Research Interest [back to Index]

Phytopathogenic fungi cause severe crop losses on agriculturally important plants and thereby have an enormous impact on human welfare. Due to increasing resistance to common fungicides and the banning of existing compounds by the EU, the search for new plant protectants has acquired a new urgency. We therefore isolate natural products from fungal sources as potential lead structures for the development of new fungicides.  Besides their potential as lead structures, natural products are useful as biochemical tools to detect new targets which can be exploited for the development of safe and effective agrochemicals.

Within the past 20-30 years, research has focused to a large part on fungal pathogenicity factors as potential targets for new, selective fungicides. Compounds inhibiting pathogenicity factors, such as tricyclazole as an inhibitor of melanin biosynthesis in the rice-blast fungus Magnaporthe grisea, have proven to be environmentally safe because of their low toxic potential.

 In line with the requirement that future agrochemicals must be environmentally safe, one important aspect of our research centers on compounds which  interfere specifically with pathogenicity factors. The mode of action of such inhibitors will lead to new targets and assays suitable for high-throughput screening systems.
 

Methods

Model Organism [back to Index]

In our research, we use Magnaporthe grisea, the causal agent of rice blast disease, as a model organism to study plant-pathogen interactions and infection-related morphogenesis at a biochemical and molecular level. M. grisea is a filamentous ascomycete and it causes probably the most severe disease on cultivated rice. Besides its economic importance this fungus is a suitable model pathogen because it can be grown in culture, it is genetically well characterised, and an efficient transformation system has been established.

Life cycle of M. grisea:

A) Attachment of conidium to the plant surface. B) Germination of the conidium by sending out a short germ-tube. The apical end of the germ-tube extends and forms a ‘hook’, which is probably involved in sensing chemical and physical features of the surface. C) Formation of a nascent appressorium. D) A melanin layer forms in the inner appressorial cell wall during the maturation of the infectious structure. E) Driven by turgor pressure a penetration peg is forced through the plant cuticle to infect the leaf. F) Formation of intracellular 'bulbous' hyphe. G) Spread of the infection followed by conidiation.

 

 

Time-lapse photography of an appressorium forming conidium of M. grisea.

Plant testing [back to Index]

In an early stage of the purification, compounds of interest are tested for phytotoxicity towards Lepidium sativum, Setaria italica, Oryza sativa or Lactuca sativa.  The antifungal activity on planta is assessed on plants infected with the respective pathogen for example Magnaporthe grisea on rice or barely.  

 

Test Organisms [back to Index] 

For our ongoing screening we use a broad range of phytopathogenic and for comparison saprophytic fungi. Among them are

 

Basidiomycetes:

Rhodotorula glutinis

 

Ascomycetes and Deuteromycetes:

Bipolaris sorokiniana (Helminthosporium sativum)

Botrytis cinerea

Colletotrichum lagenarium

Drechslera oryzae

Fusarium graminearum

Paecilomyces variotii

Penicillium notatum

Saccharomyces cerevisiae

Septoria tritici

 

Zygomycetes:

Mucor miehei

 

Oomycetes:

Phytophthora infestans

Pythium ultimum

Microarray analysis [back to Index] 

Microarray-based transcriptome analysis during the infection related
morphogenesis in Magnaporthe grisea

Aim:

-    Identification of genes/factors required for pathogenicity and/or
invasive growth as potential new targets for plat protectants

 

Microarray analysis equipment at the IBWF

Statistics for Microarrays

Targets

• Established Targets: The Q-cycle mechanism of the bc1-complex and the mode of action of strobilurins and oudemansins

 

 _{_}           
Q-Pool: Ubiquinone-pool. Q, Q´, QH2: Ubiquinone, ubisemiquinone,
ubihydroquinone. c, c1: Cytochrome c, heme c1. b566: "low potential", b562:
"high potential" heme b. FeS: Iron-sulfur-protein

 

 

U. Brandt, U. Haase, H. Schägger, G. von Jagow: DECHEMA Monographs 129, 27, 1993
W.F. Becker, G. von Jagow, T. Anke, W. Steglich: FEBS Lett. 132, 329, 1981

 

 

 

• Potential targets for non-fungitoxic plant protectants during infection-related morphogenesis: [back to Index]

Results  [back to Index]
 

• From fungus to fungicide - the success story of the strobilurins

• Glisoprenins A, C, D and E were isolated from submerged cultures of the deuteromycete Gliocladium roseum HA190-95 as inhibitors of appressorium formation. The compounds prevented the formation of the infectious structure exclusively upon induction on hydrophobic surfaces. Upon stimulation with cAMP or the cutin-monomer 1,16-hexadecanediol, the compound failed to inhibit appressorium formation.
   

