The mutants opaque-9 through opaque-13

There are numerous loci at which mutations condition an opaque phenotype. We report here five additional mutants that are not allelic to previously reported opaque mutants nor to each other. Four of these mutants were provided by Robert Brawn of Funk Seeds International and one by M. G. Neuffer of the University of Missouri. All five of these mutants are simple recessives. The mutants from Brawn, o9, o11, o12, and o13, are spontaneous in origin while o10 from Neuffer is a presumptive EMS-induced mutant.

opaque-9: From Brawn and formerly designated as ox-74120. The mutant kernels have fully opaque crowns which are light in color. There may be patches of corneous starch on the abgerminal side of the kernel or the entire base of the kernel may be corneous. There is frequently a cavity in the center of the kernel. Several other spontaneous mutants from Brawn are allelic to opaque-9. The dye-binding capacity of opaque-9 in the Udy test (a measure of the content of basic amino acids) is slightly higher than that of nonmutant kernels.

opaque-10: From Neuffer (E-1356) and formerly designated by us as ox-7747. This is a solid opaque which is phenotypically much like opaque-1. The dye-binding capacity is not higher than nonmutant kernels.

opaque-11: From Brawn and formerly designated as ox-7455. The mutant kernels are thin, somewhat shrunken, and have a greyish cast. There is usually a cavity in the center of the endosperm. The dye-binding capacity is high--equal to or greater than opaque-2.

opaque-12: From Brawn and formerly ox-7638. The mutant kernels are thin, variable in size, and are etched or scarred. On germination, the mutant kernels give rise to plants that are very chlorophyll-deficient. In some genetic backgrounds, these plants survive and develop good color as they become older, but they never become more than 75 cm tall. The mutant plants will shed pollen but don't often produce ears. The dye-binding capacity of mutant kernels is intermediate between nonmutant kernels and opaque-2 kernels. The amount of alcohol-soluble proteins is only slightly reduced in the mutant kernels as compared to nonmutant sibs.

opaque-13: From Brawn and formerly ox-7729. The mutant kernels are etched and may have a thin rim of corneous starch on the abgerminal side. The dye-binding capacity of the mutant kernels is only slightly greater than nonmutant kernels.

Seeds of these five mutants are being sent to the Maize Genetics Stock Center.

Oliver Nelson

Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of the authors.

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