Distribution of the Orchid Mycorrhizal Fungus, Rhizoctonia solani, in Relation to Its Host, Pterostylis acuminata, in the Field

The plant pathology model was tested as an explanation of the distribution of orchid mycorrhizal fungi in the field. The mycorrhizal fungus, Rhizoctonia solani Kuhn AG 6, was isolated from adult plants and protocorms of Pterostylis acuminata R.Br. at a study site and from adult plants at five other locations in the Sydney region. In litter and trap seedlings, R. solani AG 6 was found within 50 cm of adult plants of the orchid P. acuminata and was more abundant close to the host plant. In the laboratory, protocorms of P. acuminata became infected with R. solani AG 6, but not with fungi isolated from the other orchids, P. concinna R.Br., P. ophioglossa R.Br. and Caladenia catenata (Smith) Druce, found at the site. It was concluded that the co-distribution model better explains the distribution of fungus and host in this case.

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

Canadian Journal of Botany ◽

10.1139/b81-006 ◽

1981 ◽

Vol 59 (1) ◽

pp. 34-39 ◽

Cited By ~ 56

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.

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Enzyme activity and phytohormone production of a mycorrhizal fungus, Laccarialaccata

Canadian Journal of Forest Research ◽

10.1139/x87-135 ◽

1987 ◽

Vol 17 (8) ◽

pp. 855-858 ◽

Cited By ~ 23

Author(s):

Iwan Ho

Keyword(s):

Enzyme Activity ◽

Acid Phosphatase ◽

Mycorrhizal Fungi ◽

Reductase Activity ◽

Mycorrhizal Fungus ◽

High Elevation ◽

The Other ◽

Forest Nursery ◽

Natural Forests ◽

Polymorphic Gene

Six isolates of Laccarialaccata, S-167 from a forest nursery and S-238, S-283, S-326, S-444, and S-472 from natural forests, were analyzed for acid phosphatase, alkaline phosphatase, and nitrate reductase activity, acid phosphatase isozyme patterns, and IAA and cytokinin production. Differences in enzyme activity and phytohormone production were prominent among the isolates. The patterns of acid phosphatase isozyme could be clearly divided into three host-related groups. Two polymorphic gene loci could be identified as coding for enzymes of acid phosphatase. Two of these gene loci, Acp-b and Acp-c, are characterized by mostly constant, host-dependent frequencies. The other, Acp-d, exhibits allele frequencies related to different habitats. Five isolates share the same Acp-a habitat. Four isolates share the Acp-b habitat, two the Acp-c habitat, and only one isolate, S-238, was from a high elevation at the Acp-d habitat. The isolate from a forest nursery differed strikingly in several characteristics from the other isolates, all of which were from a natural forest. This suggests that nursery soilmanagement practices may select for particular edaphic ecotypes of mycorrhizal fungi.

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Evaluation of Six Peanut Genotypes for Pod Rot Resistance1

Peanut Science ◽

10.3146/i0095-3679-11-1-15 ◽

1984 ◽

Vol 11 (1) ◽

pp. 49-52 ◽

Cited By ~ 1

Author(s):

Rodolfo Godoy ◽

Olin D. Smith ◽

T. E. Boswell

Keyword(s):

Rhizoctonia Solani ◽

Fruit Development ◽

The Other ◽

Pythium Myriotylum ◽

Stages Of Development ◽

Selection For ◽

Two Stages ◽

Adult Plants

Abstract Six genotypes (TxAG-3, PI 341885, Toalson, Starr, Florunner, and Goldin 1) were evaluated for reaction to Pythium myriotylum Drechs, and Rhizoctonia solani Kuhn in the greenhouse to: 1) confirm field results as to the relative disease reactions of the entries; 2) ascertain whether peg versus pod exposure to pathogens confounds selection for pod rot resistance; 3) examine the utility of greenhouse inoculation in screening for pod rot resistance; and 4) evaluate simultaneous screening of plants for reaction to these fungi. Adult plants were exposed at two stages of fruit development. TxAG-3 had significantly less pod decay from each organism singly and in combination at both times of exposure to the pathogens than did the other entries. Exposure to the pathogens at the pegging and pod-filling stages of development produced similar results.

