c-m804531 is a previously unreported c unstable mutant from the 1979 c sh wx isolation plot. This plot contained Uq and its receptor a-ruq (Peterson and Friedemann, Maydica 28:213-249,1983), and produced 3.1 X 10⁶ kernels. This mutant is spotted with a colorless background and the kernel proved to contain one Uq in a cross with a-ruq: (c-m Sh Wx/c sh wx; A; Uq/+ x C a-ruq) x C a-ruq.

The Uq relationship was established by backcrossing a-ruq spotted and colorless kernels to the c sh wx tester. If c-m804531 is Uq controlled only the a-ruq spotted selections will express c mutability. This is confirmed in Table 1A. Table 1B shows that the colorless a-ruq selections do not express the spotted c-m phenotype; instead they express a colorless phenotype.

Independent segregation of Uq and the c locus is demonstrated by sib mating colorless round and colorless shrunken progeny of c-m by c sh wx:

Nine out of nineteen sib matings produced the c-m804531 spotted phenotype. c-m804531 is due to the interaction of c-ruq (c responsive to Uq) and Uq.

Table 1.

Table 2.

Elizabeth E. Oberthur and Peter A. Peterson

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