V. 1. Linkage maps of barley, 1983. (1)
T. Tsuchiya, Department of Agronomy, Colorado State University, Fort Collins, Colorado 80523, U.S.A.
(1) Supported by USDA/SEA-CSU Cooperative Research Grant 58-9AHZ-2-265 and CSU Hatch project.
Linkage mapping in barley still has various problems. Some results are in conflict and others are fragmental. Because of the many uncertainties existing, the present author feels that an attempt for extremely accurate mapping of genes may not have merit, at least at present.
Fig. 1. Linkage maps of barley, 1983.
The following is the present situation in linkage studies in barley:
Chromosome 1:
Tazhin (1982) reported a linkage between a multiovary mutant (mo5)
found by Tazhin (1980) and n with a 3.8% crossover value.
Two esterase loci (Est 3 and Est 5) were associated with chromosome 1 by trisomic analysis (Nielsen, 1982).
The albino gene ac2 was tested using telotrisomics for both 1L and 1S. In this analysis with Triplo 1S, 48 of 228 F2 plants were albino and were diploid with 2n = 14 (Tsuchiya and Singh, 1973). Shahla and Tsuchiya (1983c) studied an additional 114 F2 plants from Triplo 1S X ac2 stock. All 35 telotrisomic plants for 1S were normal green and 10 homozygotes for ac2 were all 2n = 14. Shahla and Tsuchiya (1982) also studied genetic segregation of 116 F2 plants from a cross between Triplo 1L and ac2 stock. Two out of 39 homozygotes for ac2 were telotrisomic for 1L. These results suggest that the gene ac2 ls located in the short arm (1S) rather than 1L as suggested by Søgaard (1977).
In a previous report, Shahla (1980) reported that all three genes, br, fc and gs3, tested against telocentric chromosome 1S showed trisomic ratios in telotrisomic analysis. In that analysis, 252 F2 plants were studied. Shahla and Tsuchiya (1983c) obtained additional information on the F2 segregation in the telotrisomic analysis with triplo 1S x triple marker stock for br, fc and gs3. The total number of F2 plants from the above two experiments was 584. In the trisomic portion the numbers of recessive homozygotes were 2, 3 and 2 for br, fc and gs3, respectively. This result suggests that all three genes are far from the centromere. In the diploid portion of the F2 population, consisting of 375 plants, 50 plants were br homozygotes and 55 plants were fc and gs3 homozygotes. Based on this result, it is concluded that br is distal to fc and gs3 and the latter two genes are very closely linked to each other.
Chromosome 3.
Singh et al. (1982) reported that uz and ac
showed disomic ratios and al a trisomic ratio in telotrisomic analysis
using newly obtained telo-3S (Singh and Tsuchiya, 1982). This result is
in conflict with previously established linkage data. Telotrisomic analysis
of the gene ac is now underway with the telotrisomic for 3L (previously
3S; Singh and Tsuchiya, 1982).
This newly obtained telo 3S was genetically analyzed with two marker genes als and gs2 in 3L. Both genes showed disomic ratios in the F2 population from Triplo 3S x als gs2 double recessive stocks (Shahla and Tsuchiya, 1983a). This result confirms the identification of this arm as 3S.
Takahashi (1983) presented a latest linkage map of chromosome 3.
Chromosome 4.
A six-rowed gene, v5, was located in the long arm of chromosome
4 between f9 and K (Fukuyama, 1982).
Nielsen (1982) reported the association with chromosome 4 of Bam 1, a locus coding for beta-amylases in germinating seeds.
By Giemsa staining, all nine chromosome arms in nine telotrisomic lines were identified and designated by Singh and Tsuchiya (1982). Based on the above results, the arm designation was changed from the previous map of chromosome 4; f9 and K are now on the long arm (4L) and gl, br2 and others are on 4S (Tsuchiya, 1981; Singh and Tsuchiya, 1982).
Another important result of the Giemsa banding analysis with telotrisomics was the finding of a deficiency in the telocentric chromosome 4L in Triplo 4L (Singh and Tsuchiya, 1982). It is necessary, therefore, to re-examine some of the results of telotrisomic analysis by Tsuchiya and Singh (1982).
A recent linkage map of chromosome 4 is presented by Haus (1983).
Chromosome 5:
Netsvetaev and Sozinov (1982) reported that a dominant gene for glossy
spike (Gle 1) and some genes for hordein (Hrd A, Hrd B,
Hrd F) were located in chromosome 5.
Furst and Tsuchiya (1983), using primary trisomic analysis, reported that an incomplete dominant gene for zebra Colorado (zbc)was associated with chromosome 5.
The gene Pgd 2 for 6-phospho-gluconate-dehydrogenase was associated with the long arm of chromosome 5 (5L) by trisomic analysis (Nielsen, 1982).
A detailed linkage map of chromosome 5 is presented by Jensen (1983).
Chromosome 6:
The gene Fpd 1 for fructose-phosphate-dehydrogenese was associated
with chromosome 6 by analyzing wheat-barley addition lines (Nielsen, 1982).
