Anna Żółciak

Characterisation of some Phlebiopsis gigantea isolates with respect to enzymatic activity and decay of Norway spruce wood

Abstract The activity of cellulase, peroxidase, phosphatase and dehydrogenase enzymes, together with the content of protocatechuic and vanillic acids, in samples of Norway spruce wood inoculated with 17 different isolates of Phlebiopsis gigantea was measured. The same isolates were used to compare decay activity in samples of Norway spruce wood after incubation for 3 and 6 months. Significant differences in enzyme activity and phenol production were found between aerial mycelium overgrowing the wood sample and the underlying wood. These differences indicated that the nature of the fungal mycelium appears to change depending on whether it is in contact with wood. After 6 months, highly extensive decomposition of the wood was shown by two British isolates. The results confirm a large difference in P. gigantea inoculum among isolates in natural conditions and reinforce the need for constant evaluation of the most active isolates to use in preparations for biocontrol: a problem for both users and registration bodies.

Gas chromatographic–mass spectrometric investigation of metabolites from the needles and roots of pine seedlings at early stages of pathogenic fungi Armillaria ostoyae attack

An investigation was carried out of the composition of metabolites in pine seedlings tissues at the initial stages of the infectious process caused by pathogenic fungi Armillaria ostoyae, which causes a root rot of trees and degradation of forest resources. With the help of successive extraction with organic solvents of different polarity, more than 190 metabolites were extracted from the needles and roots of the seedlings and then identified by GC–MS method. The composition of the extracts from control plants and those inoculated with Armillaria ostoyae were compared. It was established that part of secondary metabolites (glucosamines and free amino acids, carbohydrates raffinose and trehalose) were present only in the tissues of inoculated plants. Possible roles of some of these compounds appearing in the roots of seedlings infected with the fungus are also discussed in the paper.

Evaluating the persistence of Phlebiopsis gigantea (Fr.: Fr.) Jülich mycelium and fruiting bodies in pine stumps after root-rot protection treatments

Ocena występowania grzybni i owocników Phlebiopsis gigantea (Fr.: Fr.) Jülich w pniakach sosnowych po wykonaniu zabiegu ochronnego przed hubą korzeni Evaluating the persistence of Phlebiopsis gigantea (Fr.: Fr.) Jülich mycelium and fruiting bodies in pine stumps after root-rot protection treatments Commercial preparations Rotstop and PgSuspension, used in Scandinavia and the United Kingdom, are EU-licensed biocontrol agents against root rot that contain isolates of the fungus Phlebiopsis gigantea. The composition of these two products differs from that of PgIBL, previously use in Poland, hence the need to verify their effectiveness under Polish site and stand conditions. Stumps were treated with the commercial products and subsequently checked after one year for the persistence of mycelia and fruiting bodies. Molecular methods were used on the mycelia present in the stumps to confirm that their genetic identity was consistent with fungal isolates from the preparations. Treatments with EU-licensed preparations gave satisfactory results - in about 70-80% of the stumps mycelia were present under the bark. Inoculation with Rotstop preparations was most effective during autumn 2008 (effectiveness of 82%), while PgSuspension application was most effective during spring 2008 (effectiveness of 77%). The development of the mycelia in pine stumps from the two preparations investigated (containing preserved dormant spores) was similar to that of preparation PgIBL (formulated from living mycelium within a growing medium), in terms of their relative effectiveness measured as the percentage of stumps supporting under-bark mycelia (which ranged between 70-90%, depending on the treatment term).

Decay indices for evaluating wood decomposition activity

The goal of the current study was to evaluate the efficiency of Norway spruce wood decomposition by the saprotrophic fungus Phlebiopsis gigantea (Fr.) Jülich. We identified the following indices as reliable measures of wood decay: decay acceleration index (DAI), final decay index (FD), and decay intensity index (DI). DAI was used to assess acceleration and deceleration of spruce wood loss, FD to estimate the final wood decay, and DI to evaluate the ability of the fungus to decompose wood, taking into consideration changes in mycelial activity over time. We tested the hypothesis that the wood decay activity of any fungus can be evaluated more objectively when: (i) several isolates of the tested fungus are assessed simultaneously, (ii) tests are performed for at least two time-points, and (iii) samples vary in wood density. Allowing a three-month period for wood decomposition was inadequate for reliable assessment of the wood decay ability of P. gigantea. Conversely, six months after inoculation, the tested isolates showed significant differences in their ability to generate dry wood loss, which depended on wood density. In view of these results, the DAI, FD, and DI indices are practical tools for assessing fungal activity to predict wood loss.

