UNSTABLE ELEMENTS AT THE LOCUS LUTEUS-1 IN PETUNIA-HYBRIDA - GENETIC-ANALYSIS OF THEIR MOBILITY

At the Lu1 (Luteus-1) locus from Petunia, semi-dominant mutations occu r, characterized by partial chlorophyll deficiencies. They can show ph enotypic instability with green spot reversions. Two types of unstable mutations are described. The lu-m1 type presents a low rate of somati c reversions that are regulated by non-linked various activating facto rs. In contrast the lu-m3 instability shows high reversion rates regul ated by a linked specific activating factor (La3), not found otherwise among the genome. Under the effect of the recombination modulator (Rm 1), lu-m3 and La3 were separated inducing a stabilization of lu-m3. Th is allele, lu-m3rs, however, seems to be able to respond again to a tr ansactivation by reintroduction of La3 through crossing. The high tran sposition potential of the association lu-m3rs-La3 was implemented to test its capacity to reinsert. This experiment, conducted on a large s cale, has allowed us to detect and study two unstable mutations concer ning the flower pigmentation. Those two genes that control the anthocy anin production and the flavonol synthesis, respectively, are strictly linked to Lu1. Consequently it can be assumed that those two unstable mutations are due to reinsertion of the lu-m3rs transposons through p roximal transpositions.