Meeting the Challenge of Yellow Rust in Cereal Crops - ICARDA

394
Race composition and effective resistance genes to yellow
rust in Azerbaijan
A.M. Abdullayev, J.M. Talai, E.R. Ibragimov and S.M. Mammadova
Azerbaijan Research Institute of Agriculture
Yellow rust is one of the most important factors limiting wheat productivity in
Azerbaijan, causing heavy losses. Heavy epidemics of yellow rust led to yield
losses of 28 to 60% in wheat, depending on the susceptibility the commercially
grown cultivars and the level of challenge. In addition to yield loss, yellow rust
also affects the quality of the grain. The occurrence of yellow rust increased in
Azerbaijan between 1995 and 2000, attributed to the introduction of highly
susceptible cultivars. For effective control of yellow rust, it is important to
determine the race composition of the pathogen and to identify effective genes
for resistance to be incorporated in breeding programmes for wheat. For this
purpose, we conducted field surveys in various regions of Azerbaijan. Infected
leaf samples were collected for race analysis. The collected samples were
analysed for their virulence spectrum on Yr differentials. The race analysis of
the samples revealed the presence of yellow rust races 70E6, 6E6, 6E2, 14E142,
22E6, 134E134, 134E150, 2E0 and 6E0. Using World and European differential
sets, it was found that only four differentials were totally effective against all
yellow rust races detected in Azerbaijan. These differentials were: Chinese 166
(Yr1), Strubes Dickopf (YrSD), Triticum spelta var. album (Yr5) and Spaldings
Prolific (YrSP). Therefore the genes carried by these differentials are effective
in Azerbaijan. Few differentials were susceptible to only one race. These
differentials were Vilmorin 23 (Yr3) susceptible to 14E142; Moro (Yr10)
susceptible to 22E6; Suwon 92×Omar (YrSU) susceptible to 70E6; Nord
Desprez (YrND) susceptible to 14E142; and Compair (Yr9-18), susceptible to
134E150. Two differentials were susceptible to two races and immune to the
rest: Clement (Yr2-9 +) and Hybrid 46 (Yr4). Finally, it is necessary to note that
the genes Yr2, Yr6, Yr7, Yr22 and Yr23 were not effective genes for the country.