The effect of light and darkness upon infection of Asterionella formosa hassall by the Chytrid Rhizophydium planktonicum canter emend

Abstract

Observations, both experimental and microscopic, indicate that zoospores of Rhizophydium planktonicum Canter emend., can remain alive, but rarely become adherent upon cells of Asterionella formosa Hassall under conditions of very low light or in complete darkness.The behaviour patterns of zoospores towards host cells under darkened conditions were compared with those which took place under well illuminated conditions leading to the settlement of zoospores on host cells. The differences noted may help to explain the lack of zoospores found upon inadequately illuminated diatom cells.Some evidence suggests that young zoospores lack the ability to adhere to host cells. After the encystment of zoospores upon Asterionella cells in the light, their further growth and development can continue in darkness. © 1981 Annals of Botany Company.