Thesis (Ph. D.)--Oregon State University, 1983. / Typescript (photocopy). Includes bibliographical references (leaves 108-120). Also available via the World Wide Web.

The aroma of Tuber gibbosum, a native Oregon truffle, was characterized using two distinct techniques. Volatile aroma constituents were identified by chemical analysis, and sensory characteristics were determined by examining response of the general populace to the truffle aroma. Truffle samples from four maturity ranges, as determined by microscopic examination of each specimen for spore maturity, were compared for amounts and types of aroma volatiles present. Aroma volatiles of frozen specimens of T. gibbosum were sampled using a headspace concentration technique. Volatile compounds were analyzed by gas chromatography/mass spectrometry/data system (GC/MS/DS) and the total volatile profile was found to contain up to 20 compounds, depending on sample treatment and maturity. Seven compounds were found to be the major aroma constituents and were selected for further investigation. These 7 compounds were identified from their mass spectra and the identities substantiated by determining their Kovats retention indices. Amounts of volatile compounds present in each sample were determined by capillary gas chromatographic (GO analysis using an internal standard of n-tridecane for quantitative determinations. The major aroma constituent for all the samples was oct-l-en-3-ol, representing about 50% of the total aroma profile. The other 7 major components were 8- and 6-carbon alchols, ketones and aldehydes. Quantitative data for all samples and components were analyzed statistically. A descriptive model for truffle maturity was derived based on the amounts of 5 of the 7 compounds, and the sum of the amounts of the 7 major constituents. A comparison of volatiles from ascorbic acid treated and untreated control truffle samples indicated an apparent reduction in the amounts of several compounds. The examination of public response to the aroma of T. gibbosum was conducted as part of a display on truffles at the Oregon Mycological Society Mushroom Show. The aroma of this truffle, and three other native Oregon truffles were rated for desirability and preference. Results indicate T. gibbosum was not the favored sample, but was liked by about 2/3 of the population. Comparison of responses by males and females showed no differences for individuals liking the truffle aromas. However, females rated the truffle aromas of 3 of the 4 species as more unpleasant than did males. / Graduation date: 1986

Title from PDF of title page (University of Missouri--Columbia, viewed on February 24, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dissertation advisor: Dr. Johann Bruhn. Vita. Includes bibliographical references.

Thesis (M.S.)--Oregon State University, 2003. / Typescript (photocopy). Includes bibliographical references (leaves 87-97). Also available on the World Wide Web.

Two species of desert truffles, Tirmania and Terfezia were collected from the Northern desert region in Saudi Arabia for antimicrobial and antioxidant activity testing. Both species were extracted with four types of extraction solutions, methanol, ethanol, ethyl acetate and water to test for antimicrobial activity and with three extraction solutions, methanol, ethanol and water for antioxidant activity. Using disc diffusion method, the extracts were subjected to twenty three different microorganisms to observe the antimicrobial activity by measuring clear zones. Methanol extract from Tirmania was the most effective, followed by those extracted with ethanol, water and ethyl acetate respectively. In Terfezia, ethanol extract was better than methanol extract in effectiveness. Ethyl acetate extracts were the least effective. The results indicate that truffles possess antimicrobial activity with broad spectrum effects against Gram positive, Gram negative, aerobic and anaerobic bacteria as well as Saccharomyces, while no effect was recorded with fungi. The results on antioxidant activity showed that truffles have very strong antioxidant property with 99.9% with ethanol extracts of Tirmania species and 95.5% with ethanol extract of Terfezia species using beta-carotene bleaching method and antioxidant property with 96.1% with ethanol extracts of Tirmania species and 95.3% with methanol extract of Terfezia species using DPPH free radical method.

Thesis (Ph. D.)--Oregon State University, 1998. / Typescript (photocopy). Includes bibliographical references (leaves 89-95). Also available on the World Wide Web.

No description available.

