When crossing p- x grande, why is there no compensation mechanism like there is in ro x grande?
In po x grande, the po mitochondria, without DNA, are basically recessive/neutral. Its kind of like +/Df, which is wildtype. In the diploid, the normal mitochondria are used to form new, normal mitochondria in all progeny, so that the ro trait is lost in one generation. The r- mitochondria, however, are suppressive. So even though the DNA is deleted, which usually is a recessive trait, in this case it is dominant. The r- mitochondria are proposed to have a suppressive effect either by replicating faster and outcompeting normal mitochondria or by fusion with normal mitochondria followed by recombination between normal and mutant DNA.
