This study was conducted to: 1) characterize virulence formula and diversity of prevalent isolates of Puccinia triticina in Iran, 2) postulate leaf rust resistance genes in wheat cultivars and breeding lines commercially grown in Iran, 3) identify the seedling and adult plant Lr genes carrying by "Marvdasht", a highly resistant cultivar to leaf and yellow rust diseases, using greenhouse survey, field survey and molecular analyses, 4) test the allelic relationship between Falat and Marvdasht cultivars and 5) map Lr17a in Marvdasht cultivar. The results showed that 90 to 100% of tested isolates had virulence to all three alleles of the Lr3 locus, Lr11 , Lr14b and Lr30 . On the other hand, none of the isolates were virulent on near isogenic lines (NILs) possessing leaf rust resistance genes Lr9, Lr19 , Lr25 and Lr28 . The genes Lr1 , Lr10 , Lr13 , Lr17 , Lr23 and Lr26 were the most frequent seedling leaf rust resistance genes postulated to be present in Iranian wheat cultivars and breeding line. Among the highly resistant candidate genotypes tested against leaf rust and yellow rust, Marvdasht ranked as the highest resistance cultivar and hence selected for developing mapping population for further genetic and molecular analyses. The results of genetic and molecular analyses in the F 2:3 population derived from Marvdasht (R) ×Bolani (S) indicated that resistance in‘Marvdasht’ to P. triticina isolate 84-1 is governed by two dominant seedling resistance genes. Allelism studies using inoculation of F2 population derived from Marvdasht×Falat cultivar (carries the 1BL.1RS translocation) by P. triticina isolates 84-24 and 85-28 showed that resistance sources in Marvdasht cultivar differed from ? Lr23 and Lr26 ?; those conditioning resistance to leaf rust pathogen in Falat cultivar. Molecular analysis using the STS marker “ Lrk10-D ” confirmed the presence of Lr10 as a source of resistance to leaf rust in Marvdasht cultivar and the related F 2:3 population derived from Marvdasht (R) ×Bolani (S). Furthermore, the host reactions of 160 F 2 plants derived from Bolani×Marvdasht cross, against leaf rust isolate 84-1, confirmed the presence of postulated genes Lr1 and Lr17a , in Marvdasht cultivar. To map Lr17a , firstly, all individual F 2 plants were screened using RGA-567-5 STS marker developed for Lr1 gene. A subset of F 2 plants, comprised 54 F 2:3 lines including 42 either resistant or heterozygote lines, and 12 susceptible lines which did not possess Lr1 were selected to test microsatellite markers locating in wheat chromosome 2AS. Second, The bulked segregation analysis and microsatellite 2AS) of F 2 subpopulation of Marvdasht × Bolani Lr17a was