Classification of Ectomycorrhizae

SUMMARYIn order to assess the factors influencing the extent and composition of ectomycorrhizal infection, and the consequences for seedling growth, seedlings of oak {Quercus robur L,) and birch {Betula pendula Roth,) were established in both field plots and pots of soil from two forested sites (Thetford Chase and Leith Hill), Seedlings were harvested after one growing season, and analysed for ectomycorrhizal infection.When a single root system of pot-grown oak was analysed in detail seven mycorrhizal types were differentiated. The relative abundance of these types varied depending on whether infection was assessed by counting branched mycorrhizas, or individual mycorrhizal tips. This reflected variation in the pattern of branching of the different mycorrhizal types. Of the 41 mycorrhizal types differentiated in the entire survey of 1800 seedlings, five were consistently recorded as unbranched, and six were found to produce second-order branches. Different mycorrhizal types displayed contrasting patterns of abundance, both with respect to site and host species. For example, 21 types were recorded infecting oak, whereas only 15 were found on birch; only three types were found infecting both oak and birch on both sites.In this survey, seedlings tended to be dominated by between one and three mycorrhizal types. Two types were particularly dominant: those formed by Scleroderma citrinum (Pers,) and Paxillus involutus (Batsch) Fr,, which accounted for up to 61 and 92 % of the mycorrhizas of oak and birch respectively. These fungi were exceptional amongst those encountered in the present analysis, in producing both highly branched mycorrhizas and mycelial strands.The relationship between ectomycorrhizal infection and seedling growth was assessed by correlation. Total seedling dry mass was in general found to be positively correlated with the total number of ectomycorrhizal tips, but poorly correlated with the extent of ectomycorrhizal infection, except where seedling growth had previously been shown to be limited by phosphate availability (i,e, in the case of pot-grown birch on soil from Leith Hill), Seedling dry mass was also in general poorly correlated with number of mycorrhizal types, with two exceptions (i,e, field-grown oak and pot-grown birch on soil from Thetford Chase), These results are discussed in the context of the role of ectomycorrhizal infection during seedling establishment, and implications for the methodologies utilized in assessing mycorrhizal infection are highlighted.

Section: Discussionmentioning

confidence: 99%

Mineral nutrition and mycorrhizal infection of seedling oak and birch

Newton

1991

“…This genus is considered to have an affinity w^ith Cenoeoccum geophilum which may be its imperfect stage (Trappe, 1971). Although C. geophilum and Elaphomyees were ectomycorrhizal on most species studied (Trappe, 1964), C. geophilum may also cause intracellular infection (Mikola, 1948) and Zak (1973) observed that a given fungus can be either ectomycorrhizal or ectendomycorrhizal on different hosts. The absence of a Hartig net in Hysterangium spp.…”

Section: Specificitymentioning

confidence: 99%

In vitro synthesis of ectomycorrhizas on Casuarinaceae with a range of mycorrhizal fungi

Theodorou

Reddell

1991

SUMMARYEleven species of mycorrhizal fungi, selected from stands of either Eucalyptus spp., Allocasuarina spp, or Pinus radiata D, Don were tested in an aseptic system for their abilities to initiate ectomycorrbiza with Allocasuarina littoratis (Salisb,) The comparative intensity of ectomycorrhizal infection by P. tinctorius and L. laecata was assessed on four host species. Infection intensity ranged from 13 to 70'V, of laterals infected and decreased for both fungal species in the order: A. littoralis > Eucalyptus pilularis Smith > C. equisetifolia > C. cunninghamiana.An exogenous supply of glucose induced greater and sometimes earlier, ectomycorrhizal infection of A. littoralis, C. equisetifolia and C. cunninghamiana by P. tinctorms and /.., laecata tban tbat in the absence of giucose. Tbe optimum glucose level for tbese fungi and bosts in tbis synthesis system was 750/^g glucose (g soil)"'.

“…was affected by soil types and soil compaction. Zak (1973) has given much attention to shape and colour of hyphal strands in characterizing and identifying the ectomycorrhizae produced by different fungi. Foster (1981) described the ultrastructures of hyphal strands formed under field conditions as well as in glass-sided boxes in the glasshouse.…”

Section: Introductionmentioning

confidence: 99%

DEVELOPMENT OF MYCORRHIZAE, EXTRAMATRICAL MYCELIUM AND SCLEROTIA ON PINUS STROBUS SEEDLINGS

Piché¹,

Fortin

1982

SUMMARYOn Pinus strobus seedlings cultured in growth pouches successful ectomycorrhiza formation took place upon inoculation with Pisolithus tinctorius, Cenococcum geophitum, Suillus granulatus, Suillus tomentosus, Paxillus involutus, Hebeloma cylindrosporum and Thelephora terrestris.Under the conditions used ectomycorrhizae formed within 2 weeks and some of them, P. tinctorius, P. involutus and T. terrestris, developed mantles and Hartig nets in less than 5 days. Mycelial strand formation took place around the root system of P. strobus 2 weeks after inoculation with P. tinctorius. Sampling on the 93rd day revealed no difference in ectomycorrhizal formation or the development of mycelial strands and sclerotia hetween root systems that were or were not illuminated. However, low light intensities on the aerial parts of the seedlings reduced the mycelial strands and sclerotia formation.Variation of nitrogen and phosphorus concentration added to the pouches were also studied.