Last year (MNL72:97), we reported that the class I viviparous mutant vp12 (pale yellow or white [depending on the genotype at the bn1 locus] endosperm, viviparous embryo, albino seedlings) is uncovered by TB-5La, and therefore appears to be located on the long arm of chromosome 5. We repeated this TB test last winter, and conducted allelism tests between vp12 and the only other known class I mutant on 5L, lw2 (pale yellow or white endosperm, dormant embryo, albino seedlings). Both the TB crosses and the allelism tests gave positive results, confirming that vp12 is on 5L and indicating that vp12 is an allele of lw2. The mutant kernels from the allelism test crosses were pale yellow, dormant, and gave rise to albino seedlings. lw2 had not been previously known to have viviparous alleles, but the fact that a class I viviparous mutant should be found to be allelic to a dormant class I mutant is not surprising, since other class I viviparous loci (e. g. w3, vp5, and vp9) have dormant alleles. Since the name lw2 has precedence, we propose that vp12 be renamed lw2-vp12.
vp12 was previously placed to chromosome 6 by Araujo et al. using
waxy1-marked translocations (Brazilian Journal of Genetics 20:71-74,
1997). The translocation that gave the positive chromosome 6 map location,
wx1 T6-9b, is heterozygous for the white endosperm mutant y1
(the Coop provides a vigorous hybrid between an M14 and a W23 conversion
of this translocation; the M14 version is Y1, but the W23 version
is y1.) We conclude that the erroneous mapping result reported in
the paper of Araujo et al. is due to the tight coupling of y1 and
wx1 in the T6-9b stock that they used for mapping.
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