Structure and diversity of "pathogenic" and "non-pathogenic" fungal endophyte community of Fagus sylvatica in the Mediterranean Basin
Author(s)
Ceccarelli, Barbara
Date Issued
February 2, 2011
Type
Doctoral Thesis
Abstract
This thesis has investigated diversity and distribution of "pathogenic" and "non-pathogenic" fungal endophyte communities in twigs, leaves and buds of Fagus sylvatica in beech Italian forest into Monte Cimino area. In last decade European beech has been subject to a number of biotic and abiotic stresses included the increasing impact of drought and, as a consequence, the impact of native parasites that attack weakened hosts. Among these, Biscogniauxia nummularia (Bull.) Kuntze, associated with severe beech-declines, has been studied for its importance as latent pathogen of healthy beech tissues. Understanding how fungal endophyte communities differ in abundance, diversity and taxonomic composition is key to understanding the ecology and evolutionary context of endophyte-plant associations. Fungal ITS sequences were used for validation of morphological identification and phylogenetic analysis. According to the ITS phylogeny, endophytes studied belong to the main non-parasitic and non-lichenised orders of Pezizomycotina. The effects of native tissue, site exposure, and season on endophyte assemblages were investigated. Native tissue was the major factor shaping endophyte assemblages. Exposure and seasonal differences played a significant but lesser role. Several recently developed molecular methods offer new tools for determining the presence and diversity of fungi in complex microbial communities. Terminal restriction fragment (TRF) pattern analysis was tested as a method for assessing the molecular diversity of endophyte fungal community within asymptomatic beech tissues. ITS ribosomal region of communities DNA isolated from ten beech twigs was amplified and then digested with MspI enzyme. The ITS region showed high degree of specificity in matching observed TRF profiles to those generated from GenBank sequence data for species identification. These data suggest that ITS rDNA TRF pattern analysis has great potential as a rapid and specific method for fungal community analysis and species identification. Results of quantitative Real-time PCR (Rt PCR) assay using DNA of B. nummularia isolated from different geographic areas were compared. The assay confirmed higher risk associated with our beech forest in Central Italy, compared to the other equal phyto-coenosis located at most latitudes, in terms of declining damages and loss of biodiversity.
Additional information
Dottorato di ricerca in Protezione delle piante
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