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Response of the Leek (Allium porrum)-Mycorrhizal Fungus Symbiosis to Cutting Levels, Light Exposure and Seedling Density

European Journal of Biology and Biotechnology ◽

10.24018/ejbio.2021.2.3.184 ◽

2021 ◽

Vol 2 (3) ◽

pp. 1-6

Author(s):

G. Nowo Nekou ◽

A.-M. Sontsa-Donhoung ◽

. Hawaou ◽

M. Bahdjolbe ◽

R. Tobolbaï ◽

...

Keyword(s):

Mycorrhizal Fungi ◽

Light Exposure ◽

Mycorrhizal Fungus ◽

Arbuscular Mycorrhizal ◽

The Other ◽

Allium Porrum ◽

Seedling Density ◽

Positive Effects ◽

Other Hand ◽

The Impact

This work aims to assess the leek-arbuscular fungus symbiosis response to the effect of cutting and light exposure on the one hand, and the impact of seedling density on this symbiosis on the other hand. Allium Porrum was grown in a container in two different trials. Four species of arbuscular mycorrhizal fungi, Glomus hoi, Scutellospora gregaria, Rhizophagus intraradices and Gigaspora margarita were used to constitute the mycorrhizal inoculum. After 150 days of growth and inoculation, a series of cuts were made on the aerial part (0% = zero cut, 50% = half cut, 100% = whole cut). Plants that had undergone these treatments were placed in shade and sun for 30 days. The leek density per bag was varied by the order of 1, 2, 3 and 4 plant (s) by the pocket density test. Results showed that for 0% of cut in the shade, the vesicle occurrence decreases from 83.33% to 52.22%, and from 90% to 25.5% for 50% of cut in the shade. On the other hand, there is a significant increase in intra-root spores for a complete cut compared to other levels of cuts. For extra-root sporulation, under light, cuts have a negative and weak effect (from -11 to -3%) while in the absence of light, cuts have significant positive effects (from +16 to +61%). Regarding seedling density, the best root colonization (90%) and biomass production (14 g) are obtained with three plants per pot, but it is rather with a density of two plants per pot that extra-root sporulation is higher (153 spores/g). Variation in light, cut level and density significantly affects the development of mycorrhizal fungi.

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Introduction, growth and persistence in situ of orchid mycorrhizal fungi

Australian Journal of Botany ◽

10.1071/bt06073 ◽

2007 ◽

Vol 55 (6) ◽

pp. 665 ◽

Cited By ~ 10

Author(s):

Penelope S. Hollick ◽

Jen A. McComb ◽

Kingsley W. Dixon

Keyword(s):

Seed Germination ◽

Mycorrhizal Fungi ◽

Mycorrhizal Fungus ◽

Growing Season ◽

Summer Drought ◽

Orchid Species ◽

The Third ◽

Orchid Mycorrhizal Fungi ◽

Germination And Growth

The introduction, growth and persistence of orchid mycorrhizal fungi in situ were studied by using a seed-baiting method. A mycorrhizal fungus from the carousel spider orchid, Caladenia arenicola (Hopper & A.P.Br.), was introduced to sites within an area from which the orchid and fungus were absent, adjacent to a natural population of C. arenicola. In the first growing season, the fungus grew up to 50 cm from its introduction point, usually persisted over the summer drought into the second season and even into the third season, stimulating germination and growth to tuber formation of the seeds in the baits. Watering the inoculated areas significantly increased seed germination. This suggests that it is possible to reintroduce the mycorrhizal fungi either before or together with seeds of orchid species needing re-establishment in an area.

