1887

Abstract

Free-swimming zoospores of several isolates of the oomycetous water mould demonstrate mutual attraction (adelphotaxis) which may result in auto-aggregation. In the apparent absence of exogenous chemotactic signals macroscopic globular aggregates or microscopic plaques of cysts are formed. Auto-aggregation was favoured by high concentrations of zoospores in suspension; the growth rate of spontaneous aggregates was estimated at 4–10 × 10spores min; growth of an aggregate was limited to about 7 min. By means of chemotactic assays, attractant activity for zoospores was detected in the vicinity of aggregates, and in zoospore or cyst supernatants. The attractant activity extracted from spore aggregates was heat-stable. In the absence of exogenous nutrients, the macroscopic aggregates of an homothallic isolate produced sporangia and oogonia. Aggregation was readily initiated as a result of zoospore chemotaxis towards capillary tubes containing exogenous attractant in an agar medium. Aggregating zoospores frequently assumed a slender swarm configuration moving directly towards the aggregate at the capillary-tube tip. Analysis of video recordings showed that many zoospores joining the swarm were attracted directly by the swarm rather than by the exogenous attractant. Such aggregation was a time-limited process, the duration of which was extended by the presence of amino acids in the zoospore suspension. Under natural conditions zoospore aggregation may be a dual-component chemotactic process triggered by exogenous attractants and amplified by chemical signals from the aggregating spores. The possible consequences of adelphotaxis and auto-aggregate formation, namely enhanced inoculum potential, syngamy and spore production, are discussed.

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1990-05-01
2024-04-25
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References

  1. Alcantara F., Monk M. 1974; Signal propagation during aggregation in the slime mould Dictyostelium discoideum. Journal of General Microbiology 85:321–334
    [Google Scholar]
  2. Cantino E.C., Lovett J.S. 1960; Respiration of Blastocladiella during bicarbonate-induced morphogenesis in synchronous culture. Physiologia Plantarum 13:450–458
    [Google Scholar]
  3. Carlile M.J. 1983; Motility, taxis and tropism in Phytophthora. In Phytophthora, Its Biology, Taxonomy, Ecology and Pathology pp. Erwin D.C., Bartnicki-Garcia S., Tsao P.H. Edited by St Paul, Minnesota: American Phytopathological Society;
    [Google Scholar]
  4. Fischer F.G., Werner G. 1958; Die Chemotaxis der Schwarmsporen von Wasserpilzen (Saprolegniaceen). Zeitschrift für Physiologische Chemie 310:65–91
    [Google Scholar]
  5. Hartog M.M. 1888; Adelphotaxy, an undescribed form of irritability. Reports of the British Association for the Advancement of Science 1888:72
    [Google Scholar]
  6. Hickman C.J., Ho H.H. 1966; Behaviour of zoospores in plant pathogenic Phycomycetes. Annual Review of Phytopathology 4:195–220
    [Google Scholar]
  7. Jaffe L.F. 1966; On autotropism in Botrytis: measurement technique and control by CO2. Plant Physiology 41:303–306
    [Google Scholar]
  8. Ko W.H., Chase L.L. 1973; Aggregation of zoospores of Phytophthora palmivora. Journal of General Microbiology 78:79–82
    [Google Scholar]
  9. Ko W.H., Chase L.L., Kunimoto R.K. 1973; A microsyringe method for determining concentration of fungal propagules. Phytopathology 63:1206–1207
    [Google Scholar]
  10. Kraft J.M., Endo R.M. 1966; Zoospore infection of bentgrass roots by Pythium aphanidermatum. Phytopathology 56:149
    [Google Scholar]
  11. Lechmere A.E. 1910; An investigation of a species of Saprolegnia. New Phytologist 9:305–319
    [Google Scholar]
  12. Lounsbury J.A. 1927; A case of phenomenal zoospore behaviour of an apparently sterile Isoachlya and a description of the plant. Transactions of the Wisconsin Academy 23:539–549
    [Google Scholar]
  13. Macwithey H.S. 1965; Factors affecting the prevalence of black root disease of sugar beets. Phytopathology 55:106–6
    [Google Scholar]
  14. Manavathu E.K., Thomas D.D. 1985; Chemotropism of Achlya ambisexualis to methionine and methionyl compounds. Journal of General Microbiology 131:751–756
    [Google Scholar]
  15. Musgrave A., Ero L., Scheffer R., Oehlers E. 1977; Chemotropism of Achlya bisexualis germ hyphae to casein hydrolysate and amino acids. Journal of General Microbiology 101:65–70
    [Google Scholar]
  16. Plesset M.S., Whipple C.G., Winet H. 1975; Analysis of the steady state of bioconvection in swarms of swimming microorgan-isms. In Swimming and Flying in Nature 1 pp. 339–360 Wu T.Y.-T., Brokaw C.J., Brennan C. Edited by New York: Plenum Press;
    [Google Scholar]
  17. Porter J.R., Shaw D.S. 1978; Aggregation of Phytophthora drechsleri zoospores: pattern analysis suggests a taxis. Transactions of the British Mycological Society 71:515–519
    [Google Scholar]
  18. Robinson P.M. 1973; Chemotropism in fungi. Transactions of the British Mycological Society 61:303–313
    [Google Scholar]
  19. Royle D.J., Hickman C.J. 1964a; Analysis of factors governing in vitro accumulation of zoospores of Pythium aphanidermatum on roots. I. Behaviour of zoospores. Canadian Journal of Microbiology 10:151–162
    [Google Scholar]
  20. Royle D.J., Hickman C.J. 1964b; Analysis of factors governing in vitro accumulation of zoospores of Pythium aphanidermatum on roots. II. Substances causing the response. Canadian Journal of Microbiology 10:201–219
    [Google Scholar]
  21. Schaffer B.M. 1975; Secretion of cyclic AMP induced by cyclic AMP in the cellular slime mould Dictyostelium discoideum. . Nature; London: 255549–552
    [Google Scholar]
  22. Thomas D.D. 1989; A method for preparing Achlya cysts with high zoosporogenic potential. Mycological Research 92:233–235
    [Google Scholar]
  23. Zentmyer G.A. 1961; Chemotaxis of zoospores for root exudates. Science 133:1595–1596
    [Google Scholar]
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