The Microflora of Unsuberized Roots of Eucalyptus calophylla R.Br. And Eucalyptus marginata Donn ex Sm. Seedlings Grown in Soil Suppressive and Conducive to Phytophthora cinnamomi Rands. II. Mycorrhizal Roots and Associated Microflora

1979 ◽  
Vol 27 (3) ◽  
pp. 255 ◽  
Author(s):  
N Malajczuk
Keyword(s):  
Electron Microscope ◽  
Mycorrhizal Fungi ◽  
Electron Microscope Study ◽  
Phytophthora Cinnamomi ◽  
Differential Susceptibility ◽  
Eucalyptus Marginata ◽  
Different Types ◽  
Mycorrhizal Roots ◽  
Conducive Soil ◽  
Stimulation Of

Mycorrhizal root development was more frequent in Eucalyptus calophylla than in Eucalyptus marginata in field and pot samples of soil conductive to Phytophthora cinnamomi. Morphologically different types of mycorrhizas were also observed in the two species, which suggested preferential stimulation of mycorrhizal fungi, and this was supported by cross-inoculation experiments with fungal symbionts isolated from mycorrhizal roots and from basidiomycete sporophores. Isolation of bacteria from mycorrhizal roots, and low power electron microscope study of these roots, indicated a significant mycorrhizosphere effect. Populations of bacteria varied quantitatively and qualitatively for different mycorrhizal roots. In suppressive soil few mycorrhizal roots were formed in either species. It is suggested that the different types of mycorrhizal roots and their associated bacterial microflora may contribute to differential susceptibility of the two species to infection by P. cinnamomi in conducive soil.

scholarly journals Phosphite and mycorrhizal formation in seedlings of three Australian Myrtaceae

2000 ◽  
Vol 48 (6) ◽  
pp. 725 ◽  
Author(s):  
Kay Howard ◽  
Bernie Dell ◽  
Giles E. Hardy
Keyword(s):  
Ectomycorrhizal Fungi ◽  
Mycorrhizal Fungi ◽  
Phytophthora Cinnamomi ◽  
Fold Increase ◽  
Native Plant ◽  
Negative Effects ◽  
Eucalyptus Marginata ◽  
Collar Rot ◽  
The Impact ◽  
Different Levels

Currently in Western Australia, phosphite is being used to contain the root and collar rot pathogen, Phytophthora cinnamomi, in native plant communities. There have been reports of negative effects of phosphite on arbuscular mycorrhiza (AM), so there are concerns that it may have a deleterious effect on other mycorrhizal fungi. Two glasshouse experiments were undertaken to determine the impact of phosphite on eucalypt-associated ectomycorrhizal fungi. In the first experiment, non-mycorrhizal seedlings of Eucalyptus marginata, Eucalyptus globulus and Agonis flexuosa were sprayed to runoff with several concentrations of phosphite, and then planted into soil naturally infested with early colonising mycorrhizal species. Assessments were made of percentage of roots infected with mycorrhizal fungi. There was no significant effect on ectomycorrhizal formation but there was a four-fold increase in AM colonisation of A. flexuosa roots with phosphite application. In the second experiment, E. globulus seedlings mycorrhizal with Pisolithus, Scleroderma and Descolea were treated with different levels of phosphite and infection of new roots by ectomycorrhizal fungi was assessed. There was no significant effect on ectomycorrhizal formation when phosphite was applied at the recommended rate (5 g L–1), while at 10 g L–1 phosphite significantly decreased infection by Descolea.

Periodicity of Fine Root Growth in Jarrah (Eucalyptus marginata Donn Ex Sm.)

1983 ◽  
Vol 31 (3) ◽  
pp. 247 ◽  
Author(s):  
B Dell ◽  
IM Wallace
Keyword(s):  
Root Growth ◽  
Fine Root ◽  
Phytophthora Cinnamomi ◽  
Late Summer ◽  
Late Winter ◽  
Summer Drought ◽  
Root Pathogen ◽  
Eucalyptus Marginata ◽  
Fine Root Growth ◽  
Mycorrhizal Roots

The timing of new surface root growth in jarrah (Eucalyptus marginata) was followed for a 15-month period in the field. The periodicity of new root growth was similar for long roots, non-mycorrhizal and mycorrhizal root clusters. Root growth was initiated during two peak periods in spring (September-October) and following autumn rain (May-June). Little new root activity was recorded in late winter (August) or during summer drought. Rapid root growth occurred within 2 days of a storm (47 mm rain) in February. In addition, short roots formed after very light showers of rain (<5 mm) in late summer. Much of the framework for fine feeder roots was built up after autumn rain. In contrast to new long root growth which was equally spread between spring and late autumn, the majority of new mycorrhizal roots were produced from May to July. Root growth ceased when warm surface soils dried out and commenced when the soils were moist after rain. Much of the new root growth in jarrah occurred when the root pathogen Phytophthora cinnamomi was active in the soil.

