The dwarf genotypes used in our studies represent three distinct sources of dominant dwarfing genes (Dw6, Dw7, and Dw8).
According to Federizzi and Qualset (1989), the compact panicle of NC2469-3 is due to one additive gene (C) linked (0.08 [+ or -] 0.01 recombination frequency) to Dw7 and not to a pleiotropic effect of the dwarfing gene.
1998), differed from the Dw6 and Dw7 genes in its effect on plant height.
Dwarf lines carrying the Dw7 or Dw8 genes also responded much like their nondwarf counterparts to applied GA (Table 4).
One possibility on the nature of the oat dwarfing mutations was suggested on the basis of observations that seedlings of the Dw7 line NC2469-3 grown in growth chamber and greenhouse environments often were dark green and accumulated anthocyanin (Milach and Federizzi, 2001).
The dominant oat dwarfing genes Dw6, Dw7, and Dw8 appear to be quite distinct from the wheat Rht1 and maize Dw8 dominant dwarfing genes because of their difference in GA-sensitivity; however, these oat genes may be similar to GA-sensitive dominant genes which have been identified in wheat and rye.
In summary, the three oat dwarfing genes--Dw6, Dw7, and Dw8--reduced plant height in different ways.
All [F.sub.2] populations from crosses of the Japanese dwarf lines with OT207 and NC2469-3 segregated in a 15 dwarf: 1 tall ratio (Table 5), indicating that the dwarfing genes in the seven Japanese lines were independent of the Dw6 and Dw7 genes that are found in OT207 and NC2469-3, respectively.
Proposed [F.sub.2] Height Phenotype([dagger]) genotype cm <40 Double dwarf Dw7_Dw8_ 40-51 Dwarf (similar dw7 dw7 Dw8- to AV1814/2) 52-80 Dwarf (similar Dw7- dw8 dw8 to NC2469-3) >90 Tall dw7 dw7 dw8 dw8 [chi square] (3 df, 9:3:3:1) P-value Number of [F.sub.2] plants Height Observed Expected cm <40 48 55 40-51 24 19 52-80 21 19 >90 6 6 [chi square] 2.42 (3 df, 9:3:3:1) 0.49 P-value ([dagger]) Classes determined on the basis of the plant height ranges and standard deviations of AV18W4 and NC2469-3 grown in The greenhouse in 1993.