THE PLANT CELL, Vol 6, Issue 3 375-383, Copyright © 1994 by American Society of Plant Biologists
Isolation of a Suppressor-Mutator/Enhancer-like Transposable Element, Tpn1, from Japanese Morning Glory Bearing Variegated Flowers
Y. Inagaki, Y. Hisatomi, T. Suzuki, K. Kasahara and S. Iida
Department of Biological Science and Technology, Science University of Tokyo, Yamazaki, Noda-shi, Chiba 278, Japan
The Japanese morning glory has an extensive history of genetic studies.
Many mutants in the colors and shapes of its flowers and leaves have been
isolated since the 17th century, and more than 200 genetic loci have been
localized for the 10 linkage groups. They include over 20 mutable loci,
several with variegated flower phenotypes. In a line of Japanese morning
glory bearing variegated flowers called flecked, a transposable element of
6.4 kb, termed Tpn1, was found within one of the anthocyanin biosynthesis
genes encoding dihydroflavonol-4-reductase (DFR). The 6.4-kb element
carries 28-bp perfect terminal inverted repeats, the outer 13 bp being
identical to those of the maize transposable element
Suppressor-mutator/Enhancer. It is flanked by 3-bp direct repeats within
the second intron of the DFR gene, 9 bp upstream of the third exon. When
somatic and germinal excision occurs, it produces excision sequences
characteristic of plant transposable elements. Cosegregation data of the
variegated flower phenotype and the DFR gene carrying Tpn1 indicated that
the mutable phenotype is due to excision of Tpn1 from the DFR gene.
Sequences homologous to Tpn1 are present in multiple copies in the genome
of Japanese morning glory.