Terfezia pfeilii is an edible mycorrhizal fungus that thrives in the Kalahari Desert of southern Africa. It is best known by desert dwellers for its flavour and as a source of nutrition. Although the genus Terfezia is generally regarded as being an ectomycorrhizal mycobiont, the exact mycorrhizal type formed by T. pfeilli and its' associated host plants remains uncertain. Discovery of the host plants for T. pfeilii would first be required in order to further investigate the life cycle and cultivation of this truffle. This study focussed on the isolation of mycelia from the ascocarp, optimising the growth conditions of the mycelial cultures, rapid molecular identification of T. pfeilii, investigation of potential helper bacteria and mycorrhizal synthesis experiments. T. pfeilii ascocarps were harvested from the Spitskop Nature Reserve in Upington, South Africa. Ascocarps were successfully identified using both morphological and molecular methods. Despite the delayed growth mostly caused by contaminating microorganisms, the isolation of T. pfeilii mycelia culture was successful. Molecular techniques were used to confirm the identity of the pure culture. Further studies were conducted on ways to improve the growth conditions of the mycelial culture on Fontana medium. An optimum temperature of 32°C, the addition of Bovine Serum Albumin as a nitrogen source and a pH of 7.5 significantly improved the growth of T. pfeilii in vitro. A rapid PeR-based molecular method was developed to speed up the identification of T. pfeilii. Specific primers that can exclusively amplify the ITS region of T. pfeilii were designed and used to identify both the ascocarps and the mycelial culture. The specificity of these primers was confirmed by their inability to amplify DNA from the isolates of contamining fungi obtained during the isolation process. Molecular comparison was made to confirm the reclassification of South African samples of T. pfeilii as Kalaharituber pfeilii as proposed by Ferdman et al.,(2005). However, in this study, the name T. pfeilii has been retained. A total of 17 bacterial isolates were obtained from the fruiting bodies of T. pfeaii and these were tested for stimulation of mycelial growth in vitro, indole production and phosphate solubilising capabilities. Bacterial isolates that showed potential to be Mycorrhization Helper Bacteria (MHB) were identified as Paenibacillus sp., Bacillus sp. and Rhizobium tropici. Selected plant seedlings were inoculated with T. pfeilii cultures or ascocarp slurry in order to re-establish the mycorrhizal association. After 8 months, light microscopy observations revealed an endomycorrhizal type association between Cynodon dactylon and T. pfeilii. This was confirmed with molecular analysis using specific T. pfeilii ITS primers. After 15 months, molecular methods confirmed Acacia erioloba as another host plant. These results have provided essential information paving the way for further investigation into the life cycle and biology of the Kalahari truffle. / KMBT_363 / Adobe Acrobat 9.53 Paper Capture Plug-in

The black truffle (Tuber melanosporum Vitt.) industry in Australia is relatively new and has enormous potential but some truffières (truffle farms) fail to meet anticipated harvest projections. Inappropriate soil conditions and climate, and the management of such factors are suggested as the primary reasons for inadequate yield. In addition, requirements for ascocarp initiation and development and the role of the host plant in such processes are unknown. This study examines interactions between European hazel (Corylus avellana L.) and the ectomycorrhizal (ECM) black truffle symbiont in a commercial truffière (Hazel Hill) in south-western Australia. Specific studies were initiated to examine the interactions of host physiology, mycorrhizal infection and the interaction with abiotic factors. The study related specific physiological processes of the host plant to the known life cycle of the black truffle to determine the role of the host plant in ascocarp production, if any. The work also examined the effect of silvicultural treatments intended to increase truffle production. A review of existing literature was undertaken to determine the key soil and climatic factors required for successful truffle production. Climatic conditions appeared more important than soil chemistry and structure in Western Australia, with significant seasonal variation in air and soil temperatures required plus irrigation to supplement summer rainfall. This information was used to define areas with potential for truffle production in the south-west of Western Australia: the cooler, high rainfall regions (>1000 mm annual rainfall) where there is sufficient seasonal variation in soil temperature and availability of adequate quantities of quality water for irrigation. Subsurface soil acidification and salinity, as well as groundwater salinity, are constraining factors. Lime amendment is necessary to create sufficiently high pH and CaCO3 levels required by the truffle fungus. A field trial was established to monitor the seasonal C dynamics of European hazel in the context of the life cycle of the black truffle. Maximum translocation of sucrose in the phloem sap coincided with the period of anticipated rapid growth of the truffle ascocarp implicating the use of current photosynthate in C nutrition of the ascocarp. Sampling of non-structural carbohydrates (NC) of above and belowground plant material indicated maximum storage of C in the host coincides with maturation of the ascocarp. These observations provide evidence of a synchronous growth habit of the plant host and the ascocarp. The C allocation patterns of European hazel in response to liming a loamy soil, taken from near the Hazel Hill truffière, and inoculation with ECM fungi (T. melanosporum, Hebeloma sp. and Scleroderma sp.) were examined in a glasshouse pot trial. Liming increased biomass allocation to the shoot and induced deficiencies of phosphorus and manganese. Colonisation by ECM fungi significantly increased net photosynthesis, indicating the sink strength of these fungi, but there was no relationship between the level of mycorrhizal infection and fine root NC. The maximum rate (40 g lime kg-1 soil) reduced infection by Hebeloma and Scleroderma and had no impact on T. melanosporum. Further, infection rates of T. melanosporum did not increase in response to lime suggesting lime is not necessary for ECM development in this soil type. Fertiliser is widely used in commercial truffières in Australia but the consequences for truffle production are unknown. In a field trial, the growth and physiological response of European hazel to forms of phosphorus (34 and 68 kg ha-1 apatite-P and 68 kg ha-1 triple super phosphate -P) and nitrogen (50 kg ha-1 of NO3- and NH4-N) were examined as well as the mycorrhizal response to fertiliser. Apatite-P increased phloem sap sucrose concentrations which was attributed to increased root biomass and associated sink capacity. Fertiliser application did not change fine root NC concentrations suggesting no increase in allocation of C to ECM structures. The highest rate of apatite-P decreased mycorrhizal infection rates of T. melanosporum and, most likely, was the result of increased infection rates of Hebeloma. In contrast to the literature relating to indigenous Australian ECM fungi, the highest rate of soluble-P did not decrease ECM infection rates in T. melanosporum. Nitrogen treatments increased foliar N content and improved gas exchange efficiency of plants, and had no adverse impact on the level of ECM infection. Fertilisation with N significantly increased soil respiration rates suggesting N limits mineralisation at this site. Some truffières manage the canopies of the host tree to ensure maximum exposure of the soil surface in order to increase soil temperatures. As there are no published data on the effect of pruning on black truffle production, a field trial was established to document the impact of canopy pruning on host physiology and soil temperature. The removal of 65% of canopy leaf area reduced phloem sap sucrose concentrations, soil respiration rate and the soluble: insoluble NC ratio of fine roots in the short term (1-3 weeks). There was no compensatory response of leaf gas exchange parameters as a result of pruning. Generally, there was no long term impact on plant physiological parameters as a result of pruning. Long term effects on soil temperature were observed as a result of pruning. Mean annual temperature and amplitude increased significantly beneath pruned trees and spring, summer and autumn soil temperatures increased as did diurnal variation as a result of pruning. Pruning did not increase winter soil temperatures and therefore would probably not impact on ascocarp maturation during this period. This research has provided insight into the C physiology of hazel associated with the black truffle and the consequences for truffle production. The results provide anecdotal evidence of direct C transfer between the host and the developing truffle, contrary to the existing paradigm that the ascocarp is saprotrophic for the majority of its growth and development. There is a need to validate this finding as there are consequences for management of commercial truffières. Liming of loam duplex soils can reduce the abundance of the most common competitor ECM fungi and should be encouraged in commercial truffières. Applying phosphorus and nitrogen to commercial truffières will improve growth rates of planted trees without adversely impacting on ECM infection by black truffle fungi, although the impact on truffle production remains unknown. It is anticipated truffle production will improve in the longer term as a result of pruning and prudent canopy management. Management options should include tree removal to reduce planting density and increase soil exposure in truffières. There is a need for longer term trials to be established to determine the C nutrition of the truffle ascocarp and to clearly define the key stages of the black truffle life cycle in Western Australia.

