Unstable elements at the locusLuteus-1 inPetunias hybrida: Genetic analysis of their mobility

At theLul (Luteus-1) locus from Petunia, semi-dominant mutations occur, characterized by partial chlorophyll deficiencies. They can show phenotypic instability with green spot reversions. Two types of unstable mutations are described. Thelu-ml type presents a low rate of somatic reversions that are regulated by non-linked various activating factors. In contrast thelu-m3 instability shows high reversion rates regulated by a linked specific activating factor (La3), not found otherwise among the genome. Under the effect of therecombination modulator (Rm1), lu-m3 andLa3 were separated inducing a stabilization oflu-m3. This allele,lu-m3rs, however, seems to be able to respond again to a transactivation by reintroduction ofLa3 through crossing. The high transposition potential of the associationlu-m3rs-La3 was implemented to test its capacity to reinster. This experiment, conducted on a large scale, has allowed us to detect and study two unstable mutations concerning the flower pigmentation. Those two genes that control the anthocyanin production and the flavonol synthesis, respectively, are strictly linke toLul. Consequently it can be assumed that those two unstable mutations are due to reinsertion of thelu-m3rs transposons through proximal transpositions.