TRANSFER OF DISEASE RESISTANCE GENES FROM TRITICUM-ARARATICUM TO COMMON WHEAT

The wild tetraploid wheat species Triticum timopheevii (Zhuk.) Zhuk. v ar. araraticum is a source of pest resistance genes for Triticum aesti vum L. Our objectives were to describe the breeding behaviour of T. ar araticum when backcrossed to common wheat, and to transfer resistance to leaf rust (caused by Puccinia recondita f.sp. tritici) and powdery mildew (caused by Blumeria graminis f.sp, tritici) to wheat. Crosses w ere made between five wheat genotypes and 12 T. araraticum accessions. Fertility and chromosome numbers of BC1F1, BC2F1, and BC3F1 plants we re determined. Resistance to leaf rust was transferred to BC2-derived families from 10 different T. araraticum accessions. Leaf rust resista nce genes in nine T. araraticum accessions can be assigned to at least four loci. Leaf rust resistance transferred from three accessions was inherited in the hexaploid derivatives as a single, dominant gene in each case. Resistance to powdery mildew was also detected in the T. ar araticum backcross derivatives. Fertile hexaploid derivatives expressi ng T. araraticum-derived resistance genes can be recovered after two b ackcrosses to wheat cultivars.