II. 24. Linkage of the f6 chlorina mutant on chromosome 7.
K. C. Falk and K. J. Kasha, Crop Science Department, University of Guelph, Guelph, Ontario, Canada N1G 2W1. "R"
The f6 chlorina is a recessive mutant which was originally given the symbol yv and described as located near the centromere (probably in the long arm) of chromosome 7 on the basis of linkage with chromosome interchanges (Tuleen et al., 1968). It was later given the f6 symbol for a chlorina mutant by D. W. Robertson (Tuleen, personal communication) but unfortunately listed as being on chromosome 6 (BGN 3:101). This was later corrected by Kasha (BGN 7:89) as being on chromosome 7 and also independent of marker genes near the centromereof chromosome 6 (BGN 8:61-65). We have reciprocally crossed the f6 mutant as GBC 681 (Guelph Barley Accession number) with a line P-4 (GBC 670) of cv. Paavo. GBC 681 is recessive for o, n, f6 and r while GBC 670 is recessive for s and v. Thus, three point linkage between the three genes f6, r and s could be tested. Based on the F2 data in Table 1, s and r were linked by a recombination value of 32.9 + 3.3%. This is higher than most values summarized by Jensen (1981) which ranged from 16 to 34%. The recombination value between s and f6 (Table 1) is 36.2 + 3.2% whereas r and f6 are independent. The values presented in Table 1 are combined from 3 populations which were determined to be homogeneous by x2 tests.
Table 1. Combined F2 linkage date of f6 chlorina seedlings, s and r (cross: s x f6, r).
The gene order, based on these 3-point linkage tests, is f6 - s - r with f6 near the centromere and r being distal.
References:
Jensen, J. 1981. Construction of a barley chromosome 7 linkage map. Barley Genetics IV: 927-939.
Tuleen, N. A., L. A. Snyder, R. S. Caldecott and V. S. Hiatt. 1968. Genetics 59:45-55.
