Painted flowers: Eluta generates pigment patterning in Antirrhinum

*In the early 1900s, Erwin Baur established Antirrhinum majus as a model system, identifying and characterising numerous flower colour variants. This included Picturatum /Eluta, which restricts the accumulation of magenta anthocyanin pigments, forming bullseye markings on the flower face.
*We identified the gene underlying the Eluta locus by transposon-tagging, using an Antirrhinum line that spontaneously lost the non-suppressive el phenotype. A candidate MYB repressor gene at this locus contained a CACTA transposable element. We subsequently identified plants where this element excised, reverting to a suppressive Eluta phenotype. El alleles inhibit expression of anthocyanin biosynthetic genes, confirming it to be a regulatory locus. The modes of action of Eluta were investigated by generating stable transgenic tobacco lines, biolistic transformation of Antirrhinum petals and by promoter activation/repression assays.
*Eluta competes with MYB activators for promoter cis-elements, and also by titrating essential co-factors (bHLH proteins) to reduce transcription of target genes. Eluta restricts the pigmentation established by the R2R3-MYB factors, Rosea and Venosa, with greatest repression on those parts of the petals where Eluta is most highly expressed.
*Baur questioned the origin of heredity units determining flower colour variation in cultivated A. majus. Our findings support introgression from wild species into cultivated varieties.