Eric Danell

Pseudomonas fluorescens in association with fruit bodies of the ectomycorrhizal mushroom Cantharellus cibarius

Aerobic bacteria were isolated from fruit bodies of Cantharellus cibarius to study bacterial influence on growth and development of mycorrhizal and vegetative hyphae. Comparisons were made with seven other mushroom species. The number of bacteria in the tissue of C. cibarius was 2·4 × 10 6 g −1 f.w. This population size was of the same magnitude as in the soil of its growing site and in Hydnum rufescens , but 100–1000 times greater than in the agarics studied. The dominating bacterium was Pseudomonas fluorescens biovar. I. The population of P. fluorescens changed from 12% of the total bacterial population in soil, to 78% in fruit bodies of C. cibarius . Strains were tested with C. cibarius in vitro to study their effect on fungal growth. No growth stimulating strains were found. Non-inhibitory strains of P. fluorescens were inoculated in artificial ectomycorrhiza systems of C. cibarius with Picea abies . In TEM the naturally occurring bacteria in fruit bodies were found embedded in mucus and proliferating in the interhyphal spaces. In the mycorrhiza experiment the bacteria were only found on the surface of the mantle. Even though the bacteria are motile, they can not actively penetrate the fungal mantle. P. fluorescens is probably incidentally incorporated in the fruit body during its development. In Kings B broth, the bacterium did not grow at pH 4, although the average pH (H 2 O) of the growing site of C. cibarius was 4·1. It is suggested that growth of P. fluorescens in the immediate environment of the vegetative mycelium might be favoured by its higher pH (5·8–6·2) and trehalose.

The population of the hypogeous fungus Tuber aestivum syn. T. uncinatum on the island of Gotland.

The aim of our study was to examine the genetic variation within Tuber aestivum on the Baltic island of Gotland, Sweden. Variation in such a limited geographical area should help illuminate the dispersal abilities of T. aestivum. Knowledge of the genetic variation in this northern outpost could also be useful in the selection of inoculum for the establishment of truffle orchards. Genetic structure and homogeneity of the population were studied using principal component and parsimony analyses of randomly amplified polymorphic DNA data. Our inventories showed that T. aestivum is abundantly distributed in suitable habitats on Gotland. The genetic variation observed suggests sexual reproduction and slow dispersal on the island. It is possible that the present population was established from one introduction, which may be due to ability to survive in this habitat rather than to rare colonising events. The T. aestivum population on Gotland may be an ecotype adapted to the climate and soil conditions on the island.

The Swedish matsutake (Tricholoma nauseosum syn. T. matsutake) : Distribution, abundance and ecology

The commercially important mushroom matsutake has been considered uncommon in Sweden by most mycologists and has been unknown to the Swedish public. Between 1849 and 1997, 81 matsutake reports were registered in Sweden. A field study in 1998 resulted in 121 matsutake localities, of which at least 30% were prolific, producing 30-200 fruit bodies ha-1 in the far north of Sweden. Using DNA sequencing of rDNA internal transcribed spacer (ITS) it was shown that Japanese and Swedish matsutake (Tricholoma matsutake and T. nauseosum) should be treated as the same species. The oldest name is T. nauseosum, but it is suggested that the name T. matsutake should be conserved. This study has stimulated private companies to investigate possibilities for commercial export to Japan.

Tuber aestivum (syn. T. uncinatum ) biotopes and their history on Gotland, Sweden

This study aimed at testing the hypothesis that the genetically distinct Tuber aestivum population on the island of Gotland, Sweden, is adapted to habitats different from French T. aestivum populations. The soil structure, soil chemistry, bedrock, climate, vegetation and host tree continuity of 18 T. aestivum sites on Gotland were analysed and compared with data from France. We conclude that T. aestivum can grow in soils with a broad soil structure range and that no striking differences in soil chemistry were found. No T. aestivum indicator plants other than the host trees were found, but the host tree continuity on the T. aestivum sites on Gotland was more than 300 yr. If the T. aestivum population on Gotland constitutes an ecotype it is rather an adaptation to the colder and drier climate on Gotland. Selecting local T. aestivum inoculum for truffle orchards in northern Europe could be important for successful truffle production.