Surface Root System of Eucalyptus marginata Sm.: Anatomy of Non-Mycorrhizal Roots.

1981 ◽  
Vol 29 (5) ◽  
pp. 565 ◽  
Author(s):  
B Dell ◽  
IM Wallace
Keyword(s):  
Root System ◽  
Phytophthora Cinnamomi ◽  
Epidermal Cells ◽  
Outer Cortex ◽  
Eucalyptus Marginata ◽  
Mycorrhizal Roots

The anatomy of surface feeder roots of Eucalyptus marginata was investigated. Two types of long roots were recognized: (a) those with thick-walled epidermal cells, and (b) those with a lignified outer cortex. The hypodermis of short roots was often suberized and the inner layers of the cortex had lignified secondary walls. The occurrence of lignified and suberized layers is discussed in relation to possible infection by Phytophthora cinnamomi.

Structure of the Surface Root System of Eucalyptus Marginata Sm. And Its Infection by Phytophthora Cinnamomi Rands

1981 ◽  
Vol 29 (1) ◽  
pp. 49 ◽  
Author(s):  
SR Shea ◽  
B Dell
Keyword(s):  
Root System ◽  
Phytophthora Cinnamomi ◽  
Lateral Roots ◽  
High Density ◽  
Summer Drought ◽  
Eucalyptus Marginata ◽  
Mycorrhizal Roots ◽  
Small N ◽  
A Site

The structure of the surface root system of jarrah (Eucalyptus marginata) trees was examined on a number of freely drained upland sites with different fire and management histories. The roots typically occurred in patches but in some stands formed extensive sheets. On excavation; this surface root system was composed of pads ranging in size from 10 cm to 1-3 m in diameter and c. 5 cm thick. The pads consist of short roots 1-3 mm long (which commonly form dense clusters around lateritic pebbles) which arise from small (n - 1)*th order laterals 0.5-1.5 cm long connected to (n - 2)*th order laterals 2-5 cm long and up to 0.7 mm in diameter. Mycorrhizal roots were common throughout the surface root pads. During the summer drought many of the short lateral roots die but the main framework of the roots of the surface pads is perennial. Following rains or irrigation, new, short lateral roots form rapidly from the framework of roots in the surface pads. Phytophthora cinnamomi was consistently recovered from short lateral roots and from the perennial roots (n - 1, n - 2) which form the framework of the root pads at a site in diseased forest where a high density of P. cinnamomi had been induced in the soil by irrigation. We hypothesize that the destruction of some of the perennial components of the root pads could explain why P. cinnamonzi can cause the decline and death of jarrah in an environment only marginally favourable for the fungus.

The Microflora of Unsuberized Roots of Eucalyptus calophylla R.Br. And Eucalyptus marginata Donn ex Sm. Seedlings Grown in Soil Suppressive and Conducive to Phytophthora cinnamomi Rands. I. Rhizosphere Bacteria, Actinomycetes and Fungi

1979 ◽  
Vol 27 (3) ◽  
pp. 235 ◽  
Author(s):  
N Malajczuk ◽  
AJ Mccomb
Keyword(s):  
Unit Area ◽  
Phytophthora Cinnamomi ◽  
Natural Infection ◽  
Differential Susceptibility ◽  
Root Surface ◽  
Lateritic Soil ◽  
Eucalyptus Marginata ◽  
Rhizosphere Microflora ◽  
Rhizosphere Population ◽  
Loam Soil

