High-density genetic and physical mapping of the powdery mildew resistance gene Pm24 on chromosome ID of wheat.

摘要

The powdery mildew resistance gene Pm24, originating from the Chinese wheat landrace 'Chiyacao', was previously mapped on the short arm of chromosome ID. The major objectives of the present study were to increase marker density in the vicinity of thePm24 locus using additional microsatellite markers, and to generate a physical microsatellite map of chromosome ID by means of 11 deletion lines. A genetic map of chromosome ID was constructed, consisting of 35 markers and the Pm24 gene, with a total maplength of 291.4 cM. The Pm24 gene was flanked by Xgwm 789 (Xgwm603) and Xbarc229 with map distances of 2.4 and 3.6 cM, respectively, whereas the microsatellite marker Xgwml291 co-segregated with the Pm24 gene. The physical mapping indicated that the microsatellite markers were not randomly distributed on chromosome ID. Ten of the 14 ID short arm microsatellite markers were mapped in the distal 30%, 15 of the 18 markers mapped in the distal 59% of 1DL. The microsatellite marker Xgwml291 was mapped in the interval FL 0.70-1.00 of the chromosome arm IDS. It could be concluded that the Pm24 locus is located in 'IS 0.8 gene-rich region' of wheat. The results presented here are very helpful for the map-based cloning of this gene.