Formation and growth of the ectomycorrhiza of Cantharellus cibarius

New data on the physiology of Cantharellus cibarius mycorrhiza formation has resulted in a new aseptic routine method for in vitro formation. The advances are short formation time, healthy plants and reliable colonization. A high glucose demand and a good gas exchange with additional carbon dioxide are important factors in the mycorrhiza formation. Mycorrhiza was observed after 8 weeks, but strong colonization occurred after 10–12 weeks, when mycorrhiza was established to the depth of 5 cm. A C. cibarius strain connected to Picea abies in nature successfully colonized Pinus sylvestris in vitro, but not Betula pendula. Mycorrhizal plants have been successfully transferred to unsterile environments in greenhouses. The mycorrhizae continued to colonize new roots and the unsterile peat soil for 10 months. However, C. cibarius mycorrhiza is highly sensitive to flooding. With PCR and RFLP, fruit bodies, isolated mycelia and artificially formed mycorrhizae have been compared to prove that C. cibarius was used. Climatic changes did not induce primordia formation but factors behind fruit body formation are discussed.

Molecular systematics of Craterellus: cladistic analysis of nuclear LSU rDNA sequence data.

Considerable taxonomic confusion exists regarding many species of Cantharellus. Several taxa have been classified in either Cantharellus or Craterellus depending on which morphological characters were emphasised. Recent phylogenetic studies based on sequence analyses suggest that some species now classified in Cantharellus should be in Craterellus. We extracted DNA from dried herbarium specimens and amplified, sequenced and cladistically analysed approximately 650 bp of the 5 end of the nuclear large subunit ribosomal DNA gene. Our data confirm earlier results and provide molecular evidence for the classification of additional Cantharellus species (Ca. ignicolor and Ca. lutescens) within Craterellus. Furthermore, the data enable us to predict that all Leptocantharellus-like species currently classified within Cantharellus are more accurately classified within Craterellus. The species complexes of Cr. tubaeformis and Cr. cornucopioides were also investigated. These analyses did not support the monophyly of Ca. tubaeformis but the hypothesis that colour varieties of Cr. cornucopioides represent separate species was rejected.

The Socioeconomic Impact of Truffle Cultivation in Rural Spain1

The Socioeconomic Impact of Truffle Cultivation in Rural Spain. Commercial black truffle (Tuber melanosporum) plantations have been promoted in Europe with the intention of benefiting rural economies while conserving biodiversity through the expansion of oak woodlands. In this context, a socioeconomic study was conducted around the town of Sarrión in eastern Spain, where government subsidies have supported oak reforestation and truffle cultivation in unproductive hilly areas since 1987. Currently there are about 4,500xa0ha of truffle orchards in the surrounding county and 530 members in the local truffle association, which has provided a key forum for truffle cultivators to share technical, financial and administrative experiences. Structured interviews were carried out in 2002 with a number of orchard owners, as well as representatives of financial and governmental institutions. Truffles, which are harvested using trained dogs, typically fetch local cultivators average prices of 220–670 EUR/kg, although retail prices of high-quality specimens may reach twice this amount. In addition to the direct economic impact, an increase in local land prices was also documented, as well as a tendency for continued expansion of truffle orchards, and thus oak reforestation. In conclusion, the promotion of truffle cultivation through autonomous community and provincial government subsidies, in conjunction with support by local banks, a dedicated local truffle association, and growing interest on behalf of local farmers, seems to have achieved the mutual goals of biodiversity conservation and improving the rural economy in this region of Spain.ResumenImpacto Socioeconómico del Cultivo de la Trufa en España. Las plantaciones orientadas hacia la producción de trufa negra (Tuber melanosporum) se impulsaron en Europa con el objetivo de favorecer las economías rurales, así como de conservar la biodiversidad a través de la expansión de los encinares. Dentro de este contexto, se llevó a cabo un estudio socioeconómico en la zona del municipio de Sarrión y su contorno localizada en el la parte oriental de España, donde existen subvenciones para la reforestación y el cultivo de la trufa desde el año 1987. En la zona estudiada, actualmente hay alrededor de 4.500xa0ha de plantaciones de trufa, además de una asociación de cultivadores de trufa con 530 miembros, la cual sirve de plataforma para que sus socios compartan experiencias técnicas, financieras y administrativas. En el año 2002 se llevaron a cabo entrevistas a propietarios de plantaciones, así como a los representantes de instituciones financieras y gubernamentales. Las trufas, que son recolectadas con perros adiestrados, generalmente son vendidas por los propios cultivadores a precios que oscilan entre los 220–670 EUR/kg, aunque en la venta al detalle, el precio de las trufas de alta calidad puede doblar dichas cantidades. Además del impacto económico, también observamos un incremento en el precio del suelo rústico, así como la expansión continuada de plantaciones de trufa y de reforestación. En conclusión, el progreso del cultivo de la trufa a través de las subvenciones de la Comunidad Autónoma y la Diputación Provincial, con la colaboración de los bancos locales, una comprometida asociación de cultivadores de trufa y un creciente interés por parte de los agricultores locales, parece que ha alcanzado los objetivos comunes de biodiversidad y conservación junto con la mejora de la economía de esta región de España.

