Abstract Races 1 and 400 of Melampsosau bni the causal agent of flax [Lmum usitatissimum]), were crossed and the resulting F2 progeny evaluated on near‐isogcnic fiax lines. The infection type of the parental cultures, the F12 and the segregating f2 progeny were used to evaluate the inheritance of pathogenicity. Races 1 and 400 as well as the F2 and all the F2 progeny were avirulent on lines N and P4 genes. This indicated both races to be homozygous avirulent. The F2 and all the F2 progeny were virulent on lines containing L9, M1, M4, and P. This indicated the F to be homuzygous for virulence at these loci. Segregation ratios of the F2 cultures fit monogenic ratios on lines with host genes K. L2, L5, L6, L7, L11, M, M2, M3, N1, P1, P2, and P3. Race 1 was avirulent, race 400 virulent and tht F, avirulent on these lines. Several linkage groups were indicated including close linkage at Ap1, Ap2 and Ap3. Segregation on lines L, L3, M5, M6 and cultivars Flor, Dufferin, Linott, and Wishek fit a digenic model. The infection tvpes of the parents, the F1 and the F2, segregations could usually be explained by classical gene‐for‐gene interactions. Possible exceptions were segregations on L4, L8 and N2 which did not fit a 3: 1 ratio but did fit a 9: 7 ratio. Segregation on L 10 fit a 7: 9 ratio but line L10 may be temperature sensitive. Segregation on L1 indicated a single dominant gene for pathogenicity.

EXPLOR_STEP=$WICRI_ROOT/Bois/explor/MelampsoraV2/Data/Main/Exploration

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{{Explor lien
   |wiki=    Bois
   |area=    MelampsoraV2
   |flux=    Main
   |étape=   Exploration
   |type=    RBID
   |clé=     ISTEX:68E93D628F75B6B2FBC0E3723ED768CA9E534443
   |texte=   Inheritance of Pathogenicity of Progeny from an F1 Culture of Melampsora lini
}}