Very Light Variegated Pericarp in Maize

OST of the variegated offspring of maize plants carrying the unstable M allele Pvv, conditioning medium variegated pericarp and cob, are themselves medium variegated. Regularly, however, in the maize strain here dealt with, a few light variegated mutants also appear. A third phenotype, " very light," has now been isolated as a mutation from light variegated. Mediums, lights, and very lights differ in the frequency with which the Pvv allele changes to stable PRR (self-colored, i.e., red pericarp and cob). Medium variegated ears carry a large number of such mutations which, collectively, give a rather strongly, although irregularly pigmented phenotype. The number of mutant stripes is sharply reduced in light variegateds. Very lights, as the name indicates, show only a few scattered red stripes. These three classes of variegated ears, together with the stable colorless type, Pww, are illustrated in figure It will be shown in the present report that (1 ) mediums, lights, and very lights differ in the number of doses present of a chromosomal unit termed transposed Modlulator ( t r -M p ) which controls mutability of a common Pvv allele and (2) the second tr-Mp unit present in very light variegateds probably originated by reduplication and transposition of the transposed Modulator carried by the light variegated parent rather than as a new mutation from PT'v and ( 3 ) tr-Mp in increasing doses reduces the frequency of Pvv to PRR