The most recent RFLP map for barley has been published (Kleinhofs et al., 1993). On that map, chromosome 7 contains 48 markers over a distance of 207 cM. It contains 2 gaps of approximately 30 cM and the tolomeric region for the long arm has been mapped. The reader is referred to the above publication for further map details and comparisons to other published maps.
There is a need to establish a standard set of RFLP markers for each barley chromosome and make these available to all barley research workers. Jahoor et al., (1991) have assembled a preliminary list using clones from 4 different cross combinations compiled by three research centres. A set of 18 such probes have been selected fcr chromosome 7 based on approximations of their relative progressive distance across the linkage map of that chromosome.
Comparative RFLP mapping is now in progress across numerous species for which RFLP maps have been constructed. A preliminary report in which a total of 98 barley Pst-l genomic plus cDNA clones and 26
By means of QTL analysis on a duubled haploid population derived from the F, hybrid between cultivars Blenheim and breeding line E 224/3, a region of barley chromosome 7 was shown to have a significant effect on plant height (Barua et al., 1993).
The loci cer-b and cer- x have previously been reported to be located on chromosome 7. However cer-b has proven to be allelic to gs2 on chromosome 3 and cer-x allelic to gs4 on chromosome 6, therefore both will be removed from the linkage map of chromosome 7 (Lundqvist, 1991; von Wettstein-Knowles, 1992).
Five barley cultivars were treated with doses of 10, 20 and 30 kR of Co60 (Gramatikova, 1991). The two lower doses were most effectitve in inducing chrommsome translocations and causing minimal sterility. Of the 106 translocations induced, 14 were shown by translocation testers to involve chromosome 7.
A semi dwarf mutant in Golden Promise was tested for allelism with ari-e reported to be on chromosome 7 and found to be allelic (Franckowiak, 1991).
An update of the known barley genes that were listed in Barley Genes and Chromosomes (Søgaard and von Wettstein-Knowles, 1987) has been published (von Wettstein-Knowles, 1993). In addition to a map of morphological markers the paper also includes RFLP and C banded maps for each chromosome, a complete gene listing for each chromosome plus the chloroplast genome. The reader is referred to this review for additional details.
References
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Franckowiak, J. D. 1991. Allelism tests among selected semidwarf barleys. BGN 21:17-23.
Gramatikova, M. 1991. Translocation lines of winter barley. BGN 21: 25-26.
Jahoor, A., A. Graner and G. Fischbeck. 1991. Proposal for a standard set of RFLP
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