Kalaharituber pfeilii (Henn.) Trappe & Kagan-Zur commonly known as the “Kalahari truffle” is a desert truffle species identified from the Kalahari region of southern Africa. Two other species, Eremiomyces echinulatus (Trappe & Marasas) Trappe & Kagan-Zur and Mattirolomyces austroafricanus (Trappe & Marasas) Trappe & Kovacs are also known to occur in other parts of southern Africa. Truffles are hypogeous fruiting bodies of Ascomycetes, important to humans for their nutritional value and medicinal characteristics. These truffles are known as desert truffles as they prefer to occur under arid or semi-arid conditions characteristic of deserts. Truffle development depends on the presence of a mycorrhizal host, associated microorganisms as well as soil and climatic characteristics. It has been suggested that K. pfeilii has a suspected broad plant host range which includes herbaceous to woody trees and shrubs. However, these relationships have not been verified. Indigenous people of the Kalahari believe that truffles are found under grasses. In the Kalahari, truffle fruiting bodies are often found entangled in Stipagrostis ciliata (Desf.) De Winter var. capensis (Trin. & Rupr.) De Winter roots. S. ciliata, also known as the tall bushman-grass, is the most common grass found in the Kalahari. The objective of this study was to provide conclusive evidence that S. ciliata var. capensis is a host of the Kalahari truffle. Truffle fruiting bodies and grass roots from where the truffles were found were collected from Upington, South Africa. The fruiting bodies were identified by observing their morphological characteristics using the ‘Keys of Truffle genera’. All observed physical properties were similar to those of K. pfeilii and further identification was done using molecular techniques. DNA was extracted from the fruiting bodies, mycelial cultures, rhizosheaths and from the S. ciliata var. capensis grass roots, which were then amplified using the specific K. pfeilii specific primers TPF3 and TPR1 and sequenced. The obtained sequence results confirmed that the collected fruiting bodies were those of the K. pfeilii and the molecular techniques also confirmed that K. pfeilii DNA was present in the S. ciliata var. capensis rhizosheath and root cells. Microscopy showed an ectendomycorrhizal association between K. pfeilii and S. ciliata var. capensis. Mycorrhizal resynthesis experiments were conducted to establish this mycorrhizal association in-vitro. They were unsuccessful because of the structure of the grass and the availability of contaminants. And more...