Putative Mutator-induced etched alleles --Philip S. Stinard In the course of our studies of kernel mutants with sugary/translucent phenotype arising from Mutator populations, we found several independent mutants which produced virescent seedlings when mutant kernels were planted in the sandbench (nonmutant kernels gave rise to green seedlings). A close examination of the mutant kernels revealed that some, but not all, of them had pitted or etched endosperms. Phenotypes ranged from smooth glassy shrunken to plump translucent, and within these types, the etching varied from none to severe. Heterozygous mutant plants were crossed with etched testers, and the mutants proved to be allelic, with good expression of etched in the F1 kernels. The mutants are summarized in Table 1. Mutant and nonmutant kernels from the testcross ears were planted in the sandbench, and the resulting seedlings scored for virescence. Nonmutant kernels gave rise to green seedlings as expected, and mutant kernels produced virescent seedlings. In at least one testcross for each mutant, one or more of the virescent seedlings were mutable, suggesting that all five mutants are transposable element induced.

Table 1. Etched alleles arising from Mutator stocks.

The sugary/translucent (with or without etching) phenotype of etched kernels has not been reported previously, but this may be due more to the genetic background of the standard etched stocks than to the unique nature of our mutants. Our etched mutants arose in dent stocks. When crossed into the dent background of our purple aleurone stocks, the standard etched allele also produces a sugary/translucent phenotype. This phenotype may not be expressed as well in the flint background in which many genetic stocks are maintained.

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