Rick, C. M. and W. H. Dempsey.
During the past season we have completed more trisomic F2 tests in the attempt to place on their respective chromosomes genes that have not yet yielded to standard linkage tests. In the following table are listed those tests that indicated such association. Except for the tests of rv vs 5 and sd vs 7, the departures from normal segregation are statistically highly significant. It is gratifying to have one more chromosome, No. 5, identified with the marker gs, and possibly also with rv. The test with the latter gene definitely needs verification, especially in view of the deficiency of rv segregants that is regularly obtained in normal material.
A few explanatory notes for these data would be in order. The odorless (0d) line was derived from "Galapagos pimpinellifolium." Although dominant it seems to be more accurately scored as a recessive. Strong environmental effects render difficult the scoring of this condition so that more work needs to be done before we can be sure of the genetic determination. Nevertheless, the definitive trisomic segregation with chromosome 3, in contrast with nearly normal 3:1 ratios in other combinations suggests that inheritance likely is simple.
The chartreuse (ch) mutant is described in another note, in which the relationship with chromosome 8 is confirmed. Greenstripe (gs) may manifest itself phenotypically in a single dose under our conditions. In the segregation reported here the three classes could be clearly distinguished, although rather faintly expressed in certain plants. Classification gs/gs vs the other classes was not ambiguous.
Family Chromosome Gene 2N 2N+l Total
59L484 3 Od+ 78 5 83
Od 7 0 7
59L457 4 vg+ 66 26 92
478 vg 6 0 6
59L449 5 gs+ 33 19 52
gs+/gs 35 8 43
gs 11 0 11
59L4524 5 rv+ 43
453 Seedling rv 3
59L492 7 sd+ 45 14 59
sd 8 1 9
59L469 8 ch+ 82 26 108
ch 9 0 9