CONTROLLING ELEMENTS INDUCING MUTATIONAL CHANGES AT THE PAL LOCUS IN ANTIRRHINUM MAJUS

Abstract

In Antirrhinum majus the pal-rec-low-o is a repressed state of the pallida-recurrens allele. In heterozy¬gous condition, especially with pal-tub pal-tub tester, its mutation frequency increases from few tiny spots to very clear sectors of mutability on a recessive colourless background. This particular evocation of the pal-rec¬low-o allele is considered to be dependent on the presence of a regulatory element Pr. In the absence of such a regulatory element, the pal-rec-low-o exhibits stable expression owing to the effect of a repressor Rp residing at or near the locus. However, pal-tub regulatory element could be inactive, when inactive, can be made trans-active by introducing a fresh regulator which may segregate at meiosis.