Abstract
The role of external signals (particularly the substratum surface and light) in regulating the pre-penetration phase of Magnaporthe grisea (Herbert) Barr [anamorph,Pyricularia grisea Sacc.] were analysed on rice (Oryza sativa L.) leaves, artificial substrata and in liquid suspension. Surface contact was found to be essential for appressorium induction but not conidium germination. Both a high surface hydrophobicity and light favoured the formation of short differentiated germ tubes and large numbers of appressoria, but neither factor was essential for their induction. Light intensity had a graded effect on the lengths of differentiated germ tubes but not on the number of appressoria formed. Higher numbers of appressoria differentiated on rice leaves than on artificial substrata suggesting that the host provides additional factors, and thus a more conducive environment, for promoting appressorium formation. Our study indicates that the pre-penetration phase of rice blast infection involves a programme of growth and differentiation triggered at conidium germination and regulated by multiple signals from the host and environment. No evidence was found for a single, external signal which initiates appressorium formation. Starvation is suggested as providing the necessary intracellular signal.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
Allen, E.A., Hazen, B.E., Hoch, H.C., Kwon, Y., Leinhos, G.M.E., Staples, R.C., Stumpf, M.A., Terhune, B.T. (1991a) Appressorium formation in response to topographical signals by 27 rusts. Phytopathology81, 323–331
Allen, E.A., Hoch, H.C., Stavely, J.R., Steadman, J.R. (1991b) Uniformity among races of Uromyces appendiculatus in response to topographic signaling for appressorium formation. Phytopathology81, 883–887
Araki, F., Miyagi, Y. (1977) Effects of fungicides on penetration byPyricularia oryzae as evaluated by an improved cellophane method. Pestic. Sci. 2, 457–461
Bourett, T.M., Howard, R.J. (1990)In vitro development of penetration structures in the rice blast fungusMagnaporthe grisea. Can. J. Bot. 68, 329–342
Chumley, F.G., Valent, B. (1990) Genetic analysis of melanin-deficient, nonpathogenic mutants of Magnaporthe grisea. Mol. Plant-Microbe Interact. 3, 135–143
Dobinson, K.F., Hamer, I.E. (1992)Magnaporthe grisea. In: Molecular biology of filamentous fungi, pp. 67–86, Stahl, U., Tudzynski, P., eds. VCH, Weinheim
Emmett, R.W., Parbery, D.G. (1975) Appressoria. Annu. Rev. Phytopathol. 13, 147–167
Gerisch, G. (1987) Cyclic AMP and other signals controlling cell development and differentiation in Dictyostelium. Annu. Rev. Biochem. 56, 853–879
Hamer, J.E., Howard, R.J., Chumley, F.G., Valent, B. (1988) A mechanism for surface attachement in conidia of a plant pathogenic fungus. Science239, 288–290
Hamer, J.E., Valent, B., Chumley, F.G. (1989) Mutations at the SMO genetic locus affect the shape of diverse cell types in the rice blast fungus. Genetics122, 351–361
Hashioka, Y. (1972) Fine structure of the rice blast. IX. Scanning electronmicroscopical observations on appressoria of the rice blast fungus and other species of yricularia. Res. Bull. Fac. Agric Gifu Univ. 33, 65–73
Hirooka, T., Miyagi, Y., Araki, F., Kunoh, H., Ishizaki, H. (1982) The effect of isoprothiolane on the emergence of infection pegs from appressoria of yricularia oryzae. Pestic. Sci. 13, 379–386
Hoagland, D.R., Arnon, D.I. (1950) The water-culture method for growing plants without soil. Univ. Calif. Agric. Exp. Stn. Cir. 347
Hoch, H.C., Staples, R.C. (1991) Signaling for infection structure formation in fungi. In: The fungal spore and disease initiation in plants and animals, pp. 25–46, Cole, G.T., Hoch, H.C., eds. Plenum Press, New York
Hoch, H.C., Staples, R.C., Whitehead, B., Comeau, J., Wolf, E.D. (1987) Signaling for growth orientation and cell differentiation by surface topography byUromyces. Science253, 1659–1662
Howard, R.J., Ferrari, M. (1989) Role of melanin in appressorium function. Exp. Mycol. 13, 403–418
Howard, R.J., Ferrari, M.A., Roach, D.H., Money, N.P. (1991a) Penetration of hard substrates by a fungus employing enormous turgor pressures. Proc. Natl. Acad. Sci. USA88, 11281–11284
