Meeting the Challenge of Yellow Rust in Cereal Crops - ICARDA

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Evaluation of seedling and adult plant resistance to
Puccinia striiformis f.sp. tritici in some wheat genotypes
F. Afshari
Seed and Plant Improvement Institute (SPII), Karaj, Islamic Republic of Iran.
In order to determine the resistance of wheat genotypes in the seedling and
adult plant stages an experiment was carried out in cropping season 2002/03.
In the seedling stage, 35 cultivars and advanced lines were tested with a hot
race of Pst 134E134A+ in the greenhouse. This pathotype has virulence on lines
with Yr2, Yr6, Yr7, Yr9 and YrA. All genotypes were inoculated with the
pathotype in the greenhouse when the second leaves of seedlings were
appearing. After inoculation, seedlings were placed in an inoculation room for
24 h at 10°C and 100% RH in the dark. Following inoculation, plants were
moved to greenhouse chambers at 18–20°C. Infection types were recorded 15–
18 days after inoculation. The aim was to record reactions when the difference
between the susceptible controls and the test lines was at a maximum. The
results showed that among the seedlings, 25 genotypes carried seedling
resistance genes and 10 genotypes were susceptible. In the field, all 35
genotypes were planted in two 1-m rows 30 cm apart under artificial
inoculation with race 134E134A+. A susceptible wheat cultivar (Bolani) was
planted as spreader around the field and between the rows. The response of
plants was evaluated using a modified Cobb’s scale when the flag leaf had
appeared. Among these lines, 30 genotypes were resistant in the field. All 5
susceptible genotypes in the seedling stage were susceptible in the field. Also,
five genotypes susceptible as seedlings were resistant in the field, which is
indication of presence of adult plant resistance gene(s) in cv. Mahdavi, S-78-11,
C-78-7, N-75-16 and M-78-9 genotypes.