IV. 5. Coordinator's report: Chromosome 5.
Jens Jensen, Agricultural Research Department, Research Establishment Riso, DK-4000 Roskilde, Denmark.
The following additional information about chromosome 5 loci has been recorded.
Recombination percentages: The dominant gene Yr4 conferring+resistance against yellow rust, race 23, is linked with Ml-a with 30.1 + 3.1 percent recombination (Johnson et al. 1969). However, in a three-point test recombination percentages of 6.2 + 1.3 and 47.6 + 3.6 between Yr4 and, respectively, Ml-a and nec 1a were obtained, and the most likely order of the loci is Ml-a, Yr4, nec 1 (Jensen and Jorgensen 1977). Furthermore, Yr4 is reported to be linked with ms, whereas no linkage was found to trd, B, and at (Finch and Simpson 1975).
A spontaneous mutant gene, xan,,g (xantha), is linked with msg1 (previously ms2 with 2.0 + 1.0 percent recombination (Rahman and Eslick 1976). An erectoides mutant gene is reported to be linked with B with 28.61 + 5.06 percent recombination and with trd with 39.50 + 5.75 percent recombination (Tyagi and Das 1975). Different recombination percentages between B and trd in control and chemically treated F1's are reported by Dislers et al. (1975).
Gene Associations: An incompletely dominant gene, which confers narrow leaves and lethality in homozygous seedlings (Angustifolia), was associated with chromosome 5 in a trisomic analysis (Tsuchiya et al. 1976). A mutant gene, g (golden), similar in expression to or (orange seedling) was associated with the long arm of chromosome 5 by telotrisomic analysis (Tsuchiya 1976).
New alleles: The desynaptic locus des 6 isreported to have the alleles des 6m and des 6o in addition to des 6i previously reported (Scheuring et al. 1976).
Linkage map: A linkage map is prepared by the maximum likelihood map estimation procedure by adding the above recombination percentages involving locus Yr4 to those used to estimate the chromosome-5 map in the last coordinator's report (BGN 6:98-100, 1976). In the map estimation, Yr4 is assumed to be between nec 1 and Ml-a; therefore, the recombination percentage of 30.1 + 3.1 between Yr4 and Ml-a (Johnson et al. 1969) could not be utilized. The erectoides gene report by Tyagi and Das (1975) may be the same as or allelic to ert-b; it is not considered here. The recombination percentages between B and trd in untreated F1 controls reported by Dislers et al. (1975) did not fit into the map, and none of their data are used in the map estimation. The map, which now has 18 loci, is shown in figure 1. The symbols for the disease resistance loci proposed by Moseman (1975) and used in some stock descriptions (BGN Vol. 6, 1976) have not been adopted in the present map.
Multiple marker stocks: Several stocks with two to four chromosome-5 marker genes are available and may be obtained on request.
References:
Dislers, V., Nagle, E., Filipeka, V. and I. Rasals. 1975. Changes of recombination frequency between the linked loci trd and b in barley, caused by treatment with actinomycin D, mitomycin-C and 5-fluorouracil. Latvijas Psr Zinatnu Akademijas Vestis 7:(336): 49-52.
Finch, R. A. and E. Simpson. 1975. In: Annual Report 1974. Plant Breeding Institute Cambridge, p. 136.
Jensen, J. and J. H. Jorgensen. 1977. Location of the yellow rust resistance gene Yr4 on barley chromosome 5. Barley Genetics Newsletter 7:
Johnson, R., Wolfe, M. S., and P. R. Scott. 1969. In: Annual Report 1968. Plant Breeding Institute Cambridge, p. 122.
Moseman, J. G. 1975. Designation of genes in barley for reaction to Erysiphe graminis (DC) Merat hordei Em. Marchal. Barley Genetics Newsletter 5:87-88.
Rahman, M. M. and R. F. Eslick. 1976. Linkage of spontaneous mutant seedling lethal genes with genetic male sterile genes. Barley Genetics Newsletter 6:53-58.
Scheuring, J. F., Clarck, D. R., and R. T. Ramage. 1976. Coordinator's report: Desynaptic genes. Barley Genetics Newsletter'6:108-109.
Tsuchiya, T. 1976. Telotrisomic analysis of a multiple genetic marker stock (g - Ms - h/g - ms - h) in chromosome 5. Barley Genetics Newsletter 6:82.
Tsuchiya, T., Tanksley, S. D., and R. Ward. 1976. Trisomic analysis of three mutant genes in barley. Barley Genetics Newsletter 6:95.
Tyagi, D. V. S. and K. Das. 1975. Inheritance and linkage of four radiation induced mutants in barley. Indian J. Genet. and Plant Breeding 35:423-427.
