Ecological and anatomical characterization of some Pinus patula ectomycorrhizas from Mpumalanga, South Africa

Ectomycorrhizal (ECM) fungi are an important component of the Pinus patula Schlechdt, et Cham. forest ecosystem in Mpumalanga, South Africa. ECM roots are intimately associated with accumulated litter on the forest floor and four ECM isolates where examined to determine whether they provide plant ac cess to inorganic and organic sources of nitrogen (N) and inorganic, comple xed inorganic and organic sources of phosphorus (P). In in vitro studies, a ll isolates were found to utilize most of the organic N compounds and organ ic or complexed inorganic P compounds supplied. Thus, ECM fungi could play a significant role in providing N and P to P. patula, especially from sourc es to which the host plant would not normally have access. Temperature sens itivities and pH optima of the four isolates differed. Of the ECM isolates WITS 01 and WITS 06 were collected from a high-litter site; WITS 01 mycorrh izas, identified as Scleroderma citrinum, were white, smooth and dichotomou sly branched with smooth, pale yellow, differentiated rhizomorphs. The mant le was plectenchymatous with outer and inner layers showing ring-like arran gements of hyphal bundles. The Hartig net had a palmetti shape. The WITS 02 (not identified) mycorrhizas were brown with lighter coloured root tips, w ith simple to dichotomous branching, smooth with no distinct mantle and spa rse hyphae occurred on the root surface. The Hartig net was palmetti type w ith lobed haustoria. The results are discussed in relation to ECM distribut ion and function in nutrient cycling.