During the past two years we have attempted to establish the order and map distances on chromosome 8 for two dominant mutants, Bif (barren inflorescence) and Clt*-985 (clumped tassel, short plants) and also the recessive mutant pro (proline requiring). Bif and Clt had been located on chromosome 8 by use of the T wx series. The backcrosses showed no linkage with 16 of the 17 translocations used but the following data for wx T8-9d (breakpoints 8L.09 9S.16) show good linkage:
 

	Wx Dom.	Wx +	wx Dom.	WX +	T	% co
Bif	18	2	0	20	40	5
Clt	120	43	65	83	311	35

This evidence, along with some preliminary indication of linkage between Clt and ms8, suggests that Bif is near the T8-9d breakpoint on chromosome 8 and that Clt is some distance away on the long arm.

We attempted to set up the F1 Bif Clt . . . . /+ + pro v16 ms j to be crossed on + + + v16 ms8 j. Because the crosses involving combinations of Bif and Clt were difficult to make and because pro is a recessive lethal requiring selfing (impossible for ms8 plants) to establish genotypes of the backcross progeny, our results have been fragmentary. For these reasons no reliable 3-point data were obtained. It is possible, however, to take fragmentary data and combine it in groups of 2-point tests that will establish working distances for the genes involved.

The following are our data from these tests arranged as 2-point tests following the format of Emerson, Beadle and Fraser:

Table.

The map distances for v16, ms8 and j agree with the published map and are in harmony with the listed 3-point data obtained for these markers. Our tentative map is Bif ( pro Clt) v16 ms8 j. The parentheses indicate that there is still some doubt about the relative order of pro and Clt.

M. G. Neuffer and Dan J. England

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