Cultivation of Oudemansiella tanzanica nom. prov. on agricultural solid wastes in Tanzania

The edible mushroom Oudemansiella tanzanica nom. prov., which is new to science, has been studied as a potential crop to reduce agricultural solid wastes and increase domestic mushroom production. The substrates sawdust, sisal waste and paddy straw supplemented with chicken manure resulted in the highest biological efficiencies of any mushroom cultivated in Tanzania so far. In addition, the mushroom has one of the shortest cultivation cycles at 24 d. Despite the fact that the mushroom extracts substantial amounts of nutrients, the spent substrate can be used as fodder, as a soil conditioner and fertilizer and in bioremediation.

Truffle cultivation in Sweden: Results from Quercus robur and Corylus avellana field trials on the island of Gotland

Abstract The edible, ectomycorrhizal Burgundy truffle, Tuber aestivum Vitt., grows naturally on the islands of Gotland and Öland, Sweden. In 1999, 240 inoculated Quercus robur and Corylus avellana seedlings inoculated with French T. aestivum were planted in 10 experimental truffle orchards (truffières) on Gotland to investigate the possibility of truffle cultivation in Sweden. Truffle orchard management, mycorrhizal development and seedling growth were studied. Fourteen additional truffle orchards containing more than 2000 Q. robur were established during 2000 and 2001. In 2004, T. aestivum mycorrhizae were detected in all truffle orchards. In 2005, the first T. aestivum truffle was found, 6 years after planting. This is the first cultivated truffle in Scandinavia and despite the northerly location they were produced within a timescale comparable with France. Tuber aestivum mycorrhizae survived in soils which differed from naturally producing locations by having a sand content > 95%, pH ≤6.4 and calcium content ≤0.1%. In a second series of experiments Swedish Q. robur, C. avellana and Carpinus betulus seedlings were inoculated with Swedish T. aestivum. Eleven months after inoculation T. aestivum mycorrhizae were found in 0–78% of the seedlings, depending on species, inoculation treatment and substrate. Because of the continuing decline of oaks in Sweden and associated fauna and flora, truffle cultivation may favour oak forest restoration programmes as well as making a direct contribution to rural economies.

Basidiome formation of an edible wild, putatively ectomycorrhizal fungus, Phlebopus portentosus without host plant

Phlebopus portentosus is a popular wild edible ectomycorrhizal fungus in northern Thailand. In general ectomycorrhizal fungi produce basidiomes when associated with a host plant. In this paper mycelium growth and basidiome production of P. portentosus were examined in pure culture both in vitro and in pot-culture experiments. Five mycelial strains of P. portentosus were isolated from basidiomes and used in the experiments. The mycelia grew fastest on sorghum grains supplemented with fungal-host solution. The mycelia produced sclerotia-like structures after 3 wk incubation in darkness at 30 C. All strains of P. portentosus had the ability to form primordia. The primordia were formed under lowered temperature, high humidity and a 12 h photo-period. They developed to mature basidiomes after 8–12 d in in vitro. In the pot-culture primordia were found after 28–35 d incubation in the greenhouse and mature basidiomes released basidiospores within 6–8 d. Basidiospores were germinated on fungal-host medium and formed mycelial colonies. This fungus showed an ability to produce basidiomes even 2 y after the original isolation from tissues. This research provides valuable information concerning the techniques and protocols for the large scale commercial production of P. portentosus basidiomes in the absence of a host plant.