Howard, R.J., Bourett, T.M., Ferrari, M.A. (1991b) Infection byMagnaporthe: an in vitro analysis. In: Electron microscopy of plant pathogens, pp. 251–264, Mendgen, K., Lesemann, D.-E., eds. Springer Verlag, Berlin
Kacser, H., Porteous, J.W. (1987) Control of metabolism: what do we have to measure? TIBS12, 4–10
Lee, Y.-H., Dean, R.A (1993a) cAMP regulates infection structure formation in the plant pathogenic fungusMagnaporthe grisea. Plant Cell5, 693–700
Lee, Y.-H., Dean, R.A. (1993b) Stage-specific gene expression during appressorium formation of Magnaporthe grisea. Exp. Mycol. 17, 215–222
Macko, V. (1981) Inhibitors and stimulants of spore germination and infection structure formation. In: The fungal spore: morphogenetic controls, pp. 565–584, Turian, G., Hohl, H.R., eds. Academic Press, New York
Nicholson, R.L., Epstein, L. (1991) Adhesion of fungi to the plant surface. Prerequisite for pathogenesis. In: The fungal spore and disease initiation in plants and animals, pp. 3–23, Cole, G.T., Hoch, H.C., eds. Plenum Press, New York
Ou, S.H. (1980) A look at worldwide rice blast disease control. Plant Dis. 64, 439–445
Ou, S.H. (1985) Rice diseases, 2nd edn. Commonwealth Mycological Institute, Kew, UK
Peng, Y.-L., Shishiyama, J. (1988) Temporal sequence of cytological events in rice leaves infected withPyricularia oryzae. Can J. Bot. 66, 730–735
Read, N.D., Kellock, L.J., Knight, H., Trewavas, A.J. (1992) Contact sensing during infection by fungal pathogens. In: Perspectives in plant cell recognition, pp. 137–172, Callow, J.A., Green, J.R., eds. Cambridge University Press, Cambridge, UK
Talbot, N.J., Ebbole, D.J., Hamer, J.E. (1993) Identification and characterization of MPG1, a gene involved in pathogenicity from the rice blast fungusMagnaporthe grisea. Plant Cell5, 1575–1590
Terhune, B.T, Allen, E.A., Hoch, H.C., Wergin, W.P., Erbe, E.F. (1991) Stomatal ontogeny and morphology in Phaseolus vulgaris in relation to infection structure initiation in Uromyces appendiculatus. Can. J. Bot. 69, 477–484
Trewavas, A.J. (1987) Many a mickle makes a muckle; network maxims may mitigate controversy. BioEssays7, 84–86
Uchiyama, T., Okuyama, K. (1990) Participation of Oryza sativa leaf wax in appressorium formation byPyricularia oryzae. Phytochemistry29, 91–92
Uchiyama, T.N., Ogasawara, Y., Nanba, Y., Ito, H. (1979) Conidial germination and aprressorium formation of the plant pathogenic fungi on the cover-glass or cellophane coated with various lipid components of plant waxes. Agric. Biol. Chem. 43, 383–384
Valent, B. (1990) Rice blast as a model system for plant pathology. Phytopathology80, 33–36
Valent, B., Chumley, F.G. (1991) Molecular genetic analysis of the rice blast fungus,Magnaporthe grisea. Annu. Rev. Phytopathol. 29, 443–467
Valent, B., Farrall, L., Chumley, F.G. (1991)Magnaporthe grisea genes for pathogenicity and virulence identified through a series of backcrosses. Genetics127, 87–101
Woloshuk, C.P., Sisler, H.D., Tokousbalides, M.C., Dutky, S.R. (1983) Melanin biosynthesis in Pyricularia oryzae: site of tricyclazole inhibition and pathogenicity of melanin-deficient mutants. Pestic. Biochem. Physiol. 14, 256–264
Yaegashi, H., Matsuda, I., Sato, Z. (1987) Production of appressoria at the tips of hyphae of yricularia oryzae. Ann. Phytopathol. Soc. Japan53, 203–209
Author information
Authors and Affiliations
Additional information
We are grateful to the Science and Engineering Research Council for research studentship to T.C.J., and for financial funding (grant number GR/G 28765) to N.D.R. We thank Mr. Tony Collins, Dr. Jim Deacon, Dr. Rick Howard (DuPont Co., Wilmington, Del., USA) and Prof. Tony Trewavas for helpful comments during preparation of this manuscript. Jim Deacon also provided advice on statistical analysis.
Rights and permissions
About this article
Cite this article
Jelitto, T.C., Page, H.A. & Read, N.D. Role of external signals in regulating the pre-penetration phase of infection by the rice blast fungus, Magnaporthe grisea . Planta 194, 471–477 (1994). https://doi.org/10.1007/BF00714458
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/BF00714458