The genetics of naked oats (Avena nuda L.)

Summary The inheritance of the character complex of naked grain and multiflorous spikelets was studied in a diallel set of crosses comprising five varieties of naked oats (Avena nuda)-As 78, Manu, Caesar, Nuprime and AJ86/2/1-and one variety of husked oats (A. sativa), Maris Oberon. In the F₁ generation the distribution of multiflorous spikelets was in all cases similar to that of the mid-parent. Crosses between the varieties of A. nuda produced only naked grain on plants in the F₁ and F₂ generations, indicating that nakedness in the varieties studied was determined by the same loci.The three-gene model proposed by Moule (1972) for the determination of A. nuda characters was inadequate to account for the observed F₂ segregation in naked x husked crosses. An extension of this model is proposed to include a third modifying gene, N₃, which in the homozygous dominant condition produces the husked phenotype when the principal gene, N, is heterozygous. The model assumes complex epistatic relationships between the three modifying genes N₁, N₂ and N₃. Published information and further experimental data suggest that the genotype NN--N₃N₃ is uncommon. The expression of the genes determining nakedness was greatly influenced by the environment.