Biology of the ectomycorrhizal fungal genus, Rhizopogon

Abstract

The morphology and anatomy of ectomycorrhizas of Rhizopogon arctostaphyli, R. ellenae, R. flavofibrillosus, R. occidentalis, R. rubescens, R. smithii, R. subcaerulescens and R. truncatus synthesized on Ponderosa pine (Pinus ponderosa) in glasshouse conditions using spore slurries, are described and compared. All species produced a well‐developed Hartig net, and a well‐developed fungal mantle. The mantles of R. arctostaphyli, R. smithii and R. subcaerulescens ectomycorrhizas were two‐layered with outer mantle hyphae of wider diameter than inner mantle hyphae. The mantle of R. subcaerulescens ectomycorrhizas also had distinctive peg‐like structures (cystidia) along peripheral hyphae. Rhizopogon truncatus ectomycorrhizas were tuberculate in morphology and had a rind‐like mantle enclosing adjacent roots. In addition, several species exhibited crystal inclusions in the outer mantle, presumably at the interface between mantle and soil.

Morpho-anatomical characterization of Rhizopogon himalayensis - Cedrus deodara mycorrhiza

“…In the present study it was also observed that the hyphal mantle underwent considerable variations as the colonization progressed like an initially thin and segregated mantle was replaced by a regular uniform mantle with two distinct layers of the different hyphal constitution: thinner and compacted hyphae in inner mantle relative to loosely aggregated hyphae in the outer mantle. Present observations are in analogy with the findings of a previous study that described two-layered subcaerulescens ectomycorrhizas synthesized on Pinus ponderosa in a glasshouse condition (Massicotte et al, 1999). Similarly, a two-layered mantle with loosely interwoven hyphae in outer mantle and compacted hyphae in inner mantle was seen in ectomycorrhiza of R. rubescens-Pinus sylvestris (Pachlewski and Pachlewska, 1974).…”

“…In the present study, root morphology in ectomycorrhiza of R. himalayensis and C. deodara roots was found to be analogous to the observations of Singh (1992), who noticed racemose to coralloid branching in this association. Similar branching was illustrated in various mycorrhizal associations of Rhizopogon species, for instance, coralloid in R. vulgaris-Pinus contorta Agerer et al, 1996); monopodial to dichotomous in R. subcaerulescens -Pseudotsuga menziesii (Massicotte et al, 1999); pinnate in R. vinicolor and R. parksii with P. menziesii (Massicotte, et al, 2000). Although, different root morphologies have also been reported in other Rhizopogon species, i.e.…”

“…For instance, a definite fungal mantle organized into three layers was observed in ectomycorrhiza of R. verii growing under Pinus sylvestris (Sulzbacher et al, 2016). In another example, a thin and undifferentiated mantle was observed in R. ellenae and R. rubescens ectomycorrhiza on Pinus ponderosa (Massicotte et al, 1999). In most of the ectomycorrhizal associations of Rhizopogon species with Pinus ponderosa as well as in R. parksii-Pseudostuga, the hyphal mantle was plectenchymatous and clamp connections were absent in mantle hyphae or emanating elements (Massicotte et al, 1994).…”

Phosphorus disequilibrium in the tripartite plant-ectomycorrhiza-plant growth promoting rhizobacterial association

“…Culture studies have noted distinct host-EcM specificities. Massicotte et al (1994) noted strong mycorrhization preferences among six tree species and 15 EcM fungal species, with none of the fungi having broad host ranges. However, a study of host-EcM fungal specificity among five tree species grown in soil indicated that specificity is significantly less strict, but still present (Massicotte et al, 1999).…”