Preliminary data from telotrisomic analysis of orange lemma (o) with Triplo 6S showed that o was located in 6S (Shahla et al. 1983). Based on this result the centromere position was tentatively placed between o and gs4 (Fig. 1).
Chromosome 7:
Hayashi et al. (1983) located the gene dsk for "dusky" mutant between
s and r in chromosome 7.
The gene for chlorina 6 (f6) was erroneously assigned to chromosome 6 (Tsuchiya, 1973). This error has been pointed out by Kasha (1977) and Kasha et al. (1978). Falk and Kasha (1983) have shown linkage between f6 and s in chromosome 7.
Telocentric chromosome for the short arm of chromosome 7 were obtained from two different sources (Shahla and Tsuchiya, 1982, 1983; Furst and Tsuchiya, 1983). Both Triplo 7S sources were obtained in F2 populations of the primary trisomic stock and back crossing is underway with SE 16 stock. Some plants were crossed with several key marker genetic stocks in chromosome 7 for locating the centromere position in the linkage map.
Figure 1 shows linkage maps of barley, 1983, which are not much different from the 1982 maps.
References:
Falk, D. E. and K. J. Kasha. 1983. Linkage of the f6 chlorina mutant on chromosome 7. BGN 13:50-51.
Fukuyama, T. 1982. Locating a six-rowed gene v5 on chromosome 4 in barley. BGN 12:29-31.
Furst, E. and T. Tsuchiya. 1983a. Primary trisomic analysis of three mutant genes in barley. BGN 13:44-46
Furst, E. and T. Tsuchiya. 1983b. New telosomic and acrosomic trisomics in barley. BGN 13:47-48.
Haus, T. E. 1983. Coordinator's report: Chromosome 4. BGN 13: 93-94.
Hayashi, J., I. Moriya and R. Takahashi. 1983. A further study on linkage of the "dusky" mutant, dsk. BGN 13:42-44.
Jensen, J. 1983. Coordinator's report: Chromosome 5. BGN 13: 94-97.
Kasha, K. J. 1977. Coordinator's report: Chromosome 6. BGN 7:89-90.
Kasha, K. J., D. E. Falk and A. Ho-Tsai. 1978. Linkage data with genes on chromosome 6. BGN 8:61-65.
Netsvetaev, V. P. and A. A. Sozinov. 1982. Linkage studies of genes Gle 1 and Hrd F in barley chromosome 5. BGN 12:13-18.
Nielsen, G. 1982. Supplementary and new evidence on the location of five enzyme loci on barley chromosomes. BGN 12:68-69.
Shahla. A. 1980. Physical localization of genes in the short arm of chromosome 1 (1S) in barley. Ph.D. Thesis, Colorado State University, Fort Collins, C0.
Shahla, A. and T. Tsuchiya. 1982a. Telotrisomic analysis of the gene ac2 (albino seedling) in Triplo 1L in barley. BGN 12:32-33.
Shahla, A. and T. Tsuchiya. 1982b. Telocentric chromosome for the short arm of chromosome 7 (telo 7S) in barley. BGN 12:33.
Shahla, A. and T. Tsuchiya. 1983a. Additional information on the Triplo 7S in barley. BGN 13:22-23.
Shahla, A. and T. Tsuchiya. 1983b. barley. BGN 13:25. Telotrisomic analysis in Triplo 3S in Shahla, A. and T. Tsuchiya. 1983c. Telotrisomic analysis of the gene ac2 (albino seedling) in Triplo 1S in barley. BGN 13:26-27.
Shahla, A. and T. Tsuchiya. 1983d. Additional information on telotrisomic analysis with triple marker stock (br, fc, gs3) on the short arm of chromosome 1. BGN 13:27-28.
Shahla, A., J. W. Shim and T. Tsuchiya. 1983. Association of the gene o for orange lemma with the short arm of chromosome 6 (6S) in barley. BGN 13:83-84.
Singh, R. J., A. Shahla and T. Tsuchiya. 1982. Telotrisomic analysis of three genes with newly obtained telotrisomic, Triplo 3S, in barley. BGN 12:42-44.
Singh, R. J. and T. Tsuchiya. 1982. Identification and designation of telocentric chromosomes in barley by means of Giemsa N-banding technique. TAG 64:13-24.
Søgaard, B. 1977. The location of eceriferum loci in barley. V. Three point tests of genes on chromosome 1 and 3 in barley. Carlsberg Res. Commun. 42:67-75.
Takahashi, R. 1983. Coordinator's report: Chromosome 3. BGN 13:89-93.
Tazhin, 0. T. 1980. The linkage of the gene mo5 and n in barley. BGN 10:69-72.
Tazhin, 0. T. 1982. Value of crossing-over between linked genes mo5 and n in barley. BGN 12:18-21.
Tsuchiya, T. 1973. New linkage maps of barley. BGN 3:99-103.
Tsuchiya, T. 1981. Revised linkage maps of barley, 1981. BGN 11:96-98.
Tsuchiya, T. and R. J. Singh. 1973. Further information on telotrisomic analysis in barley. BGN 3:75-78.
Tsuchiya, T. and R. J. Singh. 1982. Chromosome mapping in barley by means of telotrisomic analysis. TAG 61:201-208.
