Tilletia indica - The Food and Environment Research Agency - Defra

Teliospore
character
Size (range) µm
Size (mean) µm
Colour
Exospore
Ornamentation
in median view
♣
Exospore
Ornamentation
in surface view
Tilletia indica 1
22–47–(61)
(26–55(–64)) †
35–41
(40–44) †
Pale orange to mainly dark,
reddish brown
to opaque-black
Sharply pointed to truncate
spines (occasionally
curved), 1.5–5.0 µm high,
covered with a hyaline
sheath
Spines densely arranged,
either individually
(densely echinulate) or in
closely spaced, narrow
ridges (finely cerebriform),
Tilletia walkeri 2
(23–45) †
30–31 *
(34–36) †
Pale yellow to mainly dark
reddish brown (never
opaque)
Conical to truncate spines
(occasionally curved), 3–6
µm high, covered with a
hyaline to yellowish-brown
sheath
Spines coarsely arranged,
forming wide,
incompletely cerebriform
(to coralloid) ridges or
thick clumps
T. horrida 3
17–36
(20–38(–41)) †
24–28 ‡
(28) †
Pale yellow to mainly light
or dark chestnut brown
(semi-opaque)
Sharply pointed or curved
spines, 1.5–4.0 µm
high, becoming truncated
scales with maturity,
covered with a hyaline to
tinted sheath
Spines appearing as
polygonal scales
(occasionally spines
forming cerebriform ridges
or small clumps) ‡
1
Based on: Bansal et al., (1984); Castlebury & Carris (1999); CMI Description No. 748 (1983); Durán
(1987); Durán & Fischer (1961); Khanna & Payak (1968); Mathur & Cunfer (1993); Milbrath et al.
(1998); Mundkur (1940); Peterson et al., (1984).
2
Based on: Castlebury & Carris (1999); Cunfer & Castlebury, 1999; Milbrath et al. (1998); Castlebury,
3
1998.
As T. barclayana: Castlebury & Carris (1999); CMI Description No. 75 (1965); Durán (1987); Durán
& Fischer (1961). Or as T. horrida: Aggarwal et al. (1990); Khanna & Payak (1968); Castlebury
(1998).
† Castlebury & Carris (1999) report larger spore sizes (in brackets) for teliospores warmed overnight at
45°C in Shear’s solution; Castlebury (1998) also reports larger teliospore sizes.
* Milbrath et al., (1998), supported by Author’s data from teliospores ex. Lolium (two isolates ex.
‡
Oregon, USA) in water.
Author’s data from teliospores ex. Oryzae (California, USA; Arkanasas, USA) in water; though not
reported in the literature, some spores may have ridges in addition to individual spines (see Figure 2.4).
♣ Hawksworth et al., (1995): Ainsworth and Bisby’s Dictionary of the Fungi.
Table 2.2. Morphological characteristics of Tilletia indica (Karnal bunt of wheat), T. walkeri
(ryegrass bunt) and T. horrida (rice smut). The literature on spore sizes is often variable.
Spore size is affected by the mounting medium and by heating treatments. For rice smut (T.
horrida, synonym T. barclayana), data from rice is potentially more reliable than data based
on T. barclayana sensu lato from various Poaceae as the latter is considered a species
complex. The rice pathogen is considered distinct from those on Paspalum and Pannicum,
but it is not known whether it is distinct from T. barclayana s.s. on Pennisetum (Pimentel,
1998; Castlebury, 1998).
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