Evaluation of leaf rust resistance in Aegilops genotypes at the seedling and adult plant stages

at the seedling and adult plant stagesAegilops species are abundantly found in Iran, of which many could be resistant to wheat rusts .However, the researches that have been conducted to study their resistance and exploit them, are insufficient. Despite having different ploidy levels, some Aegilops species are similar in appearance and hence, flow cytometry was used to determine their ploidy level.  Three species i.e. Ae. crassa, Ae. neglecta and Ae. vavilovii were studied where Ae. tauschii (2n=2x=14) was used as a reference genome. The DNA content of the species Ae. crassa and Ae. neglecta was twice that of Ae. tauschii, and hence they were tetraploid (2n=4x) while DNA content in Ae. vavilovii was three times of the reference genome, and therefore it was hexaploid (2n=6x). To identify susceptible and resistant genotypes, a greenhouse study was conducted of 49 genotypes of Ae. crassa, Ae. neglecta, Ae. geniculata, Ae. kotschyi, Ae. biuncialis and Ae. vavilovii to wheat leaf rust at the seedling and adult plant stages. First, single spores of four pathotypes of Puccinia triticina were multiplied on the wheat susceptible cultivar “Roshan” to obtain pure and fresh urediniospores. Then, at the two-leaf stage, the plants were inoculated with these pathotypes and were kept at 20 ℃ under 100 % humidity for 24 hours in dark. Two weeks later, the seedlings were scored using the 0-4 scale where different infection types from completely resistant (0;=) to highly susceptible (3+) were detected. Additionally, at the adult plant stage, different levels of resistance (R to MR) were observed. This study lays the foundation for identifying the number of resistance genes in these genotypes and their modes of action in future studies.