Wo^m - a new allele of wtoly.<p>

Rick, C. M.<p>

A new wooly mutant was discovered in a field of Rutgers and sent to me by Dr.
D. M.  Morgan of the University of Maryland.  This line has bred true for
excessive pubescence for several generations.  No reduction in vigor or
fertility is associated with the hairy condition. Crosses with + behave as if
the wooliness is determined by an incompletely dominant gene, and in most
environments tested, the three genotypes, Wo^m/Wo^m, Wo^m/+, and +/+ can be
distinguished by their degree of hairiness.  With experience it is possible to
recognize them in the seedling stage provided light intensity is sufficiently
high for good hair development.  A typical segregation is (54L330): 74 wooly,
167 intermediate, 82 normal.<p>

The degree of pubescence of Morgan's wooly is not so great as in Wo, but the
effect on the large trichomes appears to be of the same nature.  Allele test
crosses with Wo yielded approximately equal numbers of two phenotypes, one
being similar to Wo^m/+ and the other to Wo/+, although somewhat more extreme.
Pubescence of the latter is very dense and leaf segments are often irregular
in outline; plants are somewhat retarded but flower and set fruit without
difficulty.  An F2 progeny (54L667) derived from the latter type F1 comprised
44 plants of the Wo^m/Wo^m type and 86 like the parental F1. The failure of
any of normal segregants to appear and the close fit to the 2 Wo/Wo^m : 1
Wo^m/wo^m ratio prove the allelism of Wo and Wo^m.  The following linkage data
for d-Wo^m show a crossover value of 29%, which is close to the previously
measured values for the d-Wo interval:<p>
<pre>

                Wo^m/Wo^m   Wo^m/+   +/+
         ________________________________
54L320     +        70       136      45
  F2
repulsion  d         4        31      37
</pre>

The appearance of a viable allele at the Wo locus will be welcomed by those
who desire a completely viable dominant seedling marker in this region.  It
will thus be much better for identification of the very closely linked ms\10
than Wo^m. Another invaluable asset of Wo^m is the possibility of identifying
all genotypes in the seedling stage. Bob Soost is incorporating it in his
studies of the dosage effects of Wo alleles.<p>

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