IDENTIFICATION OF RFLP MARKERS LINKED TO THE CEREAL CYST-NEMATODE RESISTANCE GENE (CRE) IN WHEAT

The cereal cyst nematode (CCN) (Heterodera avenae Woll.) is an economi cally damaging pest of wheat in many of the worlds cereal growing area s. The development of CCN-resistant cultivars may be accelerated by th e use of molecular markers. The Cre gene of the wheat line ''AUS 10894 '' confers resistance to CCN. Using a pair of near-isogenic lines (NIL s) that should differ only in a small chromosome segment containing th e Cre locus, we screened 58 group-2 probes and found two (Tag605 and C DO588) that detect polymorphism between the NILs. Nulli-tetrasomic and ditelosomic lines confirmed that the restriction fragment length poly morphism (RFLP) markers identified were derived from the long arm of w heat chromosome 2. Crosses between ''AUS10894'' and ''Spear'' and the NIL ''AP'' and its recurrent parent ''Prins'' were used to produce F-2 populations that gave the expected 3:1 segregation ratio for the resi stance gene. Linkage analysis identified two RFLP markers flanking the resistance gene. Xglk605 and Xcdo588 mapped 7.3 cM (LOD=6.0) and 8.4 cM (LOD=6.7), respectively, from the Cre locus.