Last year (MNL 56:43), we reported on an x-ray induced abnormality involving reduced crossing over between Y1 and Dt2 on chromosome 6. Our data showed that the Y Dt2 linkage is very tight (less than 1%) as compared to the normal 26%. The low crossover segment's transmission is normal through the female but is reduced to only 32% through the male; there is no male or female gamete abortion in plants heterozygous for the low crossover segment. The Y linked to Dt2 is not allelic to the Y1 from Aho and suggests that Y in the low crossover segment has moved to a new position.
This year we have data suggesting that the low crossover (lco) Y Dt2 segment has moved from chromosome 6. The cross of a1, lco Y Dt2 pl1/A1, y1 dt2 Pl1 x a1, y1 dt2 pl1 was made and the colored seeds with yellow endosperm were planted. The plants were scored for Pl1. There were 45 Pl1 and 49 pl1 plants, thus suggesting the lco Y Dt2 segment is not linked to pl1 on chromosome 6.
Rodney Higgins and M. G. Neuffer
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