V.1 Linkage information as of April, 1976.
T. Tsuchiya, Department of Agronomy, Colorado State University, Fort Collins, Colorado 80523, U.S.A.
A considerable amount of information has been accumulated on linkage of various genes in recent years. Many reports have appeared in Barley Genetics Newsletters (volumes 1 to 6 ). However the information has not been used in improving linkage maps very efficiently, because often key marker genes were not included in linkage analysis. Therefore location of genes is not easy and even located loci are still arbitrary. Arm location of many genes is not known. Since the arm location of many key marker genes has been established by telotrisomic analysis, it is desirable to determine arm location of new genes. Thus these genes are incorporated into multiple marker stocks for each arm of individual chromosomes for further use in critical analysis and development of more accurate linkage maps.
The arm designation and linkage map of chromosome 3 and 4 has been questioned by some workers based on the morphology of telotrisomic plants and information on the gene-chromosome association obtained by cytogenetic analysis (Lehmann et. al. 1976; Linde-Laursen, 1975, 1976 ; Singh, 1974; Singh and Tsuchiya, 1974; Tsuchiya, 1973). It should be made clear that the arm designation has been made using cytogenetic information obtained by the telotrisomic analysis and the existing linkage maps.
It seems to be reasonable to wait until definite cytogenetic data are obtained to finally assign specific arms of some chromosomes. The present author is still waiting to obtain telotrisomics for the other arm of both chromosome 3 and 4. Telotrisomic analysis with those stocks would provide genetic identification of those arms.
Recent development of the Giemsa C-banding technique seems to be useful in the identification of chromosomes and chromosome arms. However, there still are some differences in the results obtained by different workers (Linde-Laursen, 1975, 1976; Noda and Kasha, 1976).
Under these circumstances, it would be better to wait to change the chromosome and/or arm designation until more accurate and consistent information becomes available. Many genes will be listed as "associated" with their respective chromosomes (Table 1).
Table 1. List of genes associated with respective chromosome and chromosome
The linkage maps shown in Figure 1 are not different from the ones published in BGN Vol. 5 (p. 93) with addition of some genes. The map of chromosomes 4, 5, and 6 are mostly based on the coordinator's report prepared by T.E. Haus, J. Jensen and K. Kasha, respectively.
Figure 1. Linkage maps of barley, April 1976.
The gene zbc in chromosome 4 was tentatively eliminated from the linkage map, since the genetic stock for zbc is in question (Tsuchiya, 1974).
The map in the short arm of chromosome 5 has not been changed, since the confusion in identification and the linkage data on the mildew-resistant genes have not been straightened out yet.
The gene clh for curly leaf dwarf was associated with chromosome 5 (Ramage, 1962). Kasha (1975, 1976) mentioned that clh is located on chromosome 6. Since there is no reliable report to support Kasha's statement, clh was placed on chromosome 5 (Table 1).
References:
Eslick, R.F. 1976. Approximate position of the chlorina mutants f4f4 and f8f8 on chromosome 1. BGN 6:10-13.
Eslick, R.F. 1976. Male sterile genes on chromosome 1. BGN 6:14-20.
Eslick, R.F. and M.N. Ries. 1976. Positioning sexl on chromosome 6. BGN 6: 21-22.
Fedak, G. 1976. Coordinator's report: Chromosome 7. BGN 6:101.
Haus, T.E. 1976. Coordinator's report: Chromosome 4. BGN 6:97.
Jensen, J. 1976. Additional information on the position of the centromere on barley chromosome 5. BGN 6:37-38.
Jensen, J. 1976. Coordinator's report: Chromosome 5. BGN 6:98-100.
Kasha, K.J. 1976. Coordinator's report: Chromosome 6. BGN 6:100-101.
Kasha, K.J. 1975. Coordinator's report: Chromosome 6. BGN 5:75.
Künzel, G. and H. Nicoloff. 1975. Indication for a necessary revision of the barley karyogramme. BGN 5:23-26.
Lehmann, L., P. Hagberg and G. Hagberg. 1976. Translocation linkage studies and translocation breakpoints. BGN 6:37-38.
Linde-Laursen, Ib. 1975. Giemsa C-banding of chromosomes of 'Emir' barley Hereditas 81:285-289.
Linde-Laursen, Ib. 1976. Identification by Giemsa staining of the barley chromosomes and their arms. BGN 6:41-43.
Nielsen, G. and S. Hvid. 1976. Location of the esterase locus Est1 on barley chromosome 3. BGN 6:45-46.
Noda, K., and K.J. Kasha. 1976. Barley chromosome identification with the C-banding Giemsa stain technique. BGN 6:47-50.
Ramage, R.T. 1962. Genetic and cytogenetic studies of barley. Barley Newsletter 6: 67.
Scheuring, J.F., D.R. Clark, and R.T. Ramage 1976. Coordinator's report: Desynaptic genes. BGN 6:108-109.
Søgaard, B. 1976 Three-point tests on barley chromosome 3. BGN 6:65-67.
Takashashi, R., J. Hayashi and I. Moriya. 1976. Inheritance and linkage studies of the chlorotic hybrids due to complementary dominant genes. BGN 6:71-73.
Tsuchiya, T. 1973. New linkage maps of barley. BGN 3:99-103.
Tsuchiya, T. 1974 Linkage maps of barley as of March 1974. BGN 4:126-130.
Tsuchiya, T. 1975. Linkage maps of barley as of March 1975. BGN 5:92-94.
Tsuchiya, T. and J.V. Alanko. 1976. Genetic studies of two mutations by means of primary trisomic analysis. BGN 6:84-85.
Tsuchiya, T., T. Fachan and T.E. haus. 1976. Primary trisomic analysis of lg3 (light green) and f3 (chlorina) in barley. BGN 6:82-84.
Tsuchiya, T., S.D. Tanksley and R. Ward. 1976. Trisomic analysis of three mutant genes in barley. BGN 6:95.
