New Zealand Journal of Crop and Horticultural Science abstracts
Pathogenicity of Blumeria graminis f. sp. hordei in
New
Zealand in 1997
A. DREISEITL
Agricultural Research Institute Ltd
Havlíčkova 2787
CZ-76701 Kromĕříž
Czech Republic
email: dreiseitl@vukrom.cz
R. A. PICKERING
New Zealand Institute for Crop & Food
Research Limited
Private Bag 4704, Christchurch
New Zealand
Abstract The pathogenicity of 137 isolates of
Blumeria
graminis f. sp.
hordei (progenies of single colonies)
originating
from five locations in New Zealand was analysed using a differential
set of 15
near-isogenic lines (`Pallas'). The isolates belonged to 14 pathotypes,
five of
which comprised a sub-population obtained only from the greenhouse. The
pathotypes exhibited four to seven virulences, and all possessed
Vg,
Vra, and
Vh. They were also avirulent for resistance
genes
Mla3,
Mla6, [
Mla7 Mla(No3)],
Mla9,
Mla13,
and
Mlk1, but differed by the presence (or absence) of
virulences
Va1,
Va12,
VLa,
Vat,
V(Ru2), and
Vp1.
Forty-nine isolates (35.8% of the total) belonged to the predominant
pathotype
`14055'. There were considerable differences in the composition of
individual
sub-populations, which could indicate that the vegetative (conidial)
stage is
less important for survival and distribution of the pathogen in New
Zealand.
Direct selection of the pathogen population on host varieties is
apparently
slower in New Zealand than in Central Europe. Little or no gene flow
occurs
between the New Zealand and Australian populations.
Keywords Hordeum vulgare; Blumeria
graminis f.
sp. hordei; Erysiphe graminis f. sp. hordei;
virulence;
resistance; isolates; pathotypes; pathogenic variation; virulence
complexity;
population diversity
H99008
Received 18 February 1999; accepted 29 June
1999
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