XVI International Botanical Congess

Mutations in a floral homeotic gene duplicated (dp) in the Japanese morning glory (Ipomoea nil) cause substitution of sexual organs for perianth organs. This is similar to loss-of-function phenotypes of the C-class MADS gene family of transcription factors such as AG of Arabidopsis. When duplicated and its related gene, peony were cloned, their intron-exon structures proved to be well conserved beyond species but clearly were in two different subclasses. In a dp mutant, Tpn-botan, an En/Spm type transposon was inserted. Surprisingly, there are tracks of the same type transposon insertion at the recent insertion site. Moreover, all Ipomoea species analyzed have this ancient transposon and this finding suggests that the insertion event occurred prior to the genus Ipomoea formation.