Miscellaneous allelism tests --Stinard, PS Over the past few years, we have conducted allelism tests between mutants with similar phenotype, especially if they have been found to have the same chromosome location. We report here the results of four such positive allelism tests.

We obtained preliminary TB mapping data last year placing the pale yellow endosperm mutant y2 to the short arm of chromosome 7. Since y8, also on chromosome 7, has a similar phenotype, we conducted an allelism test and found them to be allelic. We did a pedigree search on the origin of our y2 stock and found that it came from George Sprague. The lineage is not clean, and at one point, it had been reisolated by Sprague after being crossed to the y8 reference allele and to other pale endosperm factors. y2 was originally described as being a white endosperm mutant tightly linked to vp2 on chromosome 5 (Eyster, 1931. Genetics 16:574-590). Since vp2 mutant kernels have white endosperm, it is probable that Eyster was simply observing the white endosperm of vp2 and that the crossovers he observed were either dormant vp2 kernels or heterofertilization events. The y2 stock that the COOP has is certainly not the original y2 described by Eyster, and is probably identical to the y8 reference allele, which became introgressed into the line by accident.

The virescent mutant v*-JRL that we mapped to 9L last year (MNL 73:90) was crossed to the 9L virescents ar1, v1, and v30. Only the crosses to v1 produced virescent progeny. We have renamed v*-JRL as v1-JRL.

We conducted an allelism test of our uncharacterized terminal ear mutant te*-Galinat with te1 and found them to be allelic. We now call the mutant te1-Galinat.

Last year, we located the mutant y11 to the long arm of chromosome 2 using B-A translocations (MNL 73:90). Last winter, we crossed homozyous y11 plants to heterozygous w3-R plants and noted 1:1 segregation for yellow and pale yellow kernels on the progeny ears. This summer, we planted the pale yellow kernels and self-pollinated the resulting plants. All ears segregated in a 3:1 ratio for pale yellow dormant to white endosperm viviparous kernels. The most logical explanation is that the pale yellow dormant kernels are homozygous y11 or heterozygous for y11 and w3-R, and the white endosperm viviparous kernels are homozygous for w3-R. We conclude that w3 and y11 are allelic, and propose that y11 be renamed w3-y11. It should be noted that w3-y11 kernels are dormant and produce green seedlings, whereas w3-R kernels are viviparous and produce albino seedlings. This appears to be an example of allelic diversity similar to that which exists at other carotenoid loci in maize.
 
 


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