Molecular characterization of the mutable flaked allele for flower variegation in the common morning glory

The mutable flaked (or a(f)) lines of the common morning glory bear white f lowers with colored flakes and sectors. The a(f) allele shows incomplete do minance. Plants in the heterozygous state A/a(f) bear lightly colored flowe rs with intensely colored flakes and occasionally with white sectors. We sh owed that the mutable a(f) allele is caused by insertion of a new transposa ble element, Tip100, into the CHS-D gene intron. Tip100 is 3.9 kb long and belongs to the Ac/Ds family. Although the timing and frequency of the flowe r variegation vary in different lines, they carry an identical mutable alle le. We also noticed that a flaked subline, bearing variegated flowers, carr ies a Tip100 derivative, Tip100-1 The structure of Tip100-1 contains an add itional 48 bp terminal sequence as tandem repeats and its integration site is identical to that of Tip100. Another line, with stable white flowers, is a double mutant carrying two copies of Tip100 in the CHS-D gene. These res ults are discussed with regard to the variegated phenotypes of flowers in v arious mutable lines.