VAAM-Jahrestagung 2011 Karlsruhe, 3.–6. April 2011

SIV010Regulation of nutrient transporter genes in theextraradical mycelium of the arbuscular mycorrhizalfungus Glomus intraradicesS. Kressner, E. Neumann, E. George, P. Franken*Plant Nutrition, Leibniz Institute of Vegetable and Ornamental Crops,Großbeeren, GermanyThe establishment of an arbuscular mycorrhiza symbiosis between a fungaland a plant partner is mainly driven by a bidirectional exchange of nutrients.While the plant supplies the fungus with carbohydrates the fungus providesaccess to soil derived nutrients which are unavailable for the plant. Theuptake and transport of soil nutrients to the plant occurs via an extraradicalmycelium and its nutrient transporter systems, some of them are alreadycharacterized by in vitro studies. Examples are the high affinity phosphate(PT) and ammonium (AMT1) transporters from Glomus intraradices. Theirgene expression is regulated in dependence of P i (GintPT) or of ammoniumand nitrate (GintAMT1) concentrations of the surrounding medium as shownin experiments with root organ cultures [1, 2].In order to analyse GintPT, and GintAMT1 expression under more naturalconditions, a greenhouse pot culture experiment with two treatments of N-fertilization in combination with three P i concentrations was set up. The potscontained compartments filled with a mixture of soil and glass beads forharvesting the extraradical mycelium [3]. Results show a regulation of thetransporter gene expression only depending on the N fertilizations of thisexperiment. RNA accumulation of GintAMT1 was increased under lownitrogen concentrations. In contrast, GintPT expression was induced at highamounts of nitrogen. No effect was found for the P i-fertilization, but analysisof the plants phosphorus (P) concentrations at the day of harvest showed thatall plants in the trial suffered from P deficiency. Besides GintAMT1, anotherN transporter gene responsible for the uptake of nitrate (GintNT1) wasanalysed. This transporter is not characterized by in vitro studies so far. TheGintNT1 expression pattern observed in this experiment was the same as forGintAMT1.If the regulation of the transporter gene expression is directly a consequenceof the soil nutrient concentrations, of the nutritional status of the symbiosispartners or of both has to be analysed in further experiments. Especially theresults for GintPT expression suggest that nutrient concentrations in theplant shoot play a dominant role in the regulation of transporters in theextraradical hyphae of the fungal partner.[1] López-Pedrosa, A.et al (2006): GintAMT1 encodes a functional high-affinity ammoniumtransporter that is expressed in the extraradical mycelium of Glomus intraradices. Fungal Geneticsand Biology 43: 102-110.[2] Maldonado-Mendoza, I.E. et al (2001): A phosphate transporter gene from the extra-radicalmycelium of an arbuscular mycorrhizal fungus Glomus intraradices is regulated in response tophosphate in the environment. Molecular Plant-Microbe Interactions 14: 1140-1148.[3] Neumann, E. and E. George (2005): Extraction of extraradical arbuscular mycorrhizal myceliumfrom compartments filled with soil and glass beads. Mycorrhiza 15: 533-537.SIP001Improvement of yield, harvesting time andpolysaccharide-protein complex content of Agaricusblazei Murrill with beneficial microbesL.-S. Young* 1 , J.-N. Chu 2 , C.-C. Young 21 Biotechnology, National Formosa University, Huwei, Yunlin, Taiwan2 Department of Soil & Environmental Sciences, National Chung HsingUniversity, Taichung, TaiwanIt is widely known that mushrooms contain active organic ingredients thatare associated with the maintenance of human health and the healing ofdiseases. 1 Pharmacological studies have shown that Agaricus blazei Murrillcontains several bioactive substances (e.g. polysaccharides) that function asantioxidants, 2 antimutagenics, 3 and anticancer agents. 4 Furthermore, thesesubstances have been reported to reduce blood sugar, blood pressure,cholesterol, 5 and prevent osteoporosis. 6 Therefore, it is not surprising that A.blazei has drawn the attention of food scientists and biotechnologists. Theproduction of A. blazei requires extensive casing to allow fruitification ofmushrooms. In light of the growth-promoting effects of beneficial microbes(BM) in agriculture, an extensive BM screen was conducted from the baseof natural growing A. blazei stipe in attempt to increase the total yield and toreduce the harvesting time. A total of 42 different bacteria isolates wereidentified through 16S rDNA sequencing and with 15 isolates conferringmycelium growth-inducing abilities. Amongst, inoculation of Arthrobactersp. K4-10C, Exiguobacterium aurantiacum, Microbacterium humi sp. nov.or Advenella incenata strains in the casing soil resulted in