II. 15 Translocation linkage studies of a tigrina mutant tig-o.
P. Hagberg and L. Lehman. Swedish Seed Association, S-268 00 Svalöv, Sweden. "R"
The tig-o34 mutant has been described by D. von Wettstein and K. Kristiansen (1973). This mutant is linked to a microgametic lethal (let) in repulsion (D. von Wettstein and K. Kristiansen 1973, and O. Nielsen, 1974). Data of the segregating ratios from D. von Wettstein are published by O. Nielsen (1974). The tig-o34 stock segregates approximately at a 1:1 ratio (tig:wild type) with an estimated map distance of 7.5 units between tig-o34 and let loci (O. Nielsen, 1974). When the tig-o34 stock is used as the male parent, nearly all viable pollen should carry the tig-o34 lethal gene. Interest in this stock was mainly to locate the microgametic lethal (let), using tig-o34 as an appropriate marker. The mutant stock was crossed onto a translocation tester set to determine on which chromosome the gene is located. The linkage analysis was based on F3 readings and computed according to the maximum likelihood method. Table 1 shows the results of these studies. The data indicate that tig-o34 is located near the centromere of chromosome 7 because the tig-o34 showed linkage to all chromosome 7 translocations, regardless if the breakpoints were in the short or long arm.
Table 1. F2 Linkage data based on F3 plant rows.
Studies are being continued in order to determine the linkage between tig-o34 and/or let (pollen lethal), and other marker genes.
Seed of tig-o34 was kindly provided by Diter von Wettstein.
References:
Nielsen, O. F. 1974. Macromolecular physiology of plastids. XII. Tigrina mutants in barley: genetic, spectroscopic and structural characterization. Hereditas 76:269-304.
Wettstein, D. von and K. Kristiansen. 1973. Stock list for nuclear gene mutants affecting the chloroplast. Barley Genet. Newsletter 3:113-117.
