extensive external mycelium. This mycelium was the dominant factor in the aggregation of soil particles. Light and scanning electron microscope studies indicated that the sand grains were attached to the hyphae. An amorphous deposit was often present at the interfaces of sand grains and hyphae. It appeared to act as an adhesive. Staining procedures indicated that this material contained polysaccharide. Other microorganisms were observed in association with the Glomus hyphae and the amorphous deposits.

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