II.43. Linkage data for rb and mt3.
G. W. R. Walker, Department of Genetics, University of Alberta, Edmonton, Alberta, Canada.
The following data are from studies in 1963-64. The genes gp2 and li are on chromosome 2 and Tsuchiya (BGN 3:99) has suggested they may be quite close together. Ribbon grass (rb) has been shown to be independent of lg, e, v, pr, and tr; mt3 is independent of l8, e, v, pr, and tr; (ibid) these two genes have not to the author's knowledge, been assigned to chromosomes.
This could be caused by low viability of mt3 mt3 rb rb plants in the mt3 - rb crosses, but this explanation does not hold for the mt3 - gp2 cross.
The data suggest that rb may be on chromosome 2, close to gp2 but this should be checked further because of non-linkages with v and tr. The unusual behavior of mt3 might be explained by its presence on chromosome 2 at an excessive distance from gp2, since such situations can give recombination values greater than 50%. If it is on chromosome 2 it must be on the long arm since Tsuchiya's telotrisomic data exclude it from the short arm (Tsuchiya and Singh, BGN 3:75). The value for li-gp2 from total data (15.1+ 4.1) tends to confirm Tsuchiya's suspicion that previous values (22.7, 25.3; Robertson, 1971) are too high.
References:
Robertson, D. W. 1965. Crop Science 5:33.
Robertson, D. W. 1971. Barley Genetics II:221.
