The identification of an intermediate allele of D8

The identification of an intermediate allele of D8 --Oliver Nelson The dominant mutation D8 on chromosome 1 conditions the production of an extremely dwarfed plant that is nonresponsive to gibberellins. I have isolated from remnant seed of an EMS mutagenesis experiment set up some years ago by Prem Chourey and Hugo Dooner an intermediate allele of D8 (D8-81127) that when heterozygous with a nonmutant allele (D8-81127/+) produces a plant that is 3 to 3.5 feet in height and sheds pollen freely. Homozygous plants (D8-81127/D8-81127) are extreme dwarfs, and the anthers are rarely exserted.

The evidence that D8-81127 is allelic to D8 comes from the following crosses. In 1986, D8-81127/+ plants were crossed by D8/+ plants. In 1988, the extreme dwarfs in a resultant progeny were crossed by N22 (+/+, c/c). In 1989, six different progenies from the N22 crosses were planted. Two progenies produced only dwarf plants. In both of these progenies, ca. one-half of the plants were extreme dwarfs (D8/+) while the remaining plants were typical D8-81127/+. In the other four progenies, there were tall (+/+) and extreme dwarf plants (D8/+) in approximately equal numbers.

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