ULTRASTRUCTURE OF <i>PTEROSPORA ANDROMEDEA</i> NUTTALL AND <i>SARCODES SANGUINEA</i> TORREY MYCORRHIZAS

Robertson, Diane C.; Robertson, Jack A.

doi:10.1111/j.1469-8137.1982.tb03413.x

Cited by 53 publications

(32 citation statements)

References 23 publications

(31 reference statements)

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“…Mycorrhizal scientists no longer consider hyphal lysis an important means of nutrient transfer in balanced mycorrhizal associations (Smith & Smith, 1990), but lysis seems to be more important in exploitative associations. Exploitative associations have unique, highly complex interfaces that function by means that are not fully understood (Burgeff, 1959;Robertson & Robertson, 1982 ;Leake, 1994;Schmid & Oberwinkler, 1994;Rasmussen, 2002). Further work is required to determine how these mycorrhizas function.…”

Section: (3 ) Exploitative Mycorrhizal Associationsmentioning

confidence: 99%

Diversity and classification of mycorrhizal associations

2004

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Most mycorrhizas are ' balanced ' mutualistic associations in which the fungus and plant exchange commodities required for their growth and survival. Myco-heterotrophic plants have 'exploitative ' mycorrhizas where transfer processes apparently benefit only plants. Exploitative associations are symbiotic (in the broad sense), but are not mutualistic. A new definition of mycorrhizas that encompasses all types of these associations while excluding other plant-fungus interactions is provided. This definition recognises the importance of nutrient transfer at an interface resulting from synchronised plant-fungus development. The diversity of interactions between mycorrhizal fungi and plants is considered. Mycorrhizal fungi also function as endophytes, necrotrophs and antagonists of host or non-host plants, with roles that vary during the lifespan of their associations. It is recommended that mycorrhizal associations are defined and classified primarily by anatomical criteria regulated by the host plant. A revised classification scheme for types and categories of mycorrhizal associations defined by these criteria is proposed. The main categories of vesicular-arbuscular mycorrhizal associations (VAM) are 'linear' or 'coiling ', and of ectomycorrhizal associations (ECM) are ' epidermal ' or 'cortical '. Subcategories of coiling VAM and epidermal ECM occur in certain host plants. Fungus-controlled features result in ' morphotypes ' within categories of VAM and ECM. Arbutoid and monotropoid associations should be considered subcategories of epidermal ECM and ectendomycorrhizas should be relegated to an ECM morphotype. Both arbuscules and vesicles define mycorrhizas formed by glomeromycotan fungi. A new classification scheme for categories, subcategories and morphotypes of mycorrhizal associations is provided.

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Section: (3 ) Exploitative Mycorrhizal Associationsmentioning

confidence: 99%

Diversity and classification of mycorrhizal associations

2004

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“…Wall ingrowths have been observed within naturally grown mycorrhizas of Pisonia grandis R. Br. (Ashford & Allaway, 1982, 1985, of Monotropa hypopytis L. (Duddridge & Read, 1982), of Sarcodes sanguinea Torrey and Pterospora andromedea Nuttall (Robertson & Robertson, 1982). Monotropa, Sarcodes and Pterospora have monotropoid mycorrhizas, in which the transfer-cell wall ingrowths were only found on the fungal pegs.…”

Section: The Heavily-infected Rootsmentioning

confidence: 99%

Tuberculate mycorrhizas of Castanopsis horneensis King and Engelhardtia roxburghiana Wall

et al. 1991

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SUMMARYTuberculate mycorrhizas of Castanopsis borneensis King (Fagaceae) and Engelhardtia roxburghiana Wall, (Juglandaceae) were studied by light and electron microscopy. The tubercles of both trees showed similar structure and morphology. The fungal partner is an unidentified basidiomycete. Beside normally developed mycorrhizas in each tubercle some heavily-infected roots were found. These roots are characterized by a very thick hyphal mantle around a dead root tip and a circle-like ingrowth of the fungus up to the vascular tissue -the strangulation zone. All cells distal to the strangulation zone were dead, but basipetal to it, normal cortical tissue with an epidermal Hartig net was present. The outer cortex in this region showed wall ingrowths along the inner tangential walls and an accumulation of ER and mitochondria. The formation and function of the heavily-infected roots is discussed.

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“…The wall ingrowths surrounding the hyphae penetrating the basal walls of rhizoids recall the fungal pegs in monotropoid mycorrhizas (Robertson & Robertson, 1982;Duddridge & Read, 19826). However, in that case the fungus is a basidiomycete and the pegs in liverworts do not subsequently develop secondary wall ingrowths.…”

Section: Comparisons With Vascular Plant Mycorrhizasmentioning

confidence: 99%

A light and electron microscope study of rhizoid–ascomycete associations and flagelliform axes in British hepatics with observations on the effects of the fungi on host morphology

1991

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SUMMARYAscomycetous fungi, identified by the presence of simple septa and Woronin bodies, form a range of highly specialized associations with the unicellular rhizoids of 46 {16*2 °.Q) of the 284 species of British liverworts. The majority of these are in the two jungermannialian suborders Lepidoziineae and Cephaloziineae, Thirt\-three species (11'6 "o) also possess flagelliform axes. These extend to depths of 20-30 cnn in peaty substrata and in most species bear abundant fungus-infected rhizoids. When grown in sand or water culture, isolated from their natural substrata (sandstone rocks, peat, Sphagnum, rotten wood), the hepatics are free from rhizoid infections. On returning the plants to their native substrata, the rhizoid-fungus associations are re-established.Each rhizoid or fascicie of rhizoids is infected independently and a continuous strand of fungus-containing cells is absent. Internally the flagelliform axes contain elongate parenchyma cells with abundant plasmodesmata in their transverse end walls. The apices of the axes are invested by mucilage and subapical amyloplasts appear to act as graviperceptive particles.The morphology of the flagelliform axes and the ultrastructure of the rhizoid-fungus association varies greatly between taxa. The Lepidoziaceae and Calypogeiaceae produce fascicles of rhizoids from the bases of rudimentary leaves whereas the flagelliform axes in the Cephaloziaceae are leafless. In Cladopodiella the fungus forms a pseudoparenchymatous sheath around the tips of swollen rhizoids. Development of swollen rhizoids precedes fungal mfection in Lepidozia, Kurzia and Telaranea but not in other genera. Hyphae penetrating the basal walls of the rhizoids in Cephalozia, Nozvellia, Calypogeia and Odontoschisma are ensheathed by host wal! material. These diverse patterns of fungal infection suggest independent, and probably relatively recent, evolution in the various genera.The flagelliform axes in hepatics appear to be major organs of assimilation and perennation structurally and functionally analogous in the former capacity to vascular plant mycorrhizas and particularly the hairs roots in Ericaceae.

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ULTRASTRUCTURE OF PTEROSPORA ANDROMEDEA NUTTALL AND SARCODES SANGUINEA TORREY MYCORRHIZAS

Cited by 53 publications

References 23 publications

Diversity and classification of mycorrhizal associations

Diversity and classification of mycorrhizal associations

Tuberculate mycorrhizas of Castanopsis horneensis King and Engelhardtia roxburghiana Wall

A light and electron microscope study of rhizoid–ascomycete associations and flagelliform axes in British hepatics with observations on the effects of the fungi on host morphology

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