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To determine the dominant processes controlling nitrogen (N) dynamics in soils and increase insights into soil N cycling from nitrogen isotope (?15N) data, patterns of 15N enrichment in soil profiles were compiled from studies on tropical, temperate, and boreal systems. The maximum 15N enrichment between litter and deeper soil layers varied strongly with mycorrhizal fungal association, averaging 9.6 � 0.4? in ectomycorrhizal systems and 4.6 � 0.5? in arbuscular mycorrhizal systems. The 15N enrichment varied little with mean annual temperature, precipitation, or nitrification rates. One main factor controlling 15N in soil profiles, fractionation against 15N during N transfer by mycorrhizal fungi to host plants, leads...
* • Relative abundances of carbon and nitrogen isotopes in fungal sporocarps are useful in assessing mycorrhizal or saprotrophic status, and might provide insights into the evolutionary history of these traits. * • Sporocarps of known mycorrhizal or saprotrophic genera were collected at Woods Creek, OR, USA, and isotopically compared with foliage, litter, soils and wood collected from the same site. Possible trophic strategies were then isotopically assessed in archived specimens of the Pezizales of known molecular phylogeny from the western United States. * • At Woods Creek, mycorrhizal fungi were 3.5‰ ± 0.6‰ depleted in δ13C and 5.7‰ ± 0.4‰ enriched in δ15N compared with saprotrophic fungi. By...
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Although research has shown that root associated fungi (RAF) are necessary for plant success in harsh environments, few studies have examined RAF community variability between different plant species coexisting in arid habitats. We compared the diversity and composition of the fungal communities colonizing dominant and important forage grasses, Bouteloua gracilis and Sporobolus cryptandrus, inhabiting the Sevilleta National Wildlife Refuge, a semiarid grassland in New Mexico. A third sympatric plant, Yucca glauca (Agavaceae), also was analyzed. ITS rDNA from roots, collected and amplified in 2007, yielded 447 fungal sequences. Sequences obtained from all three species suggest that grasses share a core group of RAF...
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We studied the diversity of arbuscular mycorrhizal fungi (AMF) in semiarid grassland and the effect of long-term nitrogen (N) fertilization on this fungal community. Root samples of Bouteloua gracilis were collected at the Sevilleta National Wildlife Refuge (New Mexico, USA) from control and N-amended plots that have been fertilized since 1995. Small subunit rDNA was amplified using AMF specific primers NS31 and AM1. The diversity of AMF was low in comparison with other ecosystems, only seven operational taxonomic units (OTU) were found in B. gracilis and all belong to the genus Glomus. The dominant OTU was closely related to the ubiquitous G. intraradices/G. fasciculatum group. N-amended plots showed a reduction...
    map background search result map search result map A general suite of fungal endophytes dominate the roots of two dominant grasses in a semiarid grassland Effect of long-term nitrogen fertilization on mycorrhizal fungi associated with a dominant grass in a semiarid grassland A general suite of fungal endophytes dominate the roots of two dominant grasses in a semiarid grassland Effect of long-term nitrogen fertilization on mycorrhizal fungi associated with a dominant grass in a semiarid grassland