Evidence for transposition in Petunia.

In Petunia interaction is described between a trans-regulatory genetic element Bi and responsive anthocyanin alleles, resulting in a variegated flower colour pattern. Crosses segregated white-flowering plants that had lost the Bi element and could be shown to contain a responsive allele by the colour pattern resulting from interaction with the standard variegated parent. A weak mutant of the Bi element is described. Some pure lines of Petunia contained the Bi element, others did not. In two lines it could be mapped to chromosome I.