Biology of the ectomycorrhizal genus, Rhizopogon

Abstract

Seedlings oi Pseudotsuga menziesii (Mirb.) Franco, Pinus ponderosa Dougl. ex Laws, Arbutus fMeHSi' eiiV Pursh., and cuttings of Arctostaphylos uva-ursi (L.) Spreng were grown in monoculture and in conifer-hardwood dual-culture combinations in the glasshouse and inoculated with spore slurries of six Rhizopogon species. The primar\' objectives were to assess and compare the pattern of host specificity between symbionts and to study the infiuence of co-cultured plants on ectomycorrhiza development. The Rhisopogon spp. ranged from genus-specific to multiple-host compatible, ln monoculture, four

Arbutus menziesii (Ericaceae) facilitates regeneration dynamics in mixed evergreen forests by promoting mycorrhizal fungal diversity and host connectivity

“…In contrast, the number of unique Inocybe taxa in the mixed forest was four times higher than in the pure forest (8 vs. 2). The importance of neighboring plants on mycorrhizal composition was highlighted by Molina et al (1992) and experimentally A. menziesii roots in the pure forest, both of which belonged to the same Rhizopogon lineages experimentally examined by Molina et al (1997) (our present study's Rhizopogon sp. 1 = R. salebrosus and Rhizopogon sp.…”

Biology of the ectomycorrhizal fungal genus, Rhizopogon

“…In past studies, ectomycorrhizas have been synthesized between several Pinus species and different Rhizopogon species (see Molina & Trappe, 1994, for a complete listing) ; R. luteolus, R. roseolus and R. rubescens have received the most attention. In most of these studies, however, the morphological and anatomical descriptions of RhizopogonjPinus are general in nature, and focus on mantle colours, textures and layering, and the presence and extent of Hartig net development (Modess, 1941 ;Bjo$ rkman, 1947 ;Fontana & Centrella, 1967 ;Pachlewski & Pachlewska, 1968, 1974Froidevaux & Amiet, 1975 ;Molina & Trappe, 1982Massicotte et al, 1994 ;Molina et al, 1997). An exception is the thorough description of Rhizopogon luteolusjPinus sylvestris by Uhl (1988) and Rhizopogon subcaerulescensjTsuga heterophylla by Agerer et al (1996).…”

Diversity and host specificity of ectomycorrhizal fungi retrieved from three adjacent forest sites by five host species

“…Type RWP on ponderosa pine is particularly interesting because, compared with BCl, it was dominant on ponderosa pine in all soils. In a sporeinoculation trial, Molina et al (1997) found that three Rhizopogon species (R. ellenae Smith, R. occidentalis Zeller & Dodge, and R. subcaerulescens Smith), restricted to ponderosa pine in single-host culture, were able to colonize madrone in dual culture. Further evidence of companion plant influence with respect to Rhizopogon was reported for a mixed-host assay of plantation forest soils using Douglas-fir, western hemlock (Tsuga heterophylla (Raf.)…”

“…For example, following severe fire disturbance in southwestern Oregon forest communities, ectomycorrhizal hardwoods in the genera Arbutus, Quercus, Arctostaphylos, and Lithocarpus resprout from buried rootstocks and quickly revegetate sites, thereby maintaining ectomycorrhizal fungus populations and rhizosphere processes important to development of late-seral ectomycorrhizal conifers in genera such as Pseudotsuga, Abies, and Pinus. Similar rhizosphere functions of Arctostaphylos have been suggested in other forest ecosystems (Danielson 1984;Visser 1995;Dahlberg 1990; Molina et al 1997). Perry et al (1989) hypothesize that the ectomycorrhizal hardwoods and conifers operate as a guild wherein members form with compatible mycorrhizal mutualists and participate in processes that are beneficial to the resilience and sustainability of the forest type.…”

“…Thus, field-oriented evaluation of ectomycorrhizal host-fungus compatibility may reveal a higher degree of specificity than pure culture syntheses. For example, Massicotte et al (1994) and Molina et al (1997) found that mycorrhizal formation by several Rhizopogon species differed on various hosts depending on whether the mycorrhizal fungus was supported by a neighboring host plant. Smith et al (1995), Simard et al (1997b), and Jones et al (1997) further reported that neighboring plants influenced the frequency of occurrence and abundance of mycorrhizal development for specific ectomycorrhizal types.…”