GENETIC SUPPRESSION OF THE CEREAL RYE-DERIVED GENE PM8 IN WHEAT

The location of wheat gene Pm8 for resistance to powdery mildew in the 1RS chromosome segment derived from cereal rye cultivar Petkus was co nfirmed. There was reduced transmission of the 1BL.1RS chromosome rela tive to its wheat homologue in four of the five crosses examined. Pm8 was not expressed in some wheat cultivars and selections, which posses sed the 1RS chromosome identified by the presence of relevant genes fo r resistance to the three rusts, due to the presence of a dominant sup pressor gene(s) in the wheat genome. The frequency of suppression in 1 BL.1RS wheats from Mexico was significantly higher than in a group of wheats (both local and exotic) introduced from China and was probably much higher than in European wheats.