1022-7954/05/4112- © 2005 Pleiades Publishing, Inc.
Russian Journal of Genetics, Vol. 41, No. 12, 2005, pp. 1389–1394. Translated from Genetika, Vol. 41, No. 12, 2005, pp. 1674–1680.
Original Russian Text Copyright © 2005 by Mironenko, Afanasenko, Filatova, Kopahnke.
(Sacc.) Shoem. f.
Smedeg.) causes net blotch in barley. This pest is
responsible for up to 40% loss of grain yield in some
regions of Russia [1, 2]. In the recent decade, it has
caused six epiphytotics only in the Leningrad oblast.
Little is known on the presence of sexual cycle in
. Mature pseudothecia were detected in the USA
[3, 4], in Belarus , and in the Krasnodar oblast of
Russia . Only
conidia but not ascospores
were found in the air population above a ﬁeld with bar-
ley plant remains in Saskatchewan (Canada) during a
two-year study (1986–1987) . We have found mature
pseudothecia on barley straw experienced two winters
in 1977 and on last-year barley trash of cv. Pirkka in
commercial ﬁelds of the work-study unit Pushkinskii
(Leningrad oblast) in 1986 and 1987. Ascospore forma-
tion indicates the maturity of a pseudothecium, which
is temperature-dependent . Apparently, the resultant
air temperature in the Leningrad oblast is insufﬁcient
for yearly maturation of
pseudothecia. It is rea-
sonable to suggest, however, that sexual recombination
is one of the main mechanisms of fungus variability in
southern areas of barley production, such as the Krasn-
odar oblast, where it was detected .
McDonald was the ﬁrst to perform laboratory
crosses of the fungus resulting in fertile pseudothecia
. Early genetic studies of
showed that colony
morphology, mating type, and disease symptoms (net
or round spotting, caused by different fungus varieties)
follow Mendelian segregation [9, 10]. Monogenic
inheritance of the virulence of
barley cv. Harbin was reported .
This work is dedicated to genetic analysis of
virulence toward resistant barley accessions.
MATERIALS AND METHODS
Pure fungal cultures were isolated from net-
blotched barley leaves collected in the Leningrad oblast
and received from Primorski Krai (Russia) and Canada.
Isolation of the fungus from plant tissue and prepara-
tion of monoconidial isolates were performed as
described in . Isolates were grown in ChLM
medium of the following composition (g/l): KCl (0.5),
O urea (1.2), lac-
tose (20), and agar (20) . The collection included
95 monoconidial isolates of different origins. Fungal
cultures (mixtures of conidia and mycelia) were stored in
sterile ﬁlter paper in plastic bags with silica gel at 10
Mating types of the isolates were determined by pair-
wise crosses under laboratory conditions.
Crosses were performed using the McDonald
method . A mixture of conidia and mycelium of two
compatible strains were placed on autoclaved pieces of
lemon leaves on wet ﬁlter paper in Petri dishes. The
dishes were incubated in a chamber with photoperiod
of 12 h at 15
C. Mature pseudothecia were detected
after 2–4 months in 7 out of 120 crosses. Ascospores
were shot from asci of mature pseudothecia onto the
surface of Petri dish lids covered with a layer of 3%
aqueous agar. Single ascospores were transferred to
fresh ChLM medium with a needle under a binocular
Parental isolates of two crosses analyzed were of the
following origin: H-22, Primorski Krai; 181-6, Lenin-
grad oblast; 92-179/8, Canada; isolate A-80 was an
ascospore offspring of the cross 181-6
8ax . Iso-
Genetic Control of Virulence of
the Causative Agent of Net Blotch in Barley
N. V. Mironenko
, O. S. Afanasenko
, O. A. Filatova
, and D. Kopahnke
All-Russia Institute for Plant Protection, St. Petersburg, Pushkin, 196608 Russia;
fax: (812)470-51-10; e-mail: firstname.lastname@example.org
Federal Center for Breeding Research on Cultivated Plants, Head Institute of Epidemiology and Resistance,
Aschersleben, D-06449 Germany; fax: (03473)2709; e-mail: email@example.com
Received December 16, 2004
—The genetic control of virulence was studied in four isolates of the fungus
, originating from various geographic regions in experiments with nine barley accessions, possessing
known resistance genes. Experiments were performed with the ascospore progeny of two crosses. The results
of segregation for virulence in the progeny of direct crosses were conﬁrmed by analysis of backcrosses and sib
crosses. One to four genes for avirulence toward various barley genotypes were found in the isolates under
study. It is suggested that dominant suppressor genes are involved in the genetic control of avirulence toward
four barley genotypes.