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Microscopic characterization of orchid mycorrhizal fungi: Scleroderma as a putative novel orchid mycorrhizal fungus of Vanilla in different crop systems

Mycorrhiza ◽

10.1007/s00572-017-0808-6 ◽

2017 ◽

Vol 28 (2) ◽

pp. 147-157 ◽

Cited By ~ 6

Author(s):

Ma. del Carmen A. González-Chávez ◽

Terry J Torres-Cruz ◽

Samantha Albarrán Sánchez ◽

Rogelio Carrillo-González ◽

Luis Manuel Carrillo-López ◽

...

Keyword(s):

Mycorrhizal Fungi ◽

Mycorrhizal Fungus ◽

Orchid Mycorrhizal Fungi

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Isotria medeoloides, a North American Threatened Orchid: Fungal Abundance May Be as Important as Light in Species Management

Plants ◽

10.3390/plants10091924 ◽

2021 ◽

Vol 10 (9) ◽

pp. 1924

Author(s):

Dennis Whigham ◽

Melissa McCormick ◽

Hope Brooks ◽

Brian Josey ◽

Robert Floyd ◽

...

Keyword(s):

Plant Species ◽

Mycorrhizal Fungi ◽

Mycorrhizal Fungus ◽

Belowground Biomass ◽

Wide Distribution ◽

Canopy Tree ◽

Fungal Abundance ◽

Threatened Plant Species ◽

Orchid Mycorrhizal Fungi ◽

Isotria Medeoloides

The management of endangered or threatened plant species is difficult if protocols are not developed to propagate species for the purpose of restoration or the enhancement of existing populations. The management of endangered and threatened orchids is especially difficult because of the obligate interactions between orchids and orchid mycorrhizal fungi. Isotria medeoloides is a federally threatened forest-dwelling orchid species with a wide distribution in eastern North America. Seeds have not been successfully germinated and current management is based primarily on using subcanopy thinning to increase light in areas where monitoring demonstrates that populations are declining. We report the results of long-term monitoring efforts, canopy thinning, and orchid mycorrhizal fungus abundance studies at two locations in Virginia. The declining populations responded positively to the experimental and natural thinning of the canopy. At one site, the response was the result of understory canopy thinning. At the second site, the response was due to the natural death of a canopy tree. In light of the dramatic increase in fungal abundance following death of the canopy tree, we propose the Fungal Abundance Hypothesis as an additional approach to the management of endangered plant species. The removal of canopy trees in or adjacent to Isotria populations results in an increase in dead belowground biomass (i.e., roots of the dead canopy tree) that provides substrates for microbial growth, including orchid mycorrhizal fungi, that benefit Isotria.

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Effect of Vesicular–Arbuscular Mycorrhizal Fungi on Rooting of Sciadopitys verticillata Sieb & Zucc. Cuttings

HortScience ◽

10.21273/hortsci.30.1.133 ◽

1995 ◽

Vol 30 (1) ◽

pp. 133-134 ◽

Cited By ~ 6

Author(s):

D.D. Douds ◽

G. Bécard ◽

P.E. Pfeffer ◽

L.W. Doner ◽

T.J. Dymant ◽

...

Keyword(s):

Arbuscular Mycorrhizal Fungi ◽

Host Plant ◽

Mycorrhizal Fungi ◽

Arbuscular Mycorrhizal Fungus ◽

Mycorrhizal Fungus ◽

Arbuscular Mycorrhizal ◽

Root Number ◽

Vesicular Arbuscular Mycorrhizal Fungi ◽

Vesicular Arbuscular ◽

Sciadopitys Verticillata

A vesicular–arbuscular mycorrhizal fungus in a peat-based medium significantly increased survival, callus development, and rooting percentage of Sciadopitys verticillata cuttings over noninoculated cuttings. The presence of a nurse host plant for the mycorrhizal fungi to colonize in the absence of S. verticillata roots decreased survival and rooting percentage, but not callus development, relative to the fungus without the nurse host. Among plants that did produce roots, however, there were no significant differences among treatments for root number, weight, or length per cutting.

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