In 1960 we reported (TGC 10:38-39) a moderate linkage between pro and a with an estimated recombination rate of 32.5 cM. Subsequently we made extensive tests with hl. Two independent tests yielded values of 11.5 and 8.5 cM (not reported). Later Lachman reported (TGC 23:21-22) results of a test between + and our stock of pro-hl-a. His results essentially indicated independence between pro and the two chromosome 11 markers.
In the meanwhile we have had an opportunity to repeat the test, this time a backcross between
+ + +
pro-hl-a x _______ .
pro-hl-a
The results are summarized as follows. Since potato leaf (c) was also
present in the compound stock, its segregation is also reported.
+ + + + 26 pro + + + 2 + + + c 34 pro + + c 0 + + hl + 2 pro + hl + 0 + + hl c 1 pro + hl c 2 + a + + 9 pro a + + 0 + a + c 13 pro a + c 0 + a hl + 8 pro a hl + 10 + a hl c 8 pro a hl c 11Although the population was relatively small, the indices of linkage are highly significant in all combinations between pro, hl, and a, but all three show independence from c. The three-point data indicate a locus 17 cM distal to hl on the short arm. It is suspected that segregation of both c and pro may have caused confusion in Lachman's experiments. The primary phenotype of pro is weak, slender, elongate growth. A weighted mean of our data for the pro-hl interval provides a value of 11.5 cM, approximating a position of 36 on 11S.