357 research outputs found
Commentaire sur une étude récente de Handley : Mycorhizes et reboisement des landes à Calluna vulgaris
Widespread association between the ericoid mycorrhizal fungus Rhizoscyphus ericae and a leafy liverwort in the maritime and sub-Antarctic
A recent study identified a fungal isolate from the Antarctic leafy liverwort Cephaloziella varians as the ericoid mycorrhizal associate Rhizoscyphus ericae. However, nothing is known about the wider Antarctic distribution of R. ericae in C. varians, and inoculation experiments confirming the ability of the fungus to form coils in the liverwort are lacking.
Using direct isolation and baiting with Vaccinium macrocarpon seedlings, fungi were isolated from C. varians sampled from eight sites across a 1875-km transect through sub- and maritime Antarctica. The ability of an isolate to form coils in aseptically grown C. varians was also tested.
Fungi with 98â99% sequence identity to R. ericae internal transcribed spacer (ITS) region and partial large subunit ribosomal (r)DNA sequences were frequently isolated from C. varians at all sites sampled. The EF4/Fung5 primer set did not amplify small subunit rDNA from three of five R. ericae isolates, probably accounting for the reported absence of the fungus from C. varians in a previous study. Rhizoscyphus ericae was found to colonize aseptically-grown C. varians intracellularly, forming hyphal coils.
This study shows that the association between R. ericae and C. varians is apparently widespread in Antarctica, and confirms that R. ericae is at least in part responsible for the formation of the coils observed in rhizoids of field-collected C. varians
Presence of three mycorrhizal genes in the common ancestor of land plants suggests a key role of mycorrhizas in the colonization of land by plants
âą The colonization of land by plants fundamentally altered environmental conditions on earth. Plantâmycorrhizal fungus symbiosis likely played a key role in this process by assisting plants to absorb water and nutrients from soil. âą Here, in a diverse set of land plants, we investigated the evolutionary histories and functional conservation of three genes required for mycorrhiza formation in legumes and rice ( Oryza sativa ), DMI1 , DMI3 and IPD3 . âą The genes were isolated from nearly all major plant lineages. Phylogenetic analyses showed that they had been vertically inherited since the origin of land plants. Further, cross-species mutant rescue experiments demonstrated that DMI3 genes from liverworts and hornworts could rescue Medicago truncatula dmi3 mutants for mycorrhiza formation. Yeast two-hybrid assays also showed that bryophyte DMI3 proteins could bind to downstream-acting M. trunculata IPD3 protein. Finally, molecular evolutionary analyses revealed that these genes were under purifying selection for maintenance of their ancestral functions in all mycorrhizal plant lineages. âą These results indicate that the mycorrhizal genes were present in the common ancestor of land plants, and that their functions were largely conserved during land plant evolution. The evidence presented here strongly suggests that plantâmycorrhizal fungus symbiosis was one of the key processes that contributed to the origin of land flora.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78704/1/j.1469-8137.2009.03137.x.pd
Pteridophyte fungal associations : current knowledge and future perspectives
Current understanding of the nature and function of fungal associations in pteridophytes is surprisingly patchy given their key evolutionary position, current research foci on other earlyâbranching plant clades, and major efforts at unravelling mycorrhizal evolution and the mechanisms underlying this key interaction between plants and fungi. Here we provide a critical review of current knowledge of fungal associations across pteridophytes and consider future directions making recommendations along the way. From a comprehensive survey of the literature, a confused picture emerges: suggestions that members of the Lycopsida harbour Basidiomycota fungi contrast sharply with extensive cytological and recent molecular evidence pointing to exclusively Glomeromycota and/or Mucoromycotina associations in this group. Similarly, reports of dark septate, assumingly ascomycetous, hyphae in a range of pteridophytes, advocating a mutualistic relationship, are not backed by functional evidence and the fact that the fungus invariably occupies dead host tissue points to saprotrophy and not mutualism. The best conclusion that can be reached based on current evidence is that the fungal symbionts of pteridophytes belong to the two fungal lineages Mucoromycotina and Glomeromycota. Do symbiotic fungi and host pteridophytes engage in mutually beneficial partnerships? To date, only two pioneering studies have addressed this key question demonstrating reciprocal exchange of nutrients between the sporophytes of Ophioglossum vulgatum and Osmunda regalis and their fungal symbionts. There is a pressing need for more functional investigations also extending to the gametophyte generation and coupled with in vitro isolation and resynthesis studies to unravel the effect of the fungi on their host
Ecological study of a forest humus by observing a small volume I. Penetration of pine litter by mycorrhizal fungi
A la gloire de "hardis" Normands
Boullard Bernard. A la gloire de "hardis" Normands. In: Ătudes Normandes, 43e annĂ©e, n°1, 1994. Trois Normands. pp. 73-74
Provost Michel, Flore Vasculaire de Basse-Normandie, 1998
Boullard Bernard. Provost Michel, Flore Vasculaire de Basse-Normandie, 1998. In: Ătudes Normandes, 48e annĂ©e, n°3, 1999. Art et littĂ©rature en Normandie au XIXe siĂšcle. pp. 94-95
Au pays du camembert : HélÚne Mousser et Yannick Lecherbonnier (avec des photographies de P. Corbierre, F. Decaëns et J.-C. Jacques), Canton de Vimoutiers, une plaquette, Inventaire Général des Monuments et Richesses artistiques de la France, 1994
Boullard Bernard. Au pays du camembert : HĂ©lĂšne Mousser et Yannick Lecherbonnier (avec des photographies de P. Corbierre, F. DecaĂ«ns et J.-C. Jacques), Canton de Vimoutiers, une plaquette, Inventaire GĂ©nĂ©ral des Monuments et Richesses artistiques de la France, 1994. In: Ătudes Normandes, 46e annĂ©e, n°4, 1997. DĂ©putĂ©s des Villes et DĂ©putĂ©s des Champs. pp. 81-82
Nos moulins ont leur histoire (Michel HĂ©bert, La belle histoire des moulins de France - et de Normandie -, Ă vent et Ă eau, 2000)
Boullard Bernard. Nos moulins ont leur histoire (Michel HĂ©bert, La belle histoire des moulins de France - et de Normandie -, Ă vent et Ă eau, 2000). In: Ătudes Normandes, 50e annĂ©e, n°2, 2001. Les Etudes Normandes ont 50 ans. p. 71
Etre ou ne pas ĂȘtre venu en Normandie : Philippe H.C. Vatinel, Promenades en Normandie avec un guide nommĂ© William Shakespeare, 1996
Boullard Bernard. Etre ou ne pas ĂȘtre venu en Normandie : Philippe H.C. Vatinel, Promenades en Normandie avec un guide nommĂ© William Shakespeare, 1996. In: Ătudes Normandes, 45e annĂ©e, n°3, 1996. De Gaulle et la Normandie. pp. 86-87
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