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Effects of Antifungal Compounds on Conidial Germination and on the Induction of Appressorium Formation of Magnaporthe grisecfi Frank Eilbert3, Eckhard Thinesb and Heidrun Anke3 * a Departm ent for Biotechnology, University of Kaiserslautern, Paul-Ehrlich-Str. 23, D-67663 Kaiserslautern, Germany. Fax: +49 631/205-2999. E-mail: anke@rhrk.uni-kl.de b School of Biological Sciences, University of E xeter, Washington Singer Laboratories, Perry Road, Exeter E X 4 4Q L , United Kingdom * Author for correspondence and reprint requests Z. Naturforsch. 54c, 9 0 3 -9 0 8

Abstract

In the present study the degree of partial resistance (PR) of eleven hexaploid wheat (Triticum aestivum L.) genotypes was evaluated in laboratory (ratio of infection units in stage of second germ tube elongation versus stage of appressorium formation — ESH/App) and field conditions (calculating area under the disease progress curve — AUDPC). Based on the obtained data, genotypes with high degree of PR (Estica, GK Csornoc and Lívia), middle-resistant genotypes (Sana, Mv Vilma and Folio), genotypes with low portion of PR (Barbara, Torysa and Proteinka), and supersensitive genotypes (Renesansa and Am22/99) were differentiated. Both approaches appeared to be suitable for PR measuring with a good discriminating capability between the given genotypes. The results were equivalent in both instances. In addition, a new statistical approach permitting comparison of the obtained data is described.

-8530, Japan 2 Present address: Mass Spectrometry Facility, Biotechnol- ogy Resource Center, Room 143, Biotechnology Building, Cornell University, Ithaca, NY 14853, U. S. A. cystment and appressorium formation by the zoo- spores of Pythium marinum Sparrow (a sister species of Pythium porphyrae) in vitro have been described (Kerwin et al. 1992). Kazama and Fuller (1970) de- scribed the ultrastructure of infected Porphyra perfor- ata J. Agardh thalli following infection by Pythium marinum. Understanding the mechanism of this host- pathogen interaction between Pythium porphyrae

events in host-pathogen interactions on susceptible Porphyra yezoensis T-14 and resistant P. tenuipedalis. Thallus discs exposed to zoospore suspension for 30 min, rinsed and incubated further. Encystment was monitored at 30 min while, appressorium formation and penetration after further 30 min incubation. Fig. 2. High rate of encystment (arrowheads) of Pythium porphyrae zoospores onto Porphyra yezoensis T-14 thallus sur- face. Fig. 3. Germlings with short germ tubes and with appressorium formation (arrowhead) penetrating the thallus surface near the site of encystment

. Toxicol. 27, 393Ð398. Chaetomium globosum. Building and Enviroment 34, Evans C., Burns P., Dutton M. and Brown S. (1990), 2- 205Ð211. amino-4N-Ureidopropionic acid (Albizzine) and ist Thines E., Eilbert F., Sterner O. and Anke H. (1997), oxalyl derivative in hyphae of Coniophora puteana. Glisoprenin A, an inhibitor of the signal transduction Phytochemistry 49, 2159Ð2160. pathway leading to appressorium formation in germi- Gill M. and Steglich W. (1987), Pigments of fungi nating conidia of Magnaporthe grisea on hydrophobic (Macromycetes). In: Progress in the Chemistry of

, Sterner O, Anke H. Glisoprenin A, an inhibitor of the signal transduction pathway leading to appressorium formation in germinating conidia of Magnaporthe grisea on hydrophobic surfaces. FEMS Microbiol Lett 1997;151:219–24. 10.1111/j.1574-6968.1997.tb12573.x 20. Anke H, Bergendorff O, Sterner O. Assays of the biological activities of guaiane sesquiterpenoids isolated from the fruit bodies of edible Lactarius species. Food Chem Toxicol 1989;27:393–7. 2792969 10.1016/0278-6915(89)90145-2 21. Kurasawa S, Naganawa H, Takeuchi T, Umezawa H. The structure of MS-3: a glyoxalase

-related morphogenesis (Lau and Hamer, 1998). A further gene, which is involved in early processes of disease, is a catalytic subunit of a cAMP- dependent protein kinase A (CPKA). Its mutation leads to dramatically reduced pathogenicity through a loss of appressorium formation on healthy plants. However, on wounded plants, and when applying exogenous cAMP, they are able to form lesions (Xu et al., 1997). The involve- ment of toxins in plant pathogenesis is a factor that has been discussed for two decades now. Through REMI ap- proaches it was possible to create toxin deficient mutants

............................................................... Appressorium Formation Effects of Antifungal Compounds on Conidial Germination and on the Induction of Ap­ pressorium Formation of Magnaporthe grisea Araucaria angustifolia Phytochemical Evidence for the Plant Origin of Brazilian Propolis from Säo Paulo State Arcapitin A, B and C Arcapitins A - C, First Dammarane-Type Trit­ erpenes from the Convolvulaceae................... Arctiinae Androconial Hairbrushes of the Syntomis (Amata) phegea (L.) Group (Lepidoptera, Ctenuchinae): A Synapomorphic Character Supported by Sequence Data of the Mito­ chondrial 16S rRNA G ene

of their respiratory complex proteins lead to the release of copper ions previously bound to cytochrome oxidase. This in turn would cause the induction of P. anserina MT. The facultative parasite Colletotrichum gloeosporioides expresses two proteins that are homologous to other family 8MTs [22]. Interestingly, these two proteins are expressed mainly during appressorium formation. In this context they are induced by the wax of this parasite’s hosts. The induction by copper and cadmium ions is weak. Therefore, these two MTs are suggested to have a specialized

development and plant gene expression from appressorium formation to the intracellular accommodation of the fungal symbiont to ends with the formation of the characteristic tree-like structures, termed “arbus- cules”, within the root cortical cells [28]. The arbuscules which give their name to the mycorrhizal type are involved in the nutrient exchange between fungus and plant. The major nutrient flux is the transfer of carbon from plant to fungus (and thereby to the soil), and the movement of mineral nutrients from fungus to plant. Once AM fungi consolidate the internal