Influence of elevated CO2 concentrations on the growth of Armillaria ostoyae (Romagn.) Herink rhizomorphs in vitro

Abstract A comparative experiment was carried out in growth chambers to determine the effects of elevated CO2 concentrations (either 760 ppm or 1,140 ppm) versus ambient CO2 conditions on the growth of Armillaria ostoyae (Romagn.) Herink rhizomorphs, which is the infectious organ of a fungal pathogen affecting many forest trees. We found that one out of three isolates in the experiment differed significantly in rhizomorph production, which was measured as rhizomorph dry mass/100 days of growth. Rhizomorph production was also affected by the tree species used as a food source in the inoculum preparation, with beech wood being significantly different from oak and hazel. Under higher CO2 regimes the production of rhizomorphs was consistently lower for all three isolates compared to ambient CO2 concentrations. For one isolate (no. 11) the growth differences were significant between 380 ppm and both elevated CO2 concentrations (760 ppm and 1,140 ppm), while for the other two (no. 30 and 32) significance was observed only between 380 ppm and 760 ppm. No statistically significant differences have been noted between 760 ppm and 1,140 ppm CO2 for these two isolates. it was concluded that elevated concentrations of CO2 inhibited A. ostoyae rhizomorph growth and therefore have the potential to lessen the pathogenicity of the fungus.

Spruce wood degradation by Pleurotus abieticola in comparison with Phlebiopsis gigantea and Heterobasidion parviporum: in vitro experiments with isolates

ABSTRACT The objective of this study was to evaluate the in vitro mycelium growth of Pleurotus abieticola and its competitive ability to decompose sapwood and heartwood wood, as compared to the activity of Phlebiopsis gigantea and Heterobasidion parviporum. Over the last several decades, P. gigantea has routinely been used for biocontrol of the conifer pathogen Heterobasidion annosum s.l.; however, its protective effect on Norway spruce stands was recently demonstrated to be not satisfactory. P. abieticola was proposed instead, as a promising species that might successfully compete with H. parviporum. We investigated the growth of mycelium and the ability of P. abieticola isolates to decompose wood of Norway spruce, in the experiment with isolates of P. gigantea and H. parviporum. Heartwood was better decomposed than sapwood by the majority isolates used in the experiment. Linear growth of the investigated fungi showed a more rapid mycelium development for P. gigantea and H. parviporum, compared to that of P. abieticola. In dual cultures, H. parviporum was overgrown only by P. gigantea. All the tested isolates of P. abieticola showed weaker wood decomposition than those of P. gigantea and H. parviporum. Further study is required to better understand the role of P. abieticola for the protection of spruce stands.

Antrodia gossypium, Phlebiopsis gigantea and Heterobasidion parviporum: in vitro growth and Norway spruce wood block decay

ABSTRACT Polymerase chain reaction-amplified and sequenced isolates of Antrodia gossypium, Phlebiopsis gigantea and Heterobasidion parviporum from decaying Norway spruce wood blocks after three and six months, which exhibited linear growth, were investigated. P. gigantea strains showed the fastest growth, whereas A. gossypium growth was five times slower. The differences between the mean daily increment of A. gossypium and the other examined isolates (except Hp2) were statistically significant. There were also significant differences in wood decay between densities over time. These results were confirmed by the decay acceleration index (DAI) and decay activity index, which were positively correlated with wood density regardless of the fungus species. The registered P. gigantea strains (Rotstop and PG Suspension) exhibited a strong decomposition ability (28% after six months); the weight loss caused by A. gossypium after six months of decay (15.2%) was similar to the results of P. gigantea (GB) after just three months (13.2%). All tested H. parviporum isolates showed rather rapid growth and equally strong wood decay (20–25%) compared to those of P. gigantea. DAI showed that A. gossypium may significantly contribute to wood decomposition over time, particularly in less dense wood samples. The use of both saprotrophs as biological agents against root pathogens is discussed.