Development of a molecular marker for the adult plant leaf rust resistancegene Lr35 in wheat

The objective of this work was to develop a marker for the adult plant leaf rust resistance gene Lr35. The Lr35 gene was originally introgressed into chromosome 2B from. Triticum speltoides, a diploid relative of wheat. A seg regating population of 96 F-2 plants derived from a cross between the resis tant line ThatcherLr35 and the susceptible variety Frisal was analysed. Out of 80 RFLP probes previously mapped on wheat chromosome 2B, 51 detected a polymorphism between the parents of the cross. Three of them were completel y Linked with the resistance gene Lr35. The co-segregating probe BCD260 was converted into a PCR-based sequence-tagged-site (STS) marker. A set of 48 different breeding lines derived from several European breeding programs wa s tested with the STS marker. None of these lines has a donor for Lr35 in i ts pedigree and all of them reacted negatively with the STS marker. As no l eaf rust races virulent on Lr35 have been found in different areas of the w orld, the STS marker for the Lr35 resistance gene is of great value to supp ort the introgression of this gene in combination with other leaf rust (Lr) genes into breeding material by marker-assisted selection.