Use of molecular markers in wheat breeding for disease resistance

Leaf rust is one of the most important leaf diseases of wheat in Hungary. Breeding for resistance is considered to be the most economical and environmentally safe method to reduce damages. About fifty resistance genes have been characterized against leaf rust. The traditional way of transferring one or more resistance genes to a single wheat cultivar relay on field and greenhouse screening with different races, which is a very laborious and time consuming process. In recent years DNA-based markers have shown great promise in lessening the time and expense for pyramiding resistance genes. So far 26 molecular markers have been reported which are closely linked to 14 different leaf rust resistance (Lr) genes. The most widely used marker system is based on RFLPs. Now, there is a moving from the expensive and technically more difficult RFLP marker system to the user friendly PCR-based markers. In this study a search for PCR markers linked to Lr genes was carried out by screening on Thatcher-based wheat leaf rust near isogenic lines (NILs). Four RAPD (Lr20 and Lr29), SSR (Lr18) and ISSR (Lr3,3bg) markers were selected. The linkage analysis of these putative markers to Lr genes (Fz segregation analysis) is in progress.