Inheritance of leaf rust and stripe rust resistance in the Brazilian wheat cultivar Toropi

Leaf rust is the most wide-spread fungal disease of wheat globally. Leaf rust can cause reductions in grain yield and quality. There are genes in wheat, called leaf rust resistance (Lr) genes, which enable the wheat plant to defend itself from the fungus that causes leaf rust. The fungus evolves over time into difference races or strains that have the ability to overcome some resistance genes. This means that new sources of resistance genes need to be discovered or long-lasting resistance genes should be identified. Toropi is an old South American wheat variety that has maintained its resistance to leaf rust for approximately 50 years. This study analyzed the genetics of leaf rust resistance in Toropi to determine the number of Lr genes present. It was determined that Toropi carries two genes that must be present together (complementary genes) in order to provide resistance to all races of the leaf rust fungus tested. This is called race-nonspecific resistance. An additional gene was found that provides resistance to specific races of leaf rust.