Introduction to Fungi, Third Edition

650 USTILAGINOMYCETES: SMUT FUNGI AND THEIR ALLIES
Fig 23.11 Teliospores of Urocystis agropyri.
A dark-walled fertile cell is surrounded
by several flattened hyaline sterile cells.
Fig 23.12 Urocystis anemones. (a) Spore
balls showing germination after 24 h
incubation. A promycelium develops from
a fertile cell, bearing a crown of three or
four sporidia. (b) Development after 48 h.
The sporidia have fused (arrow) and a
septate infection hypha develops from the
fusion cell.
conjugate in pairs whilst still attached to the
promycelium. The two haploid nuclei then
migrate into an infection hypha which develops
from the conjugation tube (Thirumalachar &
Dickson, 1949).
Urocystis tritici infects its wheat host by
appressorium-mediated penetration of the
infection hypha through the host epidermis
(Nelson & Durán, 1984). Infection occurs at
the early seedling stage and is systemic. The outbreak
of symptoms is delayed, with the typical
stripe-like sori breaking through the epidermis
of several leaves after flowering of the host plant.
Heavily infected plants may abort their tillers.