MOLECULAR MARKERS LINKED TO THE LEAF RUST RESISTANCE GENE LR24 IN DIFFERENT WHEAT CULTIVARS

The aim of this study was to find molecular markers (RAPD and SCAR) fo r the wheat leaf rust resistance gene Lr24. A backcross line, RL 6064, possessing a single resistance gene to leaf rust (Lr24) and its recur rent parent 'Thatcher' were used to find RAPD markers linked to the Lr 24 gene. Among 125 RAPD primers tested, only one (OP-H5) detected an a dditional band in the resistant line RL 6064. The genetic linkage of t his molecular marker to Lr24 was tested on a segregating F-2 populatio n derived from a cross between the leaf rust resistant line RL 6064 an d the susceptible line 'Chinese Spring'. This marker showed complete l inkage to the Lr24 resistance gene. A more reliable and specific marke r for this resistance gene was made by converting it into a sequence c haracterized amplified region (SCAR). The presence of a single amplifi cation product allowed direct detection of the gene in the test tube b y the addition of ethidium bromide. This SCAR marker linked to the lea f rust resistance gene Lr24 could be used easily in a practical breedi ng program.