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This article in CS

  1. Vol. 9 No. 6, p. 723-725
    Received: Mar 24, 1969



Instability for Crown Rust Reaction and Kernel Color in F6 -F10 Lines of a Derived-Tetraploid ✕ Avena sativa Hybrid1

  1. R. A. Forsberg and
  2. I. Nishiyama2



Major genes governing dark kernel color and resistance to the crown rust fungus (Puccinia coronata Cda. f. sp. avenae Fraser & Led.) were linked in four F6 lines from the oat cross derived-tetraploid C.I.7232 (2n-28) ✕ Avena sativa L. var. ‘Clarion’ (2n=42). Most dark-resistant (D-R) plants were not true breeding; abnormal and irregular segregation ratios of D-R and light-susceptible (L-S) plants occurred in F6-F10 lines from D-R parents. L-S plants were highly self-fertile and bred true. Cytological investigations revealed aneuploid plants (2n=43) in which the D-R genes were carried on an extra chromosome and euploid plants (2n=42) in which the genes were in a closely paired bivalent. Differential gamete frequencies, certation, or nonviability of homozygous-resistant genotypes due to abnormal dosage effects could account for the distorted ratios obtained and for the absence of stable, resistant lines.

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