Viviparous-1 is a mutant that, in the homozygous state, prevents seed developmental arrest and has a colorless aleurone. Mutable viviparous kernels exhibiting small, numerous spots on a colorless background were uncovered in the progeny of a self-pollinated ear of a colored line (1980g 090-23). Crosses to vp and five aleurone testers (a, a2, c, c2, and r) confirmed this unstable as vp-m and as allelic to the Vp locus. The spotting pattern, demonstrated by single cell spots, indicates late mutation events. Some of the fully colored cells in the aleurone layer exhibit diffusion to adjacent cells.

Receptor alleles of five presently known controlling element systems were used to test the relationship of these systems to the regulatory element responsible for the viviparous mutability. The general method of the crosses with vp-m was to cross a et with vp-m/+, A Et, and self the F1 and testcross onto a-mrh . In selfs, heterozygotes for a et +/A + vp-m segregate 3/16 spotted viviparous, but in the testcross to a-mrh give colorless with no spots. The recovery of colorless, no spot progeny, and the accompanying confirmation of the vp-m allele, demonstrate the lack of response of the Mrh receptor, a-mrh, to the regulatory element for vp-m. Similar crosses conducted with the receptor alleles for the known regulatory elements Dt, En, Fcu, and Uq were also negative.
 

Receptor element	System tested	Mutability
a-mdt	Dt	-
a-m1/a-m(r)	En	-
r-cu	Fcu	-
a-mrh	Mrh	-
a-ruq	Uq	-

Systems not confirmed are Bg, Ac, and several others.

Brian Scheffler and Peter A. Peterson

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