In 1996 and 1997 in the southern and central-southern regions of Brazil, a field trial evaluation was peformed on 55 wheat (Triticum aestivum) genotypes representing the recommended cultivars or the advanced inbred lines, as well as differentials for Lr known genes which confer resistance to leaf rust. The wheat genotypes were inoculated at seedling stage with 22 isolates having different avirulent/virulent genes of Puccinia triticina. The types of infection resulting from these inoculations were examined and by comparison, the occurrence of resistance genes in the tested Brazilian genotypes was determined. The seedling resistance gene more frequently identified in the Brazilian genotypes were Lr26, Lr23, Lr10 and Lr24. The Lr16 gene, that confers moderate resistance to most of the fungus races, was only found in two genotypes. Many of the analyzed wheat genotypes have one or more Lr genes probably not yet described.
