Introduction to Fungi, Third Edition

PERONOSPORALES
123
Fig 5.32 Albugo candida on Capsella bursa-pastoris. (a) Mycelium, sporangiophores and chains of sporangia formed beneath the
ruptured epidermis (right). (b) Germination of sporangia showing the release of eight biflagellate zoospores.The stages illustrated
took place within 2 min. (c) Haustoria.
as evidence of secretory processes induced in the
host cell by the presence of the pathogen.
The intercellular mycelium aggregates
beneath the host epidermis to form a palisade
of cylindrical or skittle-shaped sporangiophores
which give rise to chains of spherical sporangia
in basipetal succession i.e. new sporangia
are formed at the base of the chain. The pressure
of the developing chains of sporangia raises
the host epidermis and finally ruptures it.