significantincreases in A. blazei total fresh yield at 64%, 64%, 54% and 46%,respectively. In addition, inoculation of Arthrobacter sp. K4-10C orExiguobacterium aurantiacum resulted in a significant increase in thepolysaccharide-protein complex content. Interestingly, inoculation ofExiguobacterium aurantiacum reduced the harvesting time for 14 days ascompared to the control without microbe inoculation. In conclusion, theidentification of beneficial microbes for the culturing of A. blazei resulted ina reduced harvesting time, a significantly increased total fresh yield, and anincrease polysaccharide-protein complex content show promise of beingeconomically viable for applications within the commercial mushroomindustry.[1] Lee, I.P. et al (2008): Lack of carcinogenicity of lyophilized Agaricus blazei Murill in a F344 rattwo year bioassay. Food Chem Toxicol 46:87-95.[2] Izawa, S. and Y. Inoue (2004): A screening system for antioxidants using thioredoxin-deficientyeast: discovery of thermostable antioxidant activity from Agaricus blazei Murrill. Appl MicrobiolBiotechnol 64:537-542.[3] Guterrez, Z.R. et al (2004): Variation of the antimutagenicity effects of water extracts of Agaricusblazei Murrill in vitro. Toxicol in Vitro 18:301-309.[4] Kimura, Y. et al (2004): Isolation of an anti-angiogenic substance from Agaricus blazei Murill: itsantitumor and antimetastatic actions. Cancer Sci 95:758-64.[5] Kim, Y.W. et al (2005): Anti-diabetic activity of β-glucans and their enzymatically hydrolyzedoligosaccharides from Agaricus blazei. Biotechnol Lett 27:483-487.[6] Mizuno, T.K. (1995): Agaricus blazei Murrill medicinal and dietary effects. Food Rev Int 11:167-75.SIP002Chemical crosstalk between Streptomyces sp. Ach 505 ofthe rhizosphere and plant pathogenic fungusHeterobasidionN. Horlacher* 1 , S. Schrey 1 , J. Nachtigall 2 , H.-P. Fiedler 11 Institute of Microbiology and Infection Medicine, Eberhard-Karls-University, Tübingen, Germany2 Institute für Chemistry, Berlin, GermanyThe mycorrhiza helper bacterium Streptomyces sp. AcH 505 supports themycorrhization of Picea abies (Norway spruce) with Amanita muscaria (flyagaric) by excretion of auxofuran, a growth promoting compound [1, 2].Besides auxofuran, S. sp. AcH 505 produces WS-5995 B, an antibiotic withantagonistic activity against the root pathogenic fungus Heterobasidionwhich is the causal organism of ‘annosum root rot’. Heterobasidionproduces fomannoxin, a secondary metabolite with phytotoxic, fungicidaland bactericidal activity [3]. S. sp. AcH 505 acts antagonistic against elevenof twelve investigated Heterobasidion isolates. Only strain H. abietinum 331is resistant and not affected, neither by S. sp. AcH 505 itself nor by theantifungal antibiotic WS-5995 B [4].Co-culture of S. sp. AcH 505 with resistant H. abietinum 331 in liquidmedium results in increased production of a novel compound, 331HaNZ, bythe fungus. Its production is neither induced by auxofuran nor by WS-5995B. Another compound 5-formylsalicylic acid (5-FSA) is also produced by H.abietinum 331 but it appears earlier than 331HaNZ during cultivation. Bothcompounds were isolated from liquid medium and the structures wereelucidated. Both compounds are structural analogues to salicylic acid (SA)from plants which induces the systemic acquired resistance (SAR) againstplant pathogens. SA induces the PR genes (pathogenesis related genes)which then generate the SAR. Investigations on the biological activityagainst the model organism Arabidopsis thaliana by northern blot weremade.[1] Riedlinger, J. et al (2006): Auxofuran, a novel metabolite that stimulates the growth of fly agaric,is produced by the mycorrhiza helper bacterium Streptomyces strain AcH 505. Appl. Environ.Microbiol. 72: 3550-3557.[2] Schrey, S. D. et al (2005): Mycorrhiza helper bacterium Streptomyces AcH 505 inducesdifferential gene expression in the ectomycorrhizal fungus Amanita muscaria. New Phytol. 168: 205-216.[3] Heslin, M. C. et al (1983): Fomannoxin, a phytotoxic metabolite of Fomes annosum: in vitroproduction, host toxicity and isolation from naturally infected Sitka spruce heartwood. Eur. J. For.Path. 13: 11-23.[4] Lehr, N. A. et al (2007): Suppression of plant defence response by a mycorrhiza helper bacterium.New Phytol. 174: 892-903.SIP003A surface hydrophobin in ectomycorrhiza interactionD. Senftleben*, E. Kothe, K. KrauseInstitute of Microbiology, Department of Microbial Phytopathology,Friedrich-Schiller-University, Jena, GermanyHydrophobins are small secreted proteins with a broad range of functionslike in processes of growth and development of filamentous fungi, e.g.formation of aerial structures. Mutual symbiosis like ectomycorrhiza lead todifferential gene expression. Up to 50% of fungal mRNAs is regulatedspektrum | Tagungsband 2011