An investigation was made of the microflora associated with unsuberized roots of Eucalyptus marginata and Eucalyptus calophylla raised in different soils. The studies were made for 'conducive' lateritic soil (in which E. marginata is susceptible to infection by Phytophthora cinnamomi but E. Calophylla is resistant); and in 'suppressive' loam soil in which both eucalypt species are unaffected by the pathogen. Lateritic soil in some cases contained natural infection of P. cinnamomi. Rhizospheres of both species contained larger microflora populations (expressed as numbers per g of root) than in the soils. In general, the population of rhizosphere microflora was greater for E. Marginata than E. calophylla seedlings in the uninfected lateritic soil. Qualitative differences were also recorded in populations of bacteria, actinomycetes and fungi, and in particular, fluorescent pseudomonads were more numerous in the rhizosphere of E. marginata seedlings. Eucalypt seedlings raised in loam soil harboured greater microbial populations than in lateritic soil. This could in part be attributed to the higher nutrient and organic matter status of the loam. E. marginata had a greater total rhizosphere population, but actinomycetes were more numerous in the rhizosphere of E. calophylla. Qualitative differences in populations of bacteria, actinomycetes and fungi were also noted. In naturally infected lateritic soil the microflora populations were invariably lower than for the other soils. When the counts of bacteria and actinomycetes were expressed as numbers per mm2 of root surface, E. calophylla had a significantly higher number of propagules per unit area than E. marginata. The loam soil was an exception; there E. marginata had three times as many bacteria per unit area of the root surface as E. calophylla. It is suggested that the microflora population differences recorded for the two eucalypts in lateritic soil may contribute to the differential susceptibility of species to infection by P. cinnamomi; and that the higher populations of microflora in the loam soil contribute to the suppression of P. Cinnamomi in that soil.

A Scanning Electron Microscope Study of Washer-Dryer Abrasion in Textiie Fibers

1970 ◽  
Vol 28 ◽  
pp. 346-347
Author(s):  
Wilton R. Goynes
Keyword(s):  
Electron Microscope ◽  
Electron Microscope Study ◽  
Cotton Fabrics ◽  
Cross Linking ◽  
Scanning Electron Microscope Study ◽  
Durable Press ◽  
Transmission Electron ◽  
Different Types ◽  
Ultrathin Sections ◽  
Scanning Electron

The reaction of cellulose with certain cross-linking agents has produced cotton fabrics with outstanding durable press characteristics. However, many of these reactions decrease the natural abrasion resistance of the fiber. Wet abrasion and dry abrasion are known to produce different types of damage in the cotton fiber. It was of interest to determine whether such differences occur in the machine washing and drying of cotton fabrics. To study this problem, both untreated and cross-linked cotton fabrics were made into trouser cuffs, washed repeatedly and line dried, or machine dried until extensive damage had occurred. The two reacted fabrics studied had been treated with dimethyloldihydroxyethyleneurea and tris(l-aziridinyl) phosphine oxide. Cuene solubility tests on ultrathin sections of fibers from th ese fabrics observed with the transmission electron microscope indicated that the fibers were uniformly cross-linked throughout.

Ultrastructure of Plant Leaf Tissue Infected with Mite-Borne Viral-Like Pathogens

1970 ◽  
Vol 28 ◽  
pp. 178-179 ◽  
Author(s):  
O. E. Bradfute ◽  
R. E. Whitmoyer ◽  
L. R. Nault
Keyword(s):  
Triticum Aestivum ◽  
Zea Mays ◽  
Electron Microscope ◽  
Hordeum Vulgare ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Leaf Tissue ◽  
Leaf Ultrastructure ◽  
Double Membrane ◽  
Aceria Tulipae

A pathogen transmitted by the eriophyid mite, Aceria tulipae, infects a number of Gramineae producing symptoms similar to wheat spot mosaic virus (1). An electron microscope study of leaf ultrastructure from systemically infected Zea mays, Hordeum vulgare, and Triticum aestivum showed the presence of ovoid, double membrane bodies (0.1 - 0.2 microns) in the cytoplasm of parenchyma, phloem and epidermis cells (Fig. 1 ).

Electron microscope study of the microgranules in human vaginal epithelium

1978 ◽  
Vol 36 (2) ◽  
pp. 568-569
Author(s):  
A. Campos ◽  
J. Vilches ◽  
J. Gomez
Keyword(s):  
Electron Microscope ◽  
Microscope Study ◽  
Intercellular Space ◽  
Electron Microscope Study ◽  
Vaginal Epithelium ◽  
Vaginal Mucosa ◽  
Secretory Phase ◽  
Cervical Epithelium ◽  
Keratinized Epithelium ◽  
Fertile Women

Microgranules have been described with different names in keratinized and in nonkeratinized epithelium. In keratinized epithelium it seems clear that the microgranules are lamellated bodies bounded by a membrane which empty their contents into the intercellular space. Their existence in nonkeratinized epithelium is more debatable. Until now the so-called microgranules have been described in nonkeratinized bucal, lingual and cervical epithelium. In the present work we describe the morphology and nature of such structures in human vaginal epithelium.Biopsies from the midlevel of the vaginal mucosa were taken from voluntary fertile women. The specimens were divided into three groups with four vaginal specimens. The first group was obtained in the folicular phase; those of the second in the postovulatory phase and, finally, the last group corresponded to the secretory phase.

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