Fungi with septate hyphae and a dikaryophase

5. Fungi usith septate hgptne attd a dikargophase B3
trash. The fungus can survive as teliospores on contaminated seed or in soil for
up to 3 years.
Botl. species of bunt fungi have similar life cycles. However the two species can
be distinguished by their teliospore walls which are reticulate (net-like) in
T. caries and smooth in T. Laeuis. Upon germination, each teliospore produces a
basidium on which eight terminal basidiospores develop (Fig. 5.12). These
basidiospores fuse near the middle in compatible pairs to form four H-shaped
structures. These dikaryotic structures germinate to produce either infectious
hyphae or secondary conidia.
*"'*"*M4^'"
coniusationor
^-,\ :il1'$$- W
f rF\ r*r"r'"
/ \f basidiospore dikaryotic V/ . between cells
4G4'**,fl?Lffi" fr;::J^"" ^V1'*"
:f;'n.::''i:'o'oo'"'
T6 ';:;.0",".
;n"1.iil",: M
n:::li*i
wrfgdt trglltt 15 \U\,
/
I
tlt
tefiospores on
mycerium
germinating
heatthv tqfu 8.H, becomas becomes
wheat seed ,.h"r li*t ,€Ih intracerurar
'Xf{ heads
in kerners
ffiK5
.--tV: M. l/\d"
furuWk@il:H:,;
upon harvest
and
contaminat€
heatthy wheat
kernels
smutted
wh€at
head
smutted
wheat
kernels full
of telispores
Figtrre 5.12 Disease rycle of TitLe{La caries. the cause of common bunt of wheat.
Infectious hyphae arising from the fused basidiospores or germinated
secondar1r conidia penetrate and infect the young coleoptiles of germinated wheat
seedlings before they emerge from the ground, thus the name'seedling-infecting
smut'. Only young seedlings become infected as older plants are resistant to
infection. The fungus invades the meristem tissues and is then carried upwards
with the inflorescence primordia when internodes elongate. After systemic
development in the plant, the mycelium forms teliospores which replace tJle grain
as the host matures. Another example of a seedling infecting smut is lJsttlago
btillata spp. which is common in northern New South Wales and Queensland.