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Project Number: WVA00136 ECOTYPIC VARIATION IN ECTOMYCORRHIZAL FUNGI FROM SERPENTINE SOILS Investigators: Cumming, J.R.,
and Panaccione, D.G. Termination Date: 08/31/2000 Progress Report: We are: (i) developing genetic markers for ectomycorrhizal fungi to aid in the identification and assessment of diversity of genotypes from unique, serpentine environments; (ii) investigating the influence of serpentine soil factors (high magnesium and nickel) on fungal and tree physiology, including the operation of metal detoxification systems; and (iii) assessing the ability of selected fungi to confer serpentine soil tolerance to Virginia pine seedlings. We established six plots on serpentine soils (Virginia pine scrub forest) and closely associated non-serpentine soils (northern red oak forest) at the Soldiers Delight Environmental Area in Owings Mills, Maryland. In addition, an "outgroup" plot was established on non-serpentine soils (chestnut oak forest) at Piney Run State Park in Eldersburg, Maryland (six miles distant). On these plots, we have sampled soils and foliage; chemical analyses on these samples are pending. In the summer and fall of 1998, we visited these sites regularly and identified and collected mushrooms as an estimate of fungal diversity and as a source of isolates for physiological studies on metal tolerance. To date, the genera Amanita and Russula have produced the majority of basidiocarps on these sites. We have been unsuccessful at culturing Russula species, which is expected, but have cultured numerous isolates of a large number (13) of Amanita species. We also collected micorrhizae from the study sites for more accurate assessment of fungal species diversity. We have developed DNA fingerprints from cultured fungi, mushrooms, and micorrhizae. We have generated a DNA fingerprint database from 32 identified mycorrhizal fungal species that can be used to identify fungi on roots (on the basis of fingerprint comparisons) without further culture or fruiting. Fungal diversity on the serpentine sites versus control sites is being assessed by amplifying fungal DNA directly from mycorrhizae. To study the contribution of the plant genotype to success on serpentine soils, Virginia pine seedlings were grown in a greenhouse and exposed to a set of soil solution factors designed to reflect serpentine environments. Seedlings from a range-wide seed collection and from a serpentine soil population were compared. Nickel reduced seedling root and shoot growth and foliar chlorophyll concentrations, although these effects were diminished by high magnesium availability. There were no differences between populations in their responses to nickel, suggesting that the trees growing naturally on serpentine soils are not an adapted subpopulation of the species as a whole. This finding supports our hypothesis that ectomycorrhizal fungi protect the roots, and tree growth, on serpentine soils. Publications: No publications reported. 1998.
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