IDENTIFICATION OF RAPD MARKERS FOR 11 HESSIAN FLY RESISTANCE GENES INWHEAT

The pyramiding of genes that confer race- or biotype-specfic resistanc e has become increasingly attractive as a breeding strategy now that D NA-based marker-assisted selection is feasible. Our objective here was to identify DNA markers closely linked to genes in wheat (Triticum ae stivum L.) that condition resistance to Hessian fly [Mayetiola destruc tor (Say)]. We used a set of near-isogenic wheat lines, each carrying a resistance gene at 1 of 11 loci (H3, H5, H6, H9, H10, H11, H12, H13, H14, H16 or H17) and developed by backcrossing to the Hessian fly-sus ceptible wheat cultivar 'Newton'. Using genomic DNA of these 11 lines and 'Newton', we have identified 18 randomly amplified polymorphic DNA (RAPD) markers linked to the 11 resistance genes. Seven of these mark ers were identified by denaturing gradient gel electrophoresis and the others by agarose gel electrophoresis. We confirmed linkage to the He ssian fly resistance loci by cosegregation analysis in Fz populations of 50-120 plants for each different gene. Several of the DNA markers w ere used to determine the presence/absence of specific Hessian fly res istance genes in resistant wheat lines that have 1 or possibly multipl e genes for resistance. The use of RAPD markers presents a valuable st rategy for selection of single and combined Hessian fly resistance gen es in wheat improvement.