Inhibitors of signal transduction leading to the formation of infective structures in phytopathogenic fungi:

Publications [back to Index] 
 

Thines, E., F. Eilbert, O. Sterner and H. Anke: 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. 151, 219-224, 1997.

Thines, E., F. Eilbert, O. Sterner and H. Anke: Signal transduction leading to appressorium formation in germinating conidia of Magnaporthe grisea: Effects of second messengers diacylglycerols, ceramindes and sphingomyelin. FEMS Lett. 156, 91-94, 1997.

Sterner, O., E.Thines, F. Eilbert and H. Anke: Glisoprenins C, D and E, new inhibitors of appressorium formation in Magnaporthe grisea, from cultures of Gliocladium roseum. II. Structural elucidation. J. Antibiotics 51, 228-231, 1998.

Thines, E., F. Eilbert, H. Anke and O. Sterner: Glisoprenins C, D, and E, new inhibitors of appressorium formation in Magnaporthe grisea, from cultures of Gliocladium roseum. I. Production and biological activities. J. Antibiotics 51, 117-122, 1998.

Thines, E., F. Eilbert, O. Sterner and H. Anke: Inhibitors of appressorium formation in Magnaporthe grisea: A new approach to control rice blast disease. Pest. Sci. 54, 314-316, 1998.

Eilbert, F., E. Thines, O. Sterner and H. Anke: Fatty acids and their derivatives as modulators of appressorium formation in Magnaporthe grisea (Pyricularia oryzae). Biosci. Biotechnol. Biochem. 63, 879-883, 1999.

Eilbert, F., E. Thines and H. Anke: Effects of antifungal compounds on conidial germination and on the induction of appressorium formation in Magnaporthe grisea. Z. Naturforschg. 54c, 903-908, 1999.

Thines, E., H. Anke and O. Sterner: Inhibition of signal transduction leading to appressorium formation in Magnaporthe grisea by glisoprenins. In: Proceedings 2nd International Rice Blast Disease Conference. D. Tharreau, M.H. Lebrun, N.J. Talbot, J.L. Notteghem (Eds.) pp 267-270.  Kluwer Acad. Publisher, Dordrecht, 2000.

Thines, E., R. W. S. Weber and N. J. Talbot: MAP kinase and protein kinase A-dependent mobilisation of triacylglycerol and glycogen during appressorium turgor generation by Magnaporthe grisea. The Plant Cell, 12, 1703-1718, 2000.

Eilbert, F., H. Anke and O. Sterner: Neobulgarones A-F, New Dimeric Anthraquinones from Cultures of Neobulgaria pura: Novel Inhibitors of Appressorium Formation of Magnaporthe grisea. J. Antibiotics 53, 1123-129, 2000.

Weber, R. W. S., G. E. Wakley, E. Thines and N. J. Talbot: The vacuole as central element of the lytic system and sink for lipid droplets in maturing appressoria of Magnaporthe grisea. Protoplasma, 216, 101-112, 2001.

Thines, E., H. Anke, R.W.S. Weber: Fungal secondary metabolites as inhibitors of infection-related morphogenesis in phytopathogenic fungi. Mycol. Res. 108, 14-25, 2004

Contact[back to Index]

Dr. Andrew Foster

Research Associate

Mail: foster@ibwf.de
Lab 56/202; Tel.: +631/205-4265

Office 56/141; Tel.: +631/31672-21

Dr. Karsten Andresen

Research Associate

Mail: andresen@ibwf.de
Lab 56/106;

Office 56/115; Tel.: +631/31672-22

Prof. Dr. Heidrun Anke

CEO IBWF

Mail: anke@ibwf.de

Office 56/146; Tel.: +631/31672-10

 

Dr. Eckhard Thines

CSO IBWF

Mail: thines@ibwf.de

Lab 56/202; Tel.: +631/205-4265

Office 56/142; Tel.: +631/31672-20