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Crop Science Abstract -

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


This article in CS

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

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  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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