Phytohormone changes in Bouteloua gracilis infected by vesicular–arbuscular mycorrhizae. II. Altered levels of gibberellin-like substances and abscisic acid in the host plant

1982 ◽  
Vol 60 (4) ◽  
pp. 468-471 ◽  
Author(s):  
Michael F. Allen ◽  
Thomas S. Moore Jr. ◽  
Martha Christensen
Keyword(s):  
Abscisic Acid ◽  
Mycorrhizal Fungi ◽  
High Performance ◽  
Arbuscular Mycorrhizae ◽  
Mycorrhizal Fungus ◽  
Arbuscular Mycorrhizal ◽  
Bouteloua Gracilis ◽  
Defined Medium ◽  
Liquid Chromatograph ◽  
Vesicular Arbuscular

Bouteloua gracilis (H.B.K.) Lag ex Steud (blue grama) was grown in a defined medium with and without the vesicular–arbuscular mycorrhizal fungus Glomus fasciculatus for 50 days. Levels of gibberellin-like substances (GA) and a substance like abscisic acid (ABA) of mycorrhizal and nonmycorrhizal plants were measured using the barley half-seed bioassay and UV detection of peaks from a μ-Bondapak–NH2 anion exchange high-performance liquid chromatograph column, respectively. Infection by mycorrhizal fungi resulted in significantly increased GA activity in the leaves and a tendency for decreased activity in the roots. ABA concentration decreased in leaves of infected plants but remained unchanged in roots. Increased levels of GA with reduced ABA in the leaves may alter substantially the physiology of B. gracilis.

Susceptibility of barley cultivars to vesicular-arbuscular mycorrhizal fungi

1995 ◽  
Vol 75 (1) ◽  
pp. 269-275 ◽  
Author(s):  
S. M. Boyetchko ◽  
J. P. Tewari
Keyword(s):  
Mycorrhizal Fungi ◽  
Mycorrhizal Fungus ◽  
Arbuscular Mycorrhizal ◽  
Growth And Yield ◽  
Vam Fungi ◽  
University Of Alberta ◽  
Barley Cultivars ◽  
Vesicular Arbuscular ◽  
Glomus Species ◽  
The University

The relative susceptibility of selected barley cultivars produced in western Canada to vesicular-arbuscular mycorrhizal (VAM) fungi under field and greenhouse conditions was evaluated in this study. Cultivars tested under field conditions at the University of Alberta and Lacombe research stations showed no significant differences in VAM colonization of barley roots; colonization was light. Greenhouse trials at the University of Alberta with eight cultivars inoculated with individual mycorrhizal species illustrated significant differences among the barley cultivars in their reactions to Glomus dimorphicum, G. intraradices, and G. mosseae. Distinct differences were observed in the ability of each Glomus species to colonize the barley cultivars. The VAM fungi increased growth and yield in some cultivars, depending on the Glomus species. This study indicates that a degree of host-specificity exists in VAM fungi and that the host-mycorrhizal fungus genotypes may influence the effectiveness of the symbiosis. Key words: Barley, cultivars, susceptibility, VA mycorrhizal fungi

Development of vesicular–arbuscular mycorrhizae in a young sweetgum plantation

1985 ◽  
Vol 15 (6) ◽  
pp. 1061-1064 ◽  
Author(s):  
Paul P. Kormanik
Keyword(s):  
Mycorrhizal Fungi ◽  
Arbuscular Mycorrhizae ◽  
Fungal Spores ◽  
Arbuscular Mycorrhizal ◽  
Available Phosphorus ◽  
Vesicular Arbuscular Mycorrhizae ◽  
Vesicular Arbuscular ◽  
Mycorrhizal Development ◽  
Crown Closure ◽  
Arbuscular Mycorrhizal Fungal

Sweetgum seedlings with vesicular–arbuscular mycorrhizae formed by Glomusetunicatum or Glomusdeserticola in nursery soil with 30 ppm available phosphorus (P) and nonmycorrhizal seedlings grown in nursery soil with 800 ppm available P were outplanted and whole trees were excavated periodically over the next 5 years in the plantation to follow mycorrhizal development. Four months after outplanting, roots of all initially nonmycorrhizal seedlings had formed vesicular–arbuscular mycorrhizae and the degree of root colonization was comparable to that of initially vesicular–arbuscular mycorrhizal seedlings. New feeder roots did not develop on seedlings of any treatment until almost 5 months after planting. By the end of the first growing season and for the remainder of the study, vesicular–arbuscular mycorrhizae development was approximately the same on all seedlings. The proportion of feeder roots colonized by vesicular–arbuscular mycorrhizal fungi stabilized at 65 to 70%; approximately 56% of the cortical tissues of all feeder roots were colonized with arbuscles, vesicles, and hyphae. Periodic assays of the soil in the plantation showed that vesicular–arbuscular mycorrhizal fungal spores gradually declined from an initial high of 3600 spores to 620 spores per 100-cm3 soil sample after 5 years. This decline was probably caused by crown closure of the sweetgum trees which gradually suppressed understory vegetation.

