Origin and diversification of endomycorrhizal fungi and coincidence with vascular land plants

Simon, L.; Bousquet, Jean; Lévesque, Roger C.; Lalonde, M.

doi:10.1038/363067a0

Cited by 690 publications

(359 citation statements)

References 12 publications

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“…27). The first contributions of molecular biology to the field of arbuscular mycorrhizas have covered topics more related to taxonomy, molecular ecology and phylogeny (Simon et al, 1993;Wyss & Bonfante, 1993;Lanfranco et al, 1994). The use of molecular techniques to search for functional genes controlling fungal morphogenesis, the infection process and the metabolism of mycorrhizal roots is still in its infancy.…”

Section: Resultsmentioning

confidence: 99%

“…Arbuscular mycorrhizal fungi belong to a small order within the Zygomycetes, the Glomales, whose origin has been dated to 353-452 million years ago (Simon et al, 1993) and which has been suggested to be instrumental in colonization of the land by ancient plants (Pirozynski & Malloch, 1975), The close relationship of AM fungi with their host plants is mirrored by their obligatory biotrophic status. In absence of the host, their growth is limited to a relatively short time (20-30 d), after which many modifications in fungal morphology, such as retraction of the cytoplasm from the apices, production of septa, development of lateral branches and swelling of the apices, point to a cessation of hyphal growth.…”

Section: N Fungal Growth and Activation Of The Cell Cyclementioning

confidence: 99%

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Tansley Review No. 82. Strategies of arbuscular mycorrhizal fungi when infecting host plants

1995

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summary Arbuscular mycorrhizal (AM) fungi are ancient Zygomycetes, thought to have colonized the first land plants; today, they are associated with the roots of about 80% of plant species. The symbiosis they form is potentially valuable not only for developmental programmes based on low‐input agriculture, but also as a complex experimental model, where both fungal and host plant growth are regulated. Here we review some recent progress m the area of cell and molecular biology of arbuscular mycorrhizas. Particular attention is given to strategies followed by AM fungi when, as obligate biotrophs, they establish a successful symbiosis with their host plants. Four topics are analysed: (i) parameters controlling fungal growth in the absence and presence of the host root, Le. events of DNA replication and timing of the cell cycle; (ii) mechanical and enzymatic mechanisms which allow the fungus to colonize root tissues, maintaining host viability; (iii) morphological changes induced by AM fungus host cells and, in particular, the formation de novo of a subcellular compartment termed the interface, and (iv) modifications of plant gene expression during fungal colonization, including those involving structural, symbiotic and defence‐related genes.

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Section: Resultsmentioning

confidence: 99%

Section: N Fungal Growth and Activation Of The Cell Cyclementioning

confidence: 99%

Tansley Review No. 82. Strategies of arbuscular mycorrhizal fungi when infecting host plants

1995

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“…There was strong evidence for trait conservation in root infection by pathogenic fungi, with this trait being expressed at much higher levels in the Glomeraceae. Fossil evidence suggests that endophytic fungi were common in early root-like structures (Taylor & Osborn 1996) prior to the estimated divergence between the Glomerales and Diversisporales lineages (Simon et al 1993). Others have suggested that antagonism of pathogenic fungi may have been a function of primitive AM fungi (Brundrett 2002).…”

Section: Discussionmentioning

confidence: 99%

Phylogenetic trait conservatism and the evolution of functional trade-offs in arbuscular mycorrhizal fungi

et al. 2009

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The diversity of functional and life-history traits of organisms depends on adaptation as well as the legacy of shared ancestry. Although the evolution of traits in macro-organisms is well studied, relatively little is known about character evolution in micro-organisms. Here, we surveyed an ancient and ecologically important group of microbial plant symbionts, the arbuscular mycorrhizal (AM) fungi, and tested hypotheses about the evolution of functional and life-history traits. Variation in the extent of root and soil colonization by AM fungi is constrained to a few nodes basal to the most diverse groups within the phylum, with relatively little variation associated with recent divergences. We found no evidence for a trade-off in biomass allocated to root versus soil colonization in three published glasshouse experiments; rather these traits were positively correlated. Partial support was observed for correlated evolution between fungal colonization strategies and functional benefits of the symbiosis to host plants. The evolution of increased soil colonization was positively correlated with total plant biomass and shoot phosphorus content. Although the effect of AM fungi on infection by root pathogens was phylogenetically conserved, there was no evidence for correlated evolution between the extent of AM fungal root colonization and pathogen infection. Variability in colonization strategies evolved early in the diversification of AM fungi, and we propose that these strategies were influenced by functional interactions with host plants, resulting in an evolutionary stasis resembling trait conservatism.

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“…Arbuscular mycorrhizal fungi and land plants have co-evolved since the Devonian period (Simon et al, 1993 ;Taylor et al, 1995). Fossil evidence suggests that the ancestors of present land plants had poorly developed roots or rhizoids.…”

Section: mentioning

confidence: 99%

Branched absorbing structures (BAS): a feature of the extraradical mycelium of symbiotic arbuscular mycorrhizal fungi

et al. 1998

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The present work describes the morphogenesis and cytological characteristics of ' branched absorbing structures ' (BAS, formely named arbuscule-like structures, ALS), small groups of dichotomous hyphae formed by the extraradical mycelium of arbuscular mycorrhizal (AM) fungi. Monoxenic cultures of the AM fungus Glomus intraradices Smith & Schenck and tomato (Lycopersicum esculentum Mill.) roots allowed the continuous, nondestructive study of BAS development. These structures were not observed in axenic cultures of the fungus under different nutritional conditions or in unsuccessful (asymbiotic) monoxenic cultures. However, extraradical mycelium of G. intraradices formed BAS immediately after fungal penetration of the host root and establishment of the symbiosis. The average BAS development time was 7 d under our culture conditions, after which they degenerated, becoming empty septate structures. Certain BAS were closely associated with spore formation, appearing at the spore's substending hypha. Branches of these spore-associated BAS (spore-BAS) usually formed spores. Electron microscopy studies revealed that BAS and arbuscules show several ultrastructural similarities. The possible role of BAS in nutrient uptake by the mycorrhizal plant is discussed.

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Origin and diversification of endomycorrhizal fungi and coincidence with vascular land plants

Cited by 690 publications

References 12 publications

Tansley Review No. 82. Strategies of arbuscular mycorrhizal fungi when infecting host plants

Tansley Review No. 82. Strategies of arbuscular mycorrhizal fungi when infecting host plants

Phylogenetic trait conservatism and the evolution of functional trade-offs in arbuscular mycorrhizal fungi

Branched absorbing structures (BAS): a feature of the extraradical mycelium of symbiotic arbuscular mycorrhizal fungi

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