Ectomycorrhizal symbioses in eucalyptus deep roots: new insights on the understanding of the mycorrhizal fungi ecology

Abstract

Several field observations suggest that ectomycorrhizal fungi (ECMF) contribute to a number of key ecosystem functions such as carbon cycling, nutrient mobilization from soil organic matter and soil minerals, and water dynamics, and may form symbiotic associations with species of great economic importance, such as Eucalyptus and Pinus. However, the ecology of these fungi in planted forests in tropical areas is not well understood. This project aims to determine whether or not ectomycorrhiza (ECM) occurs in intact deep roots of Eucalyptus grandis, by assessing the influence of soil depth on the total percentage of fine roots colonized. The experiment is being carried out at the Itatinga Experimental Station (University of São Paulo) using a 4-year-old E grandis plantation representative of commercial plantations in Brazil, in a Ferralsol. Soil sampling was performed in May 2013 after digging an 8 m deep trench for sampling fine roots at different depths to be certain that the sampled roots and ECM in each soil layer did not experience any disturbance. Four samples were collected for each soil layer, and 20 fine roots per sample were selected for observation and identification of the ECM under the microscope. After identifying ECM tips, total DNA will be extracted and a fragment of the 18S rRNA ITS region will be amplified by PCR and ITS sequences will be compared to sequences in the NCBI's GenBank and UNITE databases for identification of each taxon. The structures of the ECMF communities at different depths will be compared and related to the environmental conditions under which the plants were grown. This project will provide new insights into the ecology of ECMF and the importance of ECM in eucalyptus plantations (AU)