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In contact with soil, copper (Cu) formulations as preservatives are expected to inhibit wood decay by fungi and other soil-borne microorganisms. However, Cu-resistant brown-rot (BR) fungi lead to premature failures of utility poles at some sites. In this study, the service lives of 111 utility poles of Norway spruce (Picea abies (L.) H. Karst) (73 from Switzerland and 38 from Germany) impregnated with Cu-based wood preservatives were investigated. Three segments of each utility pole were analyzed. The severity of decay was dependent on the preservative formulation. BR fungi and in particular Antrodia species were predominantly isolated from utility poles that were not treated with a co-biocide, e.g. boron (B). Cu-sensitivity of several isolated BR fungi was confirmed in studies on Cu-amended medium and in Cu-treated wood. Isolates of Fibroporia vaillantii and Serpula himantioides showed a higher Cu-tolerance than the highly Cu-tolerant Empa isolate Rhodonia placenta (Empa 45) or Antrodia serialis.

[EN] The production of new generation of wood preservatives (without addition of a co-biocide) in combination with an exchange of wood poles on identical sites with high fungal inoculum, has resulted in an increase of premature failures of wood utility poles in the last decades. Wood destroying basidiomycetes inhabiting sites where poles have been installed, have developed resistance against wood preservatives. The objective of the in vitro studies was to identify a Trichoderma spp. with a highly antagonistic potential against wood destroying basidiomycetes that is capable of colonizing Cu-rich environments. For this purpose, the activity of five Trichoderma spp. on Cu-rich medium was evaluated according to its growth and sporulation rates. The influence of the selected Trichoderma spp. on wood colonization and degradation by five wood destroying basidiomycetes was quantitatively analyzed by means of dry weight loss of wood specimens. Furthermore, the preventative effect of the selected Trichoderma spp. in combination with four Cu-based preservatives was also examined by mass loss and histological changes in the wood specimens. Trichoderma harzianum (T-720) was considered the biocontrol agent with higher antagonistic potential to colonize Cu-rich environments (up to 0.1% CuSO4 amended medium). T. harzianum demonstrated significant preventative effect on wood specimens against four wood destroying basidiomycetes. The combined effect of T. harzianum and Cu-based wood preservatives demonstrated that after 9 months incubation with two wood destroying basidiomycetes, wood specimens treated with 3.8 kg m-3 copper-chromium had weight losses between 55±65%, whereas containers previously treated with T. harzianum had significantly lower weight losses (0±25%). Histological studies on one of the wood destroying basidiomycetes revealed typical decomposition of wood cells by brown-rot fungi in Cu-impregnated samples, that were notably absent in wood specimens previously exposed

The gradual elimination of chromium from wood preservative formulations results in higher Cu leaching and increased susceptibility to wood decay fungi. Finding a sustainable strategy in wood protection has become of great interest among researchers. The objective of these in vitro studies was to demonstrate the effect of T-720-enriched organic charcoal (biochar) against five wood decay basidiomycetes isolated from strongly damaged poles. For this purpose, the antagonistic potential of Trichoderma harzianum (strain T-720) was confirmed among other four Trichoderma spp. against five brown-rot basidiomycetes in dual culture tests. T-720 was genetically transformed and tagged with the green fluorescent protein (GFP) in order to study its antagonistic mechanism against wood decay basidiomycetes. It was also demonstrated that T-720 inhibits the oxalic acid production by basidiomycetes, a well-known mechanism used by brown-rot fungi to detoxify Cu from impregnated wood. Additionally, this study evaluated the effect of biochar, alone or in combination with T-720, on Cu leaching by different preservatives, pH stabilization and prevention of wood decay caused by five basidiomycetes. Addition of biochar resulted in a significant Cu binding released from impregnated wood specimens. T-720-enriched biochar showed a significant reduction of wood decay caused by four basidiomycetes. The addition of T-720-enriched biochar to the soil into which utility poles are placed may improve the efficiency of Cr-free wood preservatives.

El proyecto tiene como objetivo determinar cuáles son las condiciones más adecuadas para el proceso de extracción de ADN de material leñoso procedente de raíces, de manera que se realice con éxito la PCR, secuenciación y finalmente identificación de las especies utilizadas. El estudio se centra en la optimización del procedimiento llevado a cabo en el laboratorio de Botánica Forestal de la Universidad de Friburgo, al que se encuentra asociado un servicio de identificación de especies a través de material radical. Por lo tanto, se busca determinar qué tejidos de raíz y métodos de extracción proporcionan los mejores resultados en términos de rendimiento y pureza del ADN y de éxito en la PCR y en la identificación final. Para el estudio 4 pares de primers fueron utilizados en la PCR (ITS1-ITS4, ITS5-ITS4, trnL, psbA-trnH), y su eficacia fue comparada. Una vez obtenidas las muestras de raíces leñosas, el material es preparado distinguiendo dos tejidos: floema (corteza) y xilema (madera). A continuación, se realizan extracciones con diferentes métodos basados tanto en kits comerciales como en protocolos tradicionales CTAB; distintas modificaciones son realizadas en los protocolos buscando maximizar su efectividad. Tras las extracciones se recogen los datos de rendimiento de ADN y de pureza obtenida. Seguidamente se realiza la PCR con los extractos obtenidos y se determina su tasa de éxito mediante una electroforesis en gel que permite identificar el tamaño de los fragmentos logrados. Por último, las muestras de ADN que han mostrado una suficiente intensidad de bandas en el gel, son limpiadas y secuenciadas. Los resultados de la secuenciación son cotejados con los contenidos en la base de datos online GenBank utilizando el algoritmo de alineamiento BLAST para lograr la identificación de las muestras. El estudio analiza paralelamente otras cuestiones secundarias como el efecto de sucesivos ciclos de congelado y descongelado en la concentración de ADN y la relación entre la