Race non-specific resistance to yellow rust in some promising wheat lines

Yellow (stripe) rust caused by Puccinia striiformis f. sp. tritici is one of the most damaging diseases of wheat in Iran. Host resistance, especially race- nonspecific resistance, is the most economical way to manage wheat stripe rust. Although the life of effective race –specific resistance genes can be prolonged by using gene combinations, an alternative approach is to deploy varieties that possess race- nonspecific resistance based on combinations minor, slow rusting genes. In order to evaluate race-nonspecific resistance, seedling and adult plant reactions of 22 promising wheat lines along with susceptible check were evaluated to yellow rust. The seedling reaction was evaluated in greenhouse by using race 6E150A+, Yr27. Adult plant resistance was also evaluated by measuring of final rust severity (FRS) and coefficient of infection (CI) under natural infection conditions with two times artificial inoculations. Artificial inoculation was carried out by yellow rust inoculum having virulent genes against Yr2, Yr6, Yr7, Yr9, Yr22, Yr23, Yr24, Yr25, Yr26, Yr27, YrA, and YrSU. Field evaluation was conducted based on randomized complete block design with three replications during 2011-2012 cropping season at Ardabil Agricultural Research Station (Iran). Results showed that lines S-90-1, S-90-14, S-90-16, S-90-17, S-90-20, S-90-21 and S-90-22 along with susceptible check (Bolani) had the highest values of FRS and CI. The lines S-90-2, S-90-3, S-90-4, S-90-9, S 90-11, S- 90-13 and S-90-18 were susceptible at the seedling stage and had low values of FRS and CI at the adult plant stage. Consequently, these lines have different levels of slow rusting resistance (racenonspecific or durable resistance) based on the results of this investigation and their pedigree information. The remaining lines that had low level infection at the seedling and adult plant stages were selected as moderately resistant or resistant lines.