THE PLANT CELL, Vol 5, Issue 11 1541-1553, Copyright © 1993 by American Society of Plant Biologists
Transposon-Induced Inversion in Antirrhinum Modifies nivea Gene Expression To Give a Novel Flower Color Pattern under the Control of cycloidearadialis
C. Lister, D. Jackson and C. Martin
Department of Genetics, John Innes Institute, John Innes Centre, Colney Lane, Norwich NR4 7UH, United Kingdom
The nivea (niv) gene of Antirrhinum majus encodes chalcone synthase, an
enzyme involved in synthesis of anthocyanin pigments. The nivrec:98 allele
contains a single copy of the transposon Tam3 inserted at the niv locus. A
large chromosomal rearrangement derived from this mutant has been shown to
be flanked by two copies of Tam3. In this study, we compared sequences
involved in this rearrangement with their progenitor sequences and
concluded that the rearrangement is an inversion resulting from an aberrant
transposition occurring shortly after replication of Tam3 that left both
copies of Tam3 active after the rearrangement. Excision of Tam3 from its
position adjacent to the niv coding region resulted in a novel distribution
of anthocyanin pigment in the flower tube, caused by the interaction of the
new sequences with the remnant of the niv promoter. The new sequences
upstream of niv serve both to enhance niv transcription and to redirect the
pattern of gene expression, placing niv under the control of the gene
cycloidearadialis, which determines the morphogenetic polarity of the
flower.
