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.

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.

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.

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.

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