8th INTERNATIONAL WHEAT CONFERENCE

effeCT of WheAT CuLTIVARS oN VARIABILITy of LeAf
RuST PoPuLATIoNS
E. D. Kovalenko, A. I. Zhemchuzhina, N. N. Kurkova
All Russian Research Institute of Phytopathology, Moscow, Russia
E-mail: kovalenko@vniif.rosmail.com
Breeding for resistance of wheat cultivars is the most economic and effective method of
control to diseases. Difficulties of breeding wheat cultivars for durable resistance to leaf
rust are caused by continuously race-forming processes in populations. In this connection
monitoring leaf rust pathotypes remains the important and necessary stage in immunologic
researches. New resistant wheat cultivars and agro-climatic conditions in regions effect essentially
on formation of leaf rust population. Leaf rust populations in various regions of
Russia were differed in number and virulence spectrum of races. The greatest distinctions
between leaf rust populations from regions of the European part of Russia and Western
and Eastern Siberia were revealed. Long-term data of dynamics and frequency of occurrence
of virulence genes in leaf rust populations have shown that for the main reason of
appearance of the new virulent pathotypes are cultivation of new resistant wheat cultivars.
In the beginning of 70th of the last century on wheat crops the leaf rust isolates with gene
р26 were allocated very seldom. The increase of crop areas under cultivars Aurora and Caucaz
with resistance gene Lr 26 up to several thousand hectares in Krasnodar territory has
made strong leaf rust epidemics in 1976. In leaf rust populations the isolates virulent to Lr
26 have almost disappeared after removal from production of these cultivars. However in
2002-2003 the virulence to Lr 26 up to 70-72% was again noted in Krasnodar and Stavropol
Territory (Northern Caucasus). Possibly it is caused by that the cultivars with Lr 26 (Deay,
Krasota, Tanya) have begun to cultivate again in this region last years.
In the middle of 90th in territory of Low Volga region have been cultivated new leaf rust resistant
spring wheat cultivars L-503 and L-505 with gene Lr 19 effective in Russia within 30 years.
Many breeders have begun to use gene Lr 19 for creation leaf rust resistant wheat cultivars.
For the first time the single pathotypes overcoming resistance of Lr 19 in populations of Puccinia
triticina have been registered in Middle and Low Volga regions in 1997. Some years ago
isolates with gene р19 have been found out in territory of all regions of Russia. All cultivars
with earlier effective gene Lr 19 have lost their resistance. However the highest concentration
of virulent isolates to gene Lr 19 was identified in the Low Volga region (38-65%). At the end
of 90th winter wheat cultivar Moscovskaya 39 with gene Lr 1 has been cultivated almost in
all territory of Russia. Till 1997 frequency of occurrence of virulent isolates to Lr 1 did not
exceed 40%. However in 2000-2003 it has increased up to 85-100% for Central, Middle- and
Low Volga regions, and also for Siberia. Thus the selection and accumulation new leaf rust
pathotypes overcoming race specific resistance of new wheat cultivars have taken place. Rate
of their accumulation depends on the area under crops occupied by new cultivars. In order to
prevent fast loss of the genetic variety wheat cultivars have to be cultivated and the area under
each cultivar is not exceed 9-10% (Smirnova L.A., Romanenko А. А., 2005).
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