In my experience all red ade1 and ade2 mutations result in much less pigment
accumulation on adenine starvation if the strains are petite. This is
explained in an early reference to these mutations, and apparently is due to an
oxidative step in red pigment production. However, I have noticed that some
strongly negative ade- mutations still show some pink color in petites, but the
color intensity is alway much less than in grandes.
UMDNJ-RW Johnson Medical School