Tripartite associations in snowbrush (Ceanothus velutinus): effect of vesicular–arbuscular mycorrhizae on growth, nodulation, and nitrogen fixation

1981 ◽  
Vol 59 (1) ◽  
pp. 34-39 ◽  
Author(s):  
S. L. Rose ◽  
C. T. Youngberg
Keyword(s):  
Host Plant ◽  
Mycorrhizal Fungi ◽  
Arbuscular Mycorrhizae ◽  
Nitrogenase Activity ◽  
Mycorrhizal Fungus ◽  
Nodule Formation ◽  
Nitrogen Fixing ◽  
Symbiotic Associations ◽  
Vesicular Arbuscular ◽  
Va Mycorrhizal Fungi

Symbiotic associations were established between nitrogen-fixing nonleguminous (actinorrhizal) snowbrush (Ceanothus velutinus Dougl.) seedlings and two categories of microorganisms: vesicular–arbuscular (VA) mycorrhizal fungi and a filamentous actinomycete capable of inducing nodule formation. The actinomycete is housed in nodules where fixation of atmospheric dinitrogen occurs and is made available to the host plant; the mycorrhizal fungus is both inter- and intra-cellular within the root tissue and may be found within the nodules. The two major nutrients, N and P, are made available and can be supplied to the host plant by these two symbiotic microorganisms. The root system of snowbrush seedlings was dually colonized by VA mycorrhizal fungi and a nitrogen-fixing actinomycete and the possibility of a direct interaction between the endophytes in the symbioses was investigated. Dually infected plants showed increases in total dry weight of shoots and roots, number of nodules, weight of nodular tissue, as well as higher levels of N, Ca2+, and P, and an increase in nitrogenase activity as measured by acetylene reduction.

The influence of fixation procedure on the ultrastructure of the host–endophyte interface of vesicular-arbuscular mycorrhizae

1977 ◽  
Vol 55 (1) ◽  
pp. 48-51 ◽  
Author(s):  
D. E. Carling ◽  
J. A. White ◽  
M. F. Brown
Keyword(s):  
Arbuscular Mycorrhizal Fungi ◽  
Granular Material ◽  
Mycorrhizal Fungi ◽  
Arbuscular Mycorrhizae ◽  
Arbuscular Mycorrhizal ◽  
Interfacial Zone ◽  
Fixation Procedure ◽  
Vesicular Arbuscular Mycorrhizal Fungi ◽  
Host Cytoplasm ◽  
Vesicular Arbuscular

The ultrastructure of the interfacial zone which separates the intracellular structures of vesicular-arbuscular mycorrhizal fungi from host cytoplasm has been described in a variety of ways by recent investigators. Evidence is presented here which suggests that previous interpretations of the ultrastructure of the interfacial zone have been based on an artifact of fixation. Using an improved procedure, a dense, granular material was found in the interfacial zone. This material was preserved by simultaneous glutaraldehyde-osmium fixation but not by conventional prefixation and postfixation in glutaraldehyde and osmium, respectively.

A new method for observing the morphology of vesicular–arbuscular mycorrhizae

1984 ◽  
Vol 62 (10) ◽  
pp. 2128-2134 ◽  
Author(s):  
M. C. Brundrett ◽  
Y. Piché ◽  
R. L. Peterson
Keyword(s):  
Arbuscular Mycorrhizal Fungi ◽  
Mycorrhizal Fungi ◽  
Arbuscular Mycorrhizae ◽  
Arbuscular Mycorrhizal ◽  
Staining Procedure ◽  
Acid Fuchsin ◽  
Vesicular Arbuscular Mycorrhizal Fungi ◽  
Vesicular Arbuscular ◽  
Contrast Microscopy ◽  
Interference Contrast Microscopy

A new procedure using chlorazol black E has been developed for staining vesicular–arbuscular mycorrhizal fungi in cleared roots. In a comparative study, chlorazol black E was found to be much superior to previously used stains (acid fuchsin, trypan blue, aniline blue) for showing details of internal hyphae and particularly arbuscules. This clearing and staining procedure, combined with Nomarski interference contrast microscopy, revealed details of arbuscule structure not evident with previous techniques. Field-collected samples were also stained well by this procedure. The procedure should allow more accurate assessment of roots for colonization by vesicular–arbuscular mycorrhizal fungi.

Effects of vesicular-arbuscular mycorrhizal infection in first, second and third cereal crops

1985 ◽  
Vol 105 (3) ◽  
pp. 631-647 ◽  
Author(s):  
J. G. Buwalda ◽  
D. P. Stribley ◽  
P. B. Tinker
Keyword(s):  
Spring Wheat ◽  
Mycorrhizal Fungi ◽  
Dry Matter ◽  
Arbuscular Mycorrhizal Fungus ◽  
Mycorrhizal Fungus ◽  
Arbuscular Mycorrhizal ◽  
Residual Effects ◽  
Cereal Crops ◽  
Mycorrhizal Infection ◽  
Vesicular Arbuscular

SUMMARYThe effects of inoculation with the vesicular-arbuscular mycorrhizal fungus Olomics mosseae(Nicolson & Gerdemann) Gerdemann and Trappe, fumigation of soil with methyl bromide, and addition of superphosphate (up to 60 kg P/ha) on growth and phosphorus nutrition of spring wheat (Triticum aestivum L. cv. Highbury) were investigated in two experiments (in 1980 and 1981 respectively) on plots that had been fallowed and recently limed.Fumigation severely reduced natural levels of infection, and slightly reduced yield of above-ground dry matter in both years. In 1981 a decrease in grain yield of about 25% was accompanied by an increase in growth of straw. Plants on fumigated plots contained appreciable amounts of bromine in shoot tissue.Inoculation increased and added P decreased infection in all treatments. In 1980 inoculation had little effect on above-ground dry matter, but it increased concentration of P in shoots especially on plots without added P. In 1981 added inoculum increased yield of grain on fumigated plots by about 0·75 t/ha at all levels of added P, but had little effect on non-fumigated plots, though responses in grain production to added P were similar with and without fumigation. Increases in yield resulting from inoculation were generally accompanied by increases in concentration of P in plant tissue.Winter barley was sown on the plots after their use for spring wheat, without further application of the fumigation, inoculation or phosphorus treatments used in those experiments, to determine any residual effects on mycorrhizal infection and on growth. The levels of mycorrhizal infection on non-fumigated, inoculated plots were relatively constant in successive crops, although numbers of propagules of mycorrhizal fungi increased significantly with time for all treatments. Infection levels on fumigated and non-inoculated plots increased in successive crops, so that the relative effects of fumigation and of inoculation declined with time.The effects of inoculation on infection levels persisted for longer than those on yields, suggesting that maximum effects of mycorrhizal infection on growth did not require the maximum levels of infection found in the roots. Harvest yields continued to respond to applied phosphorus even when uniformly high levels of infection had been established, suggesting that the ability of the root system to absorb phosphate was not greatly increased by mycorrhizal infection.

Growth of Vesicular-Arbuscular-Mycorrhizal and Nonmycorrhizal Bouteloua Gracilis in a Defined Medium

Mycologia ◽  
1979 ◽  
Vol 71 (3) ◽  
pp. 666-669 ◽  
Author(s):  
M. F. Allen ◽  
T. S. Moore ◽  
M. Christensen ◽  
N. Stanton
Keyword(s):  
Arbuscular Mycorrhizal ◽  
Bouteloua Gracilis ◽  
Defined Medium ◽  
Vesicular Arbuscular

Inoculation of citrus with root fragments containing chlamydospores of the mycorrhizal fungus Glomus intraradices

1986 ◽  
Vol 64 (8) ◽  
pp. 1739-1744 ◽  
Author(s):  
J. H. Graham ◽  
D. Fardelmann
Keyword(s):  
Arbuscular Mycorrhizae ◽  
Glomus Intraradices ◽  
Mycorrhizal Fungus ◽  
Arbuscular Mycorrhizal ◽  
Most Probable Number ◽  
Probable Number ◽  
Vesicular Arbuscular ◽  
Grass Root ◽  
Colonization Potential ◽  
Potting Media

