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Genetic analysis of resistance in some
varieties of bread wheat (Triticum aestivum) to three
races of yellow rust (Pucoinia
striiformis)*
Sudhir KOCHHAR, K.S. GILL and G.S. NANDA
Department of Plant Breeding, Punjab Agricultural University
Ludhiana, India
In breeding programmes aimed at incorporating yellow rust
resistance in wheat, genetic stocks are used that show
resistance in the adult plant stage over a number of
locations and seasons. In these stocks, Iittle genetic
information on Yr-genes is available even though information
of this type is very essential to ensure genetic diversity
in the programmes. The purpose of this study was to
determine the inheritance of resistance to yellow rust in
bread wheat.
Material and Methods
Seven bread wheat vairieties, viz. CPAN 1360. CPAN 1444,
Sonalike, HD 2009, Tanori 71, Tobari 66 and Kalyansona with
undetermined Yr-genes, five varieties, viz. Bon Fermier
(yr3a), Opal (yr4b), Lee (yr7), Compair (yr8) and Nudif TP
250 (Yr1+Yr6) and Agra Local, the universal susceptible
variety, comprised the material for the present study.
Seedling reactions were recorded on parental lines
F1 hybrid and F2 progeny of several
crosses. The details of the setting up of the laboratory and
the recording of the observations are already on record
(KOCHHAR, GILL & NANDA 1982).
Results and Discussion
The varieties CPAN 1444, Sonalika and Tobari 66 probably
possess Yr3a as no segregation was observed in their crosses
with tester line Bon Fermier against any of the three races
studied. Varieties HD 2009 and Tanori 71 may also be
presumed to carry this gene as indicated by no segregation
in F2 of their crosses with Bon Fermier (Yr3a)
against two of the three races. A 63:1 ratio was observed
for HD 2009 x Bon Fermier against race 31 and for Tonori 71
x Bon Fermier against race 38A. These varieties are thus
suggested to have other loci for resistance against the
respective races. It is rather unusual that susceptible
seedlings should have been scored even when both the parents
have been postulated to carry Yr3a. It may be due to some
unknown inhibitory genes operating selectively, or Yr3a may
be a complex locus, or it may have been altered in its
reaction due to the residual genetic background. Similar
results have been reported on wheat (LUPTON & MACER
1962; JAIN & GANDHI 1978). On a similar assumption
varieties CPAN 1444, Sonalika, HD 2009 and Tonari 66 may be
postulated to carry Yr4b which determined the resistance in
the crosses of these lines with the tester line Opal against
one or more races. However, the parentage of these varieties
did not indicate any common parents which could be
postulated to have contributed Yr4b. A segregation for two
loci was observed in the cross CPAN 1360 x Opal against race
38A indicating that two other loci operated in determining
the resistance in the cross against this race.
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