Linkage data.
I have examined transphase F2's of ds and gh each with a hl and have obtained the results given below. The ds a hl and a hl gh homozygotes have not given me pollen or seed at this location, and I am pessimistic about their ever doing so. In fact, I have never been able to get seed from any kind of gh homozygote although they keep segregating nicely from a a hl/gh F1 sent to me by C. M. Rick. As a single gene homozygote, ds reproduces quite well, but not when I add a or hl to it.
The data call for a slight reconstruction of Group V but I won't do this until I decide: (1) whether I want to use these two genes as key markers in the group, and (2) the distance of gh from j\1, and the distance of ds from f. C. M. Rick (TGC 8) reported a distance of 14.0 +- 3.9 from a to ds while my data indicate 40.5 +- 4.0 from a and 38.4 +- 4.1 from hl--ambiguous, to say the least. The shortness of Rick's distance to a and the looseness of my hl linkage makes me think that ds is to the lert of a in the vicinity of f. It seems somewhat unfruitful to attempt a precise placement of these two genes at the present time, particularly in view of the nice lot of Group V mutants that have come out of Stubbe's material--mutants that may be more suitable for the production of testcross progenies.
The F2 of a hl\ds (x 514 F2) gave the following:
+ + + a hl ds a hl + + + ds a + ds + hl + + hl ds a + +
_____ _______ ______ ______ ______ ______ _______ _____
221 3 63 57 10 26 7 36
a-hl = 20.6 hl-ds = 38.4 +- 4.1 a-ds = 40.5 +- 4.0
The F2 of a hl/gh (x 520 F2) gave the following:
+ + + a hl gh a hl + + + gh a + gh + hl + + hl gh a + +
----- ------- ------ ------ ------ ------ ------- -----
291 4 94 88 16 44 3 57
a-hl = 21.5 +- 1.9 hl-gh = 26.5 +- 3.8 a-gh = 40.0 +- 3.4