IV.4. Coordinator's report: Chromosome 5.
Jens Jensen, Agricultural Research Dept., Danish Atomic Energy Commission Research Establishment Risø, DK-4000 Roskilde, Denmark.
Since the last report in this section of BGN the following information has been obtained:
1. Recombination percentages concerning the following chromosome 5 loci (independence not included): B, wst5, at, necl, ert-b, cer-e, Ml-nn (= JMl-nn), Ml-k (= JMl-k = JMl-nz see below), Ml-a (= JMl-sn), Pa-4 and ML-at (= JMl-rl2) (Jensen and Jorgensen 1972, 1973, 1974; Jorgensen and Moseman 1971; Søgaard 1973).
2. Associations: The loci des6 (desynaptic) (Hernandez-Soriano et al. 1973) and Gs (gametophyte) (Kawaguchi 1973) have been described as being on chromosome 5.
3. Removed: Locus cer-zg is not on chromosome 5 (Søgaard 1973) as indicated previously.
4. Alleles described cer-e161, -e577, -e790 -e1089 -e1106 (Lundqvist 1973), Ml-a8, -9, -10, -11 (Moseman and Jorgensen 1971).
5. Miscellaneous: An induced allele at the trd locus has been reported (Hauser and Fischbeck 1972). My own data indicate allelism between sp, ,b and nec1a, and I consider Ml-k (= JMl-k) and JMl-nz allelic from a mapping point of view. Allelism between st (striata) (Solari and Favret 1971) and wst5 has not been tested yet. By crossing with Telo 5L the loci f7, trd, at, sp, ,b, fs2, and rvl have been shown to be on the long chromosome arm (Fedak et al. 1972; Tsuchiya 1972a, 1972b; Tsuchiya and Singh 1973).
6. Linkage map: Based on the information referred to above and that presented by Jensen (1974) the present map of chromosome 5 is as follows:
The figures in brackets to the right give the distance between neighboring loci in recombination percentages. The figures to the left are the map positions of the loci according to Jensen (1973). The numerical value of the positions is the distance in centimorgans (cM) to the 0 position locus, nec1; in the direction of the long arm (always placed to the left or downwards) the positions are negative. The distance between any two loci (in centimorgans) is obtained by subtracting the left position from the right.
Table 1. Standard deviation of distances on the chromosome 5 linkage map (in centimoregans).
Standard deviations of all the distances are given in Table 1. The centromere may be placed in the region of disease resistance loci according to the map and the telotrisomic studies mentioned under point 5. The map is constructed using the procedure of Jensen (1974) which takes all the available linkage information into consideration. The map is the most likely yet, but the order of closely linked loci should be taken with reservation, as also indicated by the standard deviations. Further, the loci trd, eak, Ml-p, Ml-nn, and ml-d need further study to determine their right positions.
References:
1. Fedak, G., Tsuchiya, T., and Helgason, S. B. 1972. Use of monotelotrisomics for linkage mapping in barley. Can. J. Genet. Cytol. 14: 949-957.
2. Hauser, H., and Fischbeck, G. 1972. Translocation and genetic analysis of other mutants. BGN 2: 28-29.
3. Hernandez-Soriano, J. M., Ramage, R. T., and Eslick, R. F. 1972. In Description of Genetic Stacks. BGN 3: 129.
4. Jensen, J. 1973. Proposal for a new procedure for the preparation of gene maps in barley. BGN 3: 24-25.
5. Jensen, J. 1974. Genetic linkage map of barley chromosome 5. I. A procedure to estimate linkage maps applied to literature data. BGN 4:40-42.
6. Jensen, J., and Jorgensen, J. Helms. 1972. Gene mapping on chromosome 5. BGN 2: 29-31.
7. Jensen, J., and Jorgensen, J. Helms. 1973. Locating some genes on barley chromosome 5. BGN 3: 25-27.
8. Jensen, J., and Jorgensen, J. Helms. 1974. Genetic linkage map of barley chromosome 5. II. An experiment with nine widely spaced loci. BGN 4:42-43.
9. Jorgensen, J. Helms, and Moseman, J. G. 1971. Two new genes at the Ml-a locus in barley for resistance to Erysiphe graminis f.sp. hordei. Z. Pflanzenzucht. 66: 67-75.
10. Kawaguchi, K. 1973. Studies on artificial selection of gametaphyte (pollen) in relation to plant breeding in two-rowed barley. II. Selection of qualitative characters related to the 5th linkage group by high temperature treatment of F1 spikelets just before flowering. Jap. J. Breed. 23: 198-206.
11. Lundqvist, U. 1973. Stock list for the eceriferum mutants. II. BGN 3: 110-112.
12. Moseman, J. G. and Jorgensen, J. Helms. 1971. Identification of genes at the Ml-a locus in barley for resistance to Erysiphe graminis f.sp. hordei. Crop Sci. 11: 547-550.
13. Solari, R. M., and Favret, E. A. 1971. Polymorphism in endosperm proteins of barley and its genetic control. Barley Genetics II: 23-31.
14. Sogaard, A. B. 1973. Continued linkage studies on ecerferum mutants in barley. BGN 3: 57-61.
15. Tsuchiya, T. 1972a. Cytogenetics of telotrisomics in barley. BGN 2: 93-98
16. Tsuchiya, T. 1972b. Revision of linkage map of chromosome 5 in barley by means of telotrisomic analysis. J. Hered. 63: 373-375.
17. ----- and Singh, R. J. 1973. Further information on telotrisomic analysis in barley. BGN 3: 75-78.