The vesicular–arbuscular mycorrhizal fungus, Glomus intraradices, was found sporulating in citrus roots in an orchard soil. Dead root fragments of citrus accounted for a high proportion of the propagules in soil as measured by the most probable number technique. Sudan grass root fragments from pot cultures containing 7 and 94 chlamydospores of G. intraradices per milligram dry root had 11 and 184 (most probable number) propagules per milligram dry root, respectively. Inoculum densities of 20–40 mg of root fragments per 100 cm3 of potting media resulted in 100% inoculation success of Carrizo citrange grown from seed. A decrease in root fragment density to as low as 2.5 mg per 100 cm3 of medium reduced inoculation success and root colonization, but did not reduce growth and nutrient uptake by inoculated seedlings. The growth of vesicular–arbuscular mycorrhizal plants in a soilless medium amended with relatively insoluble rock phosphate was less than that of nonmycorrhizal plants fertilized with soluble phosphorus; copper uptake, however, was significantly increased by vesicular–arbuscular mycorrhizae. Root fragments stored up to 1 year under moist conditions did not lose colonization potential, whereas drying reduced colonization potential to near zero after 9 months.

Colonization of crop and pasture species with vesicular–arbuscular mycorrhizal fungi and a negative correlation with root infection by Bipolaris sorokiniana

1989 ◽  
Vol 67 (3) ◽  
pp. 687-693 ◽  
Author(s):  
J. P. Thompson ◽  
G. B. Wildermuth
Keyword(s):  
Arbuscular Mycorrhizal Fungi ◽  
Mycorrhizal Fungi ◽  
Arbuscular Mycorrhizae ◽  
Arbuscular Mycorrhizal ◽  
Bipolaris Sorokiniana ◽  
Mycorrhizal Colonization ◽  
Root Infection ◽  
Vesicular Arbuscular Mycorrhizal Fungi ◽  
Vesicular Arbuscular ◽  
Mycorrhizal Roots

The roots of 37 crop and pasture species were assessed for vesicular–arbuscular mycorrhizae in a vertisol containing spores of vesicular–arbuscular mycorrhizal fungi mainly Glomus mosseae, and of the pathogenic fungus, Bipolaris sorokiniana. The level of mycorrhizal colonization of different hosts is an important aspect of managing crop sequences to reduce "long fallow disorder." All species except rapeseed in the Cruciferae and lupin in the Leguminosae were hosts, although perennial rye grass in the Gramineae had only very slight colonization. The percent root length colonized as assessed by the grid-intersect method ranged up to 60.5% for wheat in the winter series and up to 98.4% for mungbean in the summer series. Greatest weights of mycorrhizal roots were produced by phalaris grass, chickpea, safflower, cocksfoot, lucerne, and barley in the winter series and by lucerne, maize, canary seed, Sudan grass, grain sorghum, and buffel grass in the summer series. Although Gramineae as a group tends to have fine roots with a low percentage of mycorrhizal colonization, the total weight of mycorrhizal roots can be large, and they should be at least equal to legumes in effectiveness for breaking long fallow disorder. Percentages of mycorrhizal colonization determined by the grid-intersect and three slide methods were generally well correlated with one another, but all were less strongly correlated with weight of mycorrhizal roots for winter crops and were entirely uncorrelated with weight of mycorrhizal roots for summer crops. Significant inverse-regression relationships were obtained between infection of root segments (but not of stem bases) by B. sorokiniana and root colonization with vesicular–arbuscular mycorrhizae, indicating that vesicular–arbuscular mycorrhizal fungi antagonise root infection by B. sorokiniana.

Vesicular–arbuscular mycorrhizal colonization in Zea mays affected by breeding for resistance to fungal pathogens

1990 ◽  
Vol 68 (5) ◽  
pp. 1039-1044 ◽  
Author(s):  
Ronald Toth ◽  
Deborah Toth ◽  
David Starke ◽  
David R. Smith
Keyword(s):  
Zea Mays ◽  
Mycorrhizal Fungi ◽  
Fungal Pathogens ◽  
Arbuscular Mycorrhizae ◽  
Zea Mays L ◽  
Arbuscular Mycorrhizal ◽  
Root Systems ◽  
Mycorrhizal Colonization ◽  
Breeding Programs ◽  
Vesicular Arbuscular

Inbred lines of Zea mays L. (maize) selected for a range of resistances to a variety of fungal pathogens were assayed for percentage colonization by vesicular–arbuscular mycorrhizal fungi. Inbreds that were generally resistant to a number of fungal pathogens had significantly lower levels of vesicular–arbuscular mycorrhizae, matured more slowly, and had larger root systems. Disease-susceptible inbreds had significantly higher levels of mycorrhizal colonization, matured more rapidly, and had smaller root systems. It is uncertain if a general resistance to fungal pathogens or rate of root development, separately or in combination, may have influenced mycorrhizal colonization levels. Irrespective of cause, present breeding programs for disease resistance in maize do influence the plants ability to form mycorrhizae.

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