'Plant Breeding: Sustaining the Future' Abstracts of the XVIth EUCARPIA Congress, Edinburgh, Scotland, 10-14 September 2001 CHROMOSOMAL LOCATION OF RESISTANCE TO SEPTORIA TRITICI IN ADULT PLANTS OF A SYNTHETIC HEXAPLOID WHEAT AND A WHEAT CULTIVAR M.R. SIMON, A.J. WORLAND, C.A. CORDO, P.C. STRUIK Cerealicultura, Facultad de Ciencias Agrarias y Forestales, U.N. La Plata. CC 31. 1900 La Plata, Argentina

Chromosomal location of resistance to two virulent Argentinean isolates of Septoria tritici Rob. ex Desm. (teleomorph Mycosphaerella graminicola (Fuckel), Schroeter, in Cohn.) was studied in adult plants of a synthetic hexaploid (Synthetic 6x) and wheat cultivar Cheyenne. Data included two years of greenhouse and field trials. Substitution lines of these resistant genotypes into (susceptible) ¨Chinese Spring¨ (CS) were selected from a previous screening. Plants were inoculated at flag leaf stage. The genotype x environment interaction was not significant. The CS substitution lines carrying Synthetic 5D and 5A were resistant to both isolates. Chromosome 7D also appeared to carry factors for resistance to one of the isolates. The CS substitution lines carrying ¨Cheyenne¨ chromosomes 5D, 1B, 2B and 4A showed levels of resistance  similar to the resistant parent for both isolates.