IDENTIFICATION AND EXPRESSION OF THE GENE-YR2 FOR RESISTANCE TO PUCCINIA-STRIIFORMIS IN THE WHEAT DIFFERENTIAL CULTIVARS HEINES-KOLBEN, HEINES-PEKO AND HEINES-VII

Genetic data showed that a common gene was present in the three differ ential wheat cultivars Heines VII (Yr2), Heines Peko (Yr2, Yr6) and He ines Kolben (Yr6) expressed against the race 109E9 of Puccinia strufor mis which possesses virulence for Yr6 and avirulence for Yr2. This sup ported the hypothesis that Heines Kolben carries the gene Yr2 in addit ion to Yr6 for resistance to yellow rust in a genetic background in wh ich Yr2 is weakly expressed in seedlings. F1, F2 and F3 progenies from the cross Heines Kolben x Peragis confirmed the monogenic segregation of Yr2 in Heines Kolben and demonstrated the Variation of